Updated on 2025/09/30

写真a

 
SAKAMOTO Tatsuya
 
Organization
Faculty of Environmental, Life, Natural Science and Technology Professor
Position
Professor
External link

Degree

  • Ph.D. ( The University of Tokyo )

Research Interests

  • Molecular Physiology of Adaptation

  • Comparative Endocrinology

  • Marine Biology

  • 適応生理学

  • 比較内分泌学

  • 海洋生物学

Research Areas

  • Life Science / Animal physiological chemistry, physiology and behavioral biology

  • Life Science / Aquatic bioproduction science

  • Life Science / Morphology and anatomical structure

Education

  • The University of Tokyo   理学系研究科   動物学

    - 1992

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    Country： Japan

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  • The University of Tokyo    

    - 1992

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  • The University of Tokyo   理学部   生物学

    - 1987

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    Country： Japan

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  • The University of Tokyo    

    - 1987

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Research History

  • - 岡山大学自然科学研究科 教授

    2004

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  • - Professor,Graduate School of Natural Science and Technology,Okayama University

    2004

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Professional Memberships

  • 国際比較内分泌学会連合(International Federation of Comparative Endocrinological Societies)

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  • 日本比較内分泌学会

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  • 日本生理学会

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  • 日本動物学会

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Papers

  • Structure of putative epidermal sensory receptors in an acoel flatworm, Praesagittifera naikaiensis Reviewed

    Tosuke Sakagami, Kaho Watanabe, Mayuko Hamada, Tatsuya Sakamoto, Toshimitsu Hatabu, Motonori Ando

    Cell and Tissue Research   395 ( 3 )   299 - 311   2024.2

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    Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

    Abstract

    Acoel flatworms possess epidermal sensory-receptor cells on their body surfaces and exhibit behavioral repertoires such as geotaxis and phototaxis. Acoel epidermal sensory receptors should be mechanical and/or chemical receptors; however, the mechanisms of their sensory reception have not been elucidated. We examined the three-dimensional relationship between epidermal sensory receptors and their innervation in an acoel flatworm, Praesagittifera naikaiensis. The distribution of the sensory receptors was different between the ventral and dorsal sides of worms. The nervous system was mainly composed of a peripheral nerve net, an anterior brain, and three pairs of longitudinal nerve cords. The nerve net was located closer to the body surface than the brain and the nerve cords. The sensory receptors have neural connections with the nerve net in the entire body of worms. We identified five homologs of polycystic kidney disease (PKD): PKD1-1, PKD1-2, PKD1-3, PKD1-4, and, PKD2, from the P. naikaiensis genome. All of these PKD genes were implied to be expressed in the epidermal sensory receptors of P. naikaiensis. PKD1-1 and PKD2 were dispersed across the entire body of worms. PKD1-2, PKD1-3, and PKD1-4 were expressed in the anterior region of worms. PKD1-4 was also expressed around the mouth opening. Our results indicated that P. naikaiensis possessed several types of epidermal sensory receptors to convert various environmental stimuli into electrical signals via the PKD channels and transmit the signals to afferent nerve and/or effector cells.

    DOI： 10.1007/s00441-024-03865-y

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    Other Link： https://link.springer.com/article/10.1007/s00441-024-03865-y/fulltext.html

  • Model systems for discovering evolutionary singularity of bilaterian physiological regulation: lessons from studies on simple/primitive flatworms Reviewed

    Shunsuke Mori, Aoshi Kobayashi, Hirotaka Sakamoto, Mayuko Hamada, Tatsuya Sakamoto, Ryo Nakamura

    Biophysics and Physicobiology   2024

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    Publishing type：Research paper (scientific journal)   Publisher：Biophysical Society of Japan  

    DOI： 10.2142/biophysico.bppb-v21.s012

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  • Identification of an additional vitellogenin gene showing hepatopancreas-specific expression in the kuruma prawn Marsupenaeus japonicus Reviewed

    Marwa Said El-Desoky, Tetsuya Jogatani, Fumihiro Yamane, Kouichi Izumikawa, Makoto Kakinuma, Tatsuya Sakamoto, Naoaki Tsutsui

    Fisheries Science   89 ( 5 )   613 - 623   2023.9

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    Publishing type：Research paper (scientific journal)  

    DOI： 10.1007/s12562-023-01705-6

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  • Chronic corticosterone exposure evokes itch hypersensitivity and sexual dysfunction in male rats: Relationship between the two distinct gastrin-releasing peptide systems in the spinal cord Reviewed

    Keiko Takanami, Makoto Morishita, Tatsuya Sakamoto, Hirotaka Sakamoto

    General and Comparative Endocrinology   339   114289 - 114289   2023.8

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    Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

    DOI： 10.1016/j.ygcen.2023.114289

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  • Evolutionary differentiation of androgen receptor is responsible for sexual characteristic development in a teleost fish. Reviewed International journal

    Yukiko Ogino, Satoshi Ansai, Eiji Watanabe, Masaki Yasugi, Yukitoshi Katayama, Hirotaka Sakamoto, Keigo Okamoto, Kataaki Okubo, Yasuhiro Yamamoto, Ikuyo Hara, Touko Yamazaki, Ai Kato, Yasuhiro Kamei, Kiyoshi Naruse, Kohei Ohta, Hajime Ogino, Tatsuya Sakamoto, Shinichi Miyagawa, Tomomi Sato, Gen Yamada, Michael E Baker, Taisen Iguchi

    Nature communications   14 ( 1 )   1428 - 1428   2023.3

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Research Square Platform LLC  

    Teleost fishes exhibit complex sexual characteristics in response to androgens, such as fin enlargement and courtship display. However, the molecular mechanisms underlying their evolutionary acquisition remain largely unknown. To address this question, we analyse medaka (Oryzias latipes) mutants deficient in teleost-specific androgen receptor ohnologs (ara and arb). We discovered that neither ar ohnolog was required for spermatogenesis, whilst they appear to be functionally redundant for the courtship display in males. However, both were required for reproductive success: ara for tooth enlargement and the reproductive behaviour eliciting female receptivity, arb for male-specific fin morphogenesis and sexual motivation. We further showed that differences between the two ar ohnologs in their transcription, cellular localisation of their encoded proteins, and their downstream genetic programmes could be responsible for the phenotypic diversity between the ara and arb mutants. These findings suggest that the ar ohnologs have diverged in two ways: first, through the loss of their roles in spermatogenesis and second, through gene duplication followed by functional differentiation that has likely resolved the pleiotropic roles derived from their ancestral gene. Thus, our results provide insights into how genome duplication impacts the massive diversification of sexual characteristics in the teleost lineage.

    DOI： 10.1038/s41467-023-37026-6

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    Other Link： https://www.researchsquare.com/article/rs-1848626/v1.html

  • De novo transcriptome analysis of the centrohelid Raphidocystis contractilis to identify genes involved in microtubule-based motility. Reviewed International journal

    Risa Ikeda, Tosuke Sakagami, Mayuko Hamada, Tatsuya Sakamoto, Toshimitsu Hatabu, Noboru Saito, Motonori Ando

    The Journal of eukaryotic microbiology   70 ( 2 )   e12955   2023

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    Language：English   Publishing type：Research paper (scientific journal)  

    The centrohelid heliozoan Raphidocystis contractilis has many radiating axopodia, each containing axopodial microtubules. The axopodia show rapid contraction at nearly a video rate (30 frames per second) in response to mechanical stimuli. The axopodial contraction is accompanied by cytoskeletal microtubule depolymerization, but the molecular mechanism of this phenomenon has not been elucidated. In this study, we performed de novo transcriptome sequencing of R. contractilis to identify genes involved in microtubule dynamics such as the rapid axopodial contraction. The transcriptome sequencing generated 7.15-Gbp clean reads in total, which were assembled as 31,771 unigenes. Using the obtained gene sets, we identified several microtubule-severing proteins which might be involved in the rapid axopodial contraction, and kinesin-like genes that occur gene duplication. On the other hand, some genes for microtubule motor proteins involved in the formation and motility of flagella were not found in R. contractilis, suggesting that the gene repertoire of R. contractilis reflected the morphological features of non-flagellated protists. Our transcriptome analysis provides basic information for the analysis of the molecular mechanism underlying microtubule dynamics in R. contractilis.

    DOI： 10.1111/jeu.12955

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  • Quantitative PCR method to detect an extremely endangered bitterling fish (Rhodeus atremius suigensis) using environmental DNA Reviewed

    Kanoko Otsuki, Mayuko Hamada, Noriyuki Koizumi, Tatsuya Sakamoto, Kazuyoshi Nakata

    Landscape and Ecological Engineering   2023

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    Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

    DOI： 10.1007/s11355-022-00531-9

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    Other Link： https://link.springer.com/article/10.1007/s11355-022-00531-9/fulltext.html

  • Footedness for scratching itchy eyes in rodents. Reviewed International journal

    Yukitoshi Katayama, Ayane Miura, Tatsuya Sakamoto, Keiko Takanami, Hirotaka Sakamoto

    Proceedings. Biological sciences   289 ( 1985 )   20221126 - 20221126   2022.10

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    Language：English   Publishing type：Research paper (scientific journal)  

    The neural bases of itchy eye transmission remain unclear compared with those involved in body itch. Here, we show in rodents that the gastrin-releasing peptide receptor (GRPR) of the trigeminal sensory system is involved in the transmission of itchy eyes. Interestingly, we further demonstrate a difference in scratching behaviour between the left and right hindfeet in rodents; histamine instillation into the conjunctival sac of both eyes revealed right-foot biased laterality in the scratching movements. Unilateral histamine instillation specifically induced neural activation in the ipsilateral sensory pathway, with no significant difference between the activations following left- and right-eye instillations. Thus, the behavioural laterality is presumably due to right-foot preference in rodents. Genetically modified rats with specific depletion of Grpr-expressing neurons in the trigeminal sensory nucleus caudalis of the medulla oblongata exhibited fewer and shorter histamine-induced scratching movements than controls and eliminated the footedness. These results taken together indicate that the Grpr-expressing neurons are required for the transmission of itch sensation from the eyes, but that foot preference is generated centrally. These findings could open up a new field of research on the mechanisms of the laterality in vertebrates and also offer new potential therapeutic approaches to refractory pruritic eye disorders.

    DOI： 10.1098/rspb.2022.1126

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  • Molecular and morphological investigations on the renal mechanisms enabling euryhalinity of red stingray Hemitrygon akajei Reviewed

    Naotaka Aburatani, Wataru Takagi, Marty Kwok-Shing Wong, Shigehiro Kuraku, Chiharu Tanegashima, Mitsutaka Kadota, Kazuhiro Saito, Waichiro Godo, Tatsuya Sakamoto, Susumu Hyodo

    Frontiers in Physiology   13   2022.8

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    Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

    Most cartilaginous fishes live in seawater (SW), but a few exceptional elasmobranchs (sharks and rays) are euryhaline and can acclimate to freshwater (FW) environments. The plasma of elasmobranchs is high in NaCl and urea concentrations, which constrains osmotic water loss. However, these euryhaline elasmobranchs maintain high levels of plasma NaCl and urea even when acclimating to low salinity, resulting in a strong osmotic gradient from external environment to body fluid. The kidney consequently produces a large volume of dilute urine to cope with the water influx. In the present study, we investigated the molecular mechanisms of dilute urine production in the kidney of Japanese red stingray, Hemitrygon akajei, transferred from SW to low-salinity environments. We showed that red stingray maintained high plasma NaCl and urea levels by reabsorbing more osmolytes in the kidney when transferred to low salinity. RNA-seq and qPCR analyses were conducted to identify genes involved in NaCl and urea reabsorption under the low-salinity conditions, and the upregulated gene expressions of Na+-K+-Cl- cotransporter 2 (nkcc2) and Na+/K+-ATPase (nka) were found in the FW-acclimated individuals. These upregulations occurred in the early distal tubule (EDT) in the bundle zone of the kidney, which coils around the proximal and collecting tubules to form the highly convoluted structure of batoid nephron. Considering the previously proposed model for urea reabsorption, the upregulation of nkcc2 and nka not only causes the reabsorption of NaCl in the EDT, but potentially also supports enhanced urea reabsorption and eventually the production of dilute urine in FW-acclimated individuals. We propose advantageous characteristics of the batoid-type nephron that facilitate acclimation to a wide range of salinities, which might have allowed the batoids to expand their habitats.

    DOI： 10.3389/fphys.2022.953665

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  • Lattice-patterned collagen fibers and their dynamics in axolotl skin regeneration. Reviewed International journal

    Rena Kashimoto, Saya Furukawa, Sakiya Yamamoto, Yasuhiro Kamei, Joe Sakamoto, Shigenori Nonaka, Tomonobu M Watanabe, Tatsuya Sakamoto, Hirotaka Sakamoto, Akira Satoh

    iScience   25 ( 7 )   104524 - 104524   2022.7

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    Language：English   Publishing type：Research paper (scientific journal)  

    The morphology of collagen-producing cells and the structure of produced collagen in the dermis have not been well-described. This lack of insights has been a serious obstacle in the evaluation of skin regeneration. We succeeded in visualizing collagen-producing cells and produced collagen using the axolotl skin, which is highly transparent. The visualized dermal collagen had a lattice-like structure. The collagen-producing fibroblasts consistently possessed the lattice-patterned filopodia along with the lattice-patterned collagen network. The dynamics of this lattice-like structure were also verified in the skin regeneration process of axolotls, and it was found that the correct lattice-like structure was not reorganized after simple skin wounding but was reorganized in the presence of nerves. These findings are not only fundamental insights in dermatology but also valuable insights into the mechanism of skin regeneration.

    DOI： 10.1016/j.isci.2022.104524

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  • Characterization of the expression of gastrin-releasing peptide and its receptor in the trigeminal and spinal somatosensory systems of Japanese macaque monkeys: Insight into humans. Reviewed International journal

    Keiko Takanami, Takumi Oti, Yasuhisa Kobayashi, Koki Hasegawa, Takashi Ito, Naoaki Tsutsui, Yasumasa Ueda, Earl Carstens, Tatsuya Sakamoto, Hirotaka Sakamoto

    The Journal of comparative neurology   2022.6

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    Language：English   Publishing type：Research paper (scientific journal)  

    Gastrin-releasing peptide (GRP) and its receptor (GRPR) have been identified as itch mediators in the spinal and trigeminal somatosensory systems in rodents. In primates, there are few reports of GRP/GRPR expression or function in the spinal sensory system and virtually nothing is known in the trigeminal system. The aim of the present study was to characterize GRP and GRPR in the trigeminal and spinal somatosensory system of Japanese macaque monkeys (Macaca fuscata). cDNA encoding GRP was isolated from the macaque dorsal root ganglion (DRG) and exhibited an amino acid sequence that was highly conserved among mammals and especially in primates. Immunohistochemical analysis demonstrated that GRP was expressed mainly in the small-sized trigeminal ganglion and DRG in adult macaque monkeys. Densely stained GRP-immunoreactive (ir) fibers were observed in superficial layers of the spinal trigeminal nucleus caudalis (Sp5C) and the spinal cord. In contrast, GRP-ir fibers were rarely observed in the principal sensory trigeminal nucleus and oral and interpolar divisions of the spinal trigeminal nucleus. cDNA cloning, in situ hybridization, and Western blot revealed substantial expression of GRPR mRNA and GRPR protein in the macaque spinal dorsal horn and Sp5C. Our Western ligand blot and ligand derivative stain for GRPR revealed that GRP directly bound in the macaque Sp5C and spinal dorsal horn as reported in rodents. Finally, GRP-ir fibers were also detected in the human spinal dorsal horn. The spinal and trigeminal itch neural circuits labeled with GRP and GRPR appear to function also in primates.

    DOI： 10.1002/cne.25376

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  • 雄ラット扁桃体内側核後背側部におけるガストリン放出ペプチド系を介した性行動調節メカニズムの解明

    大坪 秋人, 上田 涼太, 高松 廉, 大野 智輝, 前嶋 翔, 越智 拓海, 犬束 歩, 尾仲 達史, 坂本 竜哉, 坂本 浩隆

    日本内分泌学会雑誌   97 ( 5 )   1254 - 1254   2022.3

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    Language：Japanese   Publisher：(一社)日本内分泌学会  

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  • Observing Phylum-Level Metazoan Diversity by Environmental DNA Analysis at the Ushimado Area in the Seto Inland Sea. Reviewed

    Takeshi Kawashima, Masa-Aki Yoshida, Hideyuki Miyazawa, Hiroaki Nakano, Natumi Nakano, Tatsuya Sakamoto, Mayuko Hamada

    Zoological science   39 ( 1 )   157 - 165   2022.2

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    Language：English   Publishing type：Research paper (scientific journal)  

    The dynamics of microscopic marine plankton in coastal areas is a fundamental theme in marine biodiversity research, but studies have been limited because the only available methodology was collection of plankton using plankton-nets and microscopic observation. In recent years, environmental DNA (eDNA) analysis has exhibited potential for conducting comprehensive surveys of marine plankton diversity in water at fixed points and depths in the ocean. However, few studies have examined how eDNA analysis reflects the actual distribution and dynamics of organisms in the field, and further investigation is needed to determine whether it can detect distinct differences in plankton density in the field. To address this, we analyzed eDNA in seawater samples collected at 1 km intervals at three depths over a linear distance of approximately 3.0 km in the Seto Inland Sea. The survey area included a location with a high density of Acoela (Praesagittifera naikaiensis). However, the eDNA signal for this was little to none, and its presence would not have been noticed if we did not have this information beforehand. Meanwhile, eDNA analysis enabled us to confirm the presence of a species of Placozoa that was previously undiscovered in the area. In summary, our results suggest that the number of sequence reads generated from eDNA samples in our project was not sufficient to predict the density of a particular species. However, eDNA can be useful for detecting organisms that have been overlooked using other methods.

    DOI： 10.2108/zs210073

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  • Vasopressin-oxytocin–type signaling is ancient and has a conserved water homeostasis role in euryhaline marine planarians Reviewed

    Aoshi Kobayashi, Mayuko Hamada, Masa-aki Yoshida, Yasuhisa Kobayashi, Naoaki Tsutsui, Toshio Sekiguchi, Yuta Matsukawa, Sho Maejima, Joseph J. Gingell, Shoko Sekiguchi, Ayumu Hamamoto, Debbie L. Hay, John F. Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

    Science Advances   8 ( 9 )   2022

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    Publishing type：Research paper (scientific journal)   Publisher：American Association for the Advancement of Science (AAAS)  

    Vasopressin/oxytocin (VP/OT)–related peptides are essential for mammalian antidiuresis, sociosexual behavior, and reproduction. However, the evolutionary origin of this peptide system is still uncertain. Here, we identify orthologous genes to those for VP/OT in Platyhelminthes, intertidal planarians that have a simple bilaterian body structure but lack a coelom and body-fluid circulatory system. We report a comprehensive characterization of the neuropeptide derived from this VP/OT-type gene, identifying its functional receptor, and name it the “platytocin” system. Our experiments with these euryhaline planarians, living where environmental salinities fluctuate due to evaporation and rainfall, suggest that platytocin functions as an “antidiuretic hormone” and also organizes diverse actions including reproduction and chemosensory-associated behavior. We propose that bilaterians acquired physiological adaptations to amphibious lives by such regulation of the body fluids. This neuropeptide-secreting system clearly became indispensable for life even without the development of a vascular circulatory system or relevant synapses.

    DOI： 10.1126/sciadv.abk0331

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  • Squalomix: shark and ray genome analysis consortium and its data sharing platform. Reviewed International journal

    Osamu Nishimura, John Rozewicki, Kazuaki Yamaguchi, Kaori Tatsumi, Yuta Ohishi, Tazro Ohta, Masaru Yagura, Taiki Niwa, Chiharu Tanegashima, Akinori Teramura, Shotaro Hirase, Akane Kawaguchi, Milton Tan, Salvatore D'Aniello, Filipe Castro, André Machado, Mitsumasa Koyanagi, Akihisa Terakita, Ryo Misawa, Masayuki Horie, Junna Kawasaki, Takashi Asahida, Atsuko Yamaguchi, Kiyomi Murakumo, Rui Matsumoto, Iker Irisarri, Norio Miyamoto, Atsushi Toyoda, Sho Tanaka, Tatsuya Sakamoto, Yasuko Semba, Shinya Yamauchi, Kazuyuki Yamada, Kiyonori Nishida, Itsuki Kiyatake, Keiichi Sato, Susumu Hyodo, Mitsutaka Kadota, Yoshinobu Uno, Shigehiro Kuraku

    F1000Research   11   1077 - 1077   2022

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    Language：English   Publishing type：Research paper (scientific journal)  

    The taxon Elasmobranchii (sharks and rays) contains one of the long-established evolutionary lineages of vertebrates with a tantalizing collection of species occupying critical aquatic habitats. To overcome the current limitation in molecular resources, we launched the Squalomix Consortium in 2020 to promote a genome-wide array of molecular approaches, specifically targeting shark and ray species. Among the various bottlenecks in working with elasmobranchs are their elusiveness and low fecundity as well as the large and highly repetitive genomes. Their peculiar body fluid composition has also hindered the establishment of methods to perform routine cell culturing required for their karyotyping. In the Squalomix consortium, these obstacles are expected to be solved through a combination of in-house cytological techniques including karyotyping of cultured cells, chromatin preparation for Hi-C data acquisition, and high fidelity long-read sequencing. The resources and products obtained in this consortium, including genome and transcriptome sequences, a genome browser powered by JBrowse2 to visualize sequence alignments, and comprehensive matrices of gene expression profiles for selected species are accessible through https://github.com/Squalomix/info.

    DOI： 10.12688/f1000research.123591.1

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  • Behavioural osmoregulation during land invasion in fish: Prandial drinking and wetting of the dry skin. Reviewed International journal

    Yukitoshi Katayama, Takehiro Tsukada, Susumu Hyodo, Hirotaka Sakamoto, Tatsuya Sakamoto

    PloS one   17 ( 12 )   e0277968   2022

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    Osmoregulatory behaviours should have evolutionarily modified for terrestrialisation of vertebrates. In mammals, sensations of buccal food and drying have immediate effects on postprandial thirst to prevent future systemic dehydration, and is thereby considered to be 'anticipatory thirst'. However, it remains unclear whether such an anticipatory response has been acquired in the non-tetrapod lineage. Using the mudskipper goby (Periophthalmus modestus) as a semi-terrestrial ray-finned fish, we herein investigated postprandial drinking and other unique features like full-body 'rolling' over on the back although these behaviours had not been considered to have osmoregulatory functions. In our observations on tidal flats, mudskippers migrated into water areas within a minute after terrestrial eating, and exhibited rolling behaviour with accompanying pectoral-fin movements. In aquarium experiments, frequency of migration into a water area for drinking increased within a few minutes after eating onset, without systemic dehydration. During their low humidity exposure, frequency of the rolling behaviour and pectoral-fin movements increased by more than five times to moisten the skin before systemic dehydration. These findings suggest anticipatory responses which arise from oral/gastrointestinal and cutaneous sensation in the goby. These sensation and motivation seem to have evolved in distantly related species in order to solve osmoregulatory challenges during terrestrialisation.

    DOI： 10.1371/journal.pone.0277968

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  • The gastrin-releasing peptide/bombesin system revisited by a reverse-evolutionary study considering Xenopus International journal

    Asuka Hirooka, Mayuko Hamada, Daiki Fujiyama, Keiko Takanami, Yasuhisa Kobayashi, Takumi Oti, Yukitoshi Katayama, Tatsuya Sakamoto, Hirotaka Sakamoto

    Scientific Reports   11 ( 1 )   13315 - 13315   2021.12

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

    <title>Abstract</title>Bombesin is a putative antibacterial peptide isolated from the skin of the frog, <italic>Bombina bombina</italic>. Two related (bombesin-like) peptides, gastrin-releasing peptide (GRP) and neuromedin B (NMB) have been found in mammals. The history of GRP/bombesin discovery has caused little attention to be paid to the evolutionary relationship of GRP/bombesin and their receptors in vertebrates. We have classified the peptides and their receptors from the phylogenetic viewpoint using a newly established genetic database and bioinformatics. Here we show, by using a clawed frog (<italic>Xenopus tropicalis</italic>), that GRP is not a mammalian counterpart of bombesin and also that, whereas the GRP system is widely conserved among vertebrates, the NMB/bombesin system has diversified in certain lineages, in particular in frog species. To understand the derivation of GRP system in the ancestor of mammals, we have focused on the GRP system in <italic>Xenopus</italic>. Gene expression analyses combined with immunohistochemistry and Western blotting experiments demonstrated that GRP peptides and their receptors are distributed in the brain and stomach of <italic>Xenopus</italic>. We conclude that GRP peptides and their receptors have evolved from ancestral (GRP-like peptide) homologues to play multiple roles in both the gut and the brain as one of the <italic>‘gut-brain peptide’</italic> systems.

    DOI： 10.1038/s41598-021-92528-x

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    Other Link： http://www.nature.com/articles/s41598-021-92528-x

  • Sexual Experience Induces the Expression of Gastrin-Releasing Peptide and Oxytocin Receptors in the Spinal Ejaculation Generator in Rats. International journal

    Takumi Oti, Ryota Ueda, Ryoko Kumagai, Junta Nagafuchi, Takashi Ito, Tatsuya Sakamoto, Yasuhiko Kondo, Hirotaka Sakamoto

    International journal of molecular sciences   22 ( 19 )   2021.9

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    Language：English   Publishing type：Research paper (scientific journal)  

    Male sexual function in mammals is controlled by the brain neural circuits and the spinal cord centers located in the lamina X of the lumbar spinal cord (L3-L4). Recently, we reported that hypothalamic oxytocin neurons project to the lumbar spinal cord to activate the neurons located in the dorsal lamina X of the lumbar spinal cord (dXL) via oxytocin receptors, thereby facilitating male sexual activity. Sexual experiences can influence male sexual activity in rats. However, how this experience affects the brain-spinal cord neural circuits underlying male sexual activity remains unknown. Focusing on dXL neurons that are innervated by hypothalamic oxytocinergic neurons controlling male sexual function, we examined whether sexual experience affects such neural circuits. We found that >50% of dXL neurons were activated in the first ejaculation group and ~30% in the control and intromission groups in sexually naïve males. In contrast, in sexually experienced males, ~50% of dXL neurons were activated in both the intromission and ejaculation groups, compared to ~30% in the control group. Furthermore, sexual experience induced expressions of gastrin-releasing peptide and oxytocin receptors in the lumbar spinal cord. This is the first demonstration of the effects of sexual experience on molecular expressions in the neural circuits controlling male sexual activity in the spinal cord.

    DOI： 10.3390/ijms221910362

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  • Immunoelectron Microscopic Characterization of Vasopressin-Producing Neurons in the Hypothalamo-Pituitary Axis of Non-Human Primates by Use of Formaldehyde-Fixed Tissues Stored at -25 °C for Several Years. International journal

    Akito Otubo, Sho Maejima, Takumi Oti, Keita Satoh, Yasumasa Ueda, John F Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

    International journal of molecular sciences   22 ( 17 )   2021.8

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    Translational research often requires the testing of experimental therapies in primates, but research in non-human primates is now stringently controlled by law around the world. Tissues fixed in formaldehyde without glutaraldehyde have been thought to be inappropriate for use in electron microscopic analysis, particularly those of the brain. Here we report the immunoelectron microscopic characterization of arginine vasopressin (AVP)-producing neurons in macaque hypothalamo-pituitary axis tissues fixed by perfusion with 4% formaldehyde and stored at -25 °C for several years (4-6 years). The size difference of dense-cored vesicles between magnocellular and parvocellular AVP neurons was detectable in their cell bodies and perivascular nerve endings located, respectively, in the posterior pituitary and median eminence. Furthermore, glutamate and the vesicular glutamate transporter 2 could be colocalized with AVP in perivascular nerve endings of both the posterior pituitary and the external layer of the median eminence, suggesting that both magnocellular and parvocellular AVP neurons are glutamatergic in primates. Both ultrastructure and immunoreactivity can therefore be sufficiently preserved in macaque brain tissues stored long-term, initially for light microscopy. Taken together, these results suggest that this methodology could be applied to the human post-mortem brain and be very useful in translational research.

    DOI： 10.3390/ijms22179180

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  • Estrogens influence female itch sensitivity via the spinal gastrin-releasing peptide receptor neurons International journal

    Keiko Takanami, Daisuke Uta, Ken Ichi Matsuda, Mitsuhiro Kawata, Earl Carstens, Tatsuya Sakamoto, Hirotaka Sakamoto

    Proceedings of the National Academy of Sciences   118 ( 31 )   e2103536118 - e2103536118   2021.8

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Proceedings of the National Academy of Sciences  

    There are sex differences in somatosensory sensitivity. Circulating estrogens appear to have a pronociceptive effect that explains why females are reported to be more sensitive to pain than males. Although itch symptoms develop during pregnancy in many women, the underlying mechanism of female-specific pruritus is unknown. Here, we demonstrate that estradiol, but not progesterone, enhances histamine-evoked scratching behavior indicative of itch in female rats. Estradiol increased the expression of the spinal itch mediator, gastrin-releasing peptide (GRP), and increased the histamine-evoked activity of itch-processing neurons that express the GRP receptor (GRPR) in the spinal dorsal horn. The enhancement of itch behavior by estradiol was suppressed by intrathecal administration of a GRPR blocker. In vivo electrophysiological analysis showed that estradiol increased the histamine-evoked firing frequency and prolonged the response of spinal GRP-sensitive neurons in female rats. On the other hand, estradiol did not affect the threshold of noxious thermal pain and decreased touch sensitivity, indicating that estradiol separately affects itch, pain, and touch modalities. Thus, estrogens selectively enhance histamine-evoked itch in females via the spinal GRP/GRPR system. This may explain why itch sensation varies with estrogen levels and provides a basis for treating itch in females by targeting GRPR.

