記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1007/s42729-023-01418-w

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その他リンク： https://link.springer.com/article/10.1007/s42729-023-01418-w/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Salicylic acid (SA) and proline exhibit protective effects against a wide range of stresses. However, the combined impact of SA and proline on rice under drought stress is still unknown. Therefore, we investigated the protective roles of SA and/or proline in conferring drought tolerance in rice. There were eight treatments comprising the control (T1; 95-100% FC), 1.5 mM SA (T2), 2 mM proline (T3), 0.75 mM SA + 1 mM proline (T4), 45-50% FC (T5, drought stress), T5 + 1.5 mM SA (T6), T5 + 2 mM proline (T7), and T5 + 0.75 mM SA + 1 mM proline (T8), and two rice varieties: BRRI dhan66 and BRRI dhan75. Drought stress significantly decreased the plant growth, biomass, yield attributes, photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), photosynthetic pigments (chlorophyll and carotenoids content), relative water content (RWC), membrane stability index (MSI), soluble sugar and starch content, and uptake of N, P and K+ in roots and shoots. Drought-induced oxidative stress in the form of increased hydrogen peroxide (H2O2) production and lipid peroxidation (MDA) was observed. The combined application of SA (0.75 mM) + proline (1 mM) was found to be more effective than the single application of either for drought stress mitigation in rice. A combined dose of SA + proline alleviated oxidative stress through boosting antioxidant enzymatic activity in contrast to their separate application. The application of SA + proline also enhanced proline, soluble sugar and starch content, which resulted in the amelioration of osmotic stress. Consequently, the combined application of SA and proline significantly increased the gas exchange characteristics, photosynthetic pigments, RWC, MSI, nutrient uptake, plant growth, biomass and yield of rice. Therefore, the combined application of SA and proline alleviated the detrimental impacts of drought stress more pronouncedly than their separate application did by increasing osmoprotectants, improving nutrient transport, up-regulating antioxidant enzyme activity and inhibiting oxidative stress.

DOI： 10.3390/antiox12071438

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Several phytoremediation strategies have been undertaken to alleviate cadmium (Cd)-mediated injury to crop yield resulting from agricultural land pollution. In the present study, the potentially beneficial effect of melatonin (Me) was appraised. Therefore, chickpea (Cicer arietinum L.) seeds were imbibed for 12 H in distilled water or Me (10 µM) solution. Then, the seeds germinated in the presence or the absence of 200 µM CdCl2 for 6 days. Seedlings obtained from Me-pretreated seeds exhibited enhanced growth traits, reflected by fresh biomass and length increase. This beneficial effect was associated with a decreased Cd accumulation in seedling tissues (by 46 and 89% in roots and shoots, respectively). Besides, Me efficiently protected the cell membrane integrity of Cd-subjected seedlings. This protective effect was manifested by the decreased lipoxygenase activity and the subsequently reduced accumulation of 4-hydroxy-2-nonenal. Melatonin counteracted the Cd-mediated stimulation of the pro-oxidant NADPH-oxidase (90 and 45% decrease compared to non-pretreated Cd-stressed roots and shoots, respectively) and NADH-oxidase activities (almost 40% decrease compared to non-pretreated roots and shoots), preventing, thus, hydrogen peroxide overaccumulation (50 and 35% lesser than non-pretreated roots and shoots, respectively). Furthermore, Me enhanced the cellular content of pyridine nicotinamide reduced forms [NAD(P)H] and their redox state. This effect was associated with the Me-mediated stimulation of the glucose-6-phosphate dehydrogenase (G6PDH) and malate dehydrogenase activities, concomitantly with the inhibition of NAD(P)H-consuming activities. These effects were accompanied by the up-regulation of G6PDH gene expression (45% increase in roots) and the down-regulation of the respiratory burst oxidase homolog protein F (RBOHF) gene expression (53% decrease in roots and shoots). Likewise, Me induced an increased activity and gene transcription of the Asada-Halliwell cycle, namely ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase, concomitantly with a reduction of the glutathione peroxidase activity. This modulating effect led to the restoration of the redox homeostasis of the ascorbate and the glutathione pools. Overall, current results attest that seed pretreatment with Me is effective in Cd stress relief and can be a beneficial crop-protective approach.

DOI： 10.1007/s11356-023-27562-5

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/agronomy13041068

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.stress.2023.100137

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Tomato is affected by various biotic and abiotic stresses, especially salinity, which drastically hinders the growth and yield of tomato. Calcium (Ca) is a vital macronutrient which plays physiological and biochemical roles in plants. Hence, we studied the protective roles of Ca against salinity stress in tomato. There were eight treatments comprising control (nutrient solution), 5 mM Ca, 10 mM Ca, 15 mM Ca, 12 dS m-1 NaCl, 12 dS m-1 NaCl + 5 mM Ca, 12 dS m-1 NaCl + 10 mM Ca and 12 dS m-1 NaCl + 15 mM Ca, and two tomato varieties: BARI tomato-2 and Binatomato-5. Salinity significantly decreased the plant-growth and yield attributes, relative water content (RWC), photosynthetic pigments (SPAD value) and the uptake of K, Ca and Mg in leaves and roots. Salinity-induced oxidative stress was present in the form of increased Na+ ion concentration, hydrogen peroxide (H2O2) content and lipid peroxidation (MDA). Ca application reduced oxidative stress through the boosting of antioxidant enzymatic activity. Exogenous Ca application enhanced proline and glycine betaine content and reduced Na+ uptake, which resulted in the inhibition of ionic toxicity and osmotic stress, respectively. Hence, Ca application significantly increased the growth and yield attributes, RWC, SPAD value, and uptake of K, Ca and Mg. Calcium application also had a significant effect on the fruit quality of tomato and the highest total soluble solid, total sugar, reducing sugar, β-carotene, vitamin C and juice pH were found for the combined application of NaCl and Ca. Therefore, application of Ca reversed the salt-induced changes through increasing osmoprotectants, activation of antioxidants enzymes, and by optimizing mineral nutrient status.

DOI： 10.3390/antiox12030558

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Since brown rice extract is a rich source of biologically active compounds, the present study is aimed to quantify the major compounds in brown rice and to compare their cytoprotective potential against oxidative stress. The content of the main hydrophobic compounds in brown rice followed the order of cycloartenyl ferulate (CAF) (89.00 ± 8.07 nmol/g) >> α-tocopherol (αT) (19.73 ± 2.28 nmol/g) > γ-tocotrienol (γT3) (18.24 ± 1.41 nmol/g) > α-tocotrienol (αT3) (16.02 ± 1.29 nmol/g) > γ-tocopherol (γT) (3.81 ± 0.40 nmol/g). However, the percent contribution of CAF to the radical scavenging activity of one gram of whole brown rice was similar to those of αT, αT3, and γT3 because of its weaker antioxidant activity. The CAF pretreatment displayed a significant cytoprotective effect on the hydrogen peroxide-induced cytotoxicity from 10 µM, which is lower than the minimal concentrations of αT and γT required for a significant protection. CAF also enhanced the nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation coincided with the enhancement of the heme oxygenase-1 (HO-1) mRNA level. An HO-1 inhibitor, tin protoporphyrin IX (SnPP), significantly impaired the cytoprotection of CAF. The cytoprotective potential of CAF is attributable to its cycloartenyl moiety besides the ferulyl moiety. These results suggested that CAF is the predominant cytoprotector in brown rice against hydrogen peroxide-induced cytotoxicity.

DOI： 10.3390/ijms24010822

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/agronomy13010025

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

Plants secrete malate from guard cells to apoplast under stress conditions and exogenous malate induces stomatal closure. Malate is considered an extracellular chemical signal of stomatal closure. However, the molecular mechanism of malate-induced stomatal closure is not fully elucidated. We investigated responses of stomatal aperture, ion channels, and cytosolic Ca2+ to malate. A treatment with malate induced stomatal closure in Arabidopsis thaliana wild-type plants, but not in the mutants deficient in the slow (S-type) anion channel gene SLOW ANION CHANNEL-ASSOCIATED 1 (SLAC1). The treatment with malate increased S-type anion currents in guard-cell protoplasts of wild-type plants but not in the slac1 mutant. In addition, extracellular rather than intracellular application of malate increased the S-type currents of constitutively active mutants of SLAC1, which have kinase-independent activities, in a heterologous expression system using Xenopus oocytes. The treatment with malate transiently increased cytosolic Ca2+ concentration in the wild-type Arabidopsis guard cells and the malate-induced stomatal closure was inhibited by the Ca2+ channel blocker and the Ca2+ chelator. These results indicate that extracellular malate directly activates SLAC1 and simultaneously stimulates Ca2+ signalling in guard cells, resulting in steady and solid activation of SLAC1 for stomatal closure.

DOI： 10.1111/nph.18400

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その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/nph.18400

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Benzyl isothiocyanate (BITC), derived from cruciferous vegetables, is an organosulfur compound exerting antiproliferative effects in several human cancer cells. In this study, we assessed BITC as a potential osteoclastogenesis inhibitor and investigated its underlying mechanism. BITC at 5 μM significantly decreased the viability of the osteoclast-like differentiating RAW264.7 cells, coinciding with the downregulation of the primary biomarkers for osteoclast differentiation, such as the tartrate-resistant acid phosphatase activity and nuclear factor of activated T-cells gene expression. Not only BITC but also its metabolites, inhibited cell proliferation in the normal RAW264.7 cells, suggesting that BITC shows an anti-osteoclastogenesis effect in vivo after its ingestion and metabolism, possibly through an antiproliferative action. Both BITC and its metabolites also enhanced the DNA fragmentation and the caspase-3 activity, whereas their higher concentrations tended to suppress these effects. BITC was intracellularly accumulated when the cells were treated with its metabolites via their degradation into the free form. A quantitative experiment using the proteolysis/high performance liquid chromatography technique showed that the amount of BITC-lysine thiourea in the cells was also increased in a time-dependent manner, suggesting that lysine modification of the cellular proteins actually took place in the cells treated by BITC. Among the cellular proteins, the cleaved caspase-3 was identified as a potential target for lysine modification by BITC. Taken together, BITC dissociated from its metabolites as well as its free form might modulate osteoclastogenesis, possibly through inhibition of cell proliferation by protein modification.

DOI： 10.1002/jbt.23184

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/agronomy12123027

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1007/s42729-022-01007-3

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その他リンク： https://link.springer.com/article/10.1007/s42729-022-01007-3/fulltext.html

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

ABSTRACT

Salicylic acid (SA) is a ubiquitous phenolic phytohormone that induces stomatal closure. Glutathione (GSH) negatively regulates stomatal closure induced by other plant hormones such as abscisic acid (ABA) and methyl jasmonate (MeJA). However, the involvement of GSH in SA-induced stomatal closure is still unknown. We investigated the regulation of SA signaling by GSH in guard cells using an Arabidopsis thaliana mutant, cad2-1, which is deficient in the first GSH biosynthesis enzyme, γ-glutamylcysteine synthetase. Application of SA decreased stomatal apertures with decreasing intracellular GSH level in guard cells. Decreasing GSH by the cad2-1 mutation and by a GSH-decreasing chemical, 1-chloro-2,4-dinitrobenzene, enhanced the SA-induced stomatal closure. Treatment with glutathione monoethyl ester restored the GSH level in the cad2-1 guard cells and complemented the stomatal phenotype of the mutant. These results indicate that GSH negatively modulates SA-induced stomatal closure in A. thaliana.

DOI： 10.1093/bbb/zbac116

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その他リンク： https://academic.oup.com/bbb/article-pdf/86/10/1378/45978264/zbac116.pdf

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

ABSTRACT

A primary metabolite malate is secreted from guard cells in response to the phytohormone abscisic acid (ABA) and elevated CO2. The secreted malate subsequently facilitates stomatal closure in plants. Here, we investigated the molecular mechanism of malate-induced stomatal closure using inhibitors and ABA signaling component mutants of Arabidopsis thaliana. Malate-induced stomatal closure was impaired by a protein kinase inhibitor, K252a, and also by the disruption of a receptor-like kinase GHR1, which mediates activation of calcium ion (Ca2+) channel by reactive oxygen species (ROS) in guard cells. Malate induced ROS production in guard cells while the malate-induced stomatal closure was impaired by a peroxidase inhibitor, salicylhydroxamic acid, but not by the disruption of Nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) oxidases, RBOHD and RBOHF. The malate-induced stomatal closure was impaired by Ca2+ channel blockers, verapamil, and niflumic acid. These results demonstrate that the malate signaling is mediated by GHR1 and ROS in Arabidopsis guard cells.

DOI： 10.1093/bbb/zbac122

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その他リンク： https://academic.oup.com/bbb/article-pdf/86/10/1362/45978292/zbac122.pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Stomatal movement is indispensable for plant growth and survival in response to environmental stimuli. Cytosolic Ca2+ elevation plays a crucial role in ABA-induced stomatal closure during drought stress; however, to what extent the Ca2+ movement across the plasma membrane from the apoplast to the cytosol contributes to this process still needs clarification. Here the authors identify (-)-catechin gallate (CG) and (-)-gallocatechin gallate (GCG), components of green tea, as inhibitors of voltage-dependent K+ channels which regulate K+ fluxes in Arabidopsis thaliana guard cells. In Arabidopsis guard cells CG/GCG prevent ABA-induced: i) membrane depolarization; ii) activation of Ca2+ permeable cation (ICa ) channels; and iii) cytosolic Ca2+ transients. In whole Arabidopsis plants co-treatment with CG/GCG and ABA suppressed ABA-induced stomatal closure and surface temperature increase. Similar to ABA, CG/GCG inhibited stomatal closure is elicited by the elicitor peptide, flg22 but has no impact on dark-induced stomatal closure or light- and fusicoccin-induced stomatal opening, suggesting that the inhibitory effect of CG/GCG is associated with Ca2+ -related signaling pathways. This study further supports the crucial role of ICa channels of the plasma membrane in ABA-induced stomatal closure. Moreover, CG and GCG represent a new tool for the study of abiotic or biotic stress-induced signal transduction pathways.

DOI： 10.1002/advs.202201403

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/seeds1020008

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Aldehyde dehydrogenases (ALDHs) are the major enzyme superfamily for the aldehyde metabolism. Since the ALDH polymorphism leads to the accumulation of acetaldehyde, we considered that the enhancement of the liver ALDH activity by certain food ingredients could help prevent alcohol-induced chronic diseases. Here, we evaluated the modulating effects of 3-hydroxyphenylacetic acid (OPAC), the major metabolite of quercetin glycosides, on the ALDH activity and acetaldehyde-induced cytotoxicity in the cultured cell models. OPAC significantly enhanced the total ALDH activity not only in mouse hepatoma Hepa1c1c7 cells, but also in human hepatoma HepG2 cells. OPAC significantly increased not only the nuclear level of aryl hydrocarbon receptor (AhR), but also the AhR-dependent reporter gene expression, though not the nuclear factor erythroid-2-related factor 2 (Nrf2)-dependent one. The pretreatment of OPAC at the concentration required for the ALDH upregulation completely inhibited the acetaldehyde-induced cytotoxicity. Silencing AhR impaired the resistant effect of OPAC against acetaldehyde. These results strongly suggested that OPAC protects the cells from the acetaldehyde-induced cytotoxicity, mainly through the AhR-dependent and Nrf2-independent enhancement of the total ALDH activity. Our findings suggest that OPAC has a protective potential in hepatocyte models and could offer a new preventive possibility of quercetin glycosides for targeting alcohol-induced chronic diseases.

DOI： 10.3390/ijms23031762

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Responses of plant cells to reactive oxygen species (ROS), e.g., reprogramming of defense genes or progression of cell death, should include the ROS signal transmission to target proteins, but the biochemistry of this process is largely unknown. Lipid peroxide-derived α,β-unsaturated aldehydes and ketones (reactive carbonyl species; RCS), downstream products of ROS stimuli, are recently emerging endogenous agents that can mediate ROS signal to proteins via covalent modification. The involvement of RCS in certain ROS signaling in plants (oxidative injury of leaves and roots, ROS-induced programmed cell death, senescence, and abscisic acid and auxin signaling) has been verified by the determination of RCS with the use of conventional HPLC. Because distinct kinds of RCS act differently in the cell and so are metabolized, identification and quantification of each RCS in plant tissues provide central information to decipher biochemical mechanisms of plant responses to ROS. This article illustrates practical methods of plant sample preparation and extraction and analysis of RCS.

DOI： 10.1007/978-1-0716-2469-2_15

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Nitric oxide (NO) has received much attention since it can boost plant defense mechanisms, and plenty of studies have shown that exogenous NO improves salinity tolerance in plants. However, because of the wide range of experimental settings, it is difficult to assess the administration of optimal dosages, frequency, timing, and method of application and the overall favorable effects of NO on growth and yield improvements. Therefore, we conducted a meta-analysis to reveal the exact physiological and biochemical mechanisms and to understand the influence of plant-related or method-related factors on NO-mediated salt tolerance. Exogenous application of NO significantly influenced biomass accumulation, growth, and yield irrespective of salinity stress. According to this analysis, seed priming and foliar pre-treatment were the most effective methods of NO application to plants. Moreover, one-time and regular intervals of NO treatment were more beneficial for plant growth. The optimum concentration of NO ranges from 0.1 to 0.2 mM, and it alleviates salinity stress up to 150 mM NaCl. Furthermore, the beneficial effect of NO treatment was more pronounced as salinity stress was prolonged (>21 days). This meta-analysis showed that NO supplementation was significantly applicable at germination and seedling stages. Interestingly, exogenous NO treatment boosted plant growth most efficiently in dicots. This meta-analysis showed that exogenous NO alleviates salt-induced oxidative damage and improves plant growth and yield potential by regulating osmotic balance, mineral homeostasis, photosynthetic machinery, the metabolism of reactive oxygen species, and the antioxidant defense mechanism. Our analysis pointed out several research gaps, such as lipid metabolism regulation, reproductive stage performance, C4 plant responses, field-level yield impact, and economic profitability of farmers in response to exogenous NO, which need to be evaluated in the subsequent investigation.

DOI： 10.3389/fpls.2022.957735

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Informa UK Limited  

3,4-Dihydroxyphenylacetic acid (DOPAC) and 3-hydroxyphenylacetic acid (OPAC) are the predominant catabolites of quercetin glycosides, such as quercetin 4'-O-β-glucoside from the onion, produced by intestinal microbiota. Although each catabolite has been reported to protect the cells from acetaldehyde-induced cytotoxicity, the effect of their combination remains to be clarified. The purpose of this study was to determine whether the combination of DOPAC and OPAC enhances the resistance against the acetaldehyde-induced oxidative stress in the cultured hepatocytes. The pretreatment of the combination of DOPAC (5 μM) and OPAC (5 μM) showed significant protection against the acetaldehyde- and hydrogen peroxide-induced cytotoxicity, even though each compound at the same concentration did not. This combination also significantly inhibited the intracellular dichlorofluorescin diacetate-detectable reactive oxygen species (ROS) level, whereas the solo treatment did slightly, suggesting that reducing mechanisms of ROS or compounds that enhance ROS production are involved in the cytoprotective effect. The combinatory treatment significantly enhanced the gene expression of not only the aldehyde dehydrogenases (ALDHs), but also glutamate-cysteine ligase, catalytic subunit, the first rate-limiting enzyme of glutathione (GSH) synthesis. Accordingly, both the intracellular GSH level and the total ALDH activity were enhanced by DOPAC plus OPAC. Involvement of GSH in the cytoprotection as well as ALDH up-regulation by the combination was confirmed by the experiments using a GSH biosynthesis inhibitor, buthionine sulfoximine. Taken together, the present results suggested that the quercetin microbiota catabolites concertedly protect the cells from acetaldehyde through a pre-enhanced resistance against oxidative stress by the GSH-dependent up-regulation of ALDHs.

DOI： 10.1080/10715762.2022.2159820

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Experimental Biology and Agricultural Sciences  

Low and uneven germination is a serious problem for the successful production of okra seedlings. Priming of seeds as well as supplementation of different plant growth regulators exhibited better response in successful seedling production which eventually results in higher yield. Therefore, the present study was conducted to evaluate the effects of seed priming and exogenous application of salicylic acid (SA) on okra seed germination and plant development. The okra seeds were primed by 1 mM and 2 mM of SA for 60 minutes whereas the seeds were washed several times with distilled water for the control treatment. Similar doses of SA have been exogenously sprayed to the 12 days okra seedlings for 4 days. The results of the study revealed that seed priming with SA enhanced germination percentage (GP), increased coleoptile length and weight, shoot and root length, and seed vigor index (SVI). Similarly, exogenous application of 1 mM SA increased relative water content (RWC), contents of chlorophyll a, chlorophyll b, total chlorophyll while a higher dose of SA (2 mM) degraded the leaf pigments. Supplementation of SA altered photosynthetic attributes, net photosynthetic (Pn) and transpiration rate (Tr), stomatal conductance (Gs), and water use efficiency (WUE). Moreover, SA treatment reduced the time duration of flower bud initiation and days to first flowering and enhanced the yield per plant. The results of this study indicated that seed priming and exogenous application of SA enhanced germination and okra productivity by regulating RWC and photosynthetic attributes where 1 mM SA is more effective compared to 2 mM SA.

DOI： 10.18006/2021.9(6).759.769

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER INT PUBL AG  

The objective of the present study was to elucidate the mechanism by which oxalic acid (OA) alleviates cadmium (Cd) stress. Chickpea (Cicer arietinum L.) seeds were treated with 200 mu M CdCl2 for 6 days or 3 days followed by the combination 200 mu M Cd + 100 mu M OA for three additional days. Exogenous OA mitigated the growth inhibition by Cd of both roots and shoots. This positive effect can be attributed to the increased OA exudation from roots and the alleviation of the Cd-induced depletion of endogenous OA in shoots (80% increase versus Cd-stressed). The combination Cd + OA proved to be effective in protecting cell membrane integrity. This beneficial effect was reflected by 36 and 24% decrease in lipoxygenase (LOX) activity in roots and shoots, respectively, and 60% decrease in the accumulation of the harmful aldehyde, 4-hydroxy-2-nonenal (4-HNE) in roots when compared to Cd-treated samples. Besides, OA restored the Cd-imposed disruption of the plasma membrane function. This effect was depicted by an optimal H+-ATPase activity and proton exudation rate. Oxalic acid counteracted the Cd-induced overproduction of hydroxyl radical (OH center dot) and NADPH-oxidase activity increase, leading to restore a steady cellular redox state. Furthermore, OA modulated the impact of Cd on Cu/Zn-superoxide dismutase (Cu/Zn-SOD), ascorbate peroxidase (APX), and catalase (CAT) activities in chickpea seedlings. Present results indicate that OA is able to alleviate Cd toxicity by protecting plasma membrane integrity and modulating antioxidant activities. Moreover, our findings shed light on the interplay between plasma membrane H+-ATPase and the accumulation and root exudation of OA.

DOI： 10.1007/s42729-021-00675-x

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

<title>ABSTRACT</title>
Arsenic is toxic for plants. Our previous results showed that the application of proline enhanced the sensitivity of tobacco BY-2 cells to arsenate. In order to clarify the enhancement mechanism, we investigated the effects of other amino acids on the arsenate-stressed BY-2 cells. Glutamate at up to 10 m m did not affect the cell growth in the absence or presence of arsenate. Arginine at up to 10 m m did not affect the growth in the absence of arsenate but arginine at 10 m m enhanced the inhibition of the cell growth by arsenate. Alanine at up to 10 m m did not affect the cell growth under nonstressed condition but alanine at 10 m m significantly improved the cell growth under arsenate stress. These results suggest that alanine mitigates arsenate stress in BY-2 cells and that arginine like proline enhances the sensitivity of BY-2 cells to arsenate.

DOI： 10.1093/bbb/zbab191

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

It is known that rice roots take up cadmium (Cd) via the symplastic route mediated by membrane-bound mineral transporters. Here we provide evidence that apoplastic bypass flow is another Cd uptake route in rice. High concentrations of Cd rendered apoplastic bypass flow rate increased in rice seedlings. These concentrations of Cd compromised membrane integrity in the root meristem and transition zone. Polyethleneglycol and proline inhibited the Cd-induced apoplastic bypass flow and Cd transfer to the shoots. Loss-of-function mutant of the Cd uptake transporter, nramp5, showed Cd transport to the shoot comparable to the wild type. At a low Cd concentration, increased apoplastic bypass flow rate by NaCl stress resulted in an elevation of Cd transport to shoots both in the wildtype and nramp5. These observations indicate that apoplastic bypass flow in roots carries Cd transport leading to xylem loading of Cd in addition to the symplastic pathway mediated by mineral transporters under stressed conditions.

DOI： 10.1007/s10265-021-01319-y

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Cytosolic calcium ([Ca2+]cyt) elevation activates plasma membrane anion channels in guard cells, which is required for stomatal closure. However, involvement of the anion channels in the [Ca2+]cyt elevation remains unclear. We investigated the involvement using Arabidopsis thaliana anion channel mutants, slac1-4 slah3-3 and slac1-4 almt12-1. Extracellular calcium induced stomatal closure in the wild-type plants but not in the anion channel mutant plants whereas extracellular calcium induced [Ca2+]cyt elevation both in the wild-type guard cells and in the mutant guard cells. The peak height and the number of the [Ca2+]cyt spike were lower and larger in the slac1-4 slah3-3 than in the wild type and the height and the number in the slac1-4 almt12-1 were much lower and much larger than in the wild type. These results suggest that the anion channels are involved in the regulation of [Ca2+]cyt elevation in guard cells.

DOI： 10.1093/bbb/zbab118

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

KEY MESSAGE: 5-aminolevulinic acid (ALA) modulates various defense systems in plants and confers abiotic stress tolerance. Enhancement of crop production is a challenge due to numerous abiotic stresses such as, salinity, drought, temperature, heavy metals, and UV. Plants often face one or more abiotic stresses in their life cycle because of the challenging growing environment which results in reduction of growth and yield. Diverse studies have been conducted to discern suitable mitigation strategies to enhance crop production by minimizing abiotic stress. Exogenous application of different plant growth regulators is a well-renowned approach to ameliorate adverse effects of abiotic stresses on crop plants. Among the numerous plant growth regulators, 5-aminolevulinic acid (ALA) is a novel plant growth regulator, also well-known to alleviate the injurious effects of abiotic stresses in plants. ALA enhances abiotic stress tolerance as well as growth and yield by regulating photosynthetic and antioxidant machineries and nutrient uptake in plants. However, the regulatory roles of ALA in plants under different stresses have not been studied and assembled systematically. Also, ALA-mediated abiotic stress tolerance mechanisms have not been fully elucidated yet. Therefore, this review discusses the role of ALA in crop growth enhancement as well as its ameliorative role in abiotic stress mitigation and also discusses the ALA-mediated abiotic stress tolerance mechanisms and its limitation and future promises for sustainable crop production.

DOI： 10.1007/s00299-021-02690-9

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The purpose of this study is to compare the potentials to exhibit biologically-active antioxidant actions between white rice (WR) and brown rice (BR) in in vitro assays and a cellular model. The Trolox equivalent (TE) per 1 mg ethanol extract of WR for the 1,1-diphenyl-2-picrylhydrazyl assay was slightly higher than that of BR, whereas the TE per 1 g whole WR was much lower than that for BR. This tendency was very comparable to those for the oxygen radical absorbance capacity and total polyphenol content. Both of the ethanol extracts also similarly suppressed the hydrogen peroxide-induced cytotoxicity and enhanced the gene expression of drug-metabolizing enzymes. Based on the αT quantity, its contribution to the cytoprotective effect of the rice extracts is very limited. Taken together, the ethanol extract of WR might be a qualitatively, but not quantitatively, equivalent source of antioxidative phytochemicals to that of BR.

DOI： 10.1093/bbb/zbab133

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Several recent studies have shown that citric acid/citrate (CA) can confer abiotic stress tolerance to plants. Exogenous CA application leads to improved growth and yield in crop plants under various abiotic stress conditions. Improved physiological outcomes are associated with higher photosynthetic rates, reduced reactive oxygen species, and better osmoregulation. Application of CA also induces antioxidant defense systems, promotes increased chlorophyll content, and affects secondary metabolism to limit plant growth restrictions under stress. In particular, CA has a major impact on relieving heavy metal stress by promoting precipitation, chelation, and sequestration of metal ions. This review summarizes the mechanisms that mediate CA-regulated changes in plants, primarily CA's involvement in the control of physiological and molecular processes in plants under abiotic stress conditions. We also review genetic engineering strategies for CA-mediated abiotic stress tolerance. Finally, we propose a model to explain how CA's position in complex metabolic networks involving the biosynthesis of phytohormones, amino acids, signaling molecules, and other secondary metabolites could explain some of its abiotic stress-ameliorating properties. This review summarizes our current understanding of CA-mediated abiotic stress tolerance and highlights areas where additional research is needed.

DOI： 10.3390/ijms22137235

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Horizon E-Publishing Group  

Crop production is unexpectedly hampered by different abiotic stresses. Salinity is one of the leading stresses, which snappishly hampers plant developmental progression. Local rice landraces exhibit noticeable salt tolerance as well as high yield. However, research is scarce about the physio-biochemical responses of local landraces and modern cultivar under saline conditions. Therefore, the present experiment was designed to reveal the physio-biochemical responses of local landraces and modern cultivar under salinity stress. Five landraces (Jotai, Icheburogolghor, Morishal, Chapail, Kumro buro) and two modern cultivars (BR23 and BRRI dhan41) were subjected to 0, 20, 40, 60 and 80 mM NaCl treatment. The effects of salt stress on morphological parameters, proline contents, and activities of antioxidant enzymes were assessed. Salt stress reduces the morphological parameters of all tested cultivars. The Morishal and BRRI dhan41 exhibited higher growth of plant and physiological parameters than other cultivars under the highest salinity. The catalase (CAT) and ascorbate peroxidase (APX), exhibited a significant increase whereas peroxidase (POX) activity significantly declined in all the cultivars under salinity stress. Morishal and BRRI dhan41 showed the highest proline content under the maximum saline condition. These results suggest that the high tolerant landrace and modern cultivars were Morishal and BRRI dhan41 respectively. These results also suggest that Morishal and BRRI dhan41 exhibited high tolerance to salinity by enhancing proline content and antioxidant enzyme activities.

DOI： 10.14719/pst.2021.8.3.1098

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その他リンク： https://horizonepublishing.com/journals/index.php/PST/article/download/1098/667

記述言語：英語   掲載種別：研究論文（学術雑誌）  

In the aim to estimate the protective role of calcium (Ca) and ethylene glycol tetraacetic acid (EGTA) against cadmium (Cd)-induced damage, chickpea (Cicer arietinum L.) seeds were exposed to 200 μM Cd stress for 6 days or 3 days then subjected to co-treatment of the metal with either 100 mM CaCl2 or 100 μM EGTA for 3 additional days. The addition of Ca and EGTA improved seedling growth. This protecting effect was correlated to the alleviation of the metal-induced oxidative stress, exemplified by the reduction of hydrogen peroxide (H2O2) contents. Besides, Ca and EGTA stimulated thioredoxin (Trx) and thioredoxin reductase (NTR) activities (2.75- and 1.75-fold increase when compared to Cd-stressed, respectively) protecting, thereby, protein -SH groups from the Cd-mediated oxidation, and modulated ferredoxin (Fdx) activity to a control level. Moreover, Ca and EGTA reinstated the glutathione redox steady state, mainly via preserving a high level of glutathione reduced form (GSH). This effect coincided with the maintaining of the Cd-stimulated glutathione reductase (GR) activity and the decline of glutathione peroxidase (GPX, 43% lower than Cd-stressed shoots) activity. Ca and EGTA counteracted the inhibitory effect of Cd on the activity and gene expression of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) isoenzyme and modulated the activities of catalase (CAT) and ascorbate peroxidase (APX). Overall, our results provided evidence that Ca and EGTA supplement could be a promising approach in the remediation of Cd-contaminated environment.

DOI： 10.1007/s00709-020-01605-x

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The increasing drug efflux through the ATP-binding cassette (ABC) transporters is the most plausible mechanism that mediates resistance to the anticancer phytochemicals, such as benzyl isothiocyanate (BITC), as well as chemotherapy drugs. To identify a potential component to overcome this resistance by combinatory utilization, we focused on multidrug resistance-associated proteins (MRPs) pumping various drug metabolites with glutathione as well as the organic anions. The pharmacological treatment of an MRP inhibitor, MK571, significantly potentiated the BITC-induced antiproliferation, coincided with the enhanced accumulation of BITC and glutathione in human colorectal cancer HCT-116 cells. MK571 also enhanced the apoptosis induction as well as activation of the mitogen-activated protein kinases and caspase-3, whereas it did not affect their basal levels. These results suggested that, since MRPs might play a pivotal role in the BITC efflux, MK571 potentiates the BITC-induced antiproliferation in human colorectal cancer cells through inhibition of the glutathione-dependent BITC efflux.

DOI： 10.1002/jbt.22791

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s00344-021-10334-1

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その他リンク： http://link.springer.com/article/10.1007/s00344-021-10334-1/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

Abstract

Copper (Cu) pollution of agricultural land is a major threat to crop production. Exogenous chemical treatment is an easily accessible and rapid approach to remediate metal toxicity, including Cu toxicity in plants.

We compared the effects of ascobin (ASC; ascorbic acid:citric acid at 2:1) and glutathione (GSH) in mitigation of Cu toxicity in rice.

Plants subjected to Cu stress displayed growth inhibition and biomass reduction, which were connected to reduced levels of chlorophylls, RWC, total phenolic compounds, carotenoids and Mg²⁺. Increased accumulation of ROS and malondialdehyde indicated oxidative stress in Cu‐stressed plants. However, application of ASC or GSH minimized the inhibitory effects of Cu stress on rice plants by restricting Cu²⁺ uptake and improving mineral balance, chlorophyll content and RWC. Both ASC and GSH pretreatments reduced levels of ROS and malondialdehyde and improved activities of antioxidant enzymes, suggesting their roles in alleviating oxidative damage. A comparison on the effects of ASC and GSH under Cu stress revealed that ASC was more effective in restricting Cu²⁺ accumulation (69.5% by ASC and 57.1% by GSH), Ca²⁺ and Mg²⁺ homeostasis, protection of photosynthetic pigments and activation of antioxidant defence mechanisms [catalase (110.4%), ascorbate peroxidase (76.5%) and guaiacol peroxidase (39.0%) by ASC, and catalase (58.9%) and ascorbate peroxidase (59.9%) by GSH] in rice than GSH, eventually resulting in better protection of ASC‐pretreated plants against Cu stress.

In conclusion, although ASC and GSH differed in induction of stress protective mechanisms, both were effective in improving rice performance in response to Cu phytotoxicity.

DOI： 10.1111/plb.13222

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その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/plb.13222

掲載種別：研究論文（学術雑誌）   出版者・発行元：ScopeMed  

DOI： 10.5455/faa.128175

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Graduate School of Environmental Science, Okayama University  

DOI： 10.3107/jesss.10.mr02

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Graduate School of Environmental Science, Okayama University  

DOI： 10.3107/jesss.10.mr03

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Allyl isothiocyanate (AITC) induces stomatal closure accompanied by reactive oxygen species (ROS) production and glutathione (GSH) depletion in Arabidopsis thaliana. In this study, stomatal responses to three other isothiocyanates (ITCs), benzyl isothiocyanate (BITC), sulforaphane (SFN), and phenethyl isothiocyanate (PEITC), were investigated in A. thaliana. All these ITCs significantly induced stomatal closure, where PEITC and BITC were most effective. The selected ITCs also induced ROS accumulation, cytosolic alkalization, and GSH depletion in guard cells. Moreover, all ITCs increased the frequency of cytosolic free calcium ([Ca2+]cyt) spikes (transient elevation), while PEITC and BITC showed the highest frequency. There was a strong positive correlation between the number of [Ca2+]cyt spikes per guard cell and the decrease in stomatal aperture. Both cytosolic alkalization and GSH content have a positive correlation with the decrease in stomatal aperture, but ROS production did not have a significant correlation with the decrease in stomatal apertures. These results indicate that the molecules with a functional ITC group induce stomatal closure that is accompanied by GSH depletion, cytosolic alkalization, [Ca2+]cyt spikes, and ROS production, and that the former three cellular events, rather than ROS production, are highly correlated with the decrease in stomatal aperture.

DOI： 10.1093/jxb/eraa420

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Plants are often exposed to abiotic stresses such as drought, salinity, heat, cold, and heavy metals that induce complex responses, which result in reduced growth as well as crop yield. Phytohormones are well known for their regulatory role in plant growth and development, and they serve as important chemical messengers, allowing plants to function during exposure to various stresses. Seed priming is a physiological technique involving seed hydration and drying to improve metabolic processes prior to germination, thereby increasing the percentage and rate of germination and improving seedling growth and crop yield under normal and various biotic and abiotic stresses. Seed priming allows plants to obtain an enhanced capacity for rapidly and effectively combating different stresses. Thus, seed priming with phytohormones has emerged as an important tool for mitigating the effects of abiotic stress. Therefore, this review discusses the potential role of priming with phytohormones to mitigate the harmful effects of abiotic stresses, possible mechanisms for how mitigation is accomplished, and roles of priming on the enhancement of crop production.

DOI： 10.3390/plants10010037

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掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/plants10010037

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Selenium (Se) causes oxidative damage to plants. Proline is accumulated as a compatible solute in plants under stress conditions and mitigates stresses. Selenate at 250 µM increased cell death and inhibited the growth of tobacco BY-2 cells while exogenous proline at 10 mM did not mitigate the inhibition by selenate. Selenate increased accumulation of Se and ROS and activities of antioxidant enzymes but not lipid peroxidation in the BY-2 cells. Proline increased Se accumulation and antioxidant enzyme activities but not either ROS accumulation or lipid peroxidation in the selenate-stressed cells. Glutathione (GSH) rather than ascorbic acid (AsA) mitigated the growth inhibition although both reduced the accumulation of ROS induced by selenate. These results indicate that proline increases both antioxidant enzyme activities and Se accumulation, which overall fails to ameliorate the growth inhibition by selenate and that the growth inhibition is not accounted for only by ROS accumulation. Abbreviations: APX: ascorbate peroxidase; AsA: ascorbic acid; BY-2: Bright Yellow-2; CAT: catalase; DAI: days after inoculation; DW: dry weight; FW: fresh weight; GSH: glutathione; ROS: reactive oxygen species.

DOI： 10.1080/09168451.2020.1799747

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Production of reactive oxygen species (ROS) is a key signal event for methyl jasmonate (MeJA)- and abscisic acid (ABA)-induced stomatal closure. We recently showed that reactive carbonyl species (RCS) stimulates stomatal closure as an intermediate downstream of hydrogen peroxide (H2O2) production in the ABA signaling pathway in guard cells of Nicotiana tabacum and Arabidopsis thaliana. In this study, we examined whether RCS functions as an intermediate downstream of H2O2 production in MeJA signaling in guard cells using transgenic tobacco plants overexpressing A. thaliana 2-alkenal reductase (n-alkanal + NAD(P)+ ⇌ 2-alkenal + NAD(P)H + H+) (AER-OE tobacco) and Arabidopsis plants. The stomatal closure induced by MeJA was impaired in the AER-OE tobacco and was inhibited by RCS scavengers, carnosine and pyridoxamine, in the wild-type (WT) tobacco plants and Arabidopsis plants. Application of MeJA significantly induced the accumulation of RCS, including acrolein and 4-hydroxy-(E)-2-nonenal, in the WT tobacco but not in the AER-OE plants. Application of MeJA induced H2O2 production in the WT tobacco and the AER-OE plants and the H2O2 production was not inhibited by the RCS scavengers. These results suggest that RCS functions as an intermediate downstream of ROS production in MeJA signaling and in ABA signaling in guard cells.

DOI： 10.1093/pcp/pcaa107

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Many pathogenic fungi exploit stomata as invasion routes, causing destructive diseases of major cereal crops. Intensive interaction is expected to occur between guard cells and fungi. In the present study, we took advantage of well-conserved molecules derived from the fungal cell wall, chitin oligosaccharide (CTOS), and chitosan oligosaccharide (CSOS) to study how guard cells respond to fungal invasion. In Arabidopsis, CTOS induced stomatal closure through a signaling mediated by its receptor CERK1, Ca2+, and a major S-type anion channel, SLAC1. CSOS, which is converted from CTOS by chitin deacetylases from invading fungi, did not induce stomatal closure, suggesting that this conversion is a fungal strategy to evade stomatal closure. At higher concentrations, CSOS but not CTOS induced guard cell death in a manner dependent on Ca2+ but not CERK1. These results suggest that stomatal immunity against fungal invasion comprises not only CTOS-induced stomatal closure but also CSOS-induced guard cell death.

DOI： 10.1073/pnas.1922319117

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Being a chilling-sensitive staple crop, rice (Oryza sativa L.) is vulnerable to climate change. The competence of rice to withstand chilling stress should, therefore, be enhanced through technological tools. The present study employed chemical intervention like application of sodium nitroprusside (SNP) as nitric oxide (NO) donor and elucidated the underlying morpho-physiological and biochemical mechanisms of NO-mediated chilling tolerance in rice plants. At germination stage, germination indicators were interrupted by chilling stress (5.0 ± 1.0 °C for 8 h day-1), while pretreatment with 100 μM SNP markedly improved all the indicators. At seedling stage (14-day-old), chilling stress caused stunted growth with visible toxicity along with alteration of biochemical markers, for example, increase in oxidative stress markers (superoxide, hydrogen peroxide, and malondialdehyde) and osmolytes (total soluble sugar; proline and soluble protein content, SPC), and decrease in chlorophyll (Chl), relative water content (RWC), and antioxidants. However, NO application attenuated toxicity symptoms with improving growth attributes which might be related to enhance activities of antioxidants, mineral contents, Chl, RWC and SPC. Furthermore, principal component analysis indicated that water imbalance and increased oxidative damage were the main contributors to chilling injury, whereas NO-mediated mineral homeostasis and antioxidant defense were the critical determinants for chilling tolerance in rice. Collectively, our findings revealed that NO protects against chilling stress through valorizing cellular defense mechanisms, suggesting that exogenous application of NO could be a potential tool to evolve cold tolerance as well as climate resilience in rice.

DOI： 10.1016/j.niox.2020.04.001

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Reactive oxygen species and nitric oxide (NO•) concomitantly play essential roles in guard cell signaling. Studies using catalase mutants have revealed that the inducible and constitutive elevations of intracellular hydrogen peroxide (H2O2) have different roles: only the inducible H2O2 production transduces the abscisic acid (ABA) signal leading stomatal closure. However, the involvement of inducible or constitutive NO• productions, if exists, in this process remains unknown. We studied H2O2 and NO• mobilization in guard cells of catalase mutants. Constitutive H2O2 level was higher in the mutants than that in wild type, but constitutive NO• level was not different among lines. Induced NO• and H2O2 levels elicited by ABA showed a high correlation with each other in all lines. Furthermore, NO• levels increased by exogenous H2O2 also showed a high correlation with stomatal aperture size. Our results demonstrate that ABA-induced intracellular H2O2 accumulation triggers NO• production leading stomatal closure. ABBREVIATIONS: ABA: abscisic acid; CAT: catalase; cGMP: cyclic guanosine monophosphate; DAF-2DA: 4,5-diaminofluorescein-2 diacetate; H2DCF-DA: 2',7'-dichlorodihydrofluorescein diacetate; MeJA: methyljasmonate; NOS: nitric oxide synthetase; NR: nitrate reductase; POX: peroxidase; ROS: reactive oxygen species; SNAP: S-nitroso-N-acetyl-DL-penicillamine; SNP: sodium nitroprusside; NOX: NADP(H) oxidase.

DOI： 10.1080/09168451.2020.1743168

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Upon recognition of microbes, pattern recognition receptors (PRRs) activate pattern-triggered immunity. FLAGELLIN SENSING2 (FLS2) and BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1 (BAK1) form a typical PRR complex that senses bacteria. Here, we report that the kinase activity of the malectin-like receptor-like kinase STRESS INDUCED FACTOR 2 (SIF2) is critical for Arabidopsis (Arabidopsis thaliana) resistance to bacteria by regulating stomatal immunity. SIF2 physically associates with the FLS2-BAK1 PRR complex and interacts with and phosphorylates the guard cell SLOW ANION CHANNEL1 (SLAC1), which is necessary for abscisic acid (ABA)-mediated stomatal closure. SIF2 is also required for the activation of ABA-induced S-type anion currents in Arabidopsis protoplasts, and SIF2 is sufficient to activate SLAC1 anion channels in Xenopus oocytes. SIF2-mediated activation of SLAC1 depends on specific phosphorylation of Ser 65. This work reveals that SIF2 functions between the FLS2-BAK1 initial immunity receptor complex and the final actuator SLAC1 in stomatal immunity.

DOI： 10.1105/tpc.19.00578

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The glucosinolate-myrosinase system is a well-known defense system that has been shown to induce stomatal closure in Brassicales. Isothiocyanates are highly reactive hydrolysates of glucosinolates, and an isothiocyanate, allyl isothiocyanate (AITC), induces stomatal closure accompanied by elevation of free cytosolic Ca2+ concentration ([Ca2+]cyt) in Arabidopsis. It remains unknown whether AITC inhibits light-induced stomatal opening. This study investigated the role of Ca2+ in AITC-induced stomatal closure and inhibition of light-induced stomatal opening. AITC induced stomatal closure and inhibited light-induced stomatal opening in a dose-dependent manner. A Ca2+ channel inhibitor, La3+, a Ca2+chelator, EGTA, and an inhibitor of Ca2+ release from internal stores, nicotinamide, inhibited AITC-induced [Ca2+]cyt elevation and stomatal closure, but did not affect inhibition of light-induced stomatal opening. AITC activated non-selective Ca2+-permeable cation channels and inhibited inward-rectifying K+ (K+in) channels in a Ca2+-independent manner. AITC also inhibited stomatal opening induced by fusicoccin, a plasma membrane H+-ATPase activator, but had no significant effect on fusicoccin-induced phosphorylation of the penultimate threonine of H+-ATPase. Taken together, these results suggest that AITC induces Ca2+ influx and Ca2+ release to elevate [Ca2+]cyt, which is essential for AITC-induced stomatal closure but not for inhibition of K+in channels and light-induced stomatal opening.

DOI： 10.1093/jxb/eraa073

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Myrosinase (β-thioglucoside glucohydrolase, enzyme nomenclature, EC 3.2.1.147, TGG) is a highly abundant protein in Arabidopsis guard cells, of which TGG1 and TGG2 function redundantly in abscisic acid (ABA)- and methyl jasmonate-induced stomatal closure. Reactive carbonyl species (RCS) are α,β-unsaturated aldehydes and ketones, which function downstream of reactive oxygen species (ROS) production in the ABA signalling pathway in guard cells. Among the RCS, acrolein is the most highly reactive, which is significantly produced in ABA-treated guard cells. To clarify the ABA signal pathway downstream of ROS production, we investigated the responses of tgg mutants (tgg1-3, tgg2-1 and tgg1-3 tgg2-1) to acrolein. Acrolein induced stomatal closure and triggered cytosolic alkalization in wild type (WT), tgg1-3 single mutants and in tgg2-1 single mutants, but not in tgg1-3 tgg2-1 double mutants. Exogenous Ca2+ induced stomatal closure and cytosolic alkalization not only in WT but also in all of the mutants. Acrolein- and Ca2+-induced stomatal closures were inhibited by an intracellular acidifying agent, butyrate, a Ca2+ chelator, ethylene glycol tetraacetic acid (EGTA) and a Ca2+ channel blocker, LaCl3. Acrolein induced cytosolic free calcium concentration ([Ca2+]cyt) elevation in guard cells of WT plants but not in the tgg1-3 tgg2-1 double mutants. Exogenous Ca2+ elicited [Ca2+]cyt elevation in guard cells of WT and tgg1-3 tgg2-1. Our results suggest that TGG1 and TGG2 function redundantly, not between ROS production and RCS production, but downstream of RCS production in the ABA signal pathway in Arabidopsis guard cells.

DOI： 10.1093/pcp/pcaa024

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Chitosan (CHT) induces stomatal closure and thus plays a crucial role in plants to adapt to the adverse environments. Our previous results of a SA-deficient mutant nahG suggest that endogenous salicylic acid (SA) is involved in the CHT signaling in guard cells. Here in order to make the involvement definite, we examined stomatal responses to CHT of another SA-deficient mutant, sid2, and an SA receptor mutant, npr1-3. The sid2 mutation impaired CHT-induced stomatal closure and reactive oxygen species production and both impairments were complemented with exogenous SA application. Moreover, the CHT-induced stomatal closure is disrupted in the npr1-3 mutant. These results suggest that endogenous SA is involved in the CHT-induced stomatal closure via the SA receptor, NPR1.Abbreviations: SA: salicylic acid; ABA: abscisic acid; ROS: reactive oxygen species; NPR1: nonexpresser of pathogenesis-related genes1; CHT: chitosan; DAB: 3,3'-diaminobenzidine.

DOI： 10.1080/09168451.2020.1718485

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The aim of this study was to extract benzyl isothiocyanate (BITC) from green papaya by distillation apparatus without using organic solvents, and to improve the stability of BITC in aqueous solution. The distillation of mashed green papaya successfully yielded BITC as a water solution with more than 80% purity with good reproducibility. The amount of BITC in the distilled water gradually decreased during its storage at 4 °C, whereas it was not significantly changed at -20 °C for a few months. Moreover, the addition of l-cysteine ameliorated the BITC decomposition by the 4 °C-storage, but not affected by N-acetyl-cysteine and glutathione. These results suggested that the combination of BITC extraction by distillation and cysteine supplementation as well as frozen storage might be a useful method for the preparation and storage of the safer grade of BITC-containing extract.

DOI： 10.1016/j.foodchem.2019.125118

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Signal crosstalk between jasmonate and ethylene is crucial for a proper maintenance of defense responses and development. Although previous studies reported that both jasmonate and ethylene also function as modulators of stomatal movements, the signal crosstalk mechanism in stomatal guard cells remains unclear. Here, we show that the ethylene signaling inhibits jasmonate signaling as well as abscisic acid (ABA) signaling in guard cells of Arabidopsis thaliana and reveal the signaling crosstalk mechanism. Both an ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and an ethylene-releasing compound ethephon induced transient stomatal closure, and also inhibited methyl jasmonate (MeJA)-induced stomatal closure as well as ABA-induced stomatal closure. The ethylene inhibition of MeJA-induced stomatal closure was abolished in the ethylene-insensitive mutant etr1-1, whereas MeJA-induced stomatal closure was impaired in the ethylene-overproducing mutant eto1-1. Pretreatment with ACC inhibited MeJA-induced reactive oxygen species (ROS) production as well as ABA-induced ROS production in guard cells but did not suppress ABA activation of OPEN STOMATA 1 (OST1) kinase in guard cell-enriched epidermal peels. The whole-cell patch-clamp analysis revealed that ACC attenuated MeJA and ABA activation of S-type anion channels in guard cell protoplasts. However, MeJA and ABA inhibitions of Kin channels were not affected by ACC pretreatment. These results suggest that ethylene signaling inhibits MeJA signaling and ABA signaling by targeting S-type anion channels and ROS but not OST1 kinase and K+ channels in Arabidopsis guard cells.

