| Project/Area Number |
14540637
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
動物生理・代謝
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| Research Institution | Toho University |
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Principal Investigator |
OSHIMA Noriko Toho University, Faculty of Science, Professor, 理学部, 教授 (70057735)
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| Co-Investigator(Kenkyū-buntansha) |
SUGIMOTO Masazumi Toho University, Faculty of Science, Associate Professor, 理学部, 助教授 (20235899)
OHTOMI Michiko Toho University, Faculty of Science, Associate Professor, 理学部, 助教授 (60057742)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2004: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2003: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2002: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Nile tilapia / erythrophores / neon tetra / iridophores / visual pigment / endothelin / light-sensitivity / G protein / ロドプシン / 細胞内情報伝達 / 紫外線 / Gtタンパク質 / エンドセリン受容体 |
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| Research Abstract |
1.Nile tilapia erythrophores respond directly to light at 365 nm, 400nm and 600nm by pigment aggregation, while light at 500 nm induces pigment dispersion. Using cultured erythrophores isolated from tail fins, the effects of pertussis toxin, cholera toxin, Ca^<2+> and Mg^<2+>-free K solution etc. on the photoresponses were examined. Pigment aggregation and dispersion responses were suggested to couple to Gi and Gs, respectively. KT-PCR showed the expression of mRNAs encoding red and green opsins in tilapia fins, only where erythrophores exist.
2.Light-sensitive iridophores (light-reflecting chromatophores) in the skin of neon tetra were also analyzed. The photoresponses of these cells depended on the light intensity, and light near 500 nm was most effective in inducing the shift in wavelengths of reflected light toward longer wavelengths. The decrease in cyclic AMP may be related in the photoresponse. RT-PCR showed the expression of rhodopsin mRNA in the skin of neontetra, in addition to retina. However, the mRNA expression was not detected in muscle tissues. Cloning of cDNA of neon tetra rhodopsin was also performed.
3.Using split tail-fin preparations and cultured chromatophores, the effects of endothelin(ET) on fish chromatophores were examined. ET-1,2 and 3 were found to cause pigment aggregation in melanophores and the shift in wavelengths of reflected light toward longer wavelengths in iridophores, which may be triggered by the decrease in cAMP via Gi. In leucophores, dispersion responses were induced probably mediated by Gs. By pharmacological analyses and immunofluorescence technique, it was suggested that ET_B receptors were present in the chromatophore membrane.
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