    DOI： 10.1073/pnas.2103536118

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    Other Link： https://syndication.highwire.org/content/doi/10.1073/pnas.2103536118

  • Systemic effects of oxytocin on male sexual activity via the spinal ejaculation generator in rats. International journal

    Takumi Oti, Tatsuya Sakamoto, Hirotaka Sakamoto

    Communicative & integrative biology   14 ( 1 )   55 - 60   2021.3

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    Language：English   Publishing type：Research paper (scientific journal)  

    Oxytocin is produced in the hypothalamus and stimulates uterine contraction and milk ejection. While many people consider oxytocin to be a female hormone, it is reported that, in men, the plasma oxytocin level increases markedly after ejaculation. However, this aspect of oxytocin physiology is poorly understood. The spinal ejaculation generator (SEG), which expresses the neuropeptide, gastrin-releasing peptide (GRP), can trigger ejaculation in rats. Therefore, we focused on systemic effects of oxytocin on the GRP/SEG neuron system in the lumbar spinal cord controlling sexual activity in male rats. We found that systemic administration of oxytocin significantly shortened the latency to the first mount, intromission and ejaculation during male copulatory behavior. In addition, the local oxytocin level in the lumbar cord was significantly higher in males than in females. Histological analysis showed that oxytocin-binding is apparent in spinal GRP/SEG neurons. We therefore conclude that oxytocin influences male sexual activity via the SEG.

    DOI： 10.1080/19420889.2021.1902056

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  • In Vivo Electrophysiology of Peptidergic Neurons in Deep Layers of the Lumbar Spinal Cord after Optogenetic Stimulation of Hypothalamic Paraventricular Oxytocin Neurons in Rats International journal

    Daisuke Uta, Takumi Oti, Tatsuya Sakamoto, Hirotaka Sakamoto

    International Journal of Molecular Sciences   22 ( 7 )   3400 - 3400   2021.3

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

    The spinal ejaculation generator (SEG) is located in the central gray (lamina X) of the rat lumbar spinal cord and plays a pivotal role in the ejaculatory reflex. We recently reported that SEG neurons express the oxytocin receptor and are activated by oxytocin projections from the paraventricular nucleus of hypothalamus (PVH). However, it is unknown whether the SEG responds to oxytocin in vivo. In this study, we analyzed the characteristics of the brain–spinal cord neural circuit that controls male sexual function using a newly developed in vivo electrophysiological technique. Optogenetic stimulation of the PVH of rats expressing channel rhodopsin under the oxytocin receptor promoter increased the spontaneous firing of most lamina X SEG neurons. This is the first demonstration of the in vivo electrical response from the deeper (lamina X) neurons in the spinal cord. Furthermore, we succeeded in the in vivo whole-cell recordings of lamina X neurons. In vivo whole-cell recordings may reveal the features of lamina X SEG neurons, including differences in neurotransmitters and response to stimulation. Taken together, these results suggest that in vivo electrophysiological stimulation can elucidate the neurophysiological response of a variety of spinal neurons during male sexual behavior.

    DOI： 10.3390/ijms22073400

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  • Oxytocin Influences Male Sexual Activity via Non-synaptic Axonal Release in the Spinal Cord. International journal

    Takumi Oti, Keita Satoh, Daisuke Uta, Junta Nagafuchi, Sayaka Tateishi, Ryota Ueda, Keiko Takanami, Larry J Young, Antony Galione, John F Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

    Current biology : CB   31 ( 1 )   103 - 114   2021.1

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    Language：English   Publishing type：Research paper (scientific journal)  

    Oxytocinergic neurons in the paraventricular nucleus of the hypothalamus that project to extrahypothalamic brain areas and the lumbar spinal cord play an important role in the control of erectile function and male sexual behavior in mammals. The gastrin-releasing peptide (GRP) system in the lumbosacral spinal cord is an important component of the neural circuits that control penile reflexes in rats, circuits that are commonly referred to as the "spinal ejaculation generator (SEG)." We have examined the functional interaction between the SEG neurons and the hypothalamo-spinal oxytocin system in rats. Here, we show that SEG/GRP neurons express oxytocin receptors and are activated by oxytocin during male sexual behavior. Intrathecal injection of oxytocin receptor antagonist not only attenuates ejaculation but also affects pre-ejaculatory behavior during normal sexual activity. Electron microscopy of potassium-stimulated acute slices of the lumbar cord showed that oxytocin-neurophysin-immunoreactivity was detected in large numbers of neurosecretory dense-cored vesicles, many of which are located close to the plasmalemma of axonal varicosities in which no electron-lucent microvesicles or synaptic membrane thickenings were visible. These results suggested that, in rats, release of oxytocin in the lumbar spinal cord is not limited to conventional synapses but occurs by exocytosis of the dense-cored vesicles from axonal varicosities and acts by diffusion-a localized volume transmission-to reach oxytocin receptors on GRP neurons and facilitate male sexual function.

    DOI： 10.1016/j.cub.2020.09.089

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  • Prolactin-releasing peptide

    Tetsuya Tachibana, Tatsuya Sakamoto

    Handbook of Hormones   33 - 36   2021

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    Publishing type：Part of collection (book)   Publisher：Elsevier  

    DOI： 10.1016/b978-0-12-820649-2.00008-5

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  • Prolactin

    Yoko Yamaguchi, Tatsuya Sakamoto

    Handbook of Hormones   203 - 205   2021

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    Publishing type：Part of collection (book)   Publisher：Elsevier  

    DOI： 10.1016/b978-0-12-820649-2.00054-1

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  • Growth hormone/prolactin family

    Yoko Yamaguchi, Tatsuya Sakamoto

    Handbook of Hormones   197 - 198   2021

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    Publishing type：Part of collection (book)   Publisher：Elsevier  

    DOI： 10.1016/b978-0-12-820649-2.00052-8

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  • Visual Docking Against Bubble Noise With 3-D Perception Using Dual-Eye Cameras

    Khin Nwe Lwin, Naoki Mukada, Myo Myint, Daiki Yamada, Akira Yanou, Takayuki Matsuno, Kazuhiro Saitou, Waichiro Godou, Tatsuya Sakamoto, Mamoru Minami

    IEEE JOURNAL OF OCEANIC ENGINEERING   45 ( 1 )   247 - 270   2020.1

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1109/JOE.2018.2871651

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  • Diverse mechanisms for body fluid regulation in teleost fishes Invited Reviewed

    Yoshio Takei, Junya Hiroi, Hideya Takahashi, Tatsuya Sakamoto

    AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY   307 ( 7 )   R778 - R792   2014.10

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1152/ajpregu.00104.2014

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Books

  • "Growth Hormone/Prolactin Family." Handbook of Hormones: Comparative Endocrinology for Basic and Clinical Research

    Elsevier  2021 

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  • "Prolactin-Releasing Peptide." Handbook of Hormones: Comparative Endocrinology for Basic and Clinical Research

    Elsevier  2021 

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  • "Prolactin." Handbook of Hormones: Comparative Endocrinology for Basic and Clinical Research

    Elsevier  2021 

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  • Japanese Marine Life - A Practical Training Guide in Marine Biology.

    Springer Nature  2020 

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  • Evolution of calcium homeostasis and its hormonal regulation in vertebrates

    坂本 竜哉

    2012 

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  • Prolactin. B.E. Toth (ed.)

    坂本 竜哉

    2012 

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  • Recent Advances in Comparative Endocrinology

    2001 

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  • Growth and Growth Regulation in Fish

    American Fisheries Society  2000 

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  • Osamoregulatory roles of prolactin and growth hormone in teleosts(共著)

    Prolactin gene family and its receptors, Elsevier, Amsterdam 

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  • Growth hormone endocrinology of Atlantic salmon during parr-smolt transformation.(共著)

    Growth and Growth Regulation in Fish American Fisheries Society 

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  • Growth hormone endocrinology of Atlantic salmon during parr-smolt transformation.(共著)

    Growth and Growth Regulation in Fish American Fisheries Society 

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  • Osamoregulatory roles of prolactin and growth hormone in teleosts(共著)

    Prolactin gene family and its receptors, Elsevier, Amsterdam 

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  • Hepatic growth hormone receptors in the eel and trout(共著)

    Hormones and environment. Hong Kong Univ. Press, Hong Kong 

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  • Roles of growth hormone and prolactin during adaptation of the gobies to various environments.(共著)

    Growth and Growth Regulation in Fish. American Fisheries Society 

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  • Hepatic growth hormone receptors in the eel and trout(共著)

    Hormones and environment. Hong Kong Univ. Press, Hong Kong 

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  • Roles of growth hormone and prolactin during adaptation of the gobies to various environments.(共著)

    Growth and Growth Regulation in Fish. American Fisheries Society 

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MISC

  • Ushimado Marine Institute (UMI), Faculty of Science, Okayama University

    竜哉 坂本

    NIPPON SUISAN GAKKAISHI   88 ( 3 )   186 - 186   2022.5

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    Publisher：Japanese Society of Fisheries Science  

    DOI： 10.2331/suisan.wa2945

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  • Directors-Council of National Marine and Inland Biological Stations in Japan

    竜哉 坂本

    NIPPON SUISAN GAKKAISHI   88 ( 1 )   23 - 23   2022.1

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    Publisher：Japanese Society of Fisheries Science  

    DOI： 10.2331/suisan.wa2905

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  • オキシトシンによる脊髄射精中枢を介した男性性機能の調節メカニズム

    越智拓海, 越智拓海, 坂本竜哉, 坂本浩隆

    日本性機能学会中部総会プログラム・抄録集   32nd   2022

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  • オキシトシン放出を調節する1回膜貫通型タンパク質CD38のはたらき

    坂本浩隆, 越智拓海, 越智拓海, 大坪秋人, 川上奈津子, 坂本竜哉

    日本解剖学会総会・全国学術集会講演プログラム・抄録集   127th (CD-ROM)   2022

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  • Localization of Oxytocin and Oxytocin Receptors in the Rat Testis

    ZUN Miho, 伊藤隆志, 坂本竜哉, 小谷享, 坂本浩隆, 越智拓海, 越智拓海

    Science Journal of Kanagawa University   32   2021

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  • 17β-エストラジオールによる痒み閾値調節

    高浪景子, 歌大介, 松田賢一, 河田光博, 河田光博, CARSTENS Earl, 坂本竜哉, 坂本浩隆

    日本神経内分泌学会学術集会プログラム・抄録集   47th   2021

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  • コペプチン動態に着目したバソプレシン前駆体・プロセシング機構の解明

    大坪秋人, 川上奈津子, 前嶋翔, 坂本竜哉, 坂本浩隆

    バゾプレシン研究会プログラム・講演抄録   31st   2021

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  • 内側視索前野の性的二型核に発現するガストリン放出ペプチド系は雄ラットの性的活性を制御する

    前嶋翔, 野村黎, 高浪景子, 坂本竜哉, 坂本浩隆

    日本神経内分泌学会学術集会プログラム・抄録集   47th   2021

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  • 扁形動物ヒラムシから紐解くGnRHの祖先型機能

    森俊輔, 酒井丈実, 濱田麻友子, 坂本竜哉, 坂本浩隆

    日本比較内分泌学会大会及びシンポジウムプログラム・講演要旨   45th   2021

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  • ミネラルコルチコイド受容体ノックアウト(MR-KO)メダカにおける異常な視覚依存行動の観察

    唐嘉榮, 今野紀文, 中町智哉, 坂本浩隆, 坂本竜哉, 松田恒平

    日本比較内分泌学会大会及びシンポジウムプログラム・講演要旨   45th   2021

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  • Oxytocin Influences Male Sexual Activity via Non-synaptic Axonal Release in the Spinal Cord International journal

    Takumi Oti, Keita Satoh, Daisuke Uta, Junta Nagafuchi, Sayaka Tateishi, Ryota Ueda, Keiko Takanami, Larry J. Young, Antony Galione, John F. Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

    Current Biology   31 ( 1 )   103 - 114   2020.10

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    Language：English   Publisher：Elsevier BV  

    Oxytocinergic neurons in the paraventricular nucleus of the hypothalamus that project to extrahypothalamic brain areas and the lumbar spinal cord play an important role in the control of erectile function and male sexual behavior in mammals. The gastrin-releasing peptide (GRP) system in the lumbosacral spinal cord is an important component of the neural circuits that control penile reflexes in rats, circuits that are commonly referred to as the "spinal ejaculation generator (SEG)." We have examined the functional interaction between the SEG neurons and the hypothalamo-spinal oxytocin system in rats. Here, we show that SEG/GRP neurons express oxytocin receptors and are activated by oxytocin during male sexual behavior. Intrathecal injection of oxytocin receptor antagonist not only attenuates ejaculation but also affects pre-ejaculatory behavior during normal sexual activity. Electron microscopy of potassium-stimulated acute slices of the lumbar cord showed that oxytocin-neurophysin-immunoreactivity was detected in large numbers of neurosecretory dense-cored vesicles, many of which are located close to the plasmalemma of axonal varicosities in which no electron-lucent microvesicles or synaptic membrane thickenings were visible. These results suggested that, in rats, release of oxytocin in the lumbar spinal cord is not limited to conventional synapses but occurs by exocytosis of the dense-cored vesicles from axonal varicosities and acts by diffusion-a localized volume transmission-to reach oxytocin receptors on GRP neurons and facilitate male sexual function.

    DOI： 10.1016/j.cub.2020.09.089

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  • Variation of pro‐vasopressin processing in parvocellular and magnocellular neurons in the paraventricular nucleus of the hypothalamus: Evidence from the vasopressin‐related glycopeptide copeptin

    Natsuko Kawakami, Akito Otubo, Sho Maejima, Ashraf H. Talukder, Keita Satoh, Takumi Oti, Keiko Takanami, Yasumasa Ueda, Keiichi Itoi, John F. Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

    Journal of Comparative Neurology   2020.9

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  • Introducing the Amphibious Mudskipper Goby as a Unique Model to Evaluate Neuro/Endocrine Regulation of Behaviors Mediated by Buccal Sensation and Corticosteroids

    Yukitoshi Katayama, Kazuhiro Saito, Tatsuya Sakamoto

    International Journal of Molecular Sciences   21 ( 18 )   6748 - 6748   2020.9

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    Publisher：MDPI AG  

    Some fish have acquired the ability to breathe air, but these fish can no longer flush their gills effectively when out of water. Hence, they have developed characteristic means for defense against external stressors, including thirst (osmolarity/ions) and toxicity. Amphibious fish, extant air-breathing fish emerged from water, may serve as models to examine physiological responses to these stressors. Some of these fish, including mudskipper gobies such as Periophthalmodon schlosseri, Boleophthalmus boddarti and our Periophthalmus modestus, display distinct adaptational behaviors to these factors compared with fully aquatic fish. In this review, we introduce the mudskipper goby as a unique model to study the behaviors and the neuro/endocrine mechanisms of behavioral responses to the stressors. Our studies have shown that a local sensation of thirst in the buccal cavity—this being induced by dipsogenic hormones—motivates these fish to move to water through a forebrain response. The corticosteroid system, which is responsive to various stressors, also stimulates migration, possibly via the receptors in the brain. We suggest that such fish are an important model to deepen insights into the stress-related neuro/endocrine-behavioral effects.

    DOI： 10.3390/ijms21186748

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  • Transcriptomic Analysis of the Kuruma Prawn Marsupenaeus japonicus Reveals Possible Peripheral Regulation of the Ovary Invited Reviewed

    Naoaki Tsutsui, Yasuhisa Kobayashi, Kouichi Izumikawa, Tatsuya Sakamoto

    Frontiers in Endocrinology   11   2020.8

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    Publisher：Frontiers Media SA  

    DOI： 10.3389/fendo.2020.00541

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  • Vasopressin gene products are colocalised with corticotrophin‐releasing factor within neurosecretory vesicles in the external zone of the median eminence of the Japanese macaque monkey ( Macaca fuscata )

    Akito Otubo, Natsuko Kawakami, Sho Maejima, Yasumasa Ueda, John F. Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

    Journal of Neuroendocrinology   32 ( 8 )   2020.8

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  • Facilitated NaCl Uptake in the Highly Developed Bundle of the Nephron in Japanese Red Stingray Hemitrygon akajei Revealed by Comparative Anatomy and Molecular Mapping

    Naotaka Aburatani, Wataru Takagi, Marty Kwok-Sing Wong, Mitsutaka Kadota, Shigehiro Kuraku, Kotaro Tokunaga, Kazuya Kofuji, Kazuhiro Saito, Waichiro Godo, Tatsuya Sakamoto, Susumu Hyodo

    Zoological Science   37 ( 5 )   1 - 1   2020.7

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    Publisher：Zoological Society of Japan  

    DOI： 10.2108/zs200038

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  • Detection and Characterization of Estrogen Receptor Beta Expression in the Brain with Newly Developed Transgenic Mice

    Shoko Sagoshi, Sho Maejima, Masahiro Morishita, Satoshi Takenawa, Akito Otubo, Keiko Takanami, Tatsuya Sakamoto, Hirotaka Sakamoto, Shinji Tsukahara, Sonoko Ogawa

    Neuroscience   438   182 - 197   2020.7

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    Publisher：Elsevier BV  

    DOI： 10.1016/j.neuroscience.2020.04.047

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  • Ghrelin and food acquisition in wild and cultured Japanese eel (Anguilla japonica)

    Takashi Yada, Michihisa Abe, Kenzo Kaifu, Kazuki Yokouchi, Nobuto Fukuda, Sakie Kodama, Hiroshi Hakoyama, Maho Ogoshi, Hiroyuki Kaiya, Tatsuya Sakamoto, Shunsuke Moriyama, Katsumi Tsukamoto

    Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology   245   110700 - 110700   2020.7

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  • Current and Future Research at Japanese National Marine and Inland Water Stations

    Ocean Newsletter   2019.12

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  • Hormonal regulation of thirst in the amphibious ray-finned fish suggests the requirement for terrestrialization during evolution. International journal

    Yukitoshi Katayama, Yoshio Takei, Makoto Kusakabe, Tatsuya Sakamoto

    Scientific reports   9 ( 1 )   16347 - 16347   2019.11

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    Language：English  

    Thirst has evolved for vertebrate terrestrial adaptation. We previously showed that buccal drying induced a series of drinking behaviours (migration to water-taking water into the mouth-swallowing) in the amphibious mudskipper goby, thereby discovering thirst in ray-finned fish. However, roles of dipsogenic/antidipsogenic hormones, which act on the thirst center in terrestrial tetrapods, have remained unclear in the mudskipper thirst. Here we examined the hormonal effects on the mudskipper drinking behaviours, particularly the antagonistic interaction between angiotensin II (AngII) and atrial natriuretic peptide (ANP) which is important for thirst regulation in mammalian 'forebrain'. Expectedly, intracerebroventricular injection of ANP in mudskippers reduced AngII-increased drinking rate. ANP also suppressed the neural activity at the 'hindbrain' region for the swallowing reflex, and the maintenance of buccopharyngeal water due to the swallowing inhibition may attenuate the motivation to move to water. Thus, the hormonal molecules involved in drinking regulation, as well as the influence of buccopharyngeal water, appear to be conserved in distantly related species to solve osmoregulatory problems, whereas hormonal control of thirst at the forebrain might have been acquired only in tetrapod lineage during evolution.

    DOI： 10.1038/s41598-019-52870-7

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  • Sea Docking by Dual-eye Pose Estimation with Optimized Genetic Algorithm Parameters

    Khin Nwe Lwin, Myo Myint, Naoki Mukada, Daiki Yamada, Takayuki Matsuno, Kazuhiro Saitou, Waichiro Godou, Tatsuya Sakamoto, Mamoru Minami

    Journal of Intelligent & Robotic Systems   96 ( 2 )   245 - 266   2019.11

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  • Discussion about Reproductive Mechanism of Eel-Grass（Zostera marina）

    Tomio FUKUDA, Yasutoshi KOHDA, Masatoshi MIZUTANI, Tatsuya SAKAMOTO

    J Kibi Int Univ Res Inst Health Welfare. (29),1-20 (2019-03-22)   2019.3

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  • 'Central' Actions of Corticosteroid Signaling Suggested by Constitutive Knockout of Corticosteroid Receptors in Small Fish

    Sakamoto T, Sakamoto H

    Nutrients. 2019 Mar 13;11(3). pii: E611. doi: 10.3390/nu11030611   2019

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  • 雄ラットにおける性行動への内側視索前野の性的二型核の関与

    前嶋翔, 野村黎, 高浪景子, 高浪景子, 坂本竜哉, 坂本浩隆

    日本比較内分泌学会大会及びシンポジウムプログラム・講演要旨   44th   2019

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  • Hyperosmotic tolerance of adult fish and early embryos are determined by discrete, single loci in the genus Oryzias

    Taijun Myosho, Hideya Takahashi, Kento Yoshida, Tadashi Sato, Satoshi Hamaguchi, Tatsuya Sakamoto, Mitsuru Sakaizumi

    Scientific Reports   8 ( 1 )   2018.12

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    Publisher：Springer Science and Business Media LLC  

    DOI： 10.1038/s41598-018-24621-7

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    Other Link： http://www.nature.com/articles/s41598-018-24621-7

  • The Amphibious Mudskipper: A Unique Model Bridging the Gap of Central Actions of Osmoregulatory Hormones Between Terrestrial and Aquatic Vertebrates. Reviewed

    Katayama K, Sakamoto T, Takanami K, Takei Y

    Frontiers in Physiology,   9   1112   2018.8

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  • Characterization of distinct ovarian isoform of crustacean female sex hormone in the kuruma prawn Marsupenaeus japonicus

    Naoaki Tsutsui, Sayaka Kotaka, Tsuyoshi Ohira, Tatsuya Sakamoto

    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR & INTEGRATIVE PHYSIOLOGY   217   7 - 16   2018.3

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  • Analyzing the effects of co-expression of chick (Gallus gallus) melanocortin receptors with either chick MRAP1 or MRAP2 in CHO cells on sensitivity to ACTH(1–24) or ACTH(1–13)NH2: Implications for the avian HPA axis and avian melanocortin circuits in the hypothalamus

    Alexa L. Thomas, Fumihiko Maekawa, Takaharu Kawashima, Hirotaka Sakamoto, Tatsuya Sakamoto, Perry Davis, Robert M. Dores

    General and Comparative Endocrinology   256   50 - 56   2018.1

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    Language：English   Publisher：Academic Press Inc.  

    DOI： 10.1016/j.ygcen.2017.09.002

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  • Drinking by amphibious fish: convergent evolution of thirst mechanisms during vertebrate terrestrialization. International journal

    Yukitoshi Katayama, Tatsuya Sakamoto, Kazuhiro Saito, Hirotsugu Tsuchimochi, Hiroyuki Kaiya, Taro Watanabe, James T Pearson, Yoshio Takei

    Scientific reports   8 ( 1 )   625 - 625   2018.1

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    Language：English  

    Thirst aroused in the forebrain by angiotensin II (AngII) or buccal drying motivates terrestrial vertebrates to search for water, whereas aquatic fish can drink surrounding water only by reflex swallowing generated in the hindbrain. Indeed, AngII induces drinking through the hindbrain even after removal of the whole forebrain in aquatic fish. Here we show that AngII induces thirst also in the amphibious mudskipper goby without direct action on the forebrain, but through buccal drying. Intracerebroventricular injection of AngII motivated mudskippers to move into water and drink as with tetrapods. However, AngII primarily increased immunoreactive c-Fos at the hindbrain swallowing center where AngII receptors were expressed, as in other ray-finned fish, and such direct action on the forebrain was not found. Behavioural analyses showed that loss of buccal water on land by AngII-induced swallowing, by piercing holes in the opercula, or by water-absorptive gel placed in the cavity motivated mudskippers to move to water for refilling. Since sensory detection of water at the bucco-pharyngeal cavity like 'dry mouth' has recently been noted to regulate thirst in mammals, similar mechanisms seem to have evolved in distantly related species in order to solve osmoregulatory problems during terrestrialization.

    DOI： 10.1038/s41598-017-18611-4

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  • Nemertean and phoronid genomes reveal lophotrochozoan evolution and the origin of bilaterian heads

    Yi-Jyun Luo, Miyuki Kanda, Ryo Koyanagi, Kanako Hisata, Tadashi Akiyama, Hirotaka Sakamoto, Tatsuya Sakamoto, Noriyuki Satoh

    Nature Ecology and Evolution   2 ( 1 )   141 - 151   2018.1

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    Language：English   Publisher：Nature Publishing Group  

    DOI： 10.1038/s41559-017-0389-y

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  • Visual Docking against Bubble Noise with Three-dimensional Perception Using Dual-eye Cameras

    Khin Lwin, Naoki Mukada, Myo Myint, Daiki Yamada, Akira Yanou, Takayuki Matsno, Kazuhiro Saitou, Waichiro Godou, Tatsuya Sakamoto, Mamoru Minami

    IEEE Journal of Oceanic Engineering DOI (identifier) 10.1109/JOE.2018.2871651   2018

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  • Robust Visual Servoing against Air Bubble Noise with

    Khin Lwin, Naoki Mukada, Myo Myint, Daiki Yamada, Akira Yanou, Takayuki Matsno, Kazuhiro Saitou, Waichiro Godou, Tatsuya Sakamoto, Mamoru Minami

    Journal of Advanced Mechanical Design, Systems, and Manufacturing   2018

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  • Molecular cloning and tissue distribution analysis of corticosteroid receptor genes in two cartilaginous fishes, catshark (Elasmobranchii) and elephant fish (Holocephali)

    Wataru Takagi, Tatsuya Sakamoto

    Data in Brief   7   2018

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  • A possible principal function of corticosteroid signaling that is conserved in vertebrate evolution: Lessons from receptor-knockout small fish

    Tatsuya Sakamoto, Susumu Hyodo, Wataru Takagi

    Journal of Steroid Biochemistry and Molecular Biology   2018

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    DOI： 10.1016/j.jsbmb.2018.02.011

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  • Effects of Sex Steroids on the Spinal Gastrin-Releasing Peptide System Controlling Male Sexual Function in Rats. International journal

    Takumi Oti, Keiko Takanami, Saya Ito, Takashi Ueda, Ken Ichi Matsuda, Mitsuhiro Kawata, Jintetsu Soh, Osamu Ukimura, Tatsuya Sakamoto, Hirotaka Sakamoto

    Endocrinology   159 ( 4 )   1886 - 1896   2018

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    The gastrin-releasing peptide (GRP) system in the lumbosacral spinal cord controls male sexual function in rats. In contrast, in female rats, GRP neurons could scarcely be detected around puberty when circulating ovarian steroid hormones such as estradiol and progesterone levels are increasing. However, little information is available on feminizing or demasculinizing effects of ovarian steroids on the central nervous system in female puberty and adulthood. In this study, to visualize the spinal GRP neurons in vivo, we generated a GRP-promoter-Venus transgenic (Tg) rat line and studied the effects of the sex steroid hormones on GRP expression in the rat lumbar cord by examining the Venus fluorescence. In these Tg rats, the sexually dimorphic spinal GRP neurons controlling male sexual function were clearly labeled with Venus fluorescence. As expected, Venus fluorescence in the male lumbar cord was markedly decreased after castration and restored by chronic androgen replacement. Furthermore, androgen-induced Venus expression in the spinal cord of adult Tg males was significantly attenuated by chronic treatment with progesterone but not with estradiol. A luciferase assay using a human GRP-promoter construct showed that androgens enhance the spinal GRP system, and more strikingly, that progesterone acts to inhibit the GRP system via an androgen receptor-mediated mechanism. These results demonstrate that circulating androgens may play an important role in the spinal GRP system controlling male sexual function not only in rats but also in humans and that progesterone could be an important feminizing factor in the spinal GRP system in females during pubertal development.