DOI： 10.1093/pcp/pcz121

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掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/agriculture9100223

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Benzyl isothiocyanate (BITC) is a naturally-occurring isothiocyanate derived from cruciferous vegetables. BITC has been reported to inhibit the proliferation of various cancer cells, which is believed to be important for the inhibition of tumorigenesis. However, the detailed mechanisms of action remain unclear. In this study, we employed a budding yeast Saccharomyces cerevisiae as a model organism for screening. Twelve genes including MTW1 were identified as the overexpression suppressors for the antiproliferative effect of BITC using the genome-wide multi-copy plasmid collection for S. cerevisiae. Overexpression of the kinetochore protein Mtw1 counteracts the antiproliferative effect of BITC in yeast. The inhibitory effect of BITC on the proliferation of human colon cancer HCT-116 cells was consistently suppressed by the overexpression of Mis12, a human orthologue of Mtw1, and enhanced by the knockdown of Mis12. We also found that BITC increased the phosphorylated and ubiquitinated Mis12 level with consequent reduction of Mis12, suggesting that BITC degrades Mis12 through an ubiquitin-proteasome system. Furthermore, cell cycle analysis showed that the change in the Mis12 level affected the cell cycle distribution and the sensitivity to the BITC-induced apoptosis. These results provide evidence that BITC suppresses cell proliferation through the post-transcriptional regulation of the kinetochore protein Mis12.

DOI： 10.1038/s41598-019-45248-2

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

We have demonstrated that reactive carbonyl species (RCS) function as an intermediate downstream of hydrogen peroxide (H2O2) production in abscisic acid (ABA) signaling for stomatal closure in guard cells using transgenic tobacco plants overexpressing alkenal reductase. We investigated the conversion of the RCS production into downstream signaling events in the guard cells. Both ABA and H2O2 induced production of the RCS, such as acrolein and 4-hydroxy-(E)-2-nonenal (HNE), in epidermal tissues of wild-type Arabidopsis thaliana plants. Application of the RCS scavengers, carnosine and pyridoxamine, did not affect the ABA-induced H2O2 production but inhibited the ABA- and H2O2-induced stomatal closure. Both acrolein and HNE induced stomatal closure in a plasma membrane NAD(P)H oxidase mutant atrbohD atrbohF as well as in the wild type, but not in a calcium-dependent kinase mutant cpk6. Acrolein activated plasma membrane Ca2+-permeable cation channels, triggered cytosolic free Ca2+ concentration ([Ca2+]cyt) elevation, and induced stomatal closure accompanied by depletion of glutathione in the guard cells. These results suggest that RCS production is a signaling event between the ROS production and [Ca2+]cyt elevation during guard cell ABA signaling.

DOI： 10.1093/pcp/pcz031

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Plants closing stomata in the presence of harmful gases is believed to be a stress avoidance mechanism. SO2 , one of the major airborne pollutants, has long been reported to induce stomatal closure, yet the mechanism remains unknown. Little is known about the stomatal response to airborne pollutants besides O3 . SLOW ANION CHANNEL-ASSOCIATED 1 (SLAC1) and OPEN STOMATA 1 (OST1) were identified as genes mediating O3 -induced closure. SLAC1 and OST1 are also known to mediate stomatal closure in response to CO2 , together with RESPIRATORY BURST OXIDASE HOMOLOGs (RBOHs). The overlaying roles of these genes in response to O3 and CO2 suggested that plants share their molecular regulators for airborne stimuli. Here, we investigated and compared stomatal closure event induced by a wide concentration range of SO2 in Arabidopsis through molecular genetic approaches. O3 - and CO2 -insensitive stomata mutants did not show significant differences from the wild type in stomatal sensitivity, guard cell viability, and chlorophyll content revealing that SO2 -induced closure is not regulated by the same molecular mechanisms as for O3 and CO2 . Nonapoptotic cell death is shown as the reason for SO2 -induced closure, which proposed the closure as a physicochemical process resulted from SO2 distress, instead of a biological protection mechanism.

DOI： 10.1111/pce.13406

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1080/09168451.2018.1514249

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1080/09168451.2018.1514247

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1080/09168451.2018.1487274

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

The phenolic hormone salicylic acid (SA) induces stomatal closure. It has been suggested that SA signaling is integrated with abscisic acid (ABA) signaling in guard cells, but the integration mechanism remains unclear. The Ca2+-independent protein kinase Open Stomata1 (OST1) and Ca2+-dependent protein kinases (CPKs) are key for ABA-induced activation of the slow-type anion channel SLAC1 and stomatal closure. Here, we show that SA-induced stomatal closure and SA activation of slow-type anion channel are impaired in the CPK disruption mutant cpk3-2 cpk6-1 but not in the OST1 disruption mutant ost1-3 We also found that the key phosphorylation sites of SLAC1 in ABA signaling, serine-59 and serine-120, also are important for SA signaling. Chemiluminescence-based detection of superoxide anion revealed that SA did not require CPK3 and CPK6 for the induction of reactive oxygen species production. Taken together, our results suggest that SA activates peroxidase-mediated reactive oxygen species signal that is integrated into Ca2+/CPK-dependent ABA signaling branch but not the OST1-dependent signaling branch in Arabidopsis (Arabidopsis thaliana) guard cells.

DOI： 10.1104/pp.18.00321

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/jbt.22054

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Stomatal immunity restricts bacterial entry to leaves through the recognition of microbe-associated molecular patterns (MAMPs) by pattern-recognition receptors (PRRs) and downstream abscisic acid and salicylic acid signaling. Through a reverse genetics approach, we characterized the function of the L-type lectin receptor kinase-V.2 (LecRK-V.2) and -VII.1 (LecRK-VII.1). Analyses of interactions with the PRR FLAGELLIN SENSING2 (FLS2) were performed by co-immunoprecipitation and bimolecular fluorescence complementation and whole-cell patch-clamp analyses were used to evaluate guard cell Ca2+ -permeable cation channels. The Arabidopsis thaliana LecRK-V.2 and LecRK-VII.1 and notably their kinase activities were required for full activation of stomatal immunity. Knockout lecrk-V.2 and lecrk-VII.1 mutants were hyper-susceptible to Pseudomonas syringae infection and showed defective stomatal closure in response to bacteria or to the MAMPs flagellin and EF-Tu. By contrast, Arabidopsis over-expressing LecRK-V.2 or LecRK-VII.1 demonstrated a potentiated stomatal immunity. LecRK-V.2 and LecRK-VII.1 are shown to be part of the FLS2 PRR complex. In addition, LecRK-V.2 and LecRK-VII.1 were critical for methyl jasmonate (MeJA)-mediated stomatal closure, notably for MeJA-induced activation of guard cell Ca2+ -permeable cation channels. This study highlights the role of LecRK-V.2 and LecRK-VII.1 in stomatal immunity at the FLS2 PRR complex and in MeJA-mediated stomatal closure.

DOI： 10.1111/nph.14953

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s11738-017-2596-1

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その他リンク： http://link.springer.com/content/pdf/10.1007/s11738-017-2596-1.pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Drought is one of the abiotic stresses which impairs the plant growth/development and restricts the yield of many crops throughout the world. Stomatal closure is a common adaptation response of plants to the onset of drought condition. Stomata are microscopic pores on the leaf epidermis, which regulate the transpiration/CO2 uptake by leaves. Stomatal guard cells can sense various abiotic and biotic stress stimuli from the internal and external environment and respond quickly to initiate closure under unfavorable conditions. Stomata also limit the entry of pathogens into leaves, restricting their invasion. Drought is accompanied by the production and/or mobilization of the phytohormone, abscisic acid (ABA), which is well-known for its ability to induce stomatal closure. Apart from the ABA, various other factors that accumulate during drought and affect the stomatal function are plant hormones (auxins, MJ, ethylene, brassinosteroids, and cytokinins), microbial elicitors (salicylic acid, harpin, Flg 22, and chitosan), and polyamines . The role of various signaling components/secondary messengers during stomatal opening or closure has been a matter of intense investigation. Reactive oxygen species (ROS) , nitric oxide (NO) , cytosolic pH, and calcium are some of the well-documented signaling components during stomatal closure. The interrelationship and interactions of these signaling components such as ROS, NO, cytosolic pH, and free Ca2+ are quite complex and need further detailed examination.Low temperatures can have deleterious effects on plants. However, plants evolved protection mechanisms to overcome the impact of this stress. Cold temperature inhibits stomatal opening and causes stomatal closure. Cold-acclimated plants often exhibit marked changes in their lipid composition, particularly of the membranes. Cold stress often leads to the accumulation of ABA, besides osmolytes such as glycine betaine and proline. The role of signaling components such as ROS, NO, and Ca2+ during cold acclimation is yet to be established, though the effects of cold stress on plant growth and development are studied extensively. The information on the mitigation processes is quite limited. We have attempted to describe consequences of drought and cold stress in plants, emphasizing stomatal closure. Several of these factors trigger signaling components in roots, shoots, and atmosphere, all leading to stomatal closure. A scheme is presented to show the possible signaling events and their convergence and divergence of action during stomatal closure. The possible directions for future research are discussed.

DOI： 10.1007/978-981-13-1244-1_12

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Stomata regulate gas exchange between plants and atmosphere by integrating opening and closing signals. Stomata open in response to low CO2 concentrations to maximize photosynthesis in the light; however, the mechanisms that coordinate photosynthesis and stomatal conductance have yet to be identified. Here we identify and characterize CBC1/2 (CONVERGENCE OF BLUE LIGHT (BL) AND CO2 1/2), two kinases that link BL, a major component of photosynthetically active radiation (PAR), and the signals from low concentrations of CO2 in guard cells. CBC1/CBC2 redundantly stimulate stomatal opening by inhibition of S-type anion channels in response to both BL and low concentrations of CO2. CBC1/CBC2 function in the signaling pathways of phototropins and HT1 (HIGH LEAF TEMPERATURE 1). CBC1/CBC2 interact with and are phosphorylated by HT1. We propose that CBCs regulate stomatal aperture by integrating signals from BL and CO2 and act as the convergence site for signals from BL and low CO2.

DOI： 10.1038/s41467-017-01237-5

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その他リンク： http://www.nature.com/articles/s41467-017-01237-5

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The regulating role of phosphatidylinositide 3-kinase (PI3K) in benzyl isothiocyanate (BITC)-induced Nrf2 activation, contributing to the inducible expression of cytoprotective genes, was investigated. BITC significantly enhanced the accumulation of Nrf2 as well as autophagic molecules in human colorectal cancer HCT-116 cells. Experiments using a PI3K-specific inhibitor suggested that PI3K plays the key role in the non-canonical Nrf2 activation by BITC.

DOI： 10.1080/09168451.2017.1374830

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

3,4-Dihydroxyphenylacetic acid (DOPAC) is one of the major colonic microflora-produced catabolites of quercetin glycosides, such as quercetin 4'-glucoside derived from onion. Here, we investigated whether DOPAC modulates the aldehyde dehydrogenase (ALDH) activity and protects the cells from the acetaldehyde-induced cytotoxicity in vitro. DOPAC was shown to enhance not only the total ALDH activity, but also the gene expression of ALDH1A1, ALDH2 and ALDH3A1 in a concentration-dependent manner. DOPAC simultaneously stimulated the nuclear translocation of NFE2-related factor 2 and aryl hydrocarbon receptor. The pretreatment of DOPAC completely protected the cells from the acetaldehyde-induced cytotoxicity. The present study suggested that DOPAC acts as a potential ALDH inducer to prevent the alcohol-induced abnormal reaction.

DOI： 10.1080/09168451.2017.1361809

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

In the present study, we assessed benzyl isothiocyanate (BITC), an organosulfur compound from cruciferous vegetables, as a potential inducer of aldehyde dehydrogenase (ALDH) activity using murine hepatoma Hepa1c1c7 cells. BITC was shown to enhance not only the total ALDH activity, but also the ALDH activity of the cytosolic/microsomal and mitochondrial fraction. BITC also significantly increased the gene and protein expression of ALDH1A1, ALDH2 and ALDH3A1 in a concentration-dependent manner. Simultaneously, the gene expression of phase 2 drug-metabolizing enzymes, such as NAD(P)H: quinone oxidoreductase 1 and heme oxygenase-1, was increased by the BITC treatment. Western blot experiments revealed that BITC not only up-regulated the Nrf2 protein expression, but also stimulated the nuclear translocation of Nrf2. Furthermore, silencing Nrf2 reduced the basal and BITC-enhanced levels of the total activity and gene expression of ALDHs. The pretreatment of BITC completely mitigated the acetaldehyde-induced cytotoxicity, which was impaired by silencing Nrf2. The present study demonstrated that BITC has been identified as a potential inducer of the total ALDH activity to prevent the acetaldehyde-induced cytotoxicity.

DOI： 10.1016/j.fct.2017.08.016

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

In the present study, we clarified the role of phosphatidylinositide 3-kinase (PI3K) in antiproliferation induced by benzyl isothiocyanate (BITC) in human colorectal cancer cells. BITC simultaneously activated the PI3K/Akt/forkhead box O (FoxO) pathway, whereas it significantly inhibited the proliferation in human colorectal cancer cells. Inhibitory experiments using a PI3K selective inhibitor, LY294002 or NVP-BEZ235, significantly enhanced the BITC-induced antiproliferation and apoptotic cell population with the attenuation of the BITC-induced activation of the PI3K/Akt/FoxO survival pathway. Furthermore, BITC enhanced the insulin-activated PI3K/Akt/FoxO pathway, possibly through its inhibition of the protein tyrosine phosphatase 1B enzymatic activity. Taken together, these results suggested that the PI3K/Akt/FoxO pathway negatively regulates the BITC-induced antiproliferation in human colorectal cancer cells.

DOI： 10.1016/j.bbrc.2017.07.078

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

<title>Abstract</title>
Arsenic causes physiological and structural disorders in plants. Proline is accumulated as a compatible solute in plants under various stress conditions and mitigates stresses. Here, we investigated the effects of exogenous proline on tobacco Bright Yellow-2 (BY-2) cultured cells under stress. Arsenate did not inhibit BY-2 cell growth at 40 and 50 μM but did it at 60 μM. Proline at 0.5 to 10 mM did not affect the cell growth but delayed it at 20 mM. At 40 μM , neither 0.5 mM nor 1 mM proline affected the cell growth but 10 mM proline inhibited it. In the presence of , 10 mM proline increased the number of Evans Blue-stained (dead) cells and decreased the number of total cells. Together, our results suggest that exogenous proline does not alleviate arsenate toxicity but enhances the sensitivity of BY-2 cells to arsenate.

DOI： 10.1080/09168451.2017.1340088

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We investigated the molecular mechanisms involved in the angiotensin-converting enzyme (ACE) inhibition by (-)-epigallocatechin-3-gallate (EGCg), a major tea catechin. EGCg inhibited both the ACE activity in the lysate of human colorectal cancer cells and human recombinant ACE (rh-ACE) in a dose-dependent manner. Co-incubation with zinc sulfate showed no influence on the rh-ACE inhibition by EGCg, whereas it completely counteracted the inhibitory effect of ethylenediaminetetraacetic acid, a chelating-type ACE inhibitor. Although hydrogen peroxide was produced by the autoxidation of EGCg, hydrogen peroxide itself had little effect on the ACE activity. Conversely, the co-incubation of EGCg with borate or ascorbic acid significantly diminished the EGCg inhibition. A redox-cycling staining experiment revealed that rh-ACE was covalently modified by EGCg. A Lineweaver-Burk plot analysis indicated that EGCg inhibited the ACE activity in a non-competitive manner. These results suggested that EGCg might allosterically inhibit the ACE activity through oxidative conversion into an electrophilic quinone.

DOI： 10.1002/jbt.21932

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

<title>Abstract</title>
An elicitor chitosan (CHT) induces stomatal closure but the mechanism remains to be clarified. A phytohormone salicylic acid (SA) is crucial for elicitor-induced defense signaling in plants. Here we investigated whether endogenous SA is required for CHT signaling in guard cells. In the SA-deficient nahG mutant, treatment of CHT did not induce either apoplastic reactive oxygen species (ROS) production or stomatal closure but co-treatment of CHT and SA induced both apoplastic ROS production and stomatal closure, indicating the involvement of endogenous SA in CHT-induced apoplastic ROS production and CHT-induced stomatal closure. Furthermore, CHT induced transient cytosolic free calcium concentration increments in the nahG mutant in the presence of exogenous SA but not in the absence of exogenous SA. These results provide evidence that endogenous SA is a crucial element in CHT-induced stomatal closure.

DOI： 10.1080/09168451.2017.1332979

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Salicylic acid (SA) induces stomatal closure sharing several components with abscisic acid (ABA) and methyl jasmonate (MeJA) signaling. We have previously shown that two guard cell-preferential mitogen-activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate ABA signaling and MeJA signaling in Arabidopsis thaliana. In this study, we examined whether these two MAPKs are involved in SA-induced stomatal closure using genetic mutants and a pharmacological, MAPKK inhibitor. Salicylic acid induced stomatal closure in mpk9 and mpk12 single mutants but not in mpk9 mpk12 double mutants. The MAPKK inhibitor PD98059 inhibited SA-induced stomatal closure in wild-type plants. Salicylic acid induced extracellular reactive oxygen species (ROS) production, intracellular ROS accumulation, and cytosolic alkalization in the mpk9, mpk12, and mpk9 mpk12 mutants. Moreover, SA-activated S-type anion channels in guard cells of wild-type plants but not in guard cells of mpk9 mpk12 double mutants. These results imply that MPK9 and MPK12 are positive regulators of SA signaling in Arabidopsis guard cells.

DOI： 10.1080/09168451.2017.1308244

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Methylglyoxal (MG) is a highly reactive stress-related α-ketoaldehyde and a physiological metabolite of glycolysis, which is accumulated in ample amount under stressful conditions. In the present study, the effect of different doses of MG on growth, anthocyanin production, MG contents, and activities of two types of glyoxalases (glyoxalase I and glyoxalase II) were examined in Arabidopsis seedlings. MG at 0.1 mM dose did not affect seedling growth, anthocyanin accumulation, MG contents, or activities of glyoxalases, whereas MG at 0.5 mM and 1 mM inhibited seedling growth and induced anthocyanin accumulation, MG accumulation, and glyoxalase (both I and II) activation. Therefore, MG can reduce plant growth as a toxic molecule and can stimulate stress responses as a signal molecule under stress conditions.

DOI： 10.1002/jbt.21901

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

Stomata within the plant epidermis regulate CO2 uptake for photosynthesis and water loss through transpiration. Stomatal opening in Arabidopsis thaliana is determined by various factors, including blue light as a signal and multiple phytohormones. Plasma membrane transporters, including H+-ATPase, K+ channels and anion channels in guard cells, mediate these processes, and the activities and expression levels of these components determine stomatal aperture. However, the regulatory mechanisms involved in these processes are not fully understood. In this study, we used infrared thermography to isolate a mutant defective in stomatal opening in response to light. The causative mutation was identified as an allele of the brassinosteroid (BR) biosynthetic mutant dwarf5. Guard cells from this mutant exhibited normal H+-ATPase activity in response to blue light, but showed reduced K+ accumulation and inward-rectifying K+ (K-in(+)) channel activity as a consequence of decreased expression of major K-in(+) channel genes. Consistent with these results, another BR bio-synthetic mutant, det2-1, and a BR receptor mutant, bri1-6, exhibited reduced blue light-dependent stomatal opening. Furthermore, application of BR to the hydroponic culture medium completely restored stomatal opening in dwarf5 and det2-1 but not in bri1-6. However, application of BR to the epidermis of dwarf5 did not restore stomatal response. From these results, we conclude that endogenous BR acts in a long-term manner and is required in guard cells with the ability to open stomata in response to light, probably through regulation of K-in(+) channel activity.

DOI： 10.1093/pcp/pcx049

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記述言語：英語  

DOI： 10.3389/fpls.2017.00114

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

Drought is responsible for a massive reduction in crop yields. In response to drought, plants synthesize the hormone ABA, which induces stomatal closure, thus reducing water loss. In guard cells, ABA triggers production of reactive oxygen species (ROS), which is mediated by NAD(P)H oxidases. The production of ROS is a key factor for ABA-induced stomatal closure, but it remains to be clarified how the production of ROS is transduced into downstream signaling components in guard cells. We investigated roles of reactive carbonyl species (RCS) in ABA-induced stomatal closure using transgenic tobacco (Nicotiana tabacum) overexpressing Arabidopsis 2-alkenal reductase (AER-OE), which scavenges RCS. ABA and hydrogen peroxide (H2O2) induced accumulation of RCS including acrolein and 4-hydroxy-(E)-2-nonenal in wild-type tobacco but not in AER-OE. Stomatal closure and RCS accumulation in response to ABA and H2O2 were inhibited in AER-OE unlike in the wild type, while ABA-induced H2O2 production in guard cells was observed in AER-OE as well as in the wild type. Moreover, ABA inhibited inward-rectifying K+ channels in wild-type guard cells but not in AER-OE guard cells. These results suggest that RCS is involved in ABA-induced stomatal closure and functions downstream of H2O2 production in the ABA signaling pathway in guard cells.

DOI： 10.1093/pcp/pcw166

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

Plant glutamate receptor homologs (GLRs) have long been proposed to function as ligand-gated Ca2+ channels, but no in planta evidence has been provided. Here, we present genetic evidence that Arabidopsis GLR3.1 and GLR3.5 form Ca2+ channels activated by L-methionine (L-Met) at physiological concentrations and regulate stomatal apertures and plant growth. The glr3.1/3.5 mutations resulted in a lower cytosolic Ca2+ level, defective Ca2+-induced stomatal closure, and Ca2+-deficient growth disorder, all of which involved L-Met. Patch-clamp analyses of guard cells showed that GLR3.1/3.5 Ca2+ channels are activated specifically by L-Met, with the activation abolished in glr3.1/3.5. Moreover, GLR3.1/3.5 Ca2+ channels are distinct from previously characterized ROS-activated Ca2+ channels and act upstream of ROS, providing Ca2+ transients necessary for the activation of NADPH oxidases. Our data indicate that GLR3.1/3.5 constitute L-Met-activated Ca2+ channels responsible for maintaining basal [Ca2+]cyt, play a pivotal role in plant growth, and act upstream of ROS, thereby regulating stomatal aperture.

DOI： 10.1016/j.celrep.2016.11.015

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s00344-016-9605-2

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その他リンク： http://link.springer.com/article/10.1007/s00344-016-9605-2/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Since dietary flavonoid glycosides, including quercetin 4'-glucoside from onion, are poorly absorbed from the gastrointestinal tract, they are converted into smaller phenolic acids, which can be absorbed into the circulation. The purpose of this study was to compare the effects of the major phenolic acid catabolites of quercetin 4'-glucoside, including 3,4-dihydroxyphenylacetic acid (DOPAC), 3-hydroxyphenylacetic acid, 3,4-dihydroxybenzoic acid (protocatechuic acid) and hippuric acid, on the antioxidant activity and phase II cytoprotective enzyme induction in vitro. Both DOPAC and protocatechuic acid, having a catechol moiety, exhibited both DPPH radical scavenging and superoxide dismutase-like activities, whereas 3-hydroxyphenyl acetic acid and hippuric acid did not. DOPAC also more potently enhanced the gene expression of several phase II drug-metabolizing enzymes than the other phenolic acid catabolites. DOPAC significantly inhibited the hydrogen peroxide-induced cytotoxicity in hepatocytes with the enhancement of the total glutathione S-transferase activity. In conclusion, DOPAC may play a key role in the antioxidative potential of the colonic lumen after the ingestion of the quercetin glycoside-rich onion.

DOI： 10.1016/j.foodres.2016.09.034

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

3,4-Dihydroxyphenylacetic acid (DOPAC) is one of the colonic microflora-produced catabolites of quercetin 4'-glucoside (Q4'G). Although the interaction of DOPAC with cellular proteins might be involved in its biological activity, the actual proteins have not yet been identified. In this study, we developed a novel tag-free DOPAC probe to label the targeted proteins by the copper(I)-catalyzed azide alkyne cycloaddition (CuAAC) and verified its efficacy. Various labeled proteins were detected by the DOPAC probe with the azide labeled biotin and a horseradish peroxidase (HRP)-streptavidin complex. Furthermore, a pulldown assay identified Keap1 and aryl hydrocarbon receptor (AhR) as the target proteins for the phase 2 enzyme up-regulation.

DOI： 10.1016/j.bbrep.2016.06.020

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Plant Physiologists  

Methyl jasmonate (MeJA) induces stomatal closure. It has been shown that stomata of many ABA-insensitive mutants are also insensitive to MeJA, and a low amount of ABA is a prerequisite for the MeJA response. However, the molecular mechanisms of the interaction between ABA and MeJA signaling remain to be elucidated. Here we studied the interplay of signaling of the two hormones in guard cells using the quadruple ABA receptor mutant pyr1 pyl1 pyl2 pyl4 and ABA-activated protein kinase mutants ost1-2 and srk2e. In the quadruple mutant, MeJA-induced stomatal closure, H2O2 production, nitric oxide (NO) production, cytosolic alkalization and plasma membrane Ca(2+)-permeable current (ICa) activation were not impaired. At the same time, the inactivation of the inward-rectifying K(+) current was impaired. In contrast to the quadruple mutant, MeJA-induced stomatal closure, H2O2 production, NO production and cytosolic alkalization were impaired in ost1-2 and srk2e as well as in aba2-2, the ABA-deficient mutant. The activation of ICa was also impaired in srk2e. Collectively, these results indicated that OST1 was essential for MeJA-induced stomatal closure, while PYR1, PYL1, PYL2 and PYL4 ABA receptors were not sufficient factors. MeJA did not appear to activate OST1 kinase activity. This implies that OST1 mediates MeJA signaling through an undetectable level of activity or a non-enzymatic action. MeJA induced the expression of an ABA synthesis gene, NCED3, and increased ABA contents only modestly. Taken together with previous reports, this study suggests that MeJA signaling in guard cells is primed by ABA and is not brought about through the pathway mediated by PYR1, PYL1 PYL2 and PYL4.

DOI： 10.1093/pcp/pcw102

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATL ACAD SCIENCES  

Stomatal movements regulate gas exchange, thus directly affecting the efficiency of photosynthesis and the sensitivity of plants to air pollutants such as ozone. The GARP family transcription factors GOLDEN 2-LIKE1 (GLK1) and GLK2 have known functions in chloroplast development. Here, we show that Arabidopsis thaliana (A. thaliana) plants expressing the chimeric repressors for GLK1 and -2 (GLK1/2-SRDX) exhibited a closed-stomata phenotype and strong tolerance to ozone. By contrast, plants that overexpress GLK1/2 exhibited an open-stomata phenotype and higher sensitivity to ozone. The plants expressing GLK1-SRDX had reduced expression of the genes for inwardly rectifying K+ (K-in(+)) channels and reduced K-in(+) channel activity. Abscisic acid treatment did not affect the stomatal phenotype of 35S:GLK1/2-SRDX plants or the transcriptional activity for K-in(+) channel gene, indicating that GLK1/2 act independently of abscisic acid signaling. Our results indicate that GLK1/2 positively regulate the expression of genes for K-in(+) channels and promote stomatal opening. Because the chimeric GLK1-SRDX repressor driven by a guard cell-specific promoter induced a closed-stomata phenotype without affecting chloroplast development in mesophyll cells, modulating GLK1/2 activity may provide an effective tool to control stomatal movements and thus to confer resistance to air pollutants.

DOI： 10.1073/pnas.1513093113

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 園芸学会  

収穫後の短時間近赤外光照射（中心波長850 nm，100 μmol・m−2・s−1，5分間）が3種の葉菜の重量減少と気孔開度および外観品質に及ぼす影響を調査した．リーフレタス，ホウレンソウ，コマツナに貯蔵前1回または毎日，近赤外光を5分間照射し，ポリ袋密封包装または有孔ポリ袋包装を行い，10°C暗所に保存した．いずれの葉菜でもポリ袋密封包装と有孔ポリ袋包装にかかわらず，貯蔵3日後の近赤外光照射区の重量減少率と気孔開度は無照射区と比較して小さくなり，照射区では外観品質も優れた．その効果は近赤外光1回照射区より毎日照射区の方が大きくなる傾向を示した．有孔ポリ袋に包んだ葉菜類を10°C下で暗所および明所に保存し，近赤外光照射の効果を経時的に調べたところ，いずれの条件でも近赤外光照射による蒸散抑制，外観品質保持効果が確認された．その効果は1回照射よりも毎日照射区で優れ，特に，ホウレンソウでその効果が大きかった．本研究の結果は収穫後の短期間近赤外光照射は流通中の葉菜類の付加的な品質保持技術として応用できる可能性を示すものである．

DOI： 10.2503/hrj.15.197

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Background: Na+ exclusion from leaf blades is one of the key mechanisms for glycophytes to cope with salinity stress. Certain class I transporters of the high-affinity K+ transporter (HKT) family have been demonstrated to mediate leaf blade-Na+ exclusion upon salinity stress via Na+-selective transport. Multiple HKT1 transporters are known to function in rice (Oryza sativa). However, the ion transport function of OsHKT1;4 and its contribution to the Na+ exclusion mechanism in rice remain to be elucidated. Results: Here, we report results of the functional characterization of the OsHKT1;4 transporter in rice. OsHKT1;4 mediated robust Na+ transport in Saccharomyces cerevisiae and Xenopus laevis oocytes. Electrophysiological experiments demonstrated that OsHKT1;4 shows strong Na+ selectivity among cations tested, including Li+, Na+, K+, Rb+, Cs+, and NH4+, in oocytes. A chimeric protein, EGFP-OsHKT1;4, was found to be functional in oocytes and targeted to the plasma membrane of rice protoplasts. The level of OsHKT1;4 transcripts was prominent in leaf sheaths throughout the growth stages. Unexpectedly however, we demonstrate here accumulation of OsHKT1;4 transcripts in the stem including internode II and peduncle in the reproductive growth stage. Moreover, phenotypic analysis of OsHKT1;4 RNAi plants in the vegetative growth stage revealed no profound influence on the growth and ion accumulation in comparison with WT plants upon salinity stress. However, imposition of salinity stress on the RNAi plants in the reproductive growth stage caused significant Na+ overaccumulation in aerial organs, in particular, leaf blades and sheaths. In addition, 22Na+ tracer experiments using peduncles of RNAi and WT plants suggested xylem Na+ unloading by OsHKT1;4. Conclusions: Taken together, our results indicate a newly recognized function of OsHKT1;4 in Na+ exclusion in stems together with leaf sheaths, thus excluding Na+ from leaf blades of a japonica rice cultivar in the reproductive growth stage, but the contribution is low when the plants are in the vegetative growth stage.

DOI： 10.1186/s12870-016-0709-4

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掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/978-3-319-44081-1_15

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Stomata, formed by pairs of guard cells in the epidermis of terrestrial plants, regulate gas exchange, thus playing a critical role in plant growth and stress responses. As natural openings, stomata are exploited by microbes as an entry route. Recent studies reveal that plants close stomata upon guard cell perception of molecular signatures from microbes, microbe associated molecular patterns (MAMPs), to prevent microbe invasion. The perception of MAMPs induces signal transduction including recruitment of second messengers, such as Ca(2+) and H2O2, phosphorylation events, and change of transporter activity, leading to stomatal movement. In the present review, we summarize recent findings in signaling underlying MAMP-induced stomatal movement by comparing with other signalings.

DOI： 10.3389/fpls.2016.00583

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We investigated the physiological effects of short-term postharvest near infrared (NIR) radiation on relative transpiration rates, stomatal apertures, and reactive oxygen species (ROS) levels in guard cells on excised young lettuce leaves and on transpiration of leaf lettuce at commercial maturity. When the young leaves were radiated by NIR of wavelengths longer than 850 nm at 100 mu mol m(-2) s(-1) for short duration (10-60) min, relative transpiration rates during subsequent storage were reduced, but not by visible light radiation and by longer radiation (180 min) of NIR. The reduction in transpiration rates by the short-term NIR radiation was greater at 10 degrees C than at 25 degrees C under both dark and light conditions during subsequent storage. The short-term NIR radiation enhanced stomatal closure and ROS accumulation in guard cells of young lettuce leaves. These results indicate that the suppression of transpiration by short-term NIR radiation is likely to be mediated through stomatal closure due to NIR-induced ROS accumulation. The reduction of transpiration by short-term NIR radiation was obtained not only in excised young leaves but also in leaf lettuce at commercial maturity, resulting in keeping freshness. The short-term NIR radiation could be an additional means to extend shelf life of leaf vegetables. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.postharvbio.2015.05.010

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Methyl jasmonate (MeJA) and abscisic acid (ABA) signalling cascades share several signalling components in guard cells. We previously showed that two guard cell-preferential mitogen-activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate ABA signalling in Arabidopsis thaliana. In this study, we examined whether these two MAP kinases function in MeJA signalling using genetic mutants for MPK9 and MPK12 combined with a pharmacological approach. MeJA induced stomatal closure in mpk9-1 and mpk12-1 single mutants as well as wild-type plants, but not in mpk9-1 mpk12-1 double mutants. Consistently, the MAPKK inhibitor PD98059 inhibited the MeJA-induced stomatal closure in wild-type plants. MeJA elicited reactive oxygen species (ROS) production and cytosolic alkalisation in guard cells of the mpk9-1, mpk12-1 and mpk9-1 mpk12-1 mutants, as well in wild-type plants. Furthermore, MeJA triggered elevation of cytosolic Ca2+ concentration ([Ca2+](cyt)) in the mpk9-1 mpk12-1 double mutant as well as wild-type plants. Activation of S-type anion channels by MeJA was impaired in mpk9-1 mpk12-1. Together, these results indicate that MPK9 and MPK12 function upstream of S-type anion channel activation and downstream of ROS production, cytosolic alkalisation and [Ca2+](cyt) elevation in guard cell MeJA signalling, suggesting that MPK9 and MPK12 are key regulators mediating both ABA and MeJA signalling in guard cells.

DOI： 10.1111/plb.12321

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

We recently demonstrated that yeast elicitor (YEL)-induced stomatal closure requires a Ca(2+)-dependent kinase, CPK6. A Ca(2+)-independent kinase, Open Stomata 1 (OST1), is involved in stomatal closure induced by various stimuli including ABA. In the present study, we investigated the role of OST1 in YEL-induced stomatal closure in Arabidopsis using a knock-out mutant, ost1-3, and a kinase-deficient mutant, ost1-2. YEL did not induce stomatal closure or activation of guard cell S-type anion channels in the ost1 mutants unlike in wild-type plants. However, YEL did not increase OST1 kinase activity in wild-type guard cells. The YEL-induced stomatal closure and activation of S-type anion channels were also impaired in a gain-of-function mutant of a clade A type 2C protein phosphatase (ABA INSENSITIVE 1), abi1-1C. In the ost1 mutants like in the wild type, YEL induced H2O2 accumulation, activation of non-selective Ca(2+)-permeable cation (ICa) channels and transient elevations in cytosolic free Ca(2+) concentration ([Ca(2+)]cyt) in guard cells. These results suggest that OST1 kinase is essential for stomatal closure and activation of S-type anion channels induced by YEL and that OST1 is not involved in H2O2 accumulation, ICa channel activation or [Ca(2+)]cyt elevations in guard cells induced by YEL.

DOI： 10.1093/pcp/pcv051

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

<title>Abstract</title>
Acrolein is a reactive α,β-unsaturated aldehyde derived from lipid peroxides, which are produced in plants under a variety of stress. We investigated effects of acrolein on light-induced stomatal opening using Arabidopsis thaliana. Acrolein inhibited light-induced stomatal opening in a dose-dependent manner. Acrolein at 100 μM inhibited plasma membrane inward-rectifying potassium (Kin) channels in guard cells. Acrolein at 100 μM inhibited Kin channel KAT1 expressed in a heterologous system using Xenopus leaves oocytes. These results suggest that acrolein inhibits light-induced stomatal opening through inhibition of Kin channels in guard cells.

DOI： 10.1080/09168451.2014.951028

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ANNUAL REVIEWS  

Guard cells perceive a variety of chemicals produced metabolically in response to abiotic and biotic stresses, integrate the signals into reactive oxygen species and calcium signatures, and convert these signatures into stomatal movements by regulating turgor pressure. Guard cell behaviors in response to such complex signals are critical for plant growth and sustenance in stressful, ever-changing environments. The key open question is how guard cells achieve the signal integration to optimize stomatal aperture. Abscisic acid is responsible for stomatal closure in plants in response to drought, and its signal transduction has been well studied. Other plant hormones and low-molecular-weight compounds function as inducers of stomatal closure and mediators of signaling in guard cells. In this review, we summarize recent advances in research on the diverse stomatal signaling pathways, with specific emphasis on signal integration and signal interaction in guard cell movement.

DOI： 10.1146/annurev-arplant-043014-114707

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Isothiocyanates are enzymatically produced from glucosinolates in plants, and allyl isothiocyanate (AITC) induces stomatal closure in Arabidopsis thaliana. In this study, we investigated stomatal responses to AITC in Vicia faba. AITC-induced stomatal closure accompanied by reactive oxygen species (ROS) and NO production, cytosolic alkalization and glutathione (GSH) depletion in V. faba. GSH monoethyl ester induced stomatal reopening and suppressed AITC-induced GSH depletion in guard cells. Exogenous catalase and a peroxidase inhibitor, salicylhydroxamic acid, inhibited AITC-induced stomatal closure, unlike an NAD(P)H oxidase inhibitor, diphenylene iodonium chloride. The peroxidase inhibitor also abolished the AITC-induced ROS production, NO production, and cytosolic alkalization. AITC-induced stomatal closure was suppressed by an NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, and an agent to acidify cytosol, butyrate. These results indicate that AITC-induced stomatal closure in V. faba as well as in A. thaliana and suggest that AITC signaling in guard cells is conserved in both plants.

DOI： 10.1080/09168451.2015.1045827

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

An allergen-stimulating cytokine, interleukin-13 (IL-13), plays a significant role in allergic inflammation. Benzyl isothiocyanate (BITC), derived from several cruciferous vegetables, significantly suppressed the IL-13 expression in the calcium ionophore-stimulated human basophilic KU812 cells. Down-regulation of phosphorylated mitogen-activated protein kinases as well as nuclear transcriptional factors might be involved in the underlying mechanism.

DOI： 10.1080/09168451.2014.963503

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Methyl jasmonate (MeJA) signalling shares several signal components with abscisic acid (ABA) signalling in guard cells. Cyclic adenosine 5-diphosphoribose (cADPR) and cyclic guanosine 3,5-monophosphate (cGMP) are second messengers in ABA-induced stomatal closure. In order to clarify involvement of cADPR and cGMP in MeJA-induced stomatal closure in Arabidopsis thaliana (Col-0), we investigated effects of an inhibitor of cADPR synthesis, nicotinamide (NA), and an inhibitor of cGMP synthesis, LY83583 (LY, 6-anilino-5,8-quinolinedione), on MeJA-induced stomatal closure. Treatment with NA and LY inhibited MeJA-induced stomatal closure. NA inhibited MeJA-induced reactive oxygen species (ROS) accumulation and nitric oxide (NO) production in guard cells. NA and LY suppressed transient elevations elicited by MeJA in cytosolic free Ca2+ concentration ([Ca2+](cyt)) in guard cells. These results suggest that cADPR and cGMP positively function in [Ca2+](cyt) elevation in MeJA-induced stomatal closure, are signalling components shared with ABA-induced stomatal closure in Arabidopsis, and that cADPR is required for MeJA-induced ROS accumulation and NO production in Arabidopsis guard cells.

DOI： 10.1111/plb.12175

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATURE PUBLISHING GROUP  

Benzyl isothiocyanate (BITC), a dietary isothiocyanate derived from cruciferous vegetables, inhibits the proliferation of colorectal cancer cells, most of which overexpress beta-catenin as a result of mutations in the genes for adenomatous polyposis coli or mutations in beta-catenin itself. Because nuclear factor-kappa B (NF-kappa B) is a plausible target of BITC signaling in inflammatory cell models, we hypothesized that it is also involved in BITC-inhibited proliferation of colorectal cancer cells. siRNA-mediated knockdown of the NF-kappa B p65 subunit significantly decreased the BITC sensitivity of human colorectal cancer HT-29 cells with mutated p53 tumor suppressor protein. Treating HT-29 cells with BITC induced the phosphorylation of I kappa B kinase, I kappa B-alpha and p65, the degradation of I kappa B-a, the translocation of p65 to the nucleus and the upregulation of NF-kappa B transcriptional activity. BITC also decreased alpha-catenin binding to a positive cis element of the cyclin D1 promoter and thus inhibited beta-catenin-dependent cyclin D1 transcription, possibly through a direct interaction between p65 and alpha-catenin. siRNA-mediated knockdown of p65 confirmed that p65 negatively affects cyclin D1 expression. On the other hand, when human colorectal cancer HCT-116 cells with wild-type p53 were treated with BITC, translocation of p65 to the nucleus was inhibited rather than enhanced. p53 knockout increased the BITC sensitivity of HCT-116 cells in a p65-dependent manner, suggesting that p53 negatively regulates p65-dependent effects. Together, these results identify BITC as a novel type of antiproliferative agent that regulates the NF-kappa B pathway in p53-deficient colorectal cancer cells.

DOI： 10.1038/cddis.2014.495

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

(-)-Epigallocatechin-3-gallate (EGCG), the most abundant polyphenolic constituent in green tea, is known as a powerful antioxidant but concomitantly possesses a prooxidant property. We investigated the effect of EGCG on phloxine B (PhB)-induced photocytotoxicity in human T lymphocytic leukemia Jurkat cells. EGCG significantly potentiated PhB-induced photocytotoxic effects, including the inhibition of cell proliferation, DNA fragmentation, and caspase-3 activity induction in Jurkat cells. Catalase attenuated the enhanced cytotoxicity by EGCG, suggesting the involvement of extracellularly produced hydrogen peroxide. Indeed, EGCG significantly enhanced extracellular hydrogen peroxide formation induced by photo-irradiated PhB. The EGCG also enhanced intracellular reactive oxygen species accumulation, c-Jun N-terminal kinase (JNK) phosphorylation, and interferon-γ (IFN-γ) gene expression, all of which are involved in PhB-induced apoptosis. Taken together, our data suggest that EGCG is capable of potentiating photodynamic therapy responses, presumably through the intracellular oxidative stress-sensitive JNK/IFN-γ pathway by exogenous hydrogen peroxide formation.

DOI： 10.1002/ptr.5152

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

A cathepsin L-like proteinase (CLP) with molecular weight of 30.9 kDa from the gut of sea cucumber (Stichopus japonicas, S. japonicus) was isolated and purified to homogeneity by several chromatographic procedures. The enzyme exhibited optimum activity at pH 5.0-5.5 and 50 °C, and showed thermostability up to 40 °C. The enzyme activity was completely inhibited by Zn(2+), strongly inhibited by Fe(2+) and Cu(2+), drastically reduced by cysteine proteinase inhibitors, but slightly enhanced by thiol-activating agents. The enzyme efficiently hydrolysed the specific substrate of cathepsin L, but hardly hydrolysed the specific substrates for cathepsin B, cathepsin H and cathepsin K. Immunohistochemical studies indicated that the CLP was more abundant in the epidermis rather than in the dermis of S. japonicus body wall. The distribution of CLP showed positive correlation with autolysis rate. Therefore, the relationship between CLP and autolysis deserved further study.

DOI： 10.1016/j.foodchem.2014.02.105

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Ascorbic acid (AsA) is known as an antioxidant but concomitantly possesses a pro-oxidant property. Because the impact of AsA on photodynamic therapy response is unclear, we investigated the effect of AsA on photocytotoxicity induced by phloxine B in human acute promyelocytic leukemia HL-60 cells. AsA synergistically enhanced phloxine B-induced photocytotoxic effects, including inhibition of cell proliferation, DNA ladder formation, and caspase-3 activation, whereas AsA itself showed no photocytotoxicity. AsA also enhanced the consumption of the reduced glutathione level compared with the cells treated with phloxine B alone under the light condition. Combination of AsA with phloxine B under the light condition enhanced the phosphorylation of c-Jun N-terminal kinase and p38 mitogen-activated protein kinase (MAPK). These effects were completely cancelled by catalase. These results suggest that AsA synergistically enhances phloxine B-induced photocytotoxicity, possibly through the extracellular oxidative stress-dependent MAPK pathway activation.

DOI： 10.1002/jbt.21549

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Landes Bioscience  

We investigated stomatal phenotype and drought tolerance of Arabidopsis salicylic acid-accumulating mutants, acd6 and cpr5. In these mutants, the light-induced stomatal opening was impaired and the impairment of stomatal opening was restored by peroxidase inhibitors, salicylhydroxamic acid, and azide. The acd6 and cpr5 mutant plants were more tolerant to drought stress than wild-type plants. Introduction of nahG gene into the acd6 and cpr5 mutants removed the inhibition of stomatal opening and reduced the drought tolerance. Drought tolerance-related genes were more highly expressed in the cpr5 and acd6 mutant plants than in the wild-type plants. These results suggest that accumulation of salicylic acid improves drought tolerance through inhibition of light-induced stomatal opening in Arabidopsisc 2014 Landes Bioscience. © 2014 Landes Bioscience.

DOI： 10.4161/psb.28085

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

In the present study, we evaluated the modifying behavior of simple phenolic compounds on the sulfhydryl groups of glutathione and proteins. The catechol-type polyphenols, including protocatechuic acid, but neither the monophenols nor O-methylated catechol, can modify the sulfhydryl groups in a phenol oxidase-dependent manner. The possible involvement of polyphenol bioactivation in the enhancement of skin inflammation was also suggested.

DOI： 10.1080/09168451.2014.905190

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Here, we analyzed the interaction between Arabidopsis (Arabidopsis thaliana) and the American serpentine leafminer (Liriomyza trifolii), an important and intractable herbivore of many cultivated plants. We examined the role of the immunity-related plant hormone jasmonate (JA) in the plant response and resistance to leafminer feeding to determine whether JA affects host suitability for leafminers. The expression of marker genes for the JA-dependent plant defense was induced by leafminer feeding on Arabidopsis wild-type plants. Analyses of JA-insensitive coi1-1 mutants suggested the importance of JA in the plant response to leafminer feeding. The JA content of wild-type plants significantly increased after leafminer feeding. Moreover, coi1-1 mutants showed lower feeding resistance against leafminer attack than did wild-type plants. The number of feeding scars caused by inoculated adult leafminers in JA-insensitive coi1-1 mutants was higher than that in wild-type plants. In addition, adults of the following generation appeared only from coi1-1 mutants and not from wild-type plants, suggesting that the loss of the JA-dependent plant defense converted nonhost plants to accessible host plants. Interestingly, the glucosinolate-myrosinase defense system may play at most a minor role in this conversion, indicating that this major antiherbivore defense of Brassica species plants probably does not have a major function in plant resistance to leafminer. Application of JA to wild-type plants before leafminer feeding enhanced feeding resistance in Chinese cabbage (Brassica rapa), tomato (Solanum lycopersicum), and garland chrysanthemum (Chrysanthemum coronarium). Our results indicate that JA plays an important role in the plant response and resistance to leafminers and, in so doing, affects host plant suitability for leafminers.

DOI： 10.1104/pp.113.222802

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC PLANT BIOLOGISTS  

Yeast elicitor (YEL) induces stomatal closure that is mediated by a Ca2+-dependent signaling pathway. A Ca2+-dependent protein kinase, CPK6, positively regulates activation of ion channels in abscisic acid and methyl jasmonate signaling, leading to stomatal closure in Arabidopsis (Arabidopsis thaliana). YEL also inhibits light-induced stomatal opening. However, it remains unknown whether CPK6 is involved in induction by YEL of stomatal closure or in inhibition by YEL of light-induced stomatal opening. In this study, we investigated the roles of CPK6 in induction by YEL of stomatal closure and inhibition by YEL of light-induced stomatal opening in Arabidopsis. Disruption of CPK6 gene impaired induction by YEL of stomatal closure and inhibition by YEL of light-induced stomatal opening. Activation by YEL of nonselective Ca2+-permeable cation channels was impaired in cpk6-2 guard cells, and transient elevations elicited by YEL in cytosolic-free Ca2+ concentration were suppressed in cpk6-2 and cpk6-1 guard cells. YEL activated slow anion channels in wild-type guard cells but not in cpk6-2 or cpk6-1 and inhibited inward-rectifying K+ channels in wild-type guard cells but not in cpk6-2 or cpk6-1. The cpk6-2 and cpk6-1 mutations inhibited YEL-induced hydrogen peroxide accumulation in guard cells and apoplast of rosette leaves but did not affect YEL-induced hydrogen peroxide production in the apoplast of rosette leaves. These results suggest that CPK6 positively functions in induction by YEL of stomatal closure and inhibition by YEL of light-induced stomatal opening in Arabidopsis and is a convergent point of signaling pathways for stomatal closure in response to abiotic and biotic stress.

DOI： 10.1104/pp.113.224055

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Abscisic acid (ABA) induces stomatal closure and inhibits light-induced stomatal opening. The mechanisms in these two processes are not necessarily the same. It has been postulated that the ABA receptors involved in opening inhibition are different from those involved in closure induction. Here, we provide evidence that four recently identified ABA receptors (PYRABACTIN RESISTANCE1 [PYR1], PYRABACTIN RESISTANCE-LIKE1 [PYL1], PYL2, and PYL4) are not sufficient for opening inhibition in Arabidopsis (Arabidopsis thaliana). ABA-induced stomatal closure was impaired in the pyr1/pyl1/pyl2/pyl4 quadruple ABA receptor mutant. ABA inhibition of the opening of the mutant's stomata remained intact. ABA did not induce either the production of reactive oxygen species and nitric oxide or the alkalization of the cytosol in the quadruple mutant, in accordance with the closure phenotype. Whole cell patch-clamp analysis of inward-rectifying K(+) current in guard cells showed a partial inhibition by ABA, indicating that the ABA sensitivity of the mutant was not fully impaired. ABA substantially inhibited blue light-induced phosphorylation of H(+)-ATPase in guard cells in both the mutant and the wild type. On the other hand, in a knockout mutant of the SNF1-related protein kinase, srk2e, stomatal opening and closure, reactive oxygen species and nitric oxide production, cytosolic alkalization, inward-rectifying K(+) current inactivation, and H(+)-ATPase phosphorylation were not sensitive to ABA.

DOI： 10.1104/pp.113.223826

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

We recently demonstrated that endogenous abscisic acid (ABA) is involved in methyl jasmonate (MeJA)-induced stomatal closure in Arabidopsis thaliana. In this study, we investigated whether endogenous ABA is involved in MeJA-induced reactive oxygen species (ROS) and nitric oxide (NO) production and cytosolic alkalization in guard cells using an ABA-deficient Arabidopsis mutant, aba2-2, and an inhibitor of ABA biosynthesis, fluridon (FLU). The aba2-2 mutation impaired MeJA-induced ROS and NO production. FLU inhibited MeJA-induced ROS production in wild-type guard cells. Pretreatment with 0.1 μM ABA, which does not induce stomatal closure in the wild type, complemented the insensitivity to MeJA of the aba2-2 mutant. However, MeJA induced cytosolic alkalization in both wild-type and aba2-2 guard cells. These results suggest that endogenous ABA is involved in MeJA-induced ROS and NO production but not in MeJA-induced cytosolic alkalization in Arabidopsis guard cells.

DOI： 10.1016/j.jplph.2013.03.011

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: In this study, whole krill oil (WKO) and phospholipid-type krill oil (PKO) with different lipid composition were prepared. The effects of KO intake on plasma cholesterol and glucose levels in Wistar rats fed a high-cholesterol diet (HCD) were investigated. RESULTS: WKO contained 37.63% triglycerides, 48.37% phospholipids, 13.54% free fatty acids and 0.66% cholesterol, whereas the corresponding values for PKO were 0.59, 69.80, 28.53 and 1.09% respectively. Meanwhile, PKO contained much more polyunsaturated fatty acids (PUFA, 37.76%) than WKO (28.36%). After 4 weeks of HCD consumption, plasma levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and glucose increased significantly, but that of high-density lipoprotein cholesterol (HDL-C) decreased significantly. The intake of PKO and WKO for 4 weeks caused a significant reduction in body weight gain and plasma levels of TC and LDL-C in HCD-fed rats. Compared with WKO, PKO was more effective in decreasing plasma TC and LDL-C levels. CONCLUSION: PKO showed better overall cholesterol-lowering effects than WKO, which may be due to its higher n-3 PUFA levels.

DOI： 10.1002/jsfa.6072

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Stomata open in response to light and close after exposure to abscisic acid (ABA). They regulate gas exchange between plants and the atmosphere, enabling plants to adapt to changing environmental conditions. ABA binding to receptors initiates a signaling cascade that involves protein phosphorylation. We show that ABA induced the phosphorylation of three basic helix-loop-helix (bHLH) transcription factors, called AKSs (ABA-responsive kinase substrates; AKS1, AKS2, and AKS3), in Arabidopsis guard cells. In their unphosphorylated state, AKSs facilitated stomatal opening through the transcription of genes encoding inwardly rectifying K⁺ channels. aks1aks2-1 double mutant plants showed decreases in light-induced stomatal opening, K⁺ accumulation in response to light, activity of inwardly rectifying K⁺ channels, and transcription of genes encoding major inwardly rectifying K⁺ channels without affecting ABA-mediated stomatal closure. Overexpression of potassium channel in Arabidopsis thaliana 1 (KAT1), which encodes a major inwardly rectifying K⁺ channel in guard cells, rescued the phenotype of aks1aks2-1 plants. AKS1 bound directly to the promoter of KAT1, an interaction that was attenuated after ABA-induced phosphorylation. The ABA agonist pyrabactin induced phosphorylation of AKSs. Our results demonstrate that the AKS family of bHLH transcription factors facilitates stomatal opening through the transcription of genes encoding inwardly rectifying K⁺ channels and that ABA suppresses the activity of these channels by triggering the phosphorylation of AKS family transcription factors.

DOI： 10.1126/scisignal.2003760

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Salicylic acid (SA), yeast elicitor (YEL), and chitosan (CHT) induced stomatal closure in Arabidopsis wild-type and aba2-2 plants, induced stomatal closure in fluridon-treated wild-type plants, and induced stomatal closure in aos mutants. These results suggest that neither endogenous abscisic acid nor endogenous jasmonic acid is involved in SA-, YEL-, or CHT-induced stomatal closure.

DOI： 10.1271/bbb.120980

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We report that two mitogen-activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate abscisic acid (ABA)-induced stomatal closure in Arabidopsis thaliana. Yeast elicitor (YEL) induced stomatal closure accompanied by intracellular reactive oxygen species (ROS) accumulation and cytosolic free calcium concentration ([Ca2+]cyt) oscillation. In this study, we examined whether these two MAP kinases are involved in YEL-induced stomatal closure using MAPKK inhibitors, PD98059 and U0126, and MAPK mutants, mpk9, mpk12 and mpk9 mpk12. Both PD98059 and U0126 inhibited YEL-induced stomatal closure. YEL induced stomatal closure in the mpk9 and mpk12 mutants but not in the mpk9 mpk12 mutant, suggesting that a MAPK cascade involving MPK9 and MPK12 functions in guard cell YEL signalling. However, YEL induced extracellular ROS production, intracellular ROS accumulation and cytosolic alkalisation in the mpk9, mpk12 and mpk9 mpk12 mutants. YEL induced [Ca2+]cyt oscillations in both wild type and mpk9 mpk12 mutant. These results suggest that MPK9 and MPK12 function redundantly downstream of extracellular ROS production, intracellular ROS accumulation, cytosolic alkalisation and [Ca2+]cyt oscillation in YEL-induced stomatal closure in Arabidopsis guard cells and are shared with ABA signalling. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

DOI： 10.1111/j.1438-8677.2012.00671.x

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1007/s00344-012-9291-7

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その他リンク： http://link.springer.com/article/10.1007/s00344-012-9291-7/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Transpiration and gas exchange occur through stomata. Thus, the control of stomatal aperture is important for the efficiency and regulation of water use, and for the response to drought. Here, we demonstrate that SIZ1-mediated endogenous salicylic acid (SA) accumulation plays an important role in stomatal closure and drought tolerance. siz1 reduced stomatal apertures. The reduced stomatal apertures of siz1 were inhibited by the application of peroxidase inhibitors, salicylhydroxamic acid and azide, which inhibits SA-dependent reactive oxygen species (ROS) production, but not by an NADPH oxidase inhibitor, diphenyl iodonium chloride, which inhibits ABA-dependent ROS production. Furthermore, the introduction of nahG into siz1, which reduces SA accumulation, restored stomatal opening. Stomatal closure is generally induced by water deficit. The siz1 mutation caused drought tolerance, whereas nahG siz1 suppressed the tolerant phenotype. Drought stresses also induced expression of SA-responsive genes, such as PR1 and PR2. Furthermore, other SA-accumulating mutants, cpr5 and acd6, exhibited stomatal closure and drought tolerance, and nahG suppressed the phenotype of cpr5 and acd6, as did siz1 and nahG siz1. Together, these results suggest that SIZ1 negatively affects stomatal closure and drought tolerance through the accumulation of SA. © 2012 The Authors.

DOI： 10.1111/tpj.12014

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記述言語：日本語   出版者・発行元：日本食品照射研究協議会  

シロイヌナズナ野生株（Col-0）及びcat2変異体への10 kGyのガンマ線照射は，H₂O₂蓄積及び脂質過酸化生成を誘起したが，0.1 kGyと1 kGyのガンマ線照射は，誘起しなかった。また，野生株と変異体との間で，H₂O₂蓄積及び脂質過酸化に有意な差はなかった。以上の結果より，カタラーゼCAT2は，ガンマ線によって誘起される損傷を軽減するための重要な酵素ではないことが示唆された。

DOI： 10.5986/jrafi.48.38

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その他リンク： http://agriknowledge.affrc.go.jp/RN/2010870113

記述言語：英語   出版者・発行元：Japanese Society for Food Science and Technology  

Aqueous solutions of dispersed lycopene in which gum arabic, gum ghatti and polyglycerol monostearate ester had been used as emulsifiers were photoirradiated. The photodegradation rate of lycopene tended to vary depending on the amount of polyglycerol monostearate ester used. We found that the photodegradation rate of lycopene with polyglycerol monostearate ester was considerably slower than those with gum arabic and gum ghatti. Therefore, this study suggests that the absorption state of the emulsifier on the crystal surface may affect the photodegradation rate of lycopene.

DOI： 10.3136/fstr.19.983

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media SA  

The phytohormone abscisic acid (ABA) induces stomatal closure in response to drought stress, leading to reduction of transpirational water loss. A thiol tripeptide glutathione (GSH) is an important regulator of cellular redox homeostasis in plants. Although it has been shown that cellular redox state of guard cells controls ABA-mediated stomatal closure, roles of GSH in guard cell ABA signaling were largely unknown. Recently we demonstrated that GSH functions as a negative regulator of ABA signaling in guard cells. In this study we performed more detailed analyses to reveal how GSH regulates guard cell ABA signaling using the GSH-deficient Arabidopsis mutant cad2-1. The cad2-1 mutant exhibited reduced water loss from rosette leaves. Whole-cell current recording using patch clamp technique revealed that the cad2-1 mutation did not affect ABA regulation of S-type anion channels. We found enhanced activation of Ca(2+) permeable channels by hydrogen peroxide (H2O2) in cad2-1 guard cells. The cad2-1 mutant showed enhanced H2O2-induced stomatal closure and significant increase of ROS accumulation in whole leaves in response to ABA. Our findings provide a new understanding of guard cell ABA signaling and a new strategy to improve plant drought tolerance.

DOI： 10.3389/fpls.2013.00472

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記述言語：日本語   出版者・発行元：日本食品照射研究協議会  

ガンマ線を用いた食品照射は，穀物やスパイスの害虫の侵入を抑制する手段の一つである。我々は，&lt;i&gt;Tribolium castaneum&lt;/i&gt;の幼虫と成虫へのガンマ線照射の影響を調べた。羽化は，500Gyの照射で完全に阻害された。成虫の生存率は，500Gy以上の照射で著しく減少した。中性条件でのコメントアッセイの結果より，500Gyまたは1000Gy照射によるDNA損傷は，不可逆的に増加したが，100Gy照射によるDNA損傷は一過的に増加した。100Gy照射ではDNAの修復が行われていることが示唆された。 以上の結果より500Gy以上のガンマ線照射は，&lt;i&gt;T. castaneum &lt;/i&gt;の幼虫と成虫の駆除に十分であることが示された。

DOI： 10.5986/jrafi.48.19

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Gamma irradiation increased catalase activities at 0.1 kGy and decreased them at 10 kGy in Arabidopsis wild type and catalase-deficient mutants, cat3-1 and cat1 cat3. Irradiation induced DNA damage, H2O2 accumulation, and lipid peroxidation in both mutants as well as the wild type. Thus catalases might not be key enzymes protecting gamma irradiation-induced damage.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Isothiocyanates, nitriles, and thiocyanates are degradation products of glucosinolates in crucifer plants. In this study, we investigated the stomatal response to allyl isothiocyanate (AITC), 3-butenenitrile (3BN), and ethyl thiocyanate (ESCN) in Arabidopsis. AITC, 3BN, and ESCN induced stomatal closure in the wild type and the atrbohD atrbohF mutant. Stomatal closure was inhibited by catalase and salicylhydroxamic acid (SHAM). The degradation products induced extracellular reactive oxygen species (ROS) production in the rosette leaves, and intracellular ROS accumulation, NO production, and cytosolic free calcium concentration ([Ca(2+)]cyt) oscillations in guard cells, which were inhibited by SHAM. These results suggest that glucosinolate degradation products induce stomatal closure accompanied by extracellular ROS production mediated by SHAM-sensitive peroxidases, intracellular ROS accumulation, and [Ca(2+)]cyt oscillation in Arabidopsis.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Food-additive grades of capsanthin, lutein, lycopene, and β-carotene dispersed in aqueous solutions were photo-irradiated using a Xenon weather meter, and the levels of carotenoids were measured by HPLC and the absorbance method. Capsanthin photo-degraded more rapidly than the carotenoids tested, with less oxygen consumption. Unlike carotenes, capsanthin was partially converted into analogous colored compounds during degradation.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

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その他リンク： http://search.jamas.or.jp/link/ui/2013124407

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Methylglyoxal (MG) is a highly reactive metabolite derived from glycolysis. In this study, we examined the effect of MG on seed germination, root elongation, chlorosis and stress-responsive gene expression in Arabidopsis using an abscisic acid (ABA)-deficient mutant, aba2-2. In the wild type, 0.1 mm MG did not affect germination but delayed root elongation, whereas 1.0 mm MG inhibited germination and root elongation and induced chlorosis. MG increased transcription levels of RD29B and RAB18 in a dose-dependent manner but did not affect RD29A transcription level. In contrast, in the aba2-2 mutant, MG inhibition of seed germination at 1.0 mm and 10.0 mm and a delay of root elongation at 0.1 mm MG were mitigated, although there was no significant difference in chlorosis between the wild type and mutant. Moreover, the aba2-2 mutation impaired MG-induced RD29B and RAB18 gene expression. These observations suggest that MG not only directly inhibits germination and root elongation but also indirectly modulates these processes via endogenous ABA in Arabidopsis.

DOI： 10.1111/j.1438-8677.2012.00607.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Methylglyoxal (MG) is one of the aldehydes accumulated in plants under environmental stress. Cytosolic ascorbate peroxidase (cAPX) plays a key role in the protection of cells from oxidative damage by scavenging reactive oxygen species in higher plants. A cDNA encoding cAPX, named NtcAPX, was isolated from Nicotiana tabacum. We characterized recombinant NtcAPX (rNtcAPX) as a fusion protein with glutathione S-transferase to investigate the effects of MG on APX. NtcAPX consists of 250 amino acids and has a deduced molecular mass of 27.5 kDa. The rNtcAPX showed a higher APX activity. MG treatments resulted in a reduction of APX activity and modifications of amino groups in rNtcAPX with increasing K(m) for ascorbate. On the contrary, neither NaCl nor cadmium reduced the activity of APX. The present study suggests that inhibition of APX is in part due to the modification of amino acids by MG.

DOI： 10.1002/jbt.21423

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Methyl jasmonate (MeJA)-induced stomatal closure is accompanied by the accumulation of hydrogen peroxide (H₂O₂) in guard cells. In this study, we investigated the roles of catalases (CATs) in MeJA-induced stomatal closure using cat mutants cat2, cat3-1 and cat1 cat3, and the CAT inhibitor, 3-aminotriazole (AT). When assessed with 2',7'-dichlorodihydrofluorescein, the reduction of catalase activity by means of mutations and the inhibitor accumulated higher basal levels of H₂O₂ in guard cells whereas they did not affect stomatal aperture in the absence of MeJA. In contrast, the cat mutations and the treatment with AT potentiated MeJA-induced stomatal closure and MeJA-induced H₂O₂ production. These results indicate that CATs negatively regulate H₂O₂ accumulation in guard cells and suggest that inducible H₂O₂ production rather than constitutive elevation modulates stomatal apertures in Arabidopsis.

DOI： 10.1016/j.jplph.2012.03.006

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Methylglyoxal (MG) is an oxygenated short aldehyde and a glycolytic intermediate that accumulates in plants under environmental stresses. Being a reactive α-oxoaldehyde, MG may act as a signaling molecule in plants during stresses. We investigated whether MG induces stomatal closure, reactive oxygen species (ROS) production, and cytosolic free calcium concentration ([Ca²⁺](cyt)) to clarify roles of MG in Arabidopsis guard cells. MG induced production of ROS and [Ca²⁺](cyt) oscillations, leading to stomatal closure. The MG-induced stomatal closure and ROS production were completely inhibited by a peroxidase inhibitor, salicylhydroxamic acid (SHAM), but were not affected by an NAD(P)H oxidase mutation, atrbohD atrbohF. Furthermore, the MG-elicited [Ca²⁺](cyt) oscillations were significantly suppressed by SHAM but not by the atrbohD atrbohF mutation. Neither endogenous abscisic acid nor endogenous methyl jasmonate was involved in MG-induced stomatal closure. These results suggest that intrinsic metabolite MG can induce stomatal closure in Arabidopsis accompanied by extracellular ROS production mediated by SHAM-sensitive peroxidases, intracellular ROS accumulation, and [Ca²⁺](cyt) oscillations.

DOI： 10.1016/j.jplph.2012.02.007

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We investigated the molecular mechanisms underlying phloxine B (PhB)-induced photocytotoxicity in human T lymphocytic leukemia Jurkat cells. In addition to apoptosis-related biochemical events, photo-irradiated PhB generated intracellular reactive oxygen species (ROS), induced phosphorylation of c-Jun-N-terminal kinase (JNK) in an oxidative stress-dependent manner and up-regulated the gene expression of interferon (IFN)-γ, an inducer of diverse apoptosis-related molecules in activated T cells. PhB-induced apoptosis was significantly inhibited by N-acetyl-l-cysteine, but not by catalase, indicating that ROS generation occurred intracellularly, and by SP600125 and AG490, specific inhibitors of JNK and IFN-γ signaling, respectively, confirming their roles in the apoptotic pathway. IFN-γ up-regulation was also inhibited by SP600125, indicating that it was downstream of JNK activation. These results suggest that PhB-induced apoptosis in Jurkat cells partially involves the intracellular oxidative stress-sensitive and T cell-specific IFN-γ pathway. These data present a novel insight into the mechanisms of photocytotoxicity induced by artificial food colorants in human T lymphocytic leukemia cells.

DOI： 10.1016/j.fct.2012.03.011

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: Hydrolysates prepared from sea urchin (Strongylocentrotus nudus) gonad by enzymatic treatment showed strong 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and reducing power. RESULTS: Hydrolysis of S. nudus gonad by the commercial protease papain was optimised for maximum degree of hydrolysis (DH) and trichloroacetic acid-soluble peptide index (TCA-SPI) using response surface methodology. Results showed that the optimal conditions were the following: temperature of 48.83 °C, pH of 6.92, enzyme-to-substrate ratio of 3143 U g(-1), and substrate concentration of 83.5 g L(-1). Under these conditions, a DH of 27.96 ± 0.54% and a TCA-SPI of 57.32 ± 0.63% were obtained. The hydrolysate prepared in the optimal conditions was fractionated by an ultra-filtration system and the resultant fraction below 10 kDa was found to effectively scavenge hydroxyl radical (EC(50) = 13.29 ± 0.33 mg mL(-1)) and hydrogen peroxide (EC(50) = 16.40 ± 0.37 mg mL(-1)), inhibit lipid peroxidation (EC(50) = 11.05 ± 0.62 mg mL(-1)), chelate Fe(2+) (EC(50) = 7.26 ± 0.44 mg mL(-1)), and protect mice macrophages against death induced by tert-butyl hydroperoxide. CONCLUSION: Hydrolysates prepared from S. nudus gonad have the potential to be applied as natural antioxidant agents.

DOI： 10.1002/jsfa.5534

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Food irradiation is a form of food processing to extend the shelf life and reduce spoilage of food. We examined the effects of γ radiation on the fatty acid composition, lipid peroxidation level, and antioxidative activity of soybean and soybean oil which both contain a large amount of unsaturated fatty acids. Irradiation at 10 to 80 kGy under aerobic conditions did not markedly change the fatty acid composition of soybean. While 10-kGy irradiation did not markedly affect the fatty acid composition of soybean oil under either aerobic or anaerobic conditions, 40-kGy irradiation considerably altered the fatty acid composition of soybean oil under aerobic conditions, but not under anaerobic conditions. Moreover, 40-kGy irradiation produced a significant amount of trans fatty acids under aerobic conditions, but not under anaerobic conditions. Irradiating soybean oil induced lipid peroxidation and reduced the radical scavenging activity under aerobic conditions, but had no effect under anaerobic conditions. These results indicate that the fatty acid composition of soybean was not markedly affected by radiation at 10 kGy, and that anaerobic conditions reduced the degradation of soybean oil that occurred with high doses of γ radiation.

DOI： 10.1271/bbb.110859

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

We investigated the mechanism of selenium (Se) tolerance using an Arabidopsis thaliana knockout mutant of a sulfate transporter, sultr1;2. Se stress inhibited plant growth, decreased chlorophyll contents, and increased protein oxidation and lipid peroxidation in the wild type, whereas the sultr1;2 mutation mitigated damage of these forms, indicating that sultr1;2 is more tolerant of Se than the wild type is. The accumulation of symplastic Se was suppressed in sultr1;2 as compared to the wild type, and the chemical speciation of Se in the mutant was different from that in the wild type. Regardless of Se stress, the activities of ascorbate peroxidase, catalase, and peroxidase in the mutant were higher than in the wild type, while the activity of superoxide dismutase in the mutant was the same as in the wild type. These results suggest that the sultr1;2 mutation confers Se tolerance on Arabidopsis by decreasing symplastic Se and maintaining antioxidant enzyme activities.

DOI： 10.1271/bbb.111000

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1104/pp.112.195578

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本農芸化学会  

Methylglyoxal (MG) is a reactive aldehyde derived by glycolysis. In Arabidopsis, MG inhibited light-induced stomatal opening in a dose-dependent manner. It significantly inhibited both inward-rectifying potassium (K_in) channels in guard-cell protoplasts and an Arabidopsis K_in channel, KAT1, heterologously expressed in Xenopus oocytes. Thus it appears that MG inhibition of stomatal opening involves MG inhibition of K⁺ influx into guard cells.

DOI： 10.1271/bbb.110885

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その他リンク： http://search.jamas.or.jp/link/ui/2012301713

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

Pathogen/microbe-or plant-derived signaling molecules (PAMPs/MAMPs/DAMPs) or elicitors induce increases in the cytosolic concentration of free Ca2+ followed by a series of defense responses including biosynthesis of antimicrobial secondary metabolites called phytoalexins; however, the molecular links and regulatory mechanisms of the phytoalexin biosynthesis remains largely unknown. A putative voltage-gated cation channel, OsTPC1 has been shown to play a critical role in hypersensitive cell death induced by a fungal xylanase protein (TvX) in suspension-cultured rice cells. Here we show that TvX induced a prolonged increase in cytosolic Ca2+, mainly due to a Ca2+ influx through the plasma membrane. Membrane fractionation by two-phase partitioning and immunoblot analyses revealed that OsTPC1 is localized predominantly at the plasma membrane. In retrotransposon- insertional Ostpc1 knock-out cell lines harboring a Ca2+-sensitive photoprotein, aequorin, TvX-induced Ca2+ elevation was significantly impaired, which was restored by expression of OsTPC1. TvX-induced production of major diterpenoid phytoalexins and the expression of a series of diterpene cyclase genes involved in phytoalexin biosynthesis were also impaired in the Ostpc1 cells. Whole cell patch clamp analyses of OsTPC1 heterologously expressed in HEK293T cells showed its voltage-dependent Ca2+-permeability. These results suggest that OsTPC1 plays a crucial role in TvX-induced Ca2+ influx as a plasma membrane Ca2+ permeable channel consequently required for the regulation of phytoalexin biosynthesis in cultured rice cells.

DOI： 10.1074/jbc.M111.337659

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Pre-treatment with α-tocopherol (α-Toc) potentiated cytotoxicity induction by benzyl isothiocyanate (BITC). Biochemical events related to apoptosis, such as DNA ladder formation and caspase-3 activation, were also enhanced by α-Toc. These results suggest a significant role of the caspase-3 pathway in apoptosis induction regulated by α-Toc in combination.

DOI： 10.1271/bbb.110665

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

In the present study, we examined the toxicity of benzyl ITC (BITC) and its urinary mercapturic acid metabolite (BITC-NAC), using a normal renal proximal tubular cell line, pig LLC-PK1. BITC increased cell death with an IC(50) value of about 7 μM, whereas the cytotoxic effect of BITC-NAC was five times weaker than that of BITC. We observed a significant necrosis of the compounds on LLC-PK1 cells with oxidative stress. In the presence of 5 mM glutathione (GSH), comparable to physiological levels, the cytotoxicity of BITC-NAC as well as BITC was significantly reduced. Furthermore, the increase in intracellular GSH levels by pretreatment with NAC before the BITC treatment resulted in inhibition of the BITC-induced necrotic events as well as intracellular oxidative stress. These results suggest that GSH is a determinant of cellular resistance against the BITC-mediated and oxidative stress-dependent cytotoxicity in renal proximal tubular cells.

DOI： 10.1021/jf2052042

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

An abscisic acid (ABA)-insensitive Vicia faba mutant, fia (fava bean impaired in ABA-induced stomatal closure) had previously been isolated. In this study, it was investigated how FIA functions in ABA signalling in guard cells of Vicia faba. Unlike ABA, methyl jasmonate (MeJA), H2O2, and nitric oxide (NO) induced stomatal closure in the fia mutant. ABA did not induce production of either reactive oxygen species or NO in the mutant. Moreover, ABA did not suppress inward-rectifying K+ (K-in) currents or activate ABA-activated protein kinase (AAPK) in mutant guard cells. These results suggest that FIA functions as an early signal component upstream of AAPK activation in ABA signalling but does not function in MeJA signalling in guard cells of Vicia faba.

DOI： 10.1093/jxb/err369

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Salinity significantly increased trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS) uptake and decreased the K⁺/Na⁺ ratio in salt-sensitive rice (Nipponbare) but did not markedly in salt-tolerant rice (Pokkali). Proline and glycinebetaine (betaine) suppressed the increase in PTS uptake and the decrease in the K⁺/Na⁺ ratio in Nipponbare, but did not affect PTS uptake or the K⁺/Na⁺ ratio in Pokkali.

DOI： 10.1271/bbb.120233

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Reactive oxygen species (ROS), including hydrogen peroxide (H(2)O(2)), are among the important second messengers in abscisic acid (ABA) signaling in guard cells. In this study, to investigate specific roles of H(2)O(2) in ABA signaling in guard cells, we examined the effects of mutations in the guard cell-expressed catalase (CAT) genes, CAT1 and CAT3, and of the CAT inhibitor 3-aminotriazole (AT) on stomatal movement. The cat3 and cat1 cat3 mutations significantly reduced CAT activities, leading to higher basal level of H(2)O(2) in guard cells, when assessed by 2',7'-dichlorodihydrofluorescein, whereas they did not affect stomatal aperture size under non-stressed condition. In addition, AT-treatment at concentrations that abolish CAT activities, showed trivial affect on stomatal aperture size, while basal H(2)O(2) level increased extensively. In contrast, cat mutations and AT-treatment potentiated ABA-induced stomatal closure. Inducible ROS production triggered by ABA was observed in these mutants and wild type as well as in AT-treated guard cells. These results suggest that ABA-inducible cytosolic H(2)O(2) elevation functions in ABA-induced stomatal closure, while constitutive increase of H(2)O(2) do not cause stomatal closure.

DOI： 10.1016/j.jplph.2011.05.006

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

We found that glutathione (GSH) is involved in abscisic acid (ABA)-induced stomatal closure. Regulation of ABA signaling by GSH in guard cells was investigated using an Arabidopsis mutant, cad2-1, that is deficient in the first GSH biosynthesis enzyme, γ-glutamylcysteine synthetase, and a GSH-decreasing chemical, 1-chloro-2,4-dinitrobenzene (CDNB). Glutathione contents in guard cells decreased along with ABA-induced stomatal closure. Decreasing GSH by both the cad2-1 mutation and CDNB treatment enhanced ABA-induced stomatal closure. Glutathione monoethyl ester (GSHmee) restored the GSH level in cad2-1 guard cells and complemented the stomatal phenotype of the mutant. Depletion of GSH did not significantly increase ABA-induced production of reactive oxygen species in guard cells and GSH did not affect either activation of plasma membrane Ca(2+)-permeable channel currents by ABA or oscillation of the cytosolic free Ca(2+) concentration induced by ABA. These results indicate that GSH negatively modulates a signal component other than ROS production and Ca(2+) oscillation in ABA signal pathway of Arabidopsis guard cells.

DOI： 10.1016/j.jplph.2011.06.002

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

Isothiocyanates (ITCs) are degradation products of glucosinolates in crucifer plants and have repellent effect on insects, pathogens and herbivores. In this study, we report that exogenously applied allyl isothiocyanate (AITC) induced stomatal closure in Arabidopsis via production of reactive oxygen species (ROS) and nitric oxide (NO), and elevation of cytosolic Ca(2+) . AITC-induced stomatal closures were partially inhibited by an inhibitor of NADPH oxidase and completely inhibited by glutathione monoethyl ester (GSHmee). AITC-induced stomatal closure and ROS production were examined in abscisic acid (ABA) deficient mutant aba2-2 and methyl jasmonate (MeJA)-deficient mutant aos to elucidate involvement of endogenous ABA and MeJA. Genetic evidences have demonstrated that AITC-induced stomatal closure required MeJA priming but not ABA priming. These results raise the possibility that crucifer plants produce ITCs to induce stomatal closure, leading to suppression of water loss and invasion of fungi through stomata.

DOI： 10.1111/j.1365-3040.2011.02385.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

Methyl jasmonate (MeJA) induces stomatal closure similar to abscisic acid (ABA), and MeJA signaling in guard cells shares some signal components with ABA signaling. As part of this process, MeJA as well as ABA induce the elevation and oscillation of cytosolic free-calcium concentrations ([Ca(2+)](cyt)) in guard cells. While abscisic acid-induced [Ca(2+)](cyt) oscillation has been extensively studied, MeJA-induced [Ca(2+)](cyt) oscillation is less well understood. In this study, we investigated the effects of K252a (a broad-range protein kinase inhibitor) and okadaic acid (OA, a protein phosphatase 1 and 2A inhibitor) on MeJA-induced [Ca(2+)](cyt) oscillation in guard cells of Arabidopsis thaliana ecotype Columbia expressing the Ca(2+) reporter yellow cameleon 3.6. The protein kinase inhibitor K252a abolished MeJA-induced stomatal closure and reduced MeJA-elicited [Ca(2+)](cyt) oscillation. The protein phosphatase inhibitor OA, on the other hand, did not inhibit these processes. These results suggest that MeJA signaling involves activation of K252a-sensitive protein kinases upstream of [Ca(2+)](cyt) oscillation but not activation of an OA-sensitive protein phosphatase in guard cells of A. thaliana ecotype Columbia.

DOI： 10.1016/j.jplph.2011.05.004

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

We investigated the roles of catalase (CAT) in abscisic acid (ABA)-induced stomatal closure using a cat2 mutant and an inhibitor of CAT, 3-aminotriazole (AT). Constitutive reactive oxygen species (ROS) accumulation due to the CAT2 mutation and AT treatment did not affect stomatal aperture in the absence of ABA, whereas ABA-induced stomatal closure, ROS production, and [Ca²⁺]_cyt oscillation were enhanced.

DOI： 10.1271/bbb.110344

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.4161/psb.6.7.15439

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER JAPAN KK  

Mg-chelatase H subunit (CHLH) is a multifunctional protein involved in chlorophyll synthesis, plastid-to-nucleus retrograde signaling, and ABA perception. However, whether CHLH acts as an actual ABA receptor remains controversial. Here we present evidence that CHLH affects ABA signaling in stomatal guard cells but is not itself an ABA receptor. We screened ethyl methanesulfonate-treated Arabidopsis thaliana plants with a focus on stomatal aperture-dependent water loss in detached leaves and isolated a rapid transpiration in detached leaves 1 (rtl1) mutant that we identified as a novel missense mutant of CHLH. The rtl1 and CHLH RNAi plants showed phenotypes in which stomatal movements were insensitive to ABA, while the rtl1 phenotype showed normal sensitivity to ABA with respect to seed germination and root growth. ABA-binding analyses using H-3-labeled ABA revealed that recombinant CHLH did not bind ABA, but recombinant pyrabactin resistance 1, a reliable ABA receptor used as a control, showed specific binding. Moreover, we found that the rtl1 mutant showed ABA-induced stomatal closure when a high concentration of extracellular Ca2+ was present and that a knockout mutant of Mg-chelatase I subunit (chli1) showed the same ABA-insensitive phenotype as rtl1. These results suggest that the Mg-chelatase complex as a whole affects the ABA-signaling pathway for stomatal movements.

DOI： 10.1007/s10265-011-0426-x

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: Phloxine B (PhB; 2',4',5',7'-tetrabromo-4,5,6,7-tetrachloro-fluorescein), an artificial xanthene colorant, has been used as a red coloring agent in drugs and cosmetics as well as foods in some countries. However, little effort has been devoted to the study of this colorant as a potentially useful medicinal agent. METHODS: We investigated the daily light-induced photocytotoxicity of PhB in two human leukemia cells, HL-60 and Jurkat, and its underlying mechanisms by in vitro experiments using antioxidants. REUSLTS AND CONCLUSIONS: PhB inhibited cell proliferation more preferentially to HL-60 cells than to Jurkat cells. Co-treatment of catalase completely blocked the photocytotoxicity by PhB in HL-60 cells, whereas the effect of histidine was only partial, suggesting that hydrogen peroxide (H(2)O(2)), rather than singlet oxygen, might be a prerequisite for the PhB-induced HL-60 cell death. Actually, PhB produced a significant amount of H(2)O(2) in the media as well as in the cells in concentration- and light-dependent manners. Furthermore, methionine, a hypochlorous acid (HOCl) scavenger, also significantly attenuated the cytotoxicity in HL-60 cells, but not in Jurkat cells, indicating the involvement of myeloperoxidase (MPO)-dependent hypohalous acid formation during the photocytotoxicity. In vitro experiments revealed that halogenated tyrosine was generated from the reaction of bovine serum albumin with PhB and HL-60 cell lysate. The present findings suggested that PhB induced a differential photodynamic action in the MPO-containing leukemia cells through an H(2)O(2)-dependent mechanism. GENERAL SIGNIFICANCE: Our findings provide new insights into the molecular mechanisms underlying the PhB-induced apoptosis and also evaluated PhB as a promising PDT agent.

DOI： 10.1016/j.bbagen.2011.04.010

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

<title>Abstract</title>
In this study, we examined the involvement of endogenous abscisic acid (ABA) in methyl jasmonate (MeJA)-induced stomatal closure using an inhibitor of ABA biosynthesis, fluridon (FLU), and an ABA-deficient Arabidopsis (Arabidopsis thaliana) mutant, aba2-2. We found that pretreatment with FLU inhibited MeJA-induced stomatal closure but not ABA-induced stomatal closure in wild-type plants. The aba2-2 mutation impaired MeJA-induced stomatal closure but not ABA-induced stomatal closure. We also investigated the effects of FLU and the aba2-2 mutation on cytosolic free calcium concentration ([Ca2+]cyt) in guard cells using a Ca2+-reporter fluorescent protein, Yellow Cameleon 3.6. In wild-type guard cells, FLU inhibited MeJA-induced [Ca2+]cyt elevation but not ABA-induced [Ca2+]cyt elevation. The aba2-2 mutation did not affect ABA-elicited [Ca2+]cyt elevation but suppressed MeJA-induced [Ca2+]cyt elevation. We also tested the effects of the aba2-2 mutation and FLU on the expression of MeJA-inducible VEGETATIVE STORAGE PROTEIN1 (VSP1). In the aba2-2 mutant, MeJA did not induce VSP1 expression. In wild-type leaves, FLU inhibited MeJA-induced VSP1 expression. Pretreatment with ABA at 0.1 μm, which is not enough concentration to evoke ABA responses in the wild type, rescued the observed phenotypes of the aba2-2 mutant. Finally, we found that in wild-type leaves, MeJA stimulates the expression of 9-CIS-EPOXYCAROTENOID DIOXYGENASE3, which encodes a crucial enzyme in ABA biosynthesis. These results suggest that endogenous ABA could be involved in MeJA signal transduction and lead to stomatal closure in Arabidopsis guard cells.

DOI： 10.1104/pp.111.172254

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

Salicylic acid (SA), a ubiquitous phenolic phytohormone, is involved in many plant physiological processes including stomatal movement. We analysed SA-induced stomatal closure, production of reactive oxygen species (ROS) and nitric oxide (NO), cytosolic calcium ion ([Ca²+](cyt)) oscillations and inward-rectifying potassium (K+(in)) channel activity in Arabidopsis. SA-induced stomatal closure was inhibited by pre-treatment with catalase (CAT) and superoxide dismutase (SOD), suggesting the involvement of extracellular ROS. A peroxidase inhibitor, SHAM (salicylhydroxamic acid) completely abolished SA-induced stomatal closure whereas neither an inhibitor of NADPH oxidase (DPI) nor atrbohD atrbohF mutation impairs SA-induced stomatal closures. 3,3'-Diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) stainings demonstrated that SA induced H₂O₂ and O₂⁻ production. Guard cell ROS accumulation was significantly increased by SA, but that ROS was suppressed by exogenous CAT, SOD and SHAM. NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) suppressed the SA-induced stomatal closure but did not suppress guard cell ROS accumulation whereas SHAM suppressed SA-induced NO production. SA failed to induce [Ca²+](cyt) oscillations in guard cells whereas K+(in) channel activity was suppressed by SA. These results indicate that SA induces stomatal closure accompanied with extracellular ROS production mediated by SHAM-sensitive peroxidase, intracellular ROS accumulation and K+(in) channel inactivation.

DOI： 10.1111/j.1365-3040.2010.02253.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

<title>Abstract</title>
Previous studies have demonstrated that methyl jasmonate (MeJA) induces stomatal closure dependent on change of cytosolic free calcium concentration in guard cells. However, these molecular mechanisms of intracellular Ca2+ signal perception remain unknown. Calcium-dependent protein kinases (CDPKs) function as Ca2+ signal transducers in various plant physiological processes. It has been reported that four Arabidopsis (Arabidopsis thaliana) CDPKs, CPK3, CPK6, CPK4, and CPK11, are involved in abscisic acid signaling in guard cells. It is also known that there is an interaction between MeJA and abscisic acid signaling in guard cells. In this study, we examined the roles of these CDPKs in MeJA signaling in guard cells using Arabidopsis mutants disrupted in the CDPK genes. Disruption of the CPK6 gene impaired MeJA-induced stomatal closure, but disruption of the other CDPK genes did not. Despite the broad expression pattern of CPK6, we did not find other remarkable MeJA-insensitive phenotypes in the cpk6-1 mutant. The whole-cell patch-clamp analysis revealed that MeJA activation of nonselective Ca2+-permeable cation channels is impaired in the cpk6-1 mutant. Consistent with this result, MeJA-induced transient cytosolic free calcium concentration increments were reduced in the cpk6-1 mutant. MeJA failed to activate slow-type anion channels in the cpk6-1 guard cells. Production of early signal components, reactive oxygen species and nitric oxide, in guard cells was elicited by MeJA in the cpk6-1 mutant as in the wild type. These results provide genetic evidence that CPK6 has a different role from CPK3 and functions as a positive regulator of MeJA signaling in Arabidopsis guard cells.

DOI： 10.1104/pp.110.162750

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Lycopene dispersed in aqueous solutions with different dissolved oxygen contents was photo-irradiated by using a xenon weather meter, and the contents of lycopene and dissolved oxygen were measured. Both the degradation of lycopene and the consumption of dissolved oxygen followed a first-order kinetics model. There was a proportional relationship between the degradation content of lycopene and the consumption of dissolved oxygen. These results indicate that dissolved oxygen would also be involved in the photolysis of lycopene.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Abscisic acid (ABA) signaling mechanisms have been studied in a broad variety of plant species using complementary analyses, taking advantage of different methodologies suitable for each plant species. Early studies on ABA biosynthesis using Solanum lycopersicum mutants suggested an importance of ABA synthesis in stomatal closure. To understand ABA signaling in guard cells, cellular, biochemical and electrophysiological studies in Vicia faba and Commelina communis have been conducted, providing fundamental knowledge that was further reconfirmed by molecular genetic studies of Arabidopsis. In this article, examples of stomatal studies in several plants and prospects in ABA research are discussed.

DOI： 10.1007/s10265-011-0435-9

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

We examined the involvement of intracellular glutathione (GSH) in methyl jasmonate (MeJA) signaling. The chlorina1-1 (ch1-1) mutation decreased GSH in guard cells and narrowed the stomatal aperture. GSH monoethyl ester increased intracellular GSH, diminishing this phenotype. GSH did not affect MeJA-induced reactive oxygen species production or cytosolic Ca²⁺ oscillation, suggesting that GSH modulates MeJA signaling downstream of production and oscillation.

DOI： 10.1271/bbb.100513

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Chitosan induced stomatal closure in wild type-plants and NADPH oxidase knock-out mutants (atrbohD atrbohF), and reactive oxygen species (ROS) production in wild-type guard cells. Closure and production were completely abolished by catalase and a peroxidase inhibitor. These results indicate that chitosan induces ROS production mediated by peroxidase, resulting in stomatal closure.

DOI： 10.1271/bbb.100340

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press  

DOI： 10.1093/pcp/pcq145

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Methylglyoxal (MG) is one of the aldehydes that accumulate in plants under environmental stress. Glutathione S-transferases (GSTs) play important roles, including detoxification, in the stress tolerance systems of plants. To determine the effects of MG, we characterized recombinant GST. MG decreased GST activity and thiol contents with increasing K_m. GST can serve as a target of MG modification, which is suppressed by application of reduced glutathione.

DOI： 10.1271/bbb.100393

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Efficient detoxification of the reactive oxygen species, nitric oxide (NO) and methylglyoxal (MG), provides protection against NaCl-induced damage in plants. To elucidate the protective mechanisms of proline and glycinebetaine (betaine) against NaCl stress, intracellular levels of hydrogen peroxide (H₂O₂), superoxide (O₂⁻), NO, and MG were investigated in tobacco Bright Yellow-2 cells. The Levels of H₂O₂, O₂⁻, NO and MG were higher in the short-term and long-term NaCl-stressed cells than in the non-stressed cells, whereas the O₂⁻ level was higher in the long-term stressed cells. Exogenous proline and betaine decreased the H₂O₂ level in both the short-term and the long-term NaCl-stressed cells and the MG level in the long-term NaCl-stressed cells, but did not change the O₂⁻ or NO levels. Under salt stress, both proline and betaine increased the transcription levels of glutathione peroxidase, which can contribute to the reduction of H₂O₂. In conclusion, proline and betaine mitigated salt stress via reduction of H₂O₂ accumulation during short-term incubation and via reduction of the accumulation of H₂O₂ and MG during long-term incubation.

DOI： 10.1271/bbb.100334

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press  

DOI： 10.1093/pcp/pcq131

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

We tested synthetic food colorants for their antioxidative potential by the in vitro superoxide generation assay in differentiated HL-60 cells in response to phorbol ester. Among the 12 colorants tested, such fluorescein-type red colorants as rose bengal showed potent inhibitory activity without any cytotoxicity under dark conditions. The intracellular accumulation and superoxide anion scavenging effect of rose bengal were at least partly involved in the inhibitory activity.

DOI： 10.1271/bbb.100314

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press  

DOI： 10.1093/pcp/pcq016

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press  

DOI： 10.1093/pcp/pcq001

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1073/pnas.0907205106

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Cadmium (Cd) stress significantly decreased membrane integrity and impaired the ascorbate (ASC)-glutathione (GSH) cycle in tobacco Bright Yellow-2 cells. Exogenous application of proline and glycinebetaine (betaine) significantly restored the membrane integrity and increased the activities of ASC-GSH cycle enzymes under Cd stress without maintenance of the rich ASC or GSH pools. Moreover, proline offered more efficient protection against Cd stress than betaine.

DOI： 10.1271/bbb.90305

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

We analyzed the effects of diffusates from six different crops on the egg hatching of Meloidogyne chitwoodi collected from young and senescing tomato plants using a non-linear model. Diffusates only from tomato and carrot significantly delayed the hatching of eggs from young plants, but did not do so from senescing plants, suggesting that delay of hatching depends on the origin of diffusates and host plant age.

DOI： 10.1271/bbb.90392

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Environmental stress, including heavy metal stress, can cause oxidative damage to plants. Up-regulation of the antioxidant defense system induced by proline and glycinebetaine (betaine) alleviates the damaging effects of oxidative stress in plants. Here, we investigated the protective effects of exogenously applied proline and betaine on growth, accumulation of proline and betaine, lipid peroxidation and activity of antioxidant enzymes in cultured tobacco Bright Yellow-2 (BY-2) cells exposed to cadmium (Cd) stress. Cadmium stress (at 100 microM Cd) caused a significant inhibition of the growth of BY-2 cells, and both proline and betaine significantly mitigated this inhibition. In addition, the mitigating effect of proline was more pronounced than that of betaine. Cadmium stress leads to an accumulation of Cd and endogenous proline in cultured cells, increased lipid peroxidation and peroxidase (POX) activity, and decreased activity of superoxide dismutase (SOD) and catalase (CAT). Exogenous application of proline resulted in a decrease in lipid peroxidation and an increase in SOD and CAT activities without reducing Cd contents under Cd stress, while application of betaine resulted in a decrease in lipid peroxidation and an increase in CAT activity with reducing Cd accumulation. Furthermore, exogenous proline and betaine intensified the accumulation of proline and betaine in Cd-stressed BY-2 cells, respectively. The present study suggests that proline and betaine confer tolerance to Cd stress in tobacco BY-2 cells by different mechanisms.

DOI： 10.1016/j.jplph.2009.04.002

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

(-)-Epigallocatechin-3-gallate (EGCG) has been reported to possess a wide range of biological and pharmacological properties. In this study, we investigated the effects of EGCG on IL-13 gene expression in human basophilic KU812 cells. The IL-13 mRNA expression level was dose-dependently increased by treatment with EGCG (5-20 microM) for 1 h and additional incubation in a medium for 23 h. EGCG significantly increased the intracellular peroxide level as detected by the peroxide-sensitive probe 2',7'-dichlorodihydrofluorescein diacetate. A pharmacological experiment using catalase and a structure-activity relationship study revealed that the exogenously produced H(2)O(2) significantly, but partially, contributed to the IL-13 expression as well as the intracellular oxidative status. Furthermore, EGCG at the concentration required for IL-13 up-regulation activated c-Jun NH(2)-terminal kinase (JNK), but not extracellular signal-regulated protein kinase or p38 mitogen-activated protein kinase in KU812 cells. Transfection of a JNK-specific siRNA as well as treatment with a JNK-specific inhibitor, SP600125, significantly reduced the EGCG-induced IL-13 mRNA expression, by 47.1 and 44.6%, respectively. In addition, we observed the nuclear translocation, mRNA up-regulation, and activation of DNA binding with the IL-13 promoter of nuclear factor of activated T cells (NFATc1) in the EGCG-treated cells. These data provide biological evidence that EGCG induces IL-13 mRNA expression via the JNK-dependent NFATc1 pathway in KU812 cells.

DOI： 10.1016/j.freeradbiomed.2009.07.011

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

The application of exogenous proline and glycinebetaine (betaine) confers salt tolerance on plants under salt stress. The effects of exogenous proline and betaine on apoplastic flow in rice plants under saline conditions were investigated using trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS), an apoplastic tracer. Rice plants took up more PTS under light conditions than under dark conditions. Salt stress increased PTS uptake and Na⁺ content of rice leaves, but did not affect K⁺ content, resulting in a lower K⁺/Na⁺ ratio. Addition of proline or betaine to the saline medium suppressed Na⁺-induced PTS uptake and Na⁺ accumulation, while the K⁺ content was slightly increased, which led to a high K⁺/Na⁺ ratio under saline conditions. These results suggest that exogenous proline and betaine suppressed Na⁺-enhanced apoplastic flow to reduce Na⁺ uptake in rice plants.

DOI： 10.1271/bbb.90244

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

P&gt;Stomatal closure in response to abscisic acid depends on mechanisms that are mediated by intracellular [Ca2+] ([Ca2+](i)), and also on mechanisms that are independent of [Ca2+](i) in guard cells. In this study, we addressed three important questions with respect to these two predicted pathways in Arabidopsis thaliana. (i) How large is the relative abscisic acid (ABA)-induced stomatal closure response in the [Ca2+](i)-elevation-independent pathway? (ii) How do ABA-insensitive mutants affect the [Ca2+](i)-elevation-independent pathway? (iii) Does ABA enhance (prime) the Ca2+ sensitivity of anion and inward-rectifying K+ channel regulation? We monitored stomatal responses to ABA while experimentally inhibiting [Ca2+](i) elevations and clamping [Ca2+](i) to resting levels. The absence of [Ca2+](i) elevations was confirmed by ratiometric [Ca2+](i) imaging experiments. ABA-induced stomatal closure in the absence of [Ca2+](i) elevations above the physiological resting [Ca2+](i) showed only approximately 30% of the normal stomatal closure response, and was greatly slowed compared to the response in the presence of [Ca2+](i) elevations. The ABA-insensitive mutants ost1-2, abi2-1 and gca2 showed partial stomatal closure responses that correlate with [Ca2+](i)-dependent ABA signaling. Interestingly, patch-clamp experiments showed that exposure of guard cells to ABA greatly enhances the ability of cytosolic Ca2+ to activate S-type anion channels and down-regulate inward-rectifying K+ channels, providing strong evidence for a Ca2+ sensitivity priming hypothesis. The present study demonstrates and quantifies an attenuated and slowed ABA response when [Ca2+](i) elevations are directly inhibited in guard cells. A minimal model is discussed, in which ABA enhances (primes) the [Ca2+](i) sensitivity of stomatal closure mechanisms.

DOI： 10.1111/j.1365-313X.2009.03872.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press  

DOI： 10.1093/pcp/pcp066

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Cellular phototoxicity induced by UVA irradiation and its potential application to therapy has been reported. In the present study, the induction of apoptosis induced by β-carotene and dimethyl tetrasulfide (Me₂S₄) assisted by UVA irradiation in HL-60 cells was assessed. β-carotene assisted by UVA significantly decreased the cell viability and induced DNA fragmentation in HL-60 cells. Me₂S₄ combined with β-carotene and assisted by UVA significantly inhibited the cell viability, and enhanced the caspase-3 activity which was completely inhibited by N-acety-<small>L</small>-cysteine. β-carotene was significantly degraded by UVA, but this was not accelerated by Me₂S₄ in a cell culture system. The photodegradation products of β-carotene prepared by UVA irradiation regardless of the addition of Me₂S₄ showed lower cytotoxicity than β-carotene itself in HL-60 cells. These results suggest that the ROS- and caspase-3-dependent apoptosis induced by β-carotene and Me₂S₄ assisted by UVA was due to a synergistic action rather than to the sole effect of the photodegradation products of β-carotene in HL-60 cells.

