研究者詳細 - 坂本　竜哉

MISC - 坂本　竜哉

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Marine macrophyte (eelgrass, Zostera marina) bed creation base research for conservation (1) The seeding depth of the seed of eelgrass and the growth beginning of cotyledon.

T. Fukuda, Y. Kohda, T. Sakamoto

J Kibi Int Univ Res Inst Health Welfare. 15 (2014) 7-12. 2014年

岡山大学の海洋教育普及への取り組み:－地域連携による「うなぎ探検隊」の文理横断学習を中心として－

小林靖尚, 筒井直昭, 齊藤和裕, 坂本竜哉, 藤井浩樹

日本科学教育学会研究会研究報告 29 ( 3 ) 79 - 82 2014年

記述言語：日本語出版者・発行元：一般社団法人日本科学教育学会

我々は岡山県において初等・中等教育課程への海洋教育の普及活動を行っている。このような取り組みを行う際に，児童・生徒の海洋に対する関心の実態を把握することは重要となる。そこで今回は，海洋教育の一環として岡山県内外の様々な組織と協力して地域連携による文理横断学習「うなぎ探検隊」を開催し，参加した児童ならびに保護者を対象とした質問紙調査によって海洋に対する関心の実態把握を試みた。調査の結果，学習に対する肯定的意見は多く，海を含めた水辺の環境を保全することの重要性を伝えるという学習の目的は達成された。そして，海洋に対する意識や関心は児童，保護者ともに高いことが明らかになった。一方，参加者の半数が身近な海や川に接する機会がないことも明らかとなった。

DOI： 10.14935/jsser.29.3_79

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Potential roles of arginine-vasotocin in the regulation of aggressive behavior in the mudskipper (Periophthalmus modestus)

Nao Kagawa, Yudai Nishiyama, Kanoko Kato, Hideya Takahashi, Yasuhisa Kobayashi, Hirotaka Sakamoto, Tatsuya Sakamoto

General and Comparative Endocrinology 194 257 - 263 2013年12月

記述言語：英語出版者・発行元：Academic Press Inc.

The hypothalamic hormones, arginine-vasotocin (VT) and isotocin (IT), play central roles in osmoregulation and in the regulation of social behaviors including aggressive behavior in many vertebrates including fish. Here, we examined whether these hormones are associated with aggressive behavior in the mudskipper (Periophthalmus modestus). The mudskipper is an amphibious fish, which lives in the brackish water of river mouths and displays unique aggressive behavior. Upon introduction to each other in an experimental tank with aquatic and terrestrial areas, a pair of males can be classified as aggressive dominant or submissive subordinate based on the frequency of their aggressive acts, which is significantly higher in dominant male. Additionally, the length of stay in terrestrial area of dominant was longer than that of the subordinate. The latter remained in aquatic area almost throughout the period of behavioral observation. The expression of brain VT mRNA was significantly higher in subordinate than in dominant, whereas neither IT mRNA expression nor plasma cortisol level differed between subordinate and dominant male. On the other hand, an intracerebroventricular injection of VT increased aggressive behaviors in mudskippers. In addition to known roles of VT in mediation of aggressive behavior, these results may shed light on the role of endogenous VT toward water migration in submissive mudskippers. The amphibious fish is a valuable experimental model to observe the relationship between effects of central VT on the osmoregulation and social behavioral regulation in vertebrates. © 2013.

DOI： 10.1016/j.ygcen.2013.09.023

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Central administration of prolactin-releasing peptide shifts the utilities of metabolic fuels from carbohydrate to lipids in chicks

