| Project/Area Number |
06044235
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Okazaki National Research Institutes |
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Principal Investigator |
NAGAHAMA Yoshitaka National Institute fof Basic Biology, Okazaki National Research Institutes, Professor, 基礎生物学研究所, 教授 (50113428)
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| Co-Investigator(Kenkyū-buntansha) |
GRAU E.Cordon Hawaii Institute of Marine Biology University of Hawaii, 海洋研究所, 教授
DONALDSON Edward M West Vancouver Laboratory, Canada, 主任
CREWS David L Department of Zoology, University of Texas, Austin, 動物学教室, 教授
NAKAMURA Masaru Department of Zoology, Faculty of Medicine, Teikyo University, 法学部, 助教授 (10101734)
KOBAYASHI Tohru National Institute fof Basic Biology, Okazaki National Research Institutes, 基礎生物学研究所, 助手 (30221972)
TANAKA Minoru National Institute fof Basic Biology, Okazaki National Research Institutes, 基礎生物学研究所, 助手 (80202175)
YOSHIKUNI Michiyasu National Institute fof Basic Biology, Okazaki National Research Institutes, 基礎生物学研究所, 助教授 (50210662)
PATINO Reyna テキサステック大学, 助教授
CRAIG Morrey ハワイ大学, 海洋研究所, 研究員
松山 倫也 九州大学, 農学部, 助教授 (00183955)
CREWS Davd L テキサス大学, 動物学教室, 教授
MORREY Craig ハワイ大学海洋研究所, 研究員
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| Project Period (FY) |
1994 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥12,100,000 (Direct Cost: ¥12,100,000)
Fiscal Year 1996: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1995: ¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 1994: ¥4,400,000 (Direct Cost: ¥4,400,000)
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| Keywords | sex differentiation / sex determination / sex hormone / fish / reptile / molecular biology / steroid metabolizing enzymes / sex change / gonads / 芳香化酵素 / エストロゲン / アンドロゲン / