| Project/Area Number |
04640674
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
動物発生・生理学
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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,LECTURER, 理学部, 講師 (20235899)
FUJII Ryozo TOHO UNIVERSITY,FACULTY OF SCIENCE,PROFESSOR, 理学部, 教授 (10045354)
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| Project Period (FY) |
1992 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1992: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Melanin concentrating hormone (MCH) / Melanophore / Teleost fish / MCH receptor / Cyclic AMP / Calcium ion / Protein kinase C / MCH fragments / 赤色素胞 / サイクリックAMP / プロティンキナーゼC / 黒色素凝集ホルモン / カルシウム / 受容体 / 白色素胞 |
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| Research Abstract |
The primary structure of melanin-concentrating hormone (MCH) purified from chum salmon pituitary was determined in 1983. In melanophores, MCH caused pigment aggregation in all teleosts studied, whereas pigment within erythrophores was not always aggregated. For example, swordtail erythrophores responded to MCH,but erythrophores present in tail fin of Nile tilapia did not at all. Moreover, the minimum effective does of MCH in swordtail erythrophores was rather higher than that in melanophores.
Five analogues of MCH were tested for their melanin-aggregating activities in the in vitro fish skin (Corydoras paleatus) bioassay. Four analogues were fragments of the native sequence : Asp-Thr-Met-Arg-Cys-Met-Val-Cly-Arg-Val-Tyr-Arg-Pro-Cys-Trp-Glu-Val with sequential elimination of substituents from both the carboxy- and amino- termini. Their relative effectiveness as follows : intact MCH > fragment (5-17) * fragment (1-15) > fragment (5-15) > fragment (1-14). Linear fragment (1-14) did not have the melanin-aggregating activity at all. From these results, we suggest the importance of S-S binding and the Trp^<15> residue for interaction with MCH receptors mediating melanosome aggregation. When intact MCH at concentrations higher than 1 muM was applied, the aggregation of melanosomes was followed by dispersion of them, suggesting that another type of MCH receptor mediating melanosome dispersion is also present on the melanophore membrane.
Radio Immuno Assay indicated that the intracellular concentration of cAMP was decreased to about 55% of control value, when melanophores were treated with 10 nM MCH for 10 min, whereas intracellular level of cAMP was increased to about 126% when melanosomes were redispersed after the maximum aggregation by the treatment with 10 muM MCH.Moreover, it was shown in the present experiments, that Protein kinase C may be partly involved in the pigment aggregation, although calcium ions may not take part in the response.
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