Tetsuya Tachibana, Shunsuke Moriyama, Md Sakirul Islam Khan, Tatsuya Sakamoto

PHYSIOLOGY & BEHAVIOR 120 40 - 45 2013年8月

記述言語：英語出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

We have recently identified prolactin (PRL)-releasing peptides (PrRPs) and their stimulating effects on feeding behavior in chicks. To investigate further metabolic functions of PrRP, the present study was performed to clarify whether intracerebroventricular (ICV) injection of PrRP31, an active form of PrRP in chicks, affects heat production (HP), respiratory quotient (RQ) and plasma concentrations of metabolic fuels in chicks. The ICV injection of PrRP31 (94 and 375 pmol) did not affect HP but significantly lowered RQ. The change in RQ implies that PrRP31 shifted the utility of metabolic fuels in the body. This idea was confirmed by subsequent results in which ICV injection of PrRP31 significantly reduced glucose but increased non-esterified fatty acid concentrations in plasma. These shifts in blood metabolic fuels would not be through the increased plasma insulin, because the ICV injection of PrRP31 significantly decreased plasma insulin concentration. On the other hand, ICV injection of another orexigenic peptide, neuropeptide Y (NPY) also induced the insulin release and the metabolic effects were similar to those of PrRP31. Because ICV injection of PrRP31 increased NPY mRNA in the diencephalon, the NPY may mediate the metabolic functions of PrRP31. In summary, the present study suggests that central PrRP31 shifts the utilities of peripheral energy sources, which is not via hyperinsulinemia but via the diencephalon. (C) 2013 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.physbeh.2013.06.017

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Static and Dynamic Hypergravity Responses of Osteoblasts and Osteoclasts in Medaka Scales

Sachiko Yano, Kei-ichiro Kitamura, Yusuke Satoh, Masaki Nakano, Atsuhiko Hattori, Toshio Sekiguchi, Mika Ikegame, Hiroshi Nakashima, Katsunori Omori, Kazuichi Hayakawa, Atsuhiko Chiba, Yuichi Sasayama, Sadakazu Ejiri, Yuko Mikuni-Takagaki, Hiroyuki Mishima, Hisayuki Funahashi, Tatsuya Sakamoto, Nobuo Suzuki

ZOOLOGICAL SCIENCE 30 ( 3 ) 217 - 223 2013年3月

記述言語：英語出版者・発行元：ZOOLOGICAL SOC JAPAN

Fish scales are a form of calcified tissue similar to that found in human bone. In medaka scales, we detected both osteoblasts and osteoclasts and subsequently developed a new scale assay system. Using this system, we analyzed the osteoblastic and osteoclastic responses under 2-, 3-, and 4-gravity (G) loading by both centrifugation and vibration. After loading for 10 min, the scales from centrifugal and vibration loading were incubated for 6 and 24 hrs, respectively, after which the osteoblastic and osteoclastic activities were measured. Osteoblastic activity significantly increased under 2- to 4-G loading by both centrifugation and vibration. In contrast, we found that osteoclastic activity significantly decreased under 2- and 3-G loading in response to both centrifugation and vibration. Under 4-G loading, osteoclastic activity also decreased on centrifugation, but significantly increased under 4-G loading by vibration, concomitant with markedly increased osteoblastic activity. Expression of the receptor activator of the NF-kappa B ligand (RANKL), an activation factor of osteoclasts expressed in osteoblasts, increased significantly under 4-G loading by vibration but was unchanged by centrifugal loading. A protein sequence similar to osteoprotegerin (OPG), which is known as an osteoclastogenesis inhibitory factor, was found in medaka using our sequence analysis. The ratio of RANKL/OPG-like mRNAs in the vibration-loaded scales was significantly higher than that in the control scales, although there was no difference between centrifugal loaded scales and the control scales. Accordingly, medaka scales provide a useful model by which to analyze bone metabolism in response to physical strain.

DOI： 10.2108/zsj.30.217

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The role of 'mineralocorticoids' in teleost fish: Relative importance of glucocorticoid signaling in the osmoregulation and 'central' actions of mineralocorticoid receptor

Hideya Takahashi, Tatsuya Sakamoto

GENERAL AND COMPARATIVE ENDOCRINOLOGY 181 223 - 228 2013年1月

記述言語：英語出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE

It has long been held that cortisol, a glucocorticoid in many vertebrates, performs glucocorticoid and mineralocorticoid actions in the teleost fish since it lacks aldosterone. However, in addition to the counterparts of tetrapod mineralocorticoid receptors (MRs), 11-deoxycorticosterone (DOC) has been recently identified as a specific endogenous ligand for the MRs in teleosts. Here, we point out the minor role of mineralocorticoid signaling (i.e., DOC-MR) in the osmoregulation compared with those of glucocorticoid signaling (i.e., cortisol-glucocorticoid receptor [GR]), and review the current findings on the physiological roles of the DOC-MR in teleosts. Cortisol promotes both freshwater and seawater adaptation via the GRs in the osmoregulatory organs such as gills and gastrointestinal tracts, but the expressions of MR mRNA are abundant in the brains especially in the key components of the stress axis and cerebellums. Together with the behavioral effects of intracerebroventricular injection with DOC, the MR is suggested to play an important role in the brain dependent behaviors. Since the abundant expression of central MRs has been reported also in higher vertebrates and the MR is thought to be ancestral to the GR, the role of MR in fish might reflect the principal and original function of corticosteroid signaling. Functional evolution of corticosteroid systems is summarized and areas in need of research like our on-going experiments with MR-knockout medaka are outlined. (C) 2012 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ygcen.2012.11.016

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Osmolality and ionic status of hemolymph and branchial Na+/K+-ATPase in adult mitten crab during seawater adaptation.

T. Sakamoto, S. Ogawa, Y. Nishiyama, W, Godo, H. Takahashi

HOAJ Biol. 2:5 (2013) 1-7. 2013年

Morphological responses of mitochondria-rich cells to hypersaline environment in the Australian mudskipper, Periophthalmus minutus (vol 29, pg 444, 2012)

N. Itoki, T. Sakamoto, M. Hayashi, T. Takeda, A. Ishimatsu

ZOOLOGICAL SCIENCE 29 ( 11 ) 794 - 794 2012年11月

Three-dimensional evaluation of the spinal local neural network revealed by the high-voltage electron microscopy: a double immunohistochemical study

Takumi Oti, Keita Satoh, Kazuhiro Saito, Kazuyoshi Murata, Mitsuhiro Kawata, Tatsuya Sakamoto, Hirotaka Sakamoto

HISTOCHEMISTRY AND CELL BIOLOGY 138 ( 4 ) 693 - 697 2012年10月

記述言語：英語出版者・発行元：SPRINGER

Three-dimensional (3-D) analysis of anatomical ultrastructures is important in biological research. However, 3-D image analysis on exact serial sets of ultra-thin sections from biological specimens is very difficult to achieve, and limited information can be obtained by 3-D reconstruction from these sections due to the small area that can be reconstructed. On the other hand, the high-penetration power of electrons by an ultra-high accelerating voltage enables thick sections of biological specimens to be examined. High-voltage electron microscopy (HVEM) is particularly useful for 3-D analysis of the central nervous system because considerably thick sections can be observed at the ultrastructure level. Here, we applied HVEM tomography assisted by light microscopy to a study of the 3-D chemical neuroanatomy of the rat lower spinal cord annotated by double-labeling immunohistochemistry. This powerful methodology is useful for studying molecular and/or chemical neuroanatomy at the 3-D ultrastructural level.

DOI： 10.1007/s00418-012-0976-6

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Growth, energetics and the cortisol-hepatic glucocorticoid receptor axis of medaka (Oryzias latipes) in various salinities

Maho Ogoshi, Kanoko Kato, Hideya Takahashi, Toshitaka Ikeuchi, Tsukasa Abe, Tatsuya Sakamoto