DOI： 10.1271/bbb.80794

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Cytosolic Ca(2+) ([Ca(2+)](cyt)) mediates diverse cellular responses in both animal and plant cells in response to various stimuli. Calcium oscillation amplitude and frequency control gene expression. In stomatal guard cells, [Ca(2+)](cyt) has been shown to regulate stomatal movements, and a defined window of Ca(2+) oscillation kinetic parameters encodes necessary information for long-term stomatal movements. However, it remains unknown how the encrypted information in the cytosolic Ca(2+) signature is decoded to maintain stomatal closure. Here we report that the Arabidopsis glutamate receptor homolog AtGLR3.1 is preferentially expressed in guard cells compared to mesophyll cells. Furthermore, over-expression of AtGLR3.1 using a viral promoter resulted in impaired external Ca(2+)-induced stomatal closure. Cytosolic Ca(2+) activation of S-type anion channels, which play a central role in Ca(2+)-reactive stomatal closure, was normal in the AtGLR3.1 over-expressing plants. Interestingly, AtGLR3.1 over-expression did not affect Ca(2+)-induced Ca(2+) oscillation kinetics, but resulted in a failure to maintain long-term 'Ca(2+)-programmed' stomatal closure when Ca(2+) oscillations containing information for maintaining stomatal closure were imposed. By contrast, prompt short-term Ca(2+)-reactive closure was not affected in AtGLR3.1 over-expressing plants. In wild-type plants, the translational inhibitor cyclohexamide partially inhibited Ca(2+)-programmed stomatal closure induced by experimentally imposed Ca(2+) oscillations without affecting short-term Ca(2+)-reactive closure, mimicking the guard cell behavior of the AtGLR3.1 over-expressing plants. Our results suggest that over-expression of AtGLR3.1 impairs Ca(2+) oscillation-regulated stomatal movements, and that de novo protein synthesis contributes to the maintenance of long-term Ca(2+)-programmed stomatal closure.

DOI： 10.1111/j.1365-313X.2009.03789.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

In the present study, we found that (-)-epigallocatechin-3-gallate (EGCG) significantly up-regulated the mRNA expression of the Th1/Th2 cytokines including IL-2, IFN-gamma, IL-5 and IL-13 in Jurkat T cells. The EGCG-induced mRNA up-regulation of IL-2 and IL-5 was predominantly affected by the extracellular signal-regulated protein kinase (ERK) signalling, whereas IL-13 gene expression, the most responsive to the EGCG treatment, was dependent on neither ERK nor c-jun NH(2)-terminal kinase (JNK) signalling. IFN-gamma gene expression was partially mitigated by both inhibitors of the ERK and JNK pathways. Furthermore, catalase significantly attenuated the intracellular peroxide production, phosphorylation of ERK and JNK, and all cytokine gene expressions induced by EGCG. In addition, physiologically relevant concentrations of both EGCG and H(2)O(2)-induced up-regulation of IL-5 gene expression. Our findings provide biological evidence that EGCG induces Th1/Th2 cytokine mRNA expression via H(2)O(2) production followed by activation of ERK or JNK in Jurkat T cells.

DOI： 10.1016/j.abb.2008.12.010

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Intracellular components in methyl jasmonate (MeJA) signaling remain largely unknown, to compare those in well-understood abscisic acid (ABA) signaling. We have reported that nitric oxide (NO) is a signaling component in MeJA-induced stomatal closure, as well as ABA-induced stomatal closure in the previous study. To gain further information about the role of NO in the guard cell signaling, NO production was examined in an ABA- and MeJA-insensitive Arabidopsis mutant, rcn1. Neither MeJA nor ABA induced NO production in rcn1 guard cells. Our data suggest that NO functions downstream of the branch point of MeJA and ABA signaling in Arabidopsis guard cells.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Salt stress causes oxidative damage and cell death in plants. Plants accumulate proline and glycinebetaine (betaine) to mitigate detrimental effects of salt stress. The aim of this study was to investigate the protective effects of proline and betaine on cell death in NaCl-unadapted tobacco (Nicotiana tabacum) Bright Yellow-2 suspension-cultured cells subjected to salt stress. Salt stress increased reactive oxygen species (ROS) accumulation, lipid peroxidation, nuclear deformation and degradation, chromatin condensation, apoptosis-like cell death and ATP contents. Neither proline nor betaine affected apoptosis-like cell death and G(1) phase population, and increased ATP contents in the 200mM NaCl-stressed cells. However, both of them effectively decreased ROS accumulation and lipid peroxidation, and suppressed nuclear deformation and chromatin condensation induced by severe salt stress. Evans Blue staining experiment showed that both proline and betaine significantly suppressed increment of membrane permeability induced by 200mM NaCl. Furthermore, among the ROS scavenging antioxidant defense genes studied here, mRNA levels of salicylic acid-binding (SAbind) catalase (CAT) and lignin-forming peroxidase (POX) were found to be increased by proline and betaine under salt stress. It is concluded that both proline and betaine provide a protection against NaCl-induced cell death via decreasing level of ROS accumulation and lipid peroxidation as well as improvement of membrane integrity.

DOI： 10.1016/j.jplph.2008.03.002

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Docosahexaenoic acid (22: 6n-3; DHA) is a long chain polyunsaturated fatty acid that exists highly enriched in fish oil, and it is one of the low molecular weight food chemicals which can pass a blood brain barrier. A preliminary survey of several fatty acids for expression of growth-associated protein-43 (GAP-43), a marker of axonal growth, identified DHA as one of the most potent inducers. The human neuroblastoma SH-SY5Y cells exposed to DHA showed significant and dose-dependent increases in the percentage of cells with longer neurites. To elucidate signaling mechanisms involved in DHA-enhanced basal neuritogenesis, we examined the role of extracellular signal-regulated kinase (ERK)1/2 and intracellular reactive oxygen species (ROS) production using SH-SY5Y cells. From immunoblotting experiments, we observed that DHA induced the ROS production, protein tyrosine phosphatase inhibition, mitogen-activated protein kinase (MAPK)/ERK kinase (MEK) phosphorylation, and sequentially ERK1/2 phosphorylation, the last of which was significantly reduced by MEK inhibitor U0126. Both antioxidants and MEK inhibitor affected DHA-induced GAP-43 expression, whereas the specific PI3K inhibitor LY294002 did not. We found that total protein tyrosine phosphatase activity was also downregulated by DHA treatment, which was counteracted by antioxidant pretreatment. These results suggest that the ROS-dependent ERK pathway, rather than PI3K, plays an important role during DHA-enhanced neurite outgrowth.

DOI： 10.1016/j.bbalip.2008.10.004

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出版者・発行元：日本植物生理学会  

植物において、様々な防御応答を司るジャスモン酸メチル（MeJA）は、アブシジン酸（ABA）と同様に気孔閉口を誘導する。MeJAが誘導する気孔閉口シグナル伝達には様々な因子が関与していることが報告されている。シロイヌナズナのタンパク質脱リン酸化酵素2A（PP2A）のAサブユニットの1つであるRCN1は、根におけるオーキシンシグナル及び孔辺細胞におけるABAシグナルに関与することが知られている。以前の我々の研究は、RCN1が、孔辺細胞におけるMeJAシグナルにも関与しており、正の調節因子として機能することを示唆した。RCN1は、MeJAによる孔辺細胞内の活性酸素種の産生、内向きカリウムイオンチャネル活性の制御に必須である。<br> 今回我々は、MeJAによる孔辺細胞内の一酸化窒素産生やカルシウムイオンチャネル及びアニオンチャネル活性の制御機構におけるRCN1の役割を明らかにする為に研究を行った。ここで得られた知見は、シロイヌナズナ孔辺細胞におけるMeJAシグナリングの新たなモデルを提唱する。

DOI： 10.14841/jspp.2009.0.0451.0

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

(−)-Epigallocatechin-3-gallate (EGCG)-induced apoptosis was along both the extracellular signal-regulated protein kinase (ERK) and c-jun N-terminal kinase (JNK) pathways in Jurkat cells. Co-treatment with EGCG potentiated the cytotoxicity induced by benzyl isothiocyanate (BITC) and H₂O₂, both being inhibited by ERK and JNK inhibitors. These results suggest the significant role of mitogen-activated protein kinase (MAPK) signaling in the apoptosis induction regulated by EGCG alone and in combination.

DOI： 10.1271/bbb.80422

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00321431040?from=CiNii

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Organosulfur compounds have been established to possess anticancer effects. To provide a better understanding of the biological function of dimethyl sulfides, dimethyl monosulfide (Me₂S), dimethyl disulfide (Me₂S₂), dimethyl trisulfide (Me₂S₃) and dimethyl tetrasulfide (Me₂S₄) were used as experimental materials to investigate their effects on apoptosis induction in human leukemia Jurkat cells and HL-60 cells. Treatment with 20 μ<small>M</small> dimethyl sulfides for 24 h decreased the viability of both cells. The cell viability-reducing effect of these sulfides was in the following order: Me₂S₄ ≈ Me₂S₃ > Me₂S₂ ≈ Me₂S for Jurkat cells and Me₂S₄ > Me₂S₃ > Me₂S₂ ≈ Me₂S for HL-60 cells. Me₂S₃ and Me₂S₄ significantly induced DNA fragmentation and caspase-3 activation. The addition of GSH or NAC completely suppressed the sulfide-induced apoptosis. Our results indicate that dimethyl sulfides with a larger number of sulfur atoms more strongly induced apoptosis in both human leukemia cells via ROS production and caspase-3 activation.

DOI： 10.1271/bbb.80453

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00321430906?from=CiNii

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

We investigated the role of glutathione (GSH) in stomatal movements using a GSH deficient mutant, chlorinal-1 (ch1-1). Guard cells of ch1-1 mutants accumulated less GSH than wild types did. Light induced stomatal opening in ch1-1 and wild-type plants. Abscisic acid (ABA) induced stomatal closure in ch1-1 mutants more than wild types without enhanced reactive oxygen species (ROS) production. Therefore, GSH functioned downstream of ROS production in the ABA signaling cascade.

DOI： 10.1271/bbb.80407

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00319864676?from=CiNii

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.bbadis.2008.07.002

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Plant Physiologists  

DOI： 10.1093/pcp/pcn106

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE  

The inward-rectifying K+ channel KAT1 is expressed mainly in Arabidopsis thaliana guard cells. The Purification of functional KAT1 has never been reported. We investigated the extraction of the plant K+ channel KAT1 with different detergents, as an example for how to select detergents for purifying a eukaryotic membrane protein. A KAT1-GFP fusion protein was used to screen a library of 46 detergents for the effective solubilization of intact KAT1. Then, a "test set" of three detergents was picked for further analysis, based on their biochemical characteristics and availability. The combination use of the selected detergents enabled the effective purification Of functional KAT1 with affinity and gel-filtration chromatography. (C) 2008 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2008.07.026

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Carotenoids are used in wide-ranging food applications, but they are susceptible to degradation by many factors including light. We examined the photodegradation of five kinds of carotenoids and three kinds of anthocyanins to clarify which structures of pigments were favorable to accelerated degradation by sulfides under UVA irradiation. Under UVA irradiation, crocetin and crocin were decomposed more rapidly in the presence of dimethyl tetrasulfide than in the absence of the sulfide, but not as rapidly as β-carotene, zeaxanthin and β-cryptoxanthin were. However, cyanidin was decomposed more slowly in the presence of sulfide than in the absence of sulfide. Moreover, the photodegradation of kuromanin and keracyanin was not affected by the addition of a sulfide. We also examined the mechanism for this accelerated degradation. Normal hexane was more favorable to the photodegradation of β-carotene than methanol and ethanol. The accelerated degradation was inhibited by free radical scavengers, but enhanced by the addition of deuterium oxide. These results suggest that conjugated double bonds were favorable to the accelerated photodegradation by sulfide and that this reaction was mediated by free radicals.

DOI： 10.1271/bbb.80251

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Cathepsin L-like enzyme was purified from the body wall of the sea cucumber Stichopus japonicus by an integral method involving ammonium sulfate precipitation and a series of column chromatographies on DEAE Sepharose CL-6B, Sephadex G-75, and TSK-GEL. The molecular mass of the purified enzyme was estimated to be 63 kDa by SDS-PAGE. The enzyme cleaved N-carbobenzoxy-phenylalanine-arginine7-amido-4-methylcoumarin with K(m) (69.92 microM) and k(cat) (12.80/S) hardly hydrolyzed N-carbobenzoxy-arginine-arginine 7-amido-4-methylcoumarin and L-arginine 7-amido-4-methylcoumarin. The optimum pH and temperature for the purified enzyme were found to be 5.0 and 50 degrees C. It showed thermal stability below 40 degrees C. The activity was inhibited by sulfhydryl reagents and activated by reducing agents. These results suggest that the purified enzyme was a cathepsin L-like enzyme and that it existed in the form of its enzyme-inhibitor complex or precursor.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Salt stress impairs reactive oxygen species (ROS) and methylglyoxal (MG) detoxification systems, and causes oxidative damage to plants. Up-regulation of the antioxidant and glyoxalase systems provides protection against NaCl-induced oxidative damage in plants. Thiol-disulfide contents, glutathione content and its associated enzyme activities involved in the antioxidant defense and glyoxalase systems, and protein carbonylation in tobacco Bright Yellow-2 cells grown in suspension culture were investigated to assess the protection offered by proline and glycinebetaine against salt stress. Salt stress increased protein carbonylation, contents of thiol, disulfide, reduced (GSH) and oxidized (GSSG) forms of glutathione, and the activity of glutathione-S-transferase and glyoxalase II enzymes, but decreased redox state of both thiol-disulfide and glutathione, and the activity of glutathione peroxidase and glyoxalase I enzymes involved in the ROS and MG detoxification systems. Exogenous application of proline or glycinebetaine resulted in a reduction of protein carbonylation, and in an increase in glutathione redox state and activity of glutathione peroxidase, glutathione-S-transferase and glyoxalase I under salt stress. Neither proline nor glycinebetaine, however, had any direct protective effect on NaCl-induced GSH-associated enzyme activities. The present study, therefore, suggests that both proline and glycinebetaine provide a protective action against NaCl-induced oxidative damage by reducing protein carbonylation, and enhancing antioxidant defense and MG detoxification systems.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

A novel bacterium exhibiting alginolytic activity was isolated from rotten algae. The alginate-degrading activity was detected in the culture supernatant by measuring the decrease in alginate viscosity or the increase in reducing sugars. Basic characterization showed that it was gram negative, rod shaped, yellow pigmented, and positive for oxidase and catalase, with a DNA G+C content of 35.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that this strain is related to members of the genus Flavobacterium. Sequence similarity values with their nearest phylogenetic neighbours ranged from 95.9% to 96.7%. Genotypic results, together with phenotypic characteristics, differentiated this species from related Flavobacterium organisms with validly published names, which suggests that the organism should be a new species of the genus Flavobacterium tentatively named as Flavobacterium sp. strain LXA.

DOI： 10.1139/w08-013

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

In this report, we describe that a salt adaptation of plant cells induces glycoform changes in N-glycoproteins. Intracellular and cell-wall glycopeptides were prepared from glycoproteins expressed in wild-type BY2 cells and salt-adapted cells. N-Glycans were liberated from those glycopeptides by hydrazinolysis, and the released oligosaccharides were N-acetylated and pyridylaminated. The structures of pyridylaminated (PA-) N-glycans were analyzed by a combination of two-dimensional sugar-chain mapping, MS analysis, and exoglycosidase digestion. In both wild-type cells and salt-adapted cells, the plant complex type structure was predominant among N-glycans expressed on glycoproteins, but we found that the Man2Xyl1Fuc1GlcNAc2 structure was significantly expressed on intracellular and cell-wall glycoproteins of the salt-adapted cells. Furthermore, enhancement of the specific activities of alpha-mannosidase and beta-N-acetylglucosaminidase was observed in the salt-adapted BY2 cells, suggesting that the glycoform changes are due to changes in glycosidase activities.

DOI： 10.1271/bbb.70592

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

The tonoplast K+ membrane transport system plays a crucial role in maintaining K+ homeostasis in plant cells. Here, we isolated cDNAs encoding a two-pore K+ channel (NtTPK1) from Nicotiana tabacum cv. SR1 and cultured BY-2 tobacco cells. Two of the four variants of NtTPK1 contained VHG and GHG instead of the GYG signature sequence in the second pore region. All four products were functional when expressed in the Escherichia coli cell membrane, and NtTPK1 was targeted to the tonoplast in tobacco cells. Two of the three promoter sequences isolated from N. tabacum cv. SR1 were active, and expression from these was increased similar to 2-fold by salt stress or high osmotic shock. To determine the properties of NtTPK1, we enlarged mutant yeast cells with inactivated endogenous tonoplast channels and prepared tonoplasts suitable for patch clamp recording allowing the NtTPK1-related channel conductance to be distinguished from the small endogenous currents. NtTPK1 exhibited strong selectivity for K+ over Na+. NtTPK1 activity was sensitive to spermidine and spermine, which were shown to be present in tobacco cells. NtTPK1 was active in the absence of Ca2+, but a cytosolic concentration of 45 mu M Ca2+ resulted in a 2-fold increase in the amplitude of the K+ current. Acidification of the cytosol topH5.5 also markedly increased NtTPK1-mediated K+ currents. These results show that NtTPK1 is a novel tonoplast K+ channel belonging to a different group from the previously characterized vacuolar channels SV, FV, and VK.

DOI： 10.1074/jbc.M708213200

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Up-regulation of the antioxidant system provides protection against NaCl-induced oxidative damage in plants. Antioxidants and activity of enzymes involved in the ascorbate-glutathione (ASC-GSH) cycle in tobacco Bright Yellow-2 (BY-2) were investigated to assess the antioxidant protection offered by exogenous proline and glycinebetaine (betaine from now on) against salt stress using cells grown in suspension culture. Reduced ascorbate (ASC) was detected in BY-2 cells but dehydroascorbate (DHA) was not. Large quantities of a reduced form of glutathione (GSH) and smaller quantities of an oxidized form of glutathione (GSSG) were detected in BY-2 cells. Salt stress significantly reduced the contents of ASC and GSH as well as activities of ASC-GSH cycle enzymes such as ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR). Exogenous proline or betaine increased the activities of all enzymes except MDHAR involved in NaCl-induced ASC-GSH cycle. Levels of ASC and GSH in BY-2 cells under salt stress were lower in the presence of proline or betaine than in the absence of proline or betaine whereas there was no difference in redox status. Proline proved more effective than betaine in maintaining the activity of enzymes involved in NaCl-induced ASC-GSH cycle. Neither proline nor betaine had any direct protective effect on NaCl-induced enzyme activity involved in the antioxidant system; however, both improved salt tolerance by increasing enzyme activity. The present study, together with our earlier findings [Hoque MA, Okuma E, Banu MNA, Nakamura Y, Shimoishi Y, Murata Y. Exogenous proline mitigates the detrimental effects of salt stress more than exogenous betaine by increasing antioxidant enzyme activities. J Plant Physiol 2006;164:553-61.], suggests that proline offered greater protection against salt stress than betaine did because proline was more effective in increasing the activity of enzymes involved in the antioxidant system.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

In the present study, papaya (Carica papaya) seed and edible pulp were carefully separated and then the contents of benzyl isothiocyanate and the corresponding glucosinolate (benzyl glucosinolate, glucotropaeolin) quantified in each part. The papaya seed with myrosinase inactivation contained >1 mmol of benzyl glucosinolate in 100 g of fresh seed. This content is equivalent to that of Karami daikon (the hottest Japanese white radish) or that of cress. The papaya seed extract also showed a very high activity of myrosinase and, without myrosinase inactivation, produced 460 micromol of benzyl isothiocyanate in 100 g of seed. In contrast, papaya pulp contained an undetectable amount of benzyl glucosinolate and showed no significant myrosinase activity. The n-hexane extract of the papaya seed homogenate was highly effective in inhibiting superoxide generation and apoptosis induction in HL-60 cells, the activities of which are comparable to those of authentic benzyl isothiocyanate.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Proline and betaine accumulate in plant cells under environmental stresses including salt stress. Here, we investigated effects of proline and betaine on the growth and activities of antioxidant enzymes in tobacco Bright Yellow-2 (BY-2) culture cells in suspension under salt stress. Both proline and betaine mitigated the inhibition of growth of BY-2 cells under salt stress and the mitigating effect of proline was more than that of betaine. Salt stress significantly decreased the activities of superoxide dismutase (SOD), catalase and peroxidase in BY-2 cells. Exogenous application of proline or betaine alleviated the reduction in catalase and peroxidase activities but not SOD activity under salt stress. In addition, proline was found to be effective in alleviating the inhibition of salt stress-induced catalase and peroxidase activities in BY-2 cells. Neither proline nor betaine directly scavenged superoxide (O(2)(-)) or hydrogen peroxide (H(2)O(2)). It is concluded that exogenous proline mitigates the detrimental effects of salt stress more than exogenous betaine because of its superior ability to increase the activities of antioxidant enzymes.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

Methyl jasmonate (MeJA) elicits stomatal closing similar to abscisic acid (ABA), but whether the two compounds use similar or different signaling mechanisms in guard cells remains to be clarified. We investigated the effects of MeJA and ABA on second messenger production and ion channel activation in guard cells of wild-type Arabidopsis (Arabidopsis thaliana) and MeJA-insensitive coronatine-insensitive 1 (coi1) mutants. The coi1 mutation impaired MeJA-induced stomatal closing but not ABA-induced stomatal closing. MeJA as well as ABA induced production of reactive oxygen species (ROS) and nitric oxide (NO) in wild-type guard cells, whereas MeJA did not induce production of ROS and NO in coi1 guard cells. The experiments using an inhibitor and scavengers demonstrated that both ROS and NO are involved in MeJA-induced stomatal closing as well as ABA-induced stomatal closing. Not only ABA but also MeJA activated slow anion channels and Ca(2+) permeable cation channels in the plasma membrane of wild-type guard cell protoplasts. However, in coi1 guard cell protoplasts, MeJA did not elicit either slow anion currents or Ca(2+) permeable cation currents, but ABA activated both types of ion channels. Furthermore, to elucidate signaling interaction between ABA and MeJA in guard cells, we examined MeJA signaling in ABA-insensitive mutant ABA-insensitive 2 (abi2-1), whose ABA signal transduction cascade has some disruption downstream of ROS production and NO production. MeJA also did not induce stomatal closing but stimulated production of ROS and NO in abi2-1. These results suggest that MeJA triggers stomatal closing via a receptor distinct from the ABA receptor and that the coi1 mutation disrupts MeJA signaling upstream of the blanch point of ABA signaling and MeJA signaling in Arabidopsis guard cells.

DOI： 10.1104/pp.106.091298

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記述言語：英語   出版者・発行元：OXFORD UNIV PRESS  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Plant Physiologists  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PUBLIC LIBRARY SCIENCE  

Abscisic acid (ABA) signal transduction has been proposed to utilize cytosolic Ca2+ in guard cell ion channel regulation. However, genetic mutants in Ca2+ sensors that impair guard cell or plant ion channel signaling responses have not been identified, and whether Ca2+-independent ABA signaling mechanisms suffice for a full response remains unclear. Calcium-dependent protein kinases (CDPKs) have been proposed to contribute to central signal transduction responses in plants. However, no Arabidopsis CDPK gene disruption mutant phenotype has been reported to date, likely due to overlapping redundancies in CDPKs. Two Arabidopsis guard cell-expressed CDPK genes, CPK3 and CPK6, showed gene disruption phenotypes. ABA and Ca2+ activation of slow-type anion channels and, interestingly, ABA activation of plasma membrane Ca2+-permeable channels were impaired in independent alleles of single and double cpk3cpk6 mutant guard cells. Furthermore, ABA- and Ca2+-induced stomatal closing were partially impaired in these cpk3cpk6 mutant alleles. However, rapid-type anion channel current activity was not affected, consistent with the partial stomatal closing response in double mutants via a proposed branched signaling network. Imposed Ca2+ oscillation experiments revealed that Ca2+-reactive stomatal closure was reduced in CDPK double mutant plants. However, long-lasting Ca2+-programmed stomatal closure was not impaired, providing genetic evidence for a functional separation of these two modes of Ca2+-induced stomatal closing. Our findings show important functions of the CPK6 and CPK3 CDPKs in guard cell ion channel regulation and provide genetic evidence for calcium sensors that transduce stomatal ABA signaling.