    DOI： 10.1210/en.2018-00043

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  • Unique Model Bridging the Gap of Central Actions of Osmoregulatory Hormones

    Katayama Y, Sakamoto T, Takanami K, Takei Y

    Front Physiol. 2018 Aug 14;9:1112.   2018

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  • Effects of Sex Steroids on the Spinal Gastrin-Releasing

    Oti T, Takanami K, Ito S, Ueda T, Matsuda KI, Kawata M, Soh J, Ukimura O

    Endocrinology. 2018 Apr 1;159(4):1886-1896   2018

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  • A sexually dimorphic peptidergic system in the lower spinal cord controlling penile function in non-human primates

    T. Ito, T. Oti, K. Takanami, K. Satoh, Y. Ueda, T. Sakamoto, H. Sakamoto

    Spinal Cord   56 ( 1 )   57 - 62   2018

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    DOI： 10.1038/sc.2017.105

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  • ラット内側視索前野において雄の性行動を司る神経回路系の解析

    野村黎, 高浪景子, 高浪景子, 坂本竜哉, 坂本浩隆

    日本神経内分泌学会学術集会プログラム・抄録集   45th   2018

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  • 霊長類ニホンザルにおけるGastrin-releasing peptide神経系の機能局在

    高浪景子, 伊藤隆志, 越智拓海, 小林靖尚, 佐藤慧太, 上田康雅, 坂本竜哉, 坂本浩隆

    日本解剖学会総会・全国学術集会講演プログラム・抄録集   123rd   2018

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  • The mineralo-corticoid receptor knockout in medaka is further validated by glucocorticoid receptor compensation

    Tatsuya Sakamoto, Madoka Yoshiki, Hirotaka Sakamoto

    SCIENTIFIC DATA   4   924 - 928   2017.12

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  • MORPHOLOGICAL AND MOLECULAR EVOLUTIONAL ANALYSES OF ITCH FOCUSED ON THE GASTRIN-RELEASING PEPTIDE SYSTEM IN MAMMALS

    Keiko Takanami, Keita Satoh, Kazuyoshi Murata, Tatsuya Sakamoto, Hirotaka Sakamoto

    ACTA DERMATO-VENEREOLOGICA   97 ( 8 )   1049 - 1050   2017.9

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  • Identification of the sexually dimorphic gastrin-releasing peptide system in the lumbosacral spinal cord that controls male reproductive function in the mouse and Asian house musk shrew (Suncus murinus)

    Kei Tamura, Yasuhisa Kobayashi, Asuka Hirooka, Keiko Takanami, Takumi Oti, Takamichi Jogahara, Sen-ichi Oda, Tatsuya Sakamoto, Hirotaka Sakamoto

    JOURNAL OF COMPARATIVE NEUROLOGY   525 ( 7 )   1586 - 1598   2017.5

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  • クルマエビの卵巣で発現するペプチドホルモン様因子

    筒井直昭, 坂本竜哉

    日本比較内分泌学会大会及びシンポジウムプログラム・講演要旨   42nd   43   2017

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  • 蛍光タンパク質Venus導入ラットを用いた雄の性機能を司る脊髄神経回路系の解析

    越智拓海, 高浪景子, 松田賢一, 河田光博, 坂本竜哉, 坂本浩隆

    日本アンドロロジー学会総会記事   36th   2017

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  • コペプチンからバソプレシン遺伝子の転写-翻訳-プロセシングを解析する試み

    坂本浩隆, 坂本浩隆, 佐藤慧太, 高浪景子, 大坪秋人, 坂本竜哉, MORRIS John F.

    日本神経内分泌学会学術集会プログラム・抄録集   44th   2017

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  • Crystal structure of a crustacean hyperglycemic hormone (CHH) precursor suggests structural variety in the C-terminal regions of CHH superfamily members

    Naoaki Tsutsui, Tatsuya Sakamoto, Fumio Arisaka, Masaru Tanokura, Hiromichi Nagasawa, Koji Nagata

    FEBS JOURNAL   283 ( 23 )   4325 - 4339   2016.12

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  • Principal function of mineralocorticoid signaling suggested by constitutive knockout of the mineralocorticoid receptor in medaka fish

    Tatsuya Sakamoto, Madoka Yoshiki, Hideya Takahashi, Masayuki Yoshida, Yukiko Ogino, Toshitaka Ikeuchi, Tomoya Nakamachi, Norifumi Konno, Kouhei Matsuda, Hirotaka Sakamoto

    SCIENTIFIC REPORTS   6   2016.11

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  • High levels of plasma cortisol and impaired hypoosmoregulation in a mutant medaka deficient in P450c17I

    Hideya Takahashi, Tadashi Sato, Toshitaka Ikeuchi, Kazuhiro Saito, Mitsuru Sakaizumi, Tatsuya Sakamoto

    MOLECULAR AND CELLULAR ENDOCRINOLOGY   430 ( C )   25 - 32   2016.7

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  • Data for amino acid alignment of Japanese stingray melanocortin receptors with other gnathostome melanocortin receptor sequences, and the ligand selectivity of Japanese stingray melanocortin receptors

    Akiyoshi Takahashi, Perry Davis, Christina Reinick, Kanta Mizusawa, Tatsuya Sakamoto, Robert M. Dores

    Data in Brief   7   1670 - 1677   2016.6

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    DOI： 10.1016/j.dib.2016.04.050

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  • Characterization of melanocortin receptors from stingray Dasyatis akajei, a cartilaginous fish

    Akiyoshi Takahashi, Perry Davis, Christina Reinick, Kanta Mizusawa, Tatsuya Sakamoto, Robert M. Dores

    GENERAL AND COMPARATIVE ENDOCRINOLOGY   232   115 - 124   2016.6

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  • Postnatal development of the gastrin-releasing peptide system in the lumbosacral spinal cord controlling male reproductive function in rats

    Nao Katayama, Takumi Oti, Keiko Takanami, Tatsuya Sakamoto, Hirotaka Sakamoto

    PROCEEDINGS OF THE JAPAN ACADEMY SERIES B-PHYSICAL AND BIOLOGICAL SCIENCES   92 ( 2 )   69 - 75   2016.2

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  • Perinatal testosterone exposure is critical for the development of the male-specific sexually dimorphic gastrin-releasing peptide system in the lumbosacral spinal cord that mediates erection and ejaculation

    Takumi Oti, Keiko Takanami, Nao Katayama, Tomoca Edey, Keita Satoh, Tatsuya Sakamoto, Hirotaka Sakamoto

    BIOLOGY OF SEX DIFFERENCES   7 ( 1 )   2016.1

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  • Comparative Anatomy of Gastrin-releasing Peptide Pathways in the Trigeminal Sensory System of Mouse and the Asian House Musk Shrew Suncus murinus

    Keiko Takanami, Kaihei Inoue, Hiroki Mukai, Kei Tamura, Takamichi Jogahara, Sen-ichi Oda, Mitsuhiro Kawata, Tatsuya Sakamoto, Hirotaka Sakamoto

    ACTA HISTOCHEMICA ET CYTOCHEMICA   49 ( 6 )   181 - 190   2016

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  • ニホンザル脊髄における痒み特異的伝達分子gastrin-releasing peptide受容体の発現

    伊藤隆志, 高浪景子, 高浪景子, 越智拓海, 小林靖尚, 小林靖尚, 佐藤慧太, 高橋俊次, 上田康雅, 坂本竜哉, 坂本浩隆

    日本組織細胞化学会総会・学術集会講演プログラム・予稿集   57th   2016

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  • 雄の性機能を司る脊髄神経回路系の機能解析:Grp-promoter-Venusトランスジェニックラットの作出と利用

    越智拓海, 高浪景子, 高浪景子, 松田賢一, 河田光博, 坂本竜哉, 坂本浩隆

    日本神経内分泌学会学術集会プログラム・抄録集   43rd   2016

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  • Three-dimensional visualization of multiple synapses in thick sections using high-voltage electron microscopy in the rat spinal cord

    Keita Satoh, Keiko Takanami, Kazuyoshi Murata, Mitsuhiro Kawata, Tatsuya Sakamoto, Hirotaka Sakamoto

    Data in Brief   4   566 - 570   2015.9

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    DOI： 10.1016/j.dib.2015.07.005

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  • Mudskipper to general behavioral neuroendocrinology

    Tatsuya Sakamoto, Yukitoshi Katayama, Yasuhisa Kobayashi, Kazuhiro Saito, Yoshio Takei

    NIPPON SUISAN GAKKAISHI   81 ( 5 )   868 - 868   2015.9

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  • Osmotic/ionic status of body fluids in the euryhaline cephalopod suggest possible parallel evolution of osmoregulation

    Tatsuya Sakamoto, Satoshi Ogawa, Yudai Nishiyama, Chiaki Akada, Hideya Takahashi, Taro Watanabe, Hiroyuki Minakata, Hirotaka Sakamoto

    SCIENTIFIC REPORTS   5   2015.9

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  • In vivo imaging of axonal transport of mitochondria in the diseased and aged mammalian CNS. International journal

    Yuji Takihara, Masaru Inatani, Kei Eto, Toshihiro Inoue, Alexander Kreymerman, Seiji Miyake, Shinji Ueno, Masatoshi Nagaya, Ayami Nakanishi, Keiichiro Iwao, Yoshihiro Takamura, Hirotaka Sakamoto, Keita Satoh, Mineo Kondo, Tatsuya Sakamoto, Jeffrey L Goldberg, Junichi Nabekura, Hidenobu Tanihara

    Proceedings of the National Academy of Sciences of the United States of America   112 ( 33 )   10515 - 20   2015.8

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    The lack of intravital imaging of axonal transport of mitochondria in the mammalian CNS precludes characterization of the dynamics of axonal transport of mitochondria in the diseased and aged mammalian CNS. Glaucoma, the most common neurodegenerative eye disease, is characterized by axon degeneration and the death of retinal ganglion cells (RGCs) and by an age-related increase in incidence. RGC death is hypothesized to result from disturbances in axonal transport and in mitochondrial function. Here we report minimally invasive intravital multiphoton imaging of anesthetized mouse RGCs through the sclera that provides sequential time-lapse images of mitochondria transported in a single axon with submicrometer resolution. Unlike findings from explants, we show that the axonal transport of mitochondria is highly dynamic in the mammalian CNS in vivo under physiological conditions. Furthermore, in the early stage of glaucoma modeled in adult (4-mo-old) mice, the number of transported mitochondria decreases before RGC death, although transport does not shorten. However, with increasing age up to 23-25 mo, mitochondrial transport (duration, distance, and duty cycle) shortens. In axons, mitochondria-free regions increase and lengths of transported mitochondria decrease with aging, although totally organized transport patterns are preserved in old (23- to 25-mo-old) mice. Moreover, axonal transport of mitochondria is more vulnerable to glaucomatous insults in old mice than in adult mice. These mitochondrial changes with aging may underlie the age-related increase in glaucoma incidence. Our method is useful for characterizing the dynamics of axonal transport of mitochondria and may be applied to other submicrometer structures in the diseased and aged mammalian CNS in vivo.

    DOI： 10.1073/pnas.1509879112

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  • Neurohypophysial Hormones Regulate Amphibious Behaviour in the Mudskipper Goby

    Tatsuya Sakamoto, Yudai Nishiyama, Aoi Ikeda, Hideya Takahashi, Susumu Hyodo, Nao Kagawa, Hirotaka Sakamoto

    PLOS ONE   10 ( 7 )   2015.7

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  • Invivo processing and release into the circulation of GFP fusion protein in arginine vasopressin enhanced GFP transgenic rats: response to osmotic stimulation

    Keita Satoh, Takumi Oti, Akiko Katoh, Yoichi Ueta, John F. Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

    FEBS JOURNAL   282 ( 13 )   2488 - 2499   2015.7

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  • Effective synaptome analysis of itch-mediating neurons in the spinal cord: A novel immunohistochemical methodology using high-voltage electron microscopy

    Keita Satoh, Keiko Takanami, Kazuyoshi Murata, Mitsuhiro Kawata, Tatsuya Sakamoto, Hirotaka Sakamoto

    NEUROSCIENCE LETTERS   599   86 - 91   2015.7

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  • Requirement of vasotocin for being a winner in love triangle relationships (two males and one female) of medaka fish

    Yokoi S, Sakamoto, T

    AQUABIOLOGY 37(6) 591-597 2015   2015

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  • 07B01 瀬戸内海を題材とした小学校理科第6学年「生き物のくらしと環境」の授業開発 : Place-Based Educationの観点を参考にして(環境教育,一般研究発表(口頭発表))

    土屋 美和, 定金 なつみ, 藤井 浩樹, 田中 喜一郎, 筒井 直昭, 小林 靖尚, 坂本 竜哉

    日本理科教育学会全国大会要項   ( 65 )   199 - 199   2015

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  • Basic reproductive biology of daggertooth pike conger, Muraenesox cinereus: A possible model for oogenesis in Anguilliformes

    Kobayashi, Y, T. Mototani

    Zoological Letters 1(1): 1-7 (2015)   2015

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  • Hormonal Regulation of Body Fluid in Teleost Fishes

    SAKAMOTO Tatsuya

    Bulletin of the Society of Sea Water Science, Japan   69 ( 4 )   244 - 246   2015

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    DOI： 10.11457/swsj.69.244

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  • Artificial burrow sizes for capturing the North American invasive crayfish Procambarus clarkii.

    USHIMI Haruna, MIYATAKE Yuta, TSUTSUI Naoaki, SAKAMOTO Tatsuya, NAKATA Kazuyoshi

    Ecology and Civil Engineering   18 ( 2 )   79 - 86   2015

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    We conducted aquarium experiments of artificial burrow preference by the North American invasive crayfish Procambarus clarkii to clarify the artificial burrow sizes for capturing P. clarkii in invaded freshwater areas （e.g., paddy fields, agricultural channels, rivers, lakes, ponds, etc.）. In the aquarium experiments, we observed the preference for internal diameters and lengths of artificial burrows by P. clarkii, which were made from straight polyvinyl chloride pipes. The relationship between the total length （TL）（X, mm） of P. clarkii and the preferred internal diameter （Y, mm） of artificial burrows was described by the significant linear regression: Y＝0.58X＋4.26（ n＝49, P＜0.001）. Among the artificial burrows of different lengths, TL×4 burrows were mainly preferred by P. clarkii. Based on these results, we propose artificial burrow sizes for use to eradicate P. clarkii.

    DOI： 10.3825/ece.18.79

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  • Effect of environmental salinity on expression of adrenomedullin genes suggests osmoregulatory activity in the medaka, Oryzias latipes.

    Ogoshi, M, K. Kato

    Zoological Letters 1(1): 1-7 (2015)   2015

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  • P4-12 AVP-eGFP TgラットにおけるインビボGFP動態(細胞生物・電子顕微鏡,ポスター発表,組織化学のモーダルシフト,第56回日本組織細胞化学会総会・学術集会)

    佐藤 慧太, 越智 拓海, 加藤 明子, 上田 陽一, Morris John F, 坂本 竜哉, 坂本 浩隆

    日本組織細胞化学会総会プログラムおよび抄録集   ( 56 )   72 - 72   2015

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    Other Link： http://search.jamas.or.jp/link/ui/2016046963

  • P8-03 霊長類ニホンザルの脊髄におけるgastrin-releasing peptide系の存在(脳機能,ポスター発表,組織化学のモーダルシフト,第56回日本組織細胞化学会総会・学術集会)

    伊藤 隆志, 高浪 景子, 越智 拓海, 小林 靖尚, 佐藤 慧太, 高橋 俊次, 上田 康雅, 坂本 竜哉, 坂本 浩隆

    日本組織細胞化学会総会プログラムおよび抄録集   ( 56 )   78 - 78   2015

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  • 卵黄形成抑制ホルモンの作用機序解明に向けたクルマエビ卵巣の遺伝子の網羅的解析

    筒井直昭, 小林靖尚, 泉川晃一, 坂本竜哉

    日本水産学会大会講演要旨集   2014   100   2014.9

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  • Distribution of Gastrin-Releasing Peptide in the Rat Trigeminal and Spinal Somatosensory Systems

    Keiko Takanami, Hirotaka Sakamoto, Ken Ichi Matsuda, Keita Satoh, Takashi Tanida, Shunji Yamada, Kaihei Inoue, Takumi Oti, Tatsuya Sakamoto, Mitsuhiro Kawata

    JOURNAL OF COMPARATIVE NEUROLOGY   522 ( 8 )   1858 - 1873   2014.6

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  • Effects of Inorganic Mercury and Methylmercury on Osteoclasts and Osteoblasts in the Scales of the Marine Teleost as a Model System of Bone

    Koji Yachiguchi, Toshio Sekiguchi, Masaki Nakano, Atsuhiko Hattori, Megumi Yamamoto, Kei-ichiro Kitamura, Masahiro Maeda, Yoshiaki Tabuchi, Takashi Kondo, Hiromitsu Kamauchi, Hajime Nakabayashi, Ajai K. Srivastav, Kazuichi Hayakawa, Tatsuya Sakamoto, Nobuo Suzuki

    ZOOLOGICAL SCIENCE   31 ( 5 )   330 - 337   2014.5

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  • 軟骨魚類アカエイの子宮内液に含まれるタンパク質の精製と解析

    筒井直昭, 小林靖尚, 坂本竜哉

    日本水産学会大会講演要旨集   2014   171   2014.3

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  • Androgen regulates development of the sexually dimorphic gastrin-releasing peptide neuron system in the lumbar spinal cord: Evidence from a mouse line lacking androgen receptor in the nervous system

    Hirotaka Sakamoto, Kazuhiro Saito, Clarisse Marie-Luce, Kalina Raskin, Takumi Oti, Keita Satoh, Kei Tamura, Tatsuya Sakamoto, Sakina Mhaouty-Kodja

    NEUROSCIENCE LETTERS   558   109 - 114   2014.1

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  • Functions of two distinct "prolactin-releasing peptides" evolved from a common ancestral gene

    Tetsuya Tachibana, Tatsuya Sakamoto

    FRONTIERS IN ENDOCRINOLOGY   5   2014

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    DOI： 10.3389/fendo.2014.00170

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  • Diverse hormonal control of osmoregulation in euryhaline teleosts

    Y. Takei, H. Takahashi, J. Hiroi, T. Sakamoto

    Am J Physiol Regul Integr Comp Physiol. 307 (2014) 778-792   2014

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  • Effects of fasting and refeeding on intestinal cell proliferation and apoptosis in hammerhead shark (Sphyrna lewini).

    H. Takahashi, S. Hyodo, T. Abe, C. Takagi, E.G. Grau, T. Sakamoto

    J Coast Life Med. 2 (2014) 253-258   2014

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  • Marine macrophyte (eelgrass, Zostera marina) bed creation base research for conservation (2) The function of coleoptile in the seed germination of the eelgrass: Factor recognising bottom mud surface.

    T. Fukuda, Y. Kohda, T. Sakamoto

    J Kibi Int Univ Res Inst Health Welfare. 15 (2014) 13-19.   2014

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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

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  • Okayama University's Approach in Spreading Marine Education:A Focus on Cross-Learning in Science and Literature based on a Local Community Linkage featuring "The Expedition of Japanese Eel"

    KOBAYASHI Yasuhisa, TSUTSUI Naoaki, SAITO Kazuhiro, SAKAMOTO Tatsuya, FUJII Hiroki

    JSSE Research Report   29 ( 3 )   79 - 82   2014

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    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   2013.12

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    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   2013.8

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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   2013.3

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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   2013.1

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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

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  • 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   2012.11

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  • 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   2012.10

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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   2012.9

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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   2012.8

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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   2012.5

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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   2012.1

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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

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  • 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

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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

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  • 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

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    DOI： 10.5983/nl2008jsce.38.209

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  • 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   2011.10

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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   2011.7

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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   2011.1

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  • Dual in vitro effects of cortisol on cell turnover in the medaka esophagus via the glucocorticoid receptor

    Chiyo Takagi, Hideya Takahashi, Hiroki Kudose, Kanoko Kato, Tatsuya Sakamoto

    LIFE SCIENCES   88 ( 5-6 )   239 - 245   2011.1

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  • Detection and activity of iodine-131 in brown algae collected in the Japanese coastal areas

    Takami Morita, Kentaro Niwa, Ken Fujimoto, Hiromi Kasai, Haruya Yamada, Kou Nishiutch, Tatsuya Sakamoto, Waichiro Godo, Seiya Taino, Yoshihiro Hayashi, Koji Takeno, Tomokazu Nishigaki, Kunihiro Fujiwara, Hisamichi Aratake, Shingo Kamonoshita, Hiroshi Hashimoto, Takuya Kobayashi, Sigeyoshi Otosaka, Tetsuji Imanaka

    SCIENCE OF THE TOTAL ENVIRONMENT   408 ( 16 )   3443 - 3447   2010.7

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  • Concentration of iodine-131 in brown algae collected in Japanese coastal areas.

    Morita T, Niwa K, Fujimoto K, Kasai H, Yamada H, Nishiutch K, Sakamoto T

    KEK Proceedings   63 - 66   2009

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  • Prolactin Inhibits Osteoclastic Activity in the Goldfish Scale: A Novel Direct Action of Prolactin in Teleosts

    Hideya Takahashi, Nobuo Suzuki, Chiyo Takagi, Mika Ikegame, Toshio Yamamoto, Akiyoshi Takahashi, Shunsuke Moriyama, Atsuhiko Hattori, Tatsuya Sakamoto

    ZOOLOGICAL SCIENCE   25 ( 7 )   739 - 745   2008.7

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  • Spawning Behavior of the kissing loach (Leptobotia curta) in temporary waters

    Tsukasa Abe, Ichiro Kobayashi, Masahiro Kon, Tatsuya Sakamoto

    ZOOLOGICAL SCIENCE   24 ( 8 )   850 - 853   2007.8

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  • Prolactin receptor and proliferating/apoptotic cells in esophagus of the Mozambique tilapia (Oreochromis mossambicus) in fresh water and in seawater

    Hideya Takahashi, Patrick Prunet, Takashi Kitahashi, Shingo Kajimura, Tetsuya Hirano, E. Gordon Grau, Tatsuya Sakamoto

    GENERAL AND COMPARATIVE ENDOCRINOLOGY   152 ( 2-3 )   326 - 331   2007.6

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  • Spawning behavior of kissing loach (Leptobotia curta) is limited after the formation of temporary waters

    Abe, T, I. Kobayashi, M. Kon, T. Sakamoto

    Zool. Sci.   24: 922-926   2007

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  • Molecular cloning and functional characterization of a prolactin-releasing peptide homol from Xenopus laevis

    Tatsuya Sakamoto, Aiko Oda, Kazutoshi Yamamoto, Miyoko Kaneko, Sakae Kikuyama, Akio Nishikawa, Akiyoshi Takahashi, Hiroshi Kawauchi, Kazuyoshi Tsutsui, Masaaki Fujimoto

    PEPTIDES   27 ( 12 )   3347 - 3351   2006.12

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  • In vivo effects of thyroid honnone, corticosteroids and prolactin on cell proliferation and apoptosis in the anterior intestine of the euryhaline mudskipper (Periophthalmus modestus)

    Hideya Takahashi, Akiyoshi Takahashi, Tatsuya Sakamoto

    LIFE SCIENCES   79 ( 19 )   1873 - 1880   2006.10

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  • Cell proliferation and apoptosis in the anterior intestine of an amphibious, euryhaline mudskipper (Periophthalmus modestus)

    H Takahashi, T Sakamoto, K Narita

    JOURNAL OF COMPARATIVE PHYSIOLOGY B-BIOCHEMICAL SYSTEMIC AND ENVIRONMENTAL PHYSIOLOGY   176 ( 5 )   463 - 468   2006.6

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  • Prolactin-releasing peptide is essential to maintain the prolactin level and osmotic balance in freshwater teleost fish

    M Fujimoto, T Sakamoto, T Kanetoh, M Osaka, S Moriyama

    PEPTIDES   27 ( 5 )   1104 - 1109   2006.5

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  • Expression of glucocorticoid receptor in the intestine of a euryhaline teleost, the mozambique tilapia (Oreochromis mossambicus): Effect of seawater exposure and cortisol treatment

    H Takahashi, T Sakamoto, S Hyodo, BS Shepherd, T Kaneko, EG Grau

    LIFE SCIENCES   78 ( 20 )   2329 - 2335   2006.4

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  • Chemical components in the pouch fluid of the seahorse, Hippocampus barbouri Jordan and Richardson 1908 and their uptake in embryos.

    Oconer,EP, CP Pascual, AA Herrera, T. Sakamoto, JT Wetzel

    Asia Life Sciences   2006

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  • Prolactin and growth hormone in fish osmoregulation

    Sakamoto, T, S. D. McCormick

    Gen. Comp. Endocrinol.   147: 24-30   2006

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  • Prolactin inhibits osteoclastic activities in the scales of goldfish

    Nobuo Suzuki, Tatsuya Sakamoto, Mika Ikegame, Toshio Yamamoto, Akiyoshi Takahashi, Shunsuke Moriyama, Hiroshi Kawauchi, Atsuhiko Hattori

    ZOOLOGICAL SCIENCE   22 ( 12 )   1498 - 1498   2005.12

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  • Primary structure of proopiomelanocortin in reptiles Reviewed

    Takahashi A, Sakamoto T, Lance VA, Kawauchi H

    Proc. Jpn. Soc. Comp. Endocrinol.   ( 20 )   48 - 48   2005.11

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  • High ambient ammonia promotes growth in a ureogenic goby, Mugilogobius abei

    K Iwata, T Sakamoto, Iwata, I, E Nishiguchi, M Kajimura

    JOURNAL OF COMPARATIVE PHYSIOLOGY B-BIOCHEMICAL SYSTEMIC AND ENVIRONMENTAL PHYSIOLOGY   175 ( 6 )   395 - 404   2005.8

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  • Expression of prolactin-releasing peptide and prolactin in the euryhaline mudskippers (Periophthalmus modestus): prolactin-releasing peptide as a primary regulator of prolactin

    T Sakamoto, M Amano, S Hyodo, S Moriyama, A Takahashi, H Kawauchi, M Ando

    JOURNAL OF MOLECULAR ENDOCRINOLOGY   34 ( 3 )   825 - 834   2005.6

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  • Prolactin: fishy tales of a primary regulator and function

    Sakamoto, T, A. Oda, H. Takahashi, T. Oda, K. Narita, J. Fujiwara

    Ann. NY Acad. Sci.   1040: 184-188   2005

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  • Intra-arterial injection of prolactin-releasing peptide elevates prolactin gene expression and plasma prolactin levels in rainbow trout

    T Sakamoto, T Agustsson, S Moriyama, T Itoh, A Takahashi, H Kawauchi, BT Bjornsson, M Ando

    JOURNAL OF COMPARATIVE PHYSIOLOGY B-BIOCHEMICAL SYSTEMIC AND ENVIRONMENTAL PHYSIOLOGY   173 ( 4 )   333 - 337   2003.6

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  • Prolactin, somatolactin and growth hormone gene expression during parr-smolt transformation of Atlantic salmon

    Agustsson, T, K. Sundell, T. Sakamoto, M. Ando, B. Th, Bj嗷nsson

    Aquaculture   2003

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  • Fishy tales of prolactin-releasing peptide

    Sakamoto, T, M. Fujimoto, M. Ando

    Int. Rev. Cytol   225: 91-130   2003

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  • Isolation and characterization of a homologue of mammalian prolactin-releasing peptide from the tilapia brain and its effect on prolactin release from the tilapia pituitary

    AP Seale, T Itoh, S Moriyama, A Takahashi, H Kawauchi, T Sakamoto, M Fujimoto, LG Riley, T Hirano, EG Grau

    GENERAL AND COMPARATIVE ENDOCRINOLOGY   125 ( 3 )   328 - 339   2002.2

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  • Calcium ion triggeres the rapid morphological oscillation of chloride cells in the mudskipper

    Sakamoto, T, M. Ando

    J. Comp. Physiol. B   2002

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  • Ureogenic function and periodic urea excretion in a gobiid fish, Mugilogobius abei.

    Iwata, K, M. Kajimura, T. Sakamoto

    Fish. Sci   2002

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  • Growth hormone and prolactin in expression during environmental adaptation of gobies

    Sakamoto, T, K. Iwata, M. Ando

    Fish. Sci.   2002

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  • Differential display of skin mRNAs regulated during adaptation of mudskipper to different environments

    Sakamoto, T, H. Yasunaga, S. Yokota, M. Ando

    J. Comp. Physiol. B   2002

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  • Medaka, Oryzias latipes, as a model for hypoosmoregulation of euryhaline fishes

    Sakamoto, T, T. Kozaka, A. Takahashi, H. Kawauchi, M. Ando

    Aquaculture   2001

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  • Regulation of the ion-transporting mitochondrion-rich cell during adaptation of teleost fishes to different salinities

    Sakamoto, T, K. Uchida, S. Yokota

    Zool. Sci.   2001

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  • Regulation of the ion-transporting mitochondrion-rich cell during adaptation of teleost fishes to different salinities

    Sakamoto, T, K. Uchida, S. Yokota

    Zool. Sci.,   18: 1163-1174   2001

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  • Growth hormone endocrinology of Atlantic salmon (Salmo salar): pituitary gene expression, hormone storage, secretion and plasma levels during parr--smolt transformation

    Agustsson, T, K. Sundell, T. Sakamoto, M. Ando, B. Th, Bj嗷nsson

    J. Endocrinol.   2001

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  • Rapid morphological oscillation of mitochondrion-rich cell in estuarine mudskipper following salinity changes

    Sakamoto, T, S. Yokota, M. Ando

    J. Exp. Zool.   2000

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  • Functional ureogenesis in the gobiid fish, Mugilogobius abei

    Iwata, K, M. Kajimura, T. Sakamoto

    J. Exp. Biol.   2000

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  • Induction of mRNAs in response to acclimation of trout cells to different osmolalities

    Sakamoto, T, N. Ojima, M. Yamashita

    Fish. Physiol. Biochem.   2000

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  • Functional ureogenesis in the gobiid fish, DBMugilogobius abei(/)-DB.(共著)

    J. Exp. Biol.   203   3703 - 3715   2000

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  • Is the primitive regulation of pituitary prolactin (tPRL(177) and tPRL(188)) secretion and gene expression in the euryhaline tilapia (Oreochromis mossambicus) hypothalamic or environmental?

    BS Shepherd, T Sakamoto, S Hyodo, RS Nishioka, C Ball, HA Bern, EG Grau

    JOURNAL OF ENDOCRINOLOGY   161 ( 1 )   121 - 129   1999.4

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  • Development of the myotomal neuromuscular system in embryonic and larval angelfish, Pterophyllum scalare

    Sakamoto, H, M. Yoshida, T. Sakamoto, K. Uematsu

    Zool. Sci.   1999

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  • Novel [3H]clonidine binding sites in the intestine of the eel acclimated to sea water

    Hung Tae Kim, Tatsuya Sakamoto, Masaaki Ando

    Zoological Science   15 ( 2 )   205 - 212   1998

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    Language：English   Publisher：Zoological Society of Japan  

    DOI： 10.2108/zsj.15.205

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  • Novel [3H]clonidine binding sites in the intestine of the eel acclimated to sea water

    Hung Tae Kim, Tatsuya Sakamoto, Masaaki Ando

    Zoological Science   15 ( 2 )   205 - 212   1998

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    Language：English   Publisher：Zoological Society of Japan  

    DOI： 10.2108/zsj.15.205

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  • Novel [3H]clonidine binding sites in the intestine of the eel acclimated to sea water

    Kim, H. T, T. Sakamoto, M. Ando

    Zool. Sci   1998

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  • A finally identified prolactin releasing factor from a mammal and a fish.

    KAGAKU TO SEIBUTSU   36 ( 12 )   798 - 799   1998

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    Language：Japanese   Publisher：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

    DOI： 10.1271/kagakutoseibutsu1962.36.798

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  • Physiological and respiratory responses of the Mozambique tilapia (Oreochromis mossambicus) to salinity acclimation

    John D. Morgan, Tatsuya Sakamoto, E. Gordon Grau, George K. Iwama

    Comparative Biochemistry and Physiology - A Physiology   117 ( 3 )   391 - 398   1997.7

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  • Physiological and respiratory responses of the Mozambique tilapia (Oreochromis mossambicus) to salinity acclimation

    John D. Morgan, Tatsuya Sakamoto, E. Gordon Grau, George K. Iwama

    Comparative Biochemistry and Physiology - A Physiology   117 ( 3 )   391 - 398   1997.7

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  • Somatotropic actions of the homologous growth hormone(tGH)and prolactin(tPRL177)in the euryhaline teleost, the tilapia, Oreochromis mossambicus(共著)

    Proc. Natl. Acad. Sci. USA   94   2068 - 2072   1997

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  • Somatotropic actions of the homologous growth hormone(tGH)and prolactin(tPRL177)in the euryhaline teleost, the tilapia, Oreochromis mossambicus

    Proc. Natl. Acad. Sci. USA   94   2068 - 2072   1997

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  • Osmoregulatory actions of growth hormone and prolactin in an advanced teleost(共著)

    SAKAMOTO T

    Gen. Comp. Endocrinol   106   95 - 101   1997

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  • Induction of proteins in response to cold acclimation of rainbow trout cells

    Michiaki Yamashita, Nobuhiko Ojima, Tatsuya Sakamoto

    FEBS Letters   382 ( 3 )   261 - 264   1996.3

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  • Molecular cloning and cold-inducible gene expression of ferritin H subunit isoforms in rainbow trout cells

    Michiaki Yamashita, Nobuhiko Ojima, Tatsuya Sakamoto

    Journal of Biological Chemistry   271 ( 43 )   26908 - 26913   1996

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  • Expression of insulin-like growth factor I gene in osmoregulatory organs during seawater adaptation of the salmonid fish : Possible mode of osmoregulatory action of growth hormone(共著)

    Proc. Natl. Acad. Sci. USA   90   1912 - 1916   1993

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  • Expression of insulin-like growth factor I gene in osmoregulatory organs during seawater adaptation of the salmonid fish : Possible mode of osmoregulatory action of growth hormone

    Proc. Natl. Acad. Sci. USA   90   1912 - 1916   1993

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Presentations

Awards

  • 日本動物学会奨励賞

    坂本 竜哉

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  • Dodd Memorial Prize

    SAKAMOTO Tatsuya

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Research Projects

  • 左右相称動物の普遍的ホルモンペプチドの祖先的機能：珍無腸動物カルシトニンの研究

    Grant number：23K05844  2023.04 - 2026.03

    日本学術振興会  科学研究費助成事業  基盤研究(C)

    関口 俊男, 坂本 竜哉, 濱田 麻友子

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    Grant amount：\4680000 （ Direct expense: \3600000 、 Indirect expense：\1080000 ）

    本研究の目的は、原始的な左右相称動物と考えられている珍無腸動物を用いカルシトニン（CT）の祖先的機能や、前口・後口動物の分岐に伴うCT機能の進化機構を提唱することにある。CTは哺乳類の骨代謝を司るホルモンである。我々は、CTが無脊椎動物にも存在することを示してきた。その後のゲノム解析等から、CT遺伝子が左右相称動物（前口・後口動物）に広く存在することが知られている。それらの機能を見渡すと、概日リズムの調整がCTの共通の作用である可能性が見出された。そこで、本研究では、原始的な左右相称動物とされる珍無腸動物ナイカイムチョウウズムシを用い、この仮説を検証し、前口・後口動物を跨ぐペプチド遺伝子スーパーファミリーの機能進化解明のモデルとする。
    令和5年度は、ナイカイムチョウウズムシのCT（Pn-CT）及びCT受容体（Pn-CTR）全長配列の決定を行った。Pn-CTは36アミノ酸残基であった。様々な動物のCTに存在する2つのCys 残基が保存されており、ジスルフィド結合による環状構造を持つと考えられる。さらにCTに特徴的なPro残基とアミド化シグナルが保存されていた。さらにPn-CTRの分子系統解析により、Pn-CTRが左右相称動物のCTRやCTR様受容体(CLR)と相同性であることを確認した。さらに Whole mount in situ hybridization 解析により、ナイカイムチョウウズムシのPn-CT及びPn-CTRの発現局在を検討した結果、Pn-CTとPn-CTR mRNAが共に頭部に局在していることが明らかとなった。その発現パターンから、Pn-CTとPn-CTR mRNAは、ニューロンに発現していると予想される。特にPn-CTの局在は、GABAニューロンのマーカー遺伝子の局在と類似していた。これらの解析によって、珍無腸動物CT機能解析の基盤を整えることができた。

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  • “ステロイドホルモン系”の原始左右相称動物での黎明は、共生藻がもたらしたか？

    Grant number：22K19312  2022.06 - 2024.03

    日本学術振興会  科学研究費助成事業 挑戦的研究(萌芽)  挑戦的研究(萌芽)

    坂本 竜哉, 永田 晋治, 濱田 麻友子, 坂本 浩隆

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    Grant amount：\6370000 （ Direct expense: \4900000 、 Indirect expense：\1470000 ）

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  • 広塩性の扁形動物を原点に探る淡水進出における体液調節能獲得の動物界を跨ぐ新概念

    Grant number：21H02520  2021.04 - 2025.03

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    坂本 竜哉, 片山 侑駿, 坂本 浩隆, 関口 俊男, 濱田 麻友子, 前嶋 翔

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    Grant amount：\17290000 （ Direct expense: \13300000 、 Indirect expense：\3990000 ）

    国際研究グループで、新しい水・塩分環境への進出をもたらした動物界を貫く体液調節機構と提唱する抗利尿ホルモン（バソプレシン）系―腎臓の原型を、原始左右相称動物の扁形動物ヒラムシ（海産プラナリアの仲間）を用いて解明している。
    まず、ヒラムシの、水陸両生、50～150%海水への順応―体液調節できること等を見出した。そして、脊椎動物の水・塩分環境適応の“要”でもある「バソプレシン/オキシトシン」の同族ペプチドをヒラムシから発見した。この神経ペプチドは、脊椎動物と無脊椎動物において広く存在することから、左右相称動物に普遍的な神経ペプチドとして、その共通祖先においてすでに存在していたと考えられるが、その進化起源は明らかになってなかった。今回、左右相称動物の共通祖先に近いとされるシンプルな体制を持つ、原始左右相称動物である扁形動物門（Platyhelminthes）から、その同族ペプチドを特定することに成功し、この祖先型ホルモンをプラチトシン（platytocin）系と名付けた。このホルモンは脳神経節の2対のニューロンのみで産生され、脱水で誘導された。さらに、プラチトシン系は扁形動物でも哺乳類と同様に抗利尿ホルモンとして機能していることを見出した。従って、『抗利尿ホルモン系による“腎臓” i.e., 体液の調節』の起源が、新しい水・塩分環境への進出をはじめた扁形動物まで遡れる。また、これまで不明であった神経シナプス系からの内分泌系/液性調節の誕生：神経内分泌の進化起源の解明も期待される。

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  • 広塩性の扁形動物を原点に探る淡水進出における体液調節能獲得の動物界を跨ぐ新概念

    Grant number：23K21320  2021.04 - 2025.03

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    坂本 竜哉, 坂本 浩隆, 関口 俊男, 濱田 麻友子, 中村 遼, 田中 祥貴, 片山 侑駿, 前嶋 翔

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    Grant amount：\17290000 （ Direct expense: \13300000 、 Indirect expense：\3990000 ）

    当初計画は順調に進み、研究目的は達成されつつあるが、その過程で、ヒラムシのGnRHの神経回路等、進化的に保存され普遍的な神経ペプチド群に関する新発見もしている。これら普遍的なペプチド系分子は、前に分岐した散在神経系の動物には見出せない。また我々は、原始的な後口動物の珍無腸動物ムチョウウズムシのシンプルな中枢神経系でも、祖先型GnRHを発見している。その中枢神経系でのTRP群の発現も見出している（Sakagami, Hamada, Sakamoto T ら Cell Tissue Res 2023等）。
    以上の興味深い成果から、解析対象にムチョウウズムシも加え、数百の細胞からなる中枢神経系の原型に、１細胞/空間トランスクリプトーム／コネクトーム解析を駆使すれば、構成細胞の浸透圧センサーのような固有特性や神経ネットワークなど細胞・分子基盤を包括的に解明できる。マウス、ショウジョウバエでの知見とも包括的に比較でき、原始左右相称動物に共通な“シン原始脳”の神経ネットワークが、前口・後口動物で、いかに保存/分化されたかに迫れる。そこで、空間トランスクリプトームも始めた。また、原始海産無脊椎動物の神経系の本技術等に優れる分担者の中村（Hayakawa, Nakamura ら Nature Ecol Evol 2022 他等）を、当実験所に採用した。非モデル生物でも１細胞トランスクリプトーム、遺伝子編集による機能解析が急速に行われている。実際、中村は前左右相称動物の有櫛動物や刺胞動物で成果を挙げている（Nakamura ら Nature Commun リバイズ中等）。研究の舵を切り、このビッグチャンスを掴みたい。

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  • “パイオニア”動物でひもとく海から淡水、陸上への進出をもたらしたシンギュラリティ

    Grant number：21H00428  2021.04 - 2023.03

    日本学術振興会  科学研究費助成事業  新学術領域研究(研究領域提案型)

    坂本 竜哉

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    Grant amount：\5720000 （ Direct expense: \4400000 、 Indirect expense：\1320000 ）

    国際研究グループで、新しい水・塩分環境への進出をもたらしたシンギュラリティとして提唱する抗利尿ホルモン（バソプレシン）系―腎臓の原型を、原始左右相称動物の扁形動物ヒラムシ（海産プラナリアの仲間）を用いて解明している。
    まず、脊椎動物の水・塩分環境適応の“要”でもある「バソプレシン/オキシトシン」の同族ペプチドをヒラムシから発見した。この神経ペプチドは、脊椎動物と無脊椎動物において広く存在することから、左右相称動物に普遍的な神経ペプチドとして、その共通祖先においてすでに存在していたと考えられるが、その進化起源は明らかになってなかった。今回、左右相称動物の共通祖先に近いとされるシンプルな体制を持つ、原始左右相称動物である扁形動物門（Platyhelminthes）から、その同族ペプチドを特定することに成功し、この祖先型ホルモンをプラチトシン（platytocin）系と名付けた。このホルモンは脳神経節の2対のニューロンのみで産生され、脱水で誘導された。このたった4個の細胞こそ、シンギュラリティ細胞かもしれない。さらに、プラチトシン系は扁形動物でも哺乳類と同様に抗利尿ホルモンとして機能していることを見出した。従って、『抗利尿ホルモン系による“腎臓” i.e., 体液の調節』の起源が、新しい水・塩分環境への進出をはじめた扁形動物まで遡れる。すなわち新しい水・塩分環境への進出をもたらしたシンギュラリティの可能性がある。また、これまで不明であった神経シナプス系からの内分泌系/液性調節の誕生：神経内分泌の進化起源（シンギュラリティ）の解明も期待される。

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  • Chordate steroid receptor is ancient in the acoel

    Grant number：20K21429  2020.07 - 2022.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Research (Exploratory)

    Sakamoto Tatsuya

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    Grant amount：\6500000 （ Direct expense: \5000000 、 Indirect expense：\1500000 ）

    We isolated and characterized the steroid hormone receptors (SRs) of the acoel Praesagittifera naikaiensis, which belongs to a clade (Xenacoelomorpha) that could be a sister group to other animals with bilateral symmetry (Bilateria) or could belong within deuterostomes, closely related to a group that includes sea stars (Ambulacraria). The P. naikaiensis genome contains two SRs: PnEER, an ortholog of the vertebrate estrogen-related receptors, and PnSR, an ortholog of the vertebrate receptors for androgens, progestins, and corticosteroids. PnSR does not activate transcription in response to conventional steroid hormones of vertebrate. These genes are expressed in the statocyst and gonad specifically, suggesting an ancient role in behaviours affected by environmental stimuli and germ cell development.

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  • Evolution of calcium homeostasis: the functional study of calcitonin in cyclostome and cartilaginous fish

    Grant number：18K06312  2018.04 - 2021.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    Toshio Sekiguchi

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    Grant amount：\4420000 （ Direct expense: \3400000 、 Indirect expense：\1020000 ）

    To elucidate the evolution of the regulation mechanism of serum calcium level involved in calcitonin (CT), functional analysis of CT in cyclostome and cartilaginous fish were performed.
    In hagfish, the CT and its receptor candidate gene were identified. Hagfish CT stimulated mammalian cells expressed by a CT receptor candidate. In addition, oral administration of calcium increased the serum calcium level, whereas hagfish CT concentration did not change. In red stingray, the CT gene was cloned from the ultimobranchial gland. Measurement of serum CT level using ELISA and serum calcium level revealed no correlation between serum CT level and serum calcium concentration. Contrary, serum CT level showed a positive correlation with gonadal weight, suggesting that CT is associated with reproductive function in cartilaginous fish.

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  • Principal function of mineralocorticoid signaling suggested by constitutive knockout of the mineralocorticoid receptor in fish

    Grant number：15H04395  2015.04 - 2019.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    Sakamoto Tatsuya

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    Grant amount：\17550000 （ Direct expense: \13500000 、 Indirect expense：\4050000 ）

    Corticosteroid receptors are critical for homeostasis maintenance including stress response, but understanding of the principal roles of the glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) throughout vertebrates is limited. In addition to lines of constitutive GR knockout zebrafish, we have recently generated that of MR-knockout medaka as the first adult-viable corticosteroid receptor-knockout animals, in contrast to the lethality of these receptor knockouts in mice. We found behavioral and physiological modifications following disruption of corticosteroid receptor function in these animal models. We suggest these data point toward a potentially conserved function of corticosteroid receptors in integrating brain-behavior and visual responses in vertebrates. Roles in behaviors might be the principal and original functions of steroid hormone systems.

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  • The possibleprincipal function of neurohypophysial hormones

    Grant number：22570065  2010 - 2012

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    SAKAMOTO Tatsuya, OGOSHI Maho, SAKAMOTO Hirotaka, TAKAHASHI Hideya

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    Grant amount：\4160000 （ Direct expense: \3200000 、 Indirect expense：\960000 ）

    Acclimation from marine to dilute environments constitutes among the most dramatic evolutionary transitions in the history of life. Such adaptations have evolved in multiple lineages, but studies of the mechanisms are limited to those using evolutionarily advanced Deuterostome (chordates) and Ecdysozoa (crustaceans). Here we examined the body-fluid homeostasis in the advanced Lophotrochozoa/mollusc, the other unexplored taxa, and its possible regulations byvasopressin/oxytocin superfamily peptides known to be implicated in fluid homeostasis in Chordata and Arthropoda. The hemolymph osmotic and ionic status in the euryhaline cephalopod (Octopus ocellatus) following transfer from normal seawater (30 ppt) to low (20 ppt) salinity indicate the hyperosmo- and hyperiono-regulatory abilities for more than 1 week, as in crustaceans and teleost fish. While ventilation frequency decreased by 1 day, Na+/K+-ATPase activity, which has been implicated in ion transport generally, was induced in two of the eight posterior gills after 1 week. Furthermore, the octopuses were intravenously injected with 1 or 100 ng/g octopressin or cephalotocin, cephalopod vasopressin/oxytocin orthologs. After 1 day, octopressin, not cephalotocin, decreased the hemolymph osmolality and Ca concentrations as well as urinary Na concentrations. These data provide evidence for convergent evolution in the hyper-ionoregulatory mechanisms and the coordination by conserved molecules.

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  • Biological function of novel adrenomedullin in vertebrates : a reverse-phylogenic approach

    Grant number：22870020  2010 - 2011

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Research Activity Start-up

    OGOSHI Maho, SAKAMOTO Tatsuya

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    Grant amount：\3146000 （ Direct expense: \2420000 、 Indirect expense：\726000 ）

    We have clarified that all five members of adrenomedullin(AM) family were expressed in tissues of medaka(Oryzias latipes) including osmoregulatory organs. The expressions of AM1, AM3, AM4 and AM5 were increased after transfer to freshwater and decreased in seawater, whereas that of AM2 was increased in seawater. The obtained data suggest that AM family genes except for AM2 are involved in freshwater adaptation, whereas AM2 is related to the adaptation to seawater.

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  • Evolution of drinking mechanism from aquatic to terrestrial habitat : Exploring its origin using fishes

    Grant number：19207005  2007 - 2009

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    TAKEI Yoshio, ANDO Masaaki, SAKAMOTO Tatsuya

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    Grant amount：\50570000 （ Direct expense: \38900000 、 Indirect expense：\11670000 ）

    In this study, we found that guanylin, adrenomedullin and relaxin form a family of diversified members in teleost fishes and play important roles in osmoregulation, particularly in seawater adaptation. We also found that natriuretic peptides that suppress drinking and angiotensin that induces drinking act on the area postrema in the medulla oblongata to regulate reflex swallowing in aquatic fishes, which is in contrast to terrestrial animals where they regulate thirst by acting on the forebrain.

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  • "The compact, freshwater migrations" for the general mechanisms of the fish migrations

    Grant number：19570057  2007 - 2008

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    SAKAMOTO Tatsuya

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    Grant amount：\4550000 （ Direct expense: \3500000 、 Indirect expense：\1050000 ）

    We have observed that kissing loach and some other freshwater fishes migrate from the main stream of rivers to spawn in flood areas. These flood areas are unstable and ephemeral, however, they contain few aquatic predators and a large amount of food suitable for the development of embryos/juveniles. The present study provides the first evidence that the spawning migration of kissing loach is stimulated by rainfall and the subsequent rise in water level, as well as the new moon. Since similar observations have been reported for downstream migrations of salmonids, these stimuli may serve as general cues for migrations of fishes in rivers. Furthermore, the spawning of kissing loach is rigidly limited spacio-temporally after the formation of flood areas. Recently we have successfully demonstrated that changes in water quality directly induce migration and spawning behavior, suggesting some particular odoriferous substances may be the environmental proximate factors.

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  • A new approach for functions of classical osmoregulatory hormones in fishes

    Grant number：17570049  2005 - 2006

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    SAKAMOTO Tatsuya

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    Grant amount：\3500000 （ Direct expense: \3500000 ）

    In the seawater (SW)-acclimated euryhaline fishes, the ion/water permeability of the gastrointestinal tract is generally greater than that of freshwater (FW)-acclimated fish. The esophageal epithelium of SW fishes is simple columnar in form, whereas that of FW fishes is stratified. We have previously shown that esophageal epithelium of a euryhaline goby and tilapia displays elevated cell proliferation in FW fish, but undergoes apoptosis during SW acclimation (1). In-vivo cortisol treatment of the goby stimulated not only the apoptosis but also cell proliferation in the esophageal epithelium, whereas 11-deoxycorticosterone, the putative teleostean mineralocorticoid (2), did not have any impact on cell proliferation or apoptosis (3). To understand the possible dual mode of action of cortisol on the esophageal cell turnover, we have developed a method of culture tissue explants of the esophagus from euryhaline medaka (Oryzias latipes). Oligonucleotide detection assay and an oxidation-reduction indicator were used as indicators of apoptosis and cell proliferations, respectively. Addition of cortisol (10 nM) to the culture medium for 8 days stimulated apoptosis in the medaka esophagus, as a well-established glucocorticoid function. No effects were seen at higher doses (100 and 1000 nM). On the other hand, addition of cortisol (1000 nM) for 8 days induced the cell proliferation. The response of cell proliferation was dose-dependent within physiological range (10-1000 nM). Thus, it is likely that cortisol induces directly not only apoptosis but also cell proliferation at the esophagus in euryhaline fishes, possibly via glucocorticoid receptor, since glucocorticoid receptor shows lower sensitivity for cortisol than mineralocorticoid receptor (2).
    References
    (1) Takahashi et al. (2006). J. Comp. Physiol. B, 176, 463-468.
    (2) Prunet et al. (2006). Gen. Comp. Endocrinol., 147, 17-23.
    (3) Takahashi et al. (2006). Life Sci., 79, 1873-1880.

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  • 広塩性両生魚トビハゼの腸上皮分化におけるプロラクチンの役割の分子細胞生物学的解析

    Grant number：14740458  2002 - 2004

    日本学術振興会  科学研究費助成事業  若手研究(B)

    坂本 竜哉

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    Grant amount：\3600000 （ Direct expense: \3600000 ）

    プロラクチンは多様な作用を持つ。本研究では、「プロラクチン作用の本質がアポトーシス/細胞増殖の制御である」という仮説を、広塩性両生魚であるトビハゼを用いて検討した。昨年度までに、淡水、海水あるいは陸上に適応する過程で、プロラクチンの発現パターンに伴い、消化管上皮における細胞増殖が淡水中で、アポトーシスが海水適応時に誘導されることを見いだした。本年度は、各種ホルモンを投与した魚の消化管におけるアポトーシスと細胞増殖を細胞レベルで解析し、以下の成果が得られた。
    プロラクチンは、淡水適応時と同様に陰窩の部分だけでなく上皮全体で細胞増殖を誘導した。一方、コルチゾルは、上皮全体において細胞増殖もアポトーシスも誘導する双方向の作用を示した。今年鉱質コルチコイドと同定されたデオキシコルチコステロンは効果がなかった。いずれのコルチゾルの作用も、鉱質コルチコイド受容体を介さないと思われる。また甲状腺ホルモンの作用も見られなかった。以上から、淡水適応過程では、プロラクチンとコルチゾルにより細胞増殖が誘導され、消化管は多重上皮となる。一方、海水適応時ではコルチゾルによりアポトーシスが誘導され、単層上皮となると考えられる。変態時のアポトーシスの、甲状腺ホルモンや糖質コルチコイドによる誘導、プロラクチンによる抑制が明らかにされつつある。よって、糖質コルチコイドやプロラクチンの細胞増殖/アポトーシス制御は広くみられ、作用の本質と考えられる。変態のような不可逆的な系と、本研究の可逆的な系の違いは、甲状腺ホルモンなのかもしれない。
    現在、以上のホルモンの受容体が同定されているティラピアを用い、これらの受容体と細胞増殖/アポトーシスの形態学的相関を調べている。さらに広塩性であるメダカのDNAアレイが使用可能なので、分子レベルで検討していく予定である。

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  • 広塩性両生魚トビハゼをもちいた水・電解質代謝におけるプロラクチン系の統合的解析

    Grant number：12740457  2000 - 2001

    日本学術振興会  科学研究費助成事業  奨励研究(A)

    坂本 竜哉

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    Grant amount：\1800000 （ Direct expense: \1800000 ）

    本研究の目的は、水・電解質代謝におけるプロラクチン(PRL)の役割を検討し、PRL作用の本質を明らかにすることにある。淡水、海水という水・電解質収支が逆の環境へ適応できる広塩性魚類をモデルとして、解析を行った。本年度においては、特に陸上にも適応できるトビハゼを用いて、以下の成果が得られた。
    昨年度、下垂体外のPRLの発現が、同じ器官のPRL放出ペプチド(PrRP)によって局所的に制御されていることを示唆した。そこで、浸透圧調節器官である消化管のPrRP-PRL系を重点的に検討した。Northern解析では、腸の前部で、PrRP、PRLとも発現も高かった。この部分での、in situ hybridization、免疫組織化学により、腸上皮特に粘液細胞に、PrRPとPRLが共存していることを見いだした。広塩性魚類の消化管は、淡水中では粘液細胞に富む多重上皮である。しかし、海水中では細胞が脱落して単層上皮となる。また、哺乳類の腸上皮細胞の更新はアポトーシスによる。従って、これまでに得られた一連の成果から、腸上皮のPrRP-PRL系は、淡水中での腸上皮脱落の抑制、腸上皮細胞の増殖/分化に寄与していると思われる。
    両生類変態時のPRLによるアポトーシスの抑制が明らかにされつつある。また、PRL受容体は、アポトーシスの抑制に重要なサイトカイン受容体スーパーファミリーに属する。さらに、PRLによる乳腺細胞の増殖も示唆されている。すなわち、アポトーシスの抑制や細胞増殖/分化は、PRLの基本的な作用であることが大いに考えられる。

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  • トビリゼの皮膚をもちいた魚類塩類細胞の多角的解析

    Grant number：10740384  1998 - 1999

    日本学術振興会  科学研究費助成事業  奨励研究(A)

    坂本 竜哉

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    Grant amount：\2000000 （ Direct expense: \2000000 ）

    本研究の目的は、環境浸透圧の変化にともなう塩類細胞の機能分化を、形態・機能・分子レベルで解明することにある。塩類細胞が高密度に存在し、扱いやすいトビハゼの皮膚をモデルとして解析を行った。本年度においては、以下の成果が得られた。
    昨年度、海水中においては塩類細胞はCl^-の分泌のためその開口部を速やかに開くこと、淡水中でのCl^-の分泌停止には開口部を速やかに閉じることを見た。そこで、トビハゼを淡水から様々な溶液に移し、この開口部の開閉が何の刺激によるのかを調べた。NaCl、マニトールといった浸透圧刺激だけでは海水の場合ほど開かない。しかし、海水と同じ濃度の10mMCaのみで海水と同じ結果がえられた。ついで、環境水のCa濃度を淡水レベルに下げると、開口部は速やかに閉じた。これらの時に、血中Caは変動しない。また、この反応は、Caチャネルブロッカーのヴェラパミルによって抑えられた。したがって、Caは(塩類)細胞内で作用していると思われる。
    昨年度の成果と併せると、魚が海水に入ると、海水中のCa(塩類)細胞内に流入しする。そして、おそらく細胞骨格系を働かせることにより、塩類細胞の開口部を速やかに開き、Cl^-を分泌していると思われる。淡水中では逆のことが起っていると考えられる。
    さらに、塩類細胞の機能分化をホルモンとの関連でも検討するための、第一段階として、トビハゼで、プロラクチン(PRL)と(GH)のcDNAをクローン化した。これらをプローブとして、PRLmRNA量は淡水中で上昇し、GHmRNA量はいくつかの硬骨魚のように海水中で増大することを、血中コルチゾルとの関連で見いだした。

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  • Marine Course IV （2022academic year） Summer concentration  - その他

  • Marine Course V （2022academic year） Summer concentration  - その他

  • Adaptational Zoology （2022academic year） Late  - その他

  • Animal Physiology （2021academic year） 1st and 2nd semester  - 水3,水4

  • Animal Physiology I （2021academic year） 1st semester  - 水3,水4

  • Animal Physiology II （2021academic year） Second semester  - 水3,水4

  • Marine Biology （2021academic year） Late  - 金1,金2

  • Seminar in Chemical Correlation and Control （2021academic year） Year-round  - その他

  • Marine Biology （2021academic year） Concentration  - その他

  • Marine Course 1 （2021academic year） 1st semester  - その他

  • Marine Course 3 （2021academic year） Second semester  - その他

  • Marine Course IV （2021academic year） Summer concentration  - その他

  • Marine Course V （2021academic year） Summer concentration  - その他

  • Adaptational Zoology （2021academic year） Late  - その他

  • Animal Physiology （2020academic year） 1st and 2nd semester  - 水3,水4

  • Animal Physiology I （2020academic year） 1st semester  - 水3,水4

  • Animal Physiology II （2020academic year） Second semester  - 水3,水4

  • Marine Biology （2020academic year） Late  - 金1,金2

  • Seminar in Chemical Correlation and Control （2020academic year） Year-round  - その他

  • Marine Biology （2020academic year） Summer concentration  - その他

  • Marine Course 1 （2020academic year） 1st semester  - その他

  • Marine Course 3 （2020academic year） Second semester  - その他

  • Marine Course IV （2020academic year） Summer concentration  - その他

  • Marine Course V （2020academic year） Summer concentration  - その他

  • Adaptational Zoology （2020academic year） Late  - その他

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