GENERAL AND COMPARATIVE ENDOCRINOLOGY 178 ( 2 ) 175 - 179 2012年9月

記述言語：英語出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE

We examined growth of euryhaline Japanese medaka (Oryzias latipes) after transfer to freshwater or seawater from isotonic saline. Growth was unaffected by the different salinities for 1 week, but the body weight increase and BMI of fish kept in freshwater for 2-3 weeks were significantly higher than those in the isotonic controls. These results may reflect the usual habitat of this species. To assess the basis for the difference in growth, energetics and the hepatic stress axis were evaluated 1 week after the transfer. Unexpectedly, despite the higher growth rate, the rate of routine oxygen consumption was significantly higher in freshwater. Plasma cortisol levels in freshwater were significantly higher than those in seawater, and the mRNA levels of the glucocorticoid receptor (GR1) in the liver were significantly lower in freshwater and seawater, compared to that in isotonic saline. Branchial Na+/K+-ATPase activities were also reduced significantly in freshwater and seawater, compared to that in isotonic saline. The higher levels of hepatic GR1 expression and branchial Na+/K+-ATPase activity in isotonic salinity than those in freshwater and seawater for 1 week may account for the lower growth rate under the isotonic condition. After 3 weeks, however, the Na+/K+-ATPase activity in seawater was significantly higher than that in freshwater. No significant difference in growth rate between freshwater and seawater groups indicates that medaka is a good model for studies of hypo- and hyperosmotic adaptations, since osmoregulation is not strongly associated with size and growth. (C) 2012 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ygcen.2012.05.001

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Prostaglandin E-2 Increases Both Osteoblastic and Osteoclastic Activity in the Scales and Participates in Calcium Metabolism in Goldfish

Katsunori Omori, Shigehito Wada, Yusuke Maruyama, Atsuhiko Hattori, Kei-Ichiro Kitamura, Yusuke Sato, Masayuki Nara, Hisayuki Funahashi, Koji Yachiguchi, Kazuichi Hayakawa, Masato Endo, Rei Kusakari, Sachiko Yano, Ajai K. Srivastav, Takashi Kusui, Sadakazu Ejiri, Wenxi Chen, Yoshiaki Tabuchi, Yukihiro Furusawa, Takashi Kondo, Yuichi Sasayama, Takumi Nishiuchi, Masaki Nakano, Tatsuya Sakamoto, Nobuo Suzuki

ZOOLOGICAL SCIENCE 29 ( 8 ) 499 - 504 2012年8月

記述言語：英語出版者・発行元：ZOOLOGICAL SOC JAPAN

Using our original in vitro assay system with goldfish scales, we examined the direct effect of prostaglandin E-2 (PGE(2)) on osteoclasts and osteoblasts in teleosts. In this assay system, we measured the activity of alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) as respective indicators of each activity in osteoblasts and osteoclasts. ALP activity in scales significantly increased following treatment at high concentration of PGE(2) (10(-7) and 10(-6) M) over 6 hrs of incubation. At 18 hrs of incubation, ALP activity also significantly increased in the PGE(2) (10(-9) to 10(-6) M)-treated scale. In the case of osteoclasts, TRAP activity tended to increase at 6 hrs of incubation, and then significantly increased at 18 hrs of incubation by PGE(2) (10(-7) to 10(-6) M) treatment. At 18 hrs of incubation, the mRNA expression of osteoclastic markers (TRAP and cathepsin K) and receptor activator of the NF-kappa B ligand (RANKL), an activating factor of osteoclasts expressed in osteoblasts, increased in PGE(2) treated-scales. Thus, PGE(2) acts on osteoblasts, and then increases the osteoclastic activity in the scales of goldfish as it does in the bone of mammals. In an in vivo experiment, plasma calcium levels and scale TRAP and ALP activities in the PGE(2)-injencted goldfish increased significantly. We conclude that, in teleosts, PGE(2) activates both osteoblasts and osteoclasts and participates in calcium metabolism.

DOI： 10.2108/zsj.29.499

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Cloning of two members of the calcitonin-family receptors from stingray, Dasyatis akajei: Possible physiological roles of the calcitonin family in osmoregulation

Nobuo Suzuki, Toshio Sekiguchi, Honoo Satake, Kanoko Kato, Yudai Nishiyama, Hideya Takahashi, Janine A. Danks, T. John Martin, Atsuhiko Hattori, Masaki Nakano, Makiko Kakikawa, Sotoshi Yamada, Maho Ogoshi, Susumu Hyodo, Yoko Yamaguchi, Vishwajit S. Chowdhury, Kazuichi Hayakawa, Hisayuki Funahashi, Tatsuya Sakamoto, Yuichi Sasayama

GENE 499 ( 2 ) 326 - 331 2012年5月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

In cartilaginous fish, two cDNAs encoding calcitonin-family receptors were isolated for the first time from the stingray brain. The open reading frame of one receptor cDNA coded a 525-amino acid protein. The amino acid identity of this receptor to human calcitonin-receptor-like receptor (CRLR) is 64.5%, frog CRLR is 64.7%, and flounder CRLR is 61.2% and this was higher than to human calcitonin receptor (CTR) (46.1%), frog CTR (54.7%), and flounder CTR (48.9%). We strongly suggested that this receptor is a ray CRLR based on phylogenetic analysis. In case of the second receptor, amino acid identity among CRLRs (human 50.5%, frog 50.7%, flounder 48.0%) and CTRs (human 43.2%, frog 49.1%, flounder 41.8%) was similar. From phylogenetic analysis of both CRLRs and CTRs, we believe that this receptor is ray CTR. The expression of ray CRLR mRNA was predominantly detected in the nervous system (brain) and vascular system (atrium, ventricle, and gill), which reflects the similar localization of CGRP in the nervous and vascular systems as mammals. It was observed that the second receptor was expressed in several tissues, namely cartilage, brain, pituitary gland, gill, atrium, ventricle, pancreas, spleen, liver, gall bladder, intestine, rectal gland, kidney, testis and ovary. This localization pattern was very similar to flounder CTR. Both receptor mRNAs were strongly expressed in the gill. This suggests that the calcitonin-family members are involved in the osmoregulation of stingray as this fish is known to be euryhaline. When a stingray was transferred to diluted seawater (20% seawater), the expression of both receptors significantly decreased in the gill. Similar results were obtained in the kidney of the stingray. Thus, our cloning and isolation of both receptors in the stingray will be helpful for elucidation of their physiological role(s) such as osmoregulation including calcium metabolism of cartilaginous fish. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.gene.2012.03.042

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Rapid signaling of steroid hormones in the vertebrate nervous system

Hirotaka Sakamoto, Hideya Takahashi, Ken-Ichi Matsuda, Mayumi Nishi, Keiko Takanami, Maho Ogoshi, Tatsuya Sakamoto, Mitsuhiro Kawata

FRONTIERS IN BIOSCIENCE-LANDMARK 17 996 - 1019 2012年1月

記述言語：英語出版者・発行元：FRONTIERS IN BIOSCIENCE INC

Steroid hormones easily cross the blood-brain barrier because of their physicochemical lipid solubility. The hormones act through nuclear receptor-mediated mechanisms and modulate gene transcription. In contrast to their genomic actions, the non-genomic rapid action of steroid hormones, acting via various types of membrane-associated receptors, reveals pharmacological properties that are distinct from the actions of the intracellular nuclear receptors. As a result, non-genomic rapid actions have gained increased scientific interest. However, insight into the phylogenic and/or comparative actions of steroids in the brain is still poorly understood. In this review, we summarize recent findings concerning the rapid, non-genomic signaling of steroid hormones in the vertebrate central nervous system, and we discuss (using a comparative view from fish to mammals) recently published data regarding the mechanism underlying physiology and behavior.

DOI： 10.2741/3970

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Prolactin inhibits osteoclastic activity in the goldfish scale: a novel direct action of prolactin in teleosts.

H. Takahashi, N. Suzuki, C. Takagi, M. Ikegame, T. Yamamoto, A. Takahashi, S. Moriyama, A. Hattori, T. Sakamoto

Zool Sci, Virtual Issue, (2012) 2012年

Hemolymph osmotic, ionic status, and branchial Na⁺/K⁺-ATPase activity under varying environmental conditions in the intertidal grapsid crab, Gaetice depressusd

Takeshi Nanba, Hideya Takahashi, Tsukasa Abe, Waichirou Godo, Maho Ogoshi, Hirotaka Sakamoto, Naoaki Tsutsui, Tatsuya Sakamoto

International Aquatic Research 4 ( 1 ) 2012年

© 2012, Nanba et al.; licensee Springer. Osmo- and ionoregulatory abilities were examined in the intertidal grapsid crab, Gaetice depressus, transferred from normal seawater (30 ppt) to low (10 ppt) or high (50 ppt) salinities for 2 and 10 days, in addition to animals kept out of water for 2 days. The results of the hemolymph osmotic and ionic status indicate that G. depressus is able to adapt for more than 10 days in these salinities and for 2 days under terrestrial conditions. Especially, the free Ca2+ concentration was relatively maintained compared with concentrations of monovalent ions and osmolality values in 10 and 50 ppt, partly using the complexed calcium (total minus free calcium) as an internal reserve in the hemolymph. In 10 ppt, complexed calcium disappeared from the hemolymph after 10 days, indicating that all the hemolymph calcium was ionized. In 50 ppt, free Ca2+ was regulated to lower levels than concentrations in the medium, while total calcium increased to higher levels after 2 days. Examination of Na+/K+-ATPase activity, which has been implicated in ion transport in many crustaceans, revealed that induction of high Na+/K+-ATPase activity varies among the posterior gills in response to salinities. Ten-ppt salinity induces activity in two of the posterior gills (gill numbers 6 and 7, eight in total), albeit with differing degrees of response. In contrast, 50-ppt salinity stimulates the activity primarily in gill number 8, suggesting that this gill may be associated specifically with ion excretion in G. depressus. As a euryhaline amphibious crab, this abundant species around Japan will serve as a model to study the osmotic/ionic regulatory mechanisms which operate in crustaceans.

DOI： 10.1186/2008-6970-4-18

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Comparative and general aspects of calcium homeostasis and its hormonal regulations.

N. Suzuki, T. Sakamoto

Zool Sci, Virtual Issue, (2012) 2012年

異なる浸透圧におけるメダカの成長と体液調節・エネルギー代謝

御輿真穂, 坂本竜哉

比較内分泌学 38 ( 147 ) 209 - 211 2012年

Corticosteroids stimulate the amphibious behavior in mudskipper: Potential role of mineralocorticoid receptors in teleost fish

Tatsuya Sakamoto, Chie Mori, Shogo Minami, Hideya Takahashi, Tsukasa Abe, Daisuke Ojima, Maho Ogoshi, Hirotaka Sakamoto

PHYSIOLOGY & BEHAVIOR 104 ( 5 ) 923 - 928 2011年10月

記述言語：英語出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

It has long been held that cortisol, a glucocorticoid in many vertebrates, carries out both glucocorticoid and mineralocorticoid actions in teleost fish. However, 11-deoxycorticosterone (DOC) has been identified as a specific endogenous ligand for the teleostean mineralocorticoid receptor (MR). Furthermore, the expressions of MR mRNA are modest in the osmoregulatory organs, but considerably higher in the brain of most teleosts. These recent findings suggest that the mineralocorticoid system (DOC/MR) may carry out some behavioral functions in fish. To test this possibility, we examined the effects of cortisol and DOC administration in the amphibious behavior in mudskipper (Periophthalmus modestus) in vivo. It was found that mudskippers remained in the water for an increased period of time when they were immersed into 5 mu M DOC or cortisol for 8 h. Additionally, an exposure to 25 mu M DOC for 4 to 8 h caused a decreased migratory frequency of mudskippers to the water, reflected a tendency to remain in the water. It was further observed that after 8 h of intracerebroventricular (ICV) injection with 0.3 pmol DOC or cortisol the staying period in the water increased in fish. The migratory frequency was decreased after ICV DOC injection which indicated that fishes stayed in the water. Concurrent ICV injections of cortisol with RU486 [a specific glucocorticoid-receptor (GR) antagonist] inhibited only the partial effects of cortisol. Together with no changes in the plasma DOC concentrations under terrestrial conditions, these results indicate the involvement of brain MRs as cortisol receptors in the preference for an aquatic habitat of mudskippers. Although the role of GR signaling cannot be excluded in the aquatic preference, our data further suggest that the MR may play an important role in the brain dependent behaviors of teleost fish. (C) 2011 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.physbeh.2011.06.002

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Embryonic development and larval behavior of the kissing loach (Parabotia curta): adaptations to an ephemeral, hypoxic environment

Tsukasa Abe, Tatsuya Sakamoto

ICHTHYOLOGICAL RESEARCH 58 ( 3 ) 238 - 244 2011年7月

記述言語：英語出版者・発行元：SPRINGER TOKYO

Many teleost fishes in lowland fresh waters spawn in ephemeral flooded areas, the bottoms of which are prone to hypoxia. Little is known about how embryos and larvae deal with these potentially hostile environments. This study examines the functional and behavioral ontogeny of one such species, the kissing loach (Parabotia curta). Kissing loach eggs are demersal and adhesive. Hatching occurs at 24.8 +/- A 0.1 h post-fertilization at 25A degrees C, much earlier than most fish species. The newly hatched larvae are precocious with no functional mouth, fins or eye pigmentation. Swimbladder inflation normally occurs at about 4 days posthatch, even before which the hatched larvae moved immediately toward the water surface to hang from water moss. Experiments with larvae 20 h after hatching showed that they spent significantly less time on the bottom in hypoxic water (2 mg/l) than in normoxic water, and suggest that hypoxia is a major directive factor in eliciting surfacing behavior. For the kissing loach, we have previously reported short-term spawning after the formation of flood areas as well as wide scattering of the spawned eggs in the temporal flooded areas. These traits with the present results of hatching at an early stage and the immediate upward movement of larvae are considered to be effective strategies for using ephemeral, hypoxic flooded areas for reproduction.

DOI： 10.1007/s10228-011-0217-3

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Isolation and Characterisation of Prolactin-Releasing Peptide in Chicks and its Effect on Prolactin Release and Feeding Behaviour

T. Tachibana, S. Moriyama, A. Takahashi, A. Tsukada, A. Oda, S. Takeuchi, T. Sakamoto

JOURNAL OF NEUROENDOCRINOLOGY 23 ( 1 ) 74 - 81 2011年1月

記述言語：英語出版者・発行元：WILEY-BLACKWELL PUBLISHING, INC

Prolactin (PRL)-releasing peptides (PrRP) have been identified in mammals, amphibians and fishes, and these animals have several PrRPs that consist of different numbers of amino acids such as 20, 31 and 37. In the present study, we identified the cDNA encoding chicken prepro-PrRP, which can generate putative PrRPs, and cloned and sequenced it. Sequences for the coding region suggested the occurrence of putative PrRPs of 20, 31 and 32 amino acid residues. The amino acid sequence of chicken PrRP20 showed 100%, 95% and 70% identity with those of PrRP20s from teleosts, Xenopus laevis and mammals, respectively. On the other hand, chicken PrRP31 showed approximately 90% and 52-55% homology to PrRP31s of X. laevis and mammals, respectively. Native chicken PrRPs were purified from an acid extract of chick brain by a Sep-Pak C18 cartridge (Waters Corp., Milford, MA, USA), affinity chromatography using anti-salmon PrRP serum, and reverse phase high-performance liquid chromatography (HPLC) on an ODS-120T column (TOSOH, Tokyo, Japan). The existence of chicken PrRP20 and PrRP31 in the brain was demonstrated by comparing them with the synthetic peptides using HPLC and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. Chicken PrRP31 increased plasma PRL concentration when administered peripherally, whereas central administration decreased the concentration, suggesting that chicken PrRP31 has a distinct effect on PRL secretion between tissues in chicks. On the other hand, plasma growth hormone concentration decreased with both peripheral and central administrations of chicken PrRP31. Furthermore, central administration of chicken PrRP31 increased food intake in chicks compared to those observed in mammals and fishes. Taken together with the results indicating that chicken PrRP20 did not show endocrine and behavioural effects, we showed that chicken PrRP has a similar amino acid sequence to teleosts, Xenopus laevis and mammals, although the actions were variable among vertebrates.

DOI： 10.1111/j.1365-2826.2010.02078.x

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