DOI： 10.1371/journal.pbio.0040327

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The effects of vitamin C, vitamin E and vitamin B12 on the noise-induced acute change in hepatic glycogen content in rats were investigated. The exposure of rats to 95 dB and 110 dB of noise acutely reduced their hepatic glycogens. Vitamin C (ascorbic acid) and vitamin E (alpha-tocopherol) attenuated the noise-induced acute reduction in the hepatic glycogen contents. This result suggests that antioxidants could reduce the change via reactive oxygen species. Vitamin B12 (cobalamin) delayed the noise-induced change, a finding that suggests that vitamin B12 could postpone the acute change via compensating for vitamin B12 deficiency.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Capsaicin (8-methyl-N-vanillyl-6-nonenamide), a major pungent ingredient in a variety of red peppers of the genus Capsicum, is a type of vanilloid. It has been shown to induce apoptosis in many cell types. The effects of vanilloids on apoptosis induction are thought to be correlated with the length and degree of the unsaturation of the fatty acyl chains. In this study, we compared the effect of capsaicin and its docosahexaenoic acid (DHA, C22:6) analog (we named as dohevanil) on human breast cancer MCF-7 cells, which do not express caspase-3. Dohevanil, which was synthesized from DHA and vanillylamine, has longer and highly unsaturated fatty acyl chain than capsaicin. We showed that both vanilloids exhibit effects of growth inhibition and DNA fragmentation induction in MCF-7 cells. These effects of dohevanil were more potent than capsaicin. Because these effects were inhibited by z-VAD-fmk, a broad-spectrum caspase inhibitor, the vanilloids induced the apoptosis via caspase-dependent pathway not involving caspase-3. In conclusion, dohevanil has a more potent effect on apoptosis induction in MCF-7 cells than capsaicin.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The photodegradation of carotenoids by UVA irradiation in the presence of sulfides was investigated. The sulfides accelerated the photodegradation of carotenoids. A larger number of sulfur atoms of coexistent sulfides was more favorable to the acceleration effect of sulfides on the photodegradation of beta-carotene, but the alk(en)yl group of sulfides was less favorable to the acceleration effect of sulfur compounds. The acceleration effect depended on light intensity, temperature, and the initial concentrations of beta-carotene and sulfide.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

OBJECTIVE: Docosahexaenoic acid (DHA) is known as a chemopreventive substance for cancers. Previously we reported that DHA induces apoptosis in HL-60 cells. The aim of this study was to clarify the role of phosphatidylinositol 3-kinase (PI3-kinase)/Akt signaling during DHA-induced apoptosis in HL-60 cells. METHODS: The inhibitory effects of dibutyryl cAMP (db-cAMP) or LY294002 (a specific inhibitor of the PI3-kinase/Akt pathway) on DHA-induced apoptosis in HL-60 cells were evaluated by the appearance of apoptosis, and from the activities of caspases (3 and 8), the phospholylation of Akt, and cleavage of Bid using DNA indexes, emzymatic measurement of fragmented substrates, and Western blotting, respectively. RESULTS: The pre-incubation of db-cAMP reduced the activation of caspasses (3 and 8) during the occurrence of DHA-induced apoptosis in HL-60. However, the inhibition of PI3-kinase/Akt signaling by LY294002 resulted in recovery of the caspases' activities, appearance of apoptotic cells, and cleavage of the Bid molecule when LY294002 was co-treated with db-cAMP before the occurrence of DHA-induced apoptosis in HL-60. It was also confirmed that LY294002 strongly inhibited phospholylation of Akt during db-cAMP induced-reduction of DHA-induced apoptosis in HL-60. CONCLUSION: We demonstrated that DHA-induced apoptosis was sensitive to the modulation of PI3-kinase activity by treatment with db-cAMP or LY294002. These results may provide new insights into the mechanisms of the anti-cancer activity of DHA.

DOI： 10.1007/BF02897709

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We attempted to determine whether docosahexaenoic acid (DHA)-induced apoptosis is mediated via the Bax-mediated pathway in human myeloid leukemia HL-60 cells. DHA-induced apoptosis was confirmed by morphological analysis and caspase-3 activation. But, cyclosporin A (CsA), an inhibitor of mitochondrial permeability transition (MPT), did not inhibit DHA-induced Bax translocation to mitochondria or caspase-3 activation. These data suggest that DHA can induce apoptosis via the Bax-independent pathway.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The ureides, allantoin and allantoic acid, are believed to play an important role in the storage and translocation of nitrogen in higher plants. Arginine is a major component in the free amino acid pool in some plants. To investigate the behavior of ureides and free amino acids, especially arginine, in developing Dioscorea opposita plants 'Tsukuneimo', their contents as well as those of water and nitrogen in leaves, stems and tubers were quantitatively analyzed. The content of allantoin in the leaves decreased after any fertilization, while that in the stems did not increase after the 1st fertilization, 96 days after planting
it significantly increased after the 2nd fertilization, 26 days later. Allantoin content in tubers remained constant during tuber development. Arginine content in leaves and stems during the growth of 'Tsukuneimo' were lower than 0.15 and 4.8 μmol·g-1FW, respectively. The time course of arginine in stems content was similar to that of allantoin. In tubers, arginine content at 170 days after planting increased to reach 14 times that at 142 days but then decreased, demonstrating that D. opposita transiently accumulates arginine in stems as well as allantoin in leaves and stems but only accumulates the latter in developing tubers.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The activities of serum glutamic pyruvic transaminase (GPT), alkaline phosphatase (ALP) and creatine kinase (CK) in rats injected or not with the Chinese medicines, Astragali, Rhodiolae and Ligusticum, were determined after noise exposure. Noise at 95 and 105 dB significantly increased the activities of GPT, ALP and CK, and showed a dependence on the exposure time. The injection of each medicine significantly suppressed the increased enzyme activities by 95 and 105 dB noise.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

A simple and sensitive spectrophotometric method combined with solid-phase extraction (SPE) for the simultaneous determination of sodium linear-dodecylbenzenesulfonate (DBS) and sodium dodecyl sulfate (SDS) is described. The C2 (ethyl group bonded silicagel) cartridge could be repeatedly used more than 500 times for SPE, and it enabled the anionic surfactants to be concentrated by 50-fold. The calibration graph for DBS was linear in the range from 1.6 x 10(-8) M to 5.0 x 10(-7) M and for SDS from 2.0 x 10(-9) M to 3.0 x 10(-7) M. The relative standard deviation (n=5) for 5.0 x 10(-7) M DBS was 3.1% and for 2.5 x 10(-7) M SDS was 1.7%. The proposed method was applied to the simultaneous determination of DBS and SDS in river-water samples.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Ethyl 4,7,10,13,16,19-docosahexaenoate (DHA-Et) dissolved in an ethanol solution or embedded in liposomes was degraded by irradiating with gamma rays in a dose-dependent manner. The degradation rate of DHA-Et embedded in liposomes was higher than that of DHA-Et dissolved in ethanol. Antioxidants suppressed the degradation of DHA-Et embedded in liposomes, the order of activity of the antioxidants being luteolin>fisetin>kaempferol>quercetin>rutin. These results suggest that the hydrophobicity (logP) of an antioxidant is one of determinants for antioxidative activity, but that a vicinal diol structure in the B ring is not favorable for the antioxidative activity.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

To investigate the structure-activity relationship of coumarins for the inhibitory activity on mushroom tyrosinase, the 50% inhibitory concentration (IC50 values) of 18 coumarins and four cinnamic acid derivatives were measured. Among these compounds, esculetin had the strongest inhibitory activity (IC50=43 microM) on mushroom tyrosinase. Introduction of a hydroxy group to the C6 and C7 positions of the coumarin ring and no substitution on the lactone ring played an important role in the expression of the strong inhibitory activity of esculetin. We performed further studies to estimate the in vitro inhibitory effects of esculetin on melanogenesis. Esculetin 5 microM significantly suppressed melanin production in murine B16 melanoma cells without affecting cell growth. Furthermore, the number of 3,4-dihydroxyphenylalanine (DOPA)-positive melanocytes in the split-epidermal sheets treated with 0.05% or 0.1% esculetin was significantly lower than that in the control. From these results, it is suggested that esculetin has inhibitory effects on tyrosinase activity in vitro. However, further detailed studies are necessary to understand the inhibitory mechanism of esculetin.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Liposomes, in which beta-carotene, beta-cryptoxanthin, zeaxanthin, beta-cryptoxanthin palmitate or beta-cryptoxanthin acetate had been embedded, were irradiated by UVA, and the rate of degradation of each carotenoid was measured. There was no significant difference in the degradation rate between beta-carotene, beta-cryptoxanthin and zeaxanthin. The degradation rates of beta-cryptoxanthin palmitate and beta-cryptoxanthin acetate were faster than that of beta-cryptoxanthin, and the degradation rate of beta-cryptoxanthin palmitate was faster than that of beta-cryptoxanthin acetate.

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記述言語：英語   出版者・発行元：日本農薬学会  

植物イオンチャネル,特に細胞膜のイオンチャネルは植物細胞と外界の間の物質の通り道となっていることから,農薬のターゲットとして期待される.しかし,植物イオンチャネルに関する情報は,特に薬理学的情報について,動物や昆虫のイオンチャネルに関する情報より少ない.ここでは,植物イオンチャネルの性質について今までの研究により明らかになった点を挙げ,動物や昆虫のイオンチャネルの性質と比較しながら,新たな農薬の開発に役立つ情報を述べる.

DOI： 10.1584/jpestics.29.304

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その他リンク： http://dl.ndl.go.jp/info:ndljp/pid/10877483

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The fermentation product of herbs by lactic acid bacteria (FHL) was assayed for antifungal activities against Rosellinia necatrix, Helicobasidium mompa, Fusarium oxysporum, Pythium graminicola and Pyricularia oryzae. FHL completely inhibited the growth of R. necatrix, H. mompa, P. graminicola and P. oryzae, and reduced the growth of F. oxysporum by 35%. When the seeds of Medicago sativa L. (alfalfa), Asparagus officinalis L. (asparagus), Brassica campestris L. (komatsuna), Oryza sativa L. (rice), Spinacia oleracea L. (spinach), Festuca arundinacea Schreb. (tall fescue), and Lycopersicum esculentum Mill. (tomato) were put on plates containing 0.69 mg/ml FHL, their germination rates did not decrease. The root elongation of A. officinalis, B. campestris, O. sativa, and L. esculentum seedlings was suppressed on plates containing 6.92 mg/ml FHL, but the root elongation of M. sativa was not suppressed on the 6.92 mg/ml FHL plate. When FHL was diluted to less than 1.73 mg/ml, the diluted FHL solution did not suppress the germination of B. campestris seeds, but it suppressed the root elongation of B. campestris seedlings. An FHL concentration higher than 0.35 mg/ml hastened the growth of seedlings of B. campestris in the presence of a chemical fertilizer but delayed the growth of these seedlings in the absence of the chemical fertilizer, suggesting that inorganic elements could affect the efficiency of FHL.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Noise is one of the factors that induces critical stress in animals. The contents of glycogen, lactic acid and cholesterol in the liver of noise-stressed rats were analyzed in order to investigate the alleviation of noise-stress-induced physiological damages by traditional medicine using Astragali and Rhodiolae radices. More than 95 dB noise ranging from 2 to 4 kHz reduced the contents of these compounds in the liver of rats not injected with the extract of Astragali or Rhodiolae, but did not change the contents in the liver of rats injected with the Astragali or Rhodiolae extract. These results show that noise induced stress in the rats via a decrease in contents of these compounds in the liver and that Astragali or Rhodiolae maintained the contents of these compounds in the liver of the noise-stressed rats. The results indicate that Astragali or Rhodiolae improved the ability for rats to resist noise stress.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

A tyrosinase inhibitor was isolated from the seeds of Euphorbia lathyris L. by bioassay-guided fractionation and purification, using silica gel column chromatography. It was identified as esculetin by comparing its physical properties and spectral data with those of an authentic sample. The IC50 value of esculetin in the mushroom tyrosinase activity test was 43 microM. The kinetic study indicates that esculetin exhibited competitive inhibition against the oxidation of 3-(3,4-dihydroxyphenyl)-alanine by mushroom tyrosinase. The structure-activity relationships among five esculetin analogs suggest that hydroxyl groups at the C6 and C7 positions of the coumarin skeleton played an important role in the expression of tyrosinase inhibitory activity.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society for Horticultural Science  

Allantoin in fresh tuber of Dioscorea opposita 'Tsukuneimo' was quantitatively analyzed because the compound is thought to prevent inflammation and ulcers in humans as well as to play an important role for storage and translocation of nitrogen in higher plants. The content of ureide (allantoin and allantoic acid) in 'Tsukuneimo' was determined by the modified method of spectrophotometry with phenylhydrazine, whereas the content of allantoin was determined by HPLC. Analyses revealed that 'Tsukuneimo' tubers contained 2.6 mg·gFW-1 of allantoin, but leaves or stems had undetectable levels. D. opposita, 'Yamatoimo' and 'Nagaimo', and D. japonica 'Jinenjo' contained 2.3, 0.47 and 1.2 mg·gFW-1 of allantoin in the tuber, respectively, but negligible amount of allantoic acid in the tuber. Furthermore, Ipomoea batatas and Solanum tuberosum contained less than 0.1 mg·gFW-1 of allantoin and a negligible amount of allantoic acid. Colocasia antiquorum, 'Ishikawawase' and 'Kyouimo' had no detectable amounts of allantoin or allantoic acid.

DOI： 10.2503/jjshs.72.321

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC PLANT BIOLOGISTS  

A variety of stimuli, such as abscisic acid (ABA), reactive oxygen species (ROS), and elicitors of plant defense reactions, have been shown to induce stomatal closure. Our study addresses commonalities in the signaling pathways that these stimuli trigger. A recent report showed that both ABA and ROS stimulate an NADPH-dependent, hyperpolarization-activated Ca2+ influx current in Arabidopsis guard cells termed "I-Ca" (Z.M. Pei, Y. Murata, G. Benning, S. Thomine, B. Klusener, G.J. Allen, E. Grill, J.I. Schroeder, Nature [2002] 406: 731-734). We found that yeast (Saccharomyces cerevisiae) elicitor and chitosan, both elicitors of plant defense responses, also activate this current and activation requires cytosolic NAD(P)H. These elicitors also induced elevations in the concentration of free cytosolic calcium ([Ca2+](cyt)) and stomatal closure in guard cells. ABA and ROS elicited [Ca2+](cyt), oscillations in guard cells only when extracellular Ca2+ was present. In a 5 mM KCl extracellular buffer, 45% of guard cells exhibited spontaneous [Ca2+](cyt) oscillations that differed in their kinetic properties from ABA-induced Ca2+ increases. These spontaneous [Ca2+](cyt) oscillations also required the availability of extracellular Ca2+ and depended on the extracellular potassium concentration. Interestingly, when ABA was applied to spontaneously oscillating cells, ABA caused cessation of [Ca2+](cyt), elevations in 62 of 101 cells, revealing a new mode of ABA signaling. These data show that fungal elicitors activate a shared branch with ABA in the stress signal transduction pathway in guard cells that activates plasma membrane I-Ca channels and support a requirement for extracellular Ca2+ for elicitor and ABA signaling, as well as for cellular [Ca2+](cyt) oscillation maintenance.

DOI： 10.1104/pp.012187

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Abscisic acid (ABA) regulates developmental processes and abiotic stress responses in plants. We recently characterized a new Arabidopsis mutant, abh1, which shows ABA-hypersensitive regulation of seed germination, stomatal closing, and cytosolic calcium increases in guard cells (V. Hugouvieux, J.M. Kwak, J.I. Schroeder [2001] Cell 106: 477-487). ABH1 encodes the large subunit of a dimeric Arabidopsis mRNA cap-binding complex and in expression profiling experiments was shown to affect mRNA levels of a subset of genes. Here, we show that the dimeric ABH1 and AtCBP20 subunits are ubiquitously expressed. Whole-plant growth phenotypes of abh1 are described and properties of ABH1 in guard cells are further analyzed. Complemented abh1 lines expressing a green fluorescent protein-ABH1 fusion protein demonstrate that ABH1 mainly localizes in guard cell nuclei. Stomatal apertures were smaller in abh1 compared with wild type (WT) when plants were grown at 40% humidity, and similar at 95% humidity. Correlated with stomatal apertures from plants grown at 40% humidity, slow anion channel currents were enhanced and inward potassium channel currents were decreased in abh1 guard cells compared with WT. Gas exchange measurements showed similar primary humidity responses in abh1 and WT, which together with results from abh1/abi1-1 double-mutant analyses suggest that abh1 shows enhanced sensitivity to endogenous ABA. Double-mutant analyses of the ABA-hypersensitive signaling mutants, era1-2 and abh1, showed complex genetic interactions, suggesting that ABH1 and ERA1 do not modulate the same negative regulator in ABA signaling. Mutations in the RNA-binding protein sad1 showed hypersensitive ABA-induced stomatal closing, whereas hyl1 did not affect this response. These data provide evidence for the model that the mRNA-processing proteins ABH1 and SAD1 function as negative regulators in guard cell ABA signaling.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Society of Plant Biologists ({ASPB})  

Pharmacological studies have led to a model in which the phytohormone abscisic acid (ABA) may be positively transduced via protein phosphatases of the type 1 (PP1) or type 2A (PP2A) families. However, pharmacological evidence also exists that PP1s or PP2As may function as negative regulators of ABA signaling. Furthermore, recessive disruption mutants in protein phosphatases that function in ABA signal transduction have not yet been identified. A guard cell-expressed PP2A gene, RCN1, which had been characterized previously as a molecular component affecting auxin transport and gravity response, was isolated. A T-DNA disruption mutation in RCN1 confers recessive ABA insensitivity to Arabidopsis. The rcn1 mutation impairs ABA-induced stomatal closing and ABA activation of slow anion channels. Calcium imaging analyses show a reduced sensitivity of ABA-induced cytosolic calcium increases in rcn1, whereas mechanisms downstream of cytosolic calcium increases show wild-type responses, suggesting that RCN1 functions in ABA signal transduction upstream of cytosolic Ca(2+) increases. Furthermore, rcn1 shows ABA insensitivity in ABA inhibition of seed germination and ABA-induced gene expression. The PP1 and PP2A inhibitor okadaic acid phenocopies the rcn1 phenotype in wild-type plants both in ABA-induced cytosolic calcium increases and in seed germination, and the wild-type RCN1 genomic DNA complements rcn1 phenotypes. These data show that RCN1 functions as a general positive transducer of early ABA signaling.

DOI： 10.1105/tpc.003335

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Cytosolic calcium increases were analyzed in guard cells of the Arabidopsis farnesyltransferase deletion mutant era1-2 (enhanced response to abscisic acid). At low abscisic acid (ABA) concentrations (0.1 microM), increases of guard cell cytosolic calcium and stomatal closure were activated to a greater extent in the era1-2 mutant compared with the wild type. Patch clamping of era1-2 guard cells showed enhanced ABA sensitivity of plasma membrane calcium channel currents. These data indicate that the ERA1 farnesyltransferase targets a negative regulator of ABA signaling that acts between the points of ABA perception and the activation of plasma membrane calcium influx channels. Experimental increases of cytosolic calcium showed that the activation of S-type anion currents downstream of cytosolic calcium and extracellular calcium-induced stomatal closure were unaffected in era1-2, further supporting the positioning of era1-2 upstream of cytosolic calcium in the guard cell ABA signaling cascade. Moreover, the suppression of ABA-induced calcium increases in guard cells by the dominant protein phosphatase 2C mutant abi2-1 was rescued partially in era1-2 abi2-1 double mutant guard cells, further reinforcing the notion that ERA1 functions upstream of cytosolic calcium and indicating the genetic interaction of these two mutations upstream of ABA-induced calcium increases.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC PLANT BIOLOGISTS  

DOI： 10.1105/tpc.13.11.2513

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The fermentation product of herbs by lactic acid bacteria (FHL), in which Enterococcus faecalis TH10 predominated, was assayed for antifungal activity against tinea. The antifungal activity of FHL was as high as that of a synthetic fungicide. Autoclaving FHL did not reduce its antifungal activity, whereas neutralizing it did. The results suggested that nonproteinaceous compounds or organic acids in FHL could inhibit the growth of the dermatophyte tinea under low-pH conditions, and that malonic acid and acetic acid could have especially high antifungal activity against tinea.

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記述言語：英語   出版者・発行元：一般社団法人日本土壌肥料学会  

The addition of exogenous proline (10 mM) to Na100-saline culture medium, modified LS medium (Linsmaier and Skoog 1965: Physiol. Plant., 18, 100-127) with 100 mM NaCl promoted the growth of tobacco (Nicotiana tabacum L., cv. Bright Yellow-2) suspension cells unadapted to salt stress without maintaining a high ratio of K^+ to Na^+ ions under salinity conditions. The addition of exogenous glutamic acid or alanine were not comparable to that of exogenous proline. The proline contents of the NaCl-unadapted cells became much higher when the cells were grown in Na100-saline culture medium with 10 mM proline than when the cells were cultured without proline. The accumulation of K^+, Na^+, and counter ions was sufficient to compensate for the increase of the water potential of the cells caused by salinity. These results suggest that exogenous proline does not act as a nitrogen store and that proline may act as a protectant for enzymes and membranes against salt inactivation rather than as a compatible solute in tobacco suspension cells.

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記述言語：英語   出版者・発行元：Japanese Society of Plant Physiologists  

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その他リンク： https://projects.repo.nii.ac.jp/?action=repository_uri&item_id=183632

記述言語：日本語   出版者・発行元：JAPANESE RESEARCH ASSOCIATION FOR FOOD IRRADIATION  

Thaumatin, egg white and soybean protein were selected as samples of proteinous food additives, and changes in the intensity of signals appearing in them after they had been irradiated with electron beams were measured by ESR. It was found by such measurement that the positions of signals of thaumatin and soy proteins are nearly the same. Changes in the intensity of radicals in thaumatin calculated on the basis of the coefficients of the respective approximations obtained by using thaumatin which had been irradiated and then stored at 4°C, 25°C, 37°C and 60°C showed that there is a temperature range to determine the remaining of such radicals (inner: 19.7°C, outer: 15.23°C) and that such radicals tend to decrease straight line-wise. It was confirmed that the intensity of signals in the protein powder such thaumatin and soy protein would not be affected at the storage condition below 15°C.

DOI： 10.5986/jrafi.34.30

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00063347975?from=CiNii

記述言語：日本語   出版者・発行元：日本食品化学学会  

In order to get prepared for the future practical use of irradiation for the purpose of controlling the microorganisms existing in proteinaceous food additives, we conducted studies on their water sorption isotherm and molecular weight distribution as their functional properties for gelation by irradiating three kind of them with electronic beams up to 25 kGy. The results of such studies were as follows: (1) In the case of a whey protein concentrate, only a few changes were observed in its water absorption volume and molecular weight distribution, and almost no change was observed in its gel strength; (2) In the case of a collagen, a decreasing tendency was observed in its water absorption volume, and a big change was observed in its molecular weight distribution, indicating that both polymerization and decomposition reaction were occurring simultaneously. In terms of its gel strength, however, no remarkable change was observed when irradiation was conducted below 20 kGy, while a weakening tendency was observed when irradiation was conducted at a high absorption dose such as at 20 kGy or above; (3) In the case of an egg white protein, slight increases were observed both in its water absorption volume and molecular weight distribution respectively, and changes in its molecular weight distribution indicated the occurrence of polymerization at a medium absorption dose and the occurrence of decomposition reaction at a high absorption dose; and (4) It is said that irradiation at 5 kGy is sufficient for the sterilization of proteinaceous food additives to kill the microorganisms existing therein, and in fact, an international absorption-dose guideline for the irradiation of foodstuffs also recommends irradiation at less than 10 kGy. It was confirmed by us that the function of gelation required of proteinaceous food additives as one of their main functional properties would not be affected by irradiation at such medium absorption-dose levels.

DOI： 10.18891/jjfcs.6.1_16

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Society of Plant Biologists  

Elevations in cytoplasmic calcium ([Ca2+](cyt)) are an important component of early abscisic acid (ABA) signal transduction. To determine whether defined mutations in ABA signal transduction affect [Ca2+](cyt) signaling, the Ca2+-sensitive fluorescent dye fura 2 was loaded into the cytoplasm of Arabidopsis guard cells. Oscillations in [Ca2+](cyt) could be induced when the external calcium concentration was increased, showing viable Ca2+ homeostasis in these dye-loaded cells. ABA-induced [Ca2+](cyt) elevations in wild-type stomata were either transient or sustained, with a mean increase of ~300 nM. Interestingly, ABA-induced [Ca2+](cyt) increases were significantly reduced but not abolished in guard cells of the ABA-insensitive protein phosphatase mutants abi1 and abi2. Plasma membrane slow anion currents were activated in wild-type, abi1, and abi2 guard cell protoplasts by increasing [Ca2+](cyt), demonstrating that the impairment in ABA activation of anion currents in the abi1 and abi2 mutants was bypassed by increasing [Ca2+](cyt). Furthermore, increases in external calcium alone (which elevate [Ca2+](cyt)) resulted in stomatal closing to the same extent in the abi1 and abi2 mutants as in the wild type. Conversely, stomatal opening assays indicated different interactions of abi1 and abi2, with Ca2+-dependent signal transduction pathways controlling stomatal closing versus stomatal opening. Together, [Ca2+](cyt) recordings, anion current activation, and stomatal closing assays demonstrate that the abi1 and abi2 mutations impair early ABA signaling events in guard cells upstream or close to ABA-induced [Ca2+](cyt) elevations. These results further demonstrate that the mutations can be bypassed during anion channel activation and stomatal closing by experimental elevation of [Ca2+](cyt).

DOI： 10.1105/tpc.11.9.1785

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記述言語：日本語   出版者・発行元：JAPANESE RESEARCH ASSOCIATION FOR FOOD IRRADIATION  

Polysaccharides widely used in the food industry were studied in terms of sterilization of bacteria by irradiation.12 items of polysaccharides irradiated by electron beam ware investigated for bacteria count and the functional property of pH, gel strength, bloom and viscosity. This study aims to determine the sterilization effectby absorption dose and the applicability of the electron beam irradiation toward polysaccharides. Results shows that 1) Over 5kGy absorption dose are enough to be able to sterilize bacteria in the polysaccharidethemselves. 2) We reconfirm that Arabic gum will be applicable for the electron beam irradiation, which hasbeen used in some foreign countries. 3) Electron beam irradiation will be useful for Gellan gum b (acetyl type), as gelling agents in the food application.

DOI： 10.5986/jrafi.33.10

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00055493017?from=CiNii

記述言語：日本語   出版者・発行元：JAPANESE RESEARCH ASSOCIATION FOR FOOD IRRADIATION  

A test was conducted on the effects of irradiation on thaumatin, a protein food additive for sweetener, by using the techniques of HPLC analysis and sensory evalution, and it was confirmedthat irradiated of 5kGy or more may prevent bacterial contamination without changing thaumatin qualitativelyand quantitatively. Such test also indicated that such irradiation will not reduce our otherwise affect thaumatin's function of sweetening foods.

DOI： 10.5986/jrafi.32.13

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00049322941?from=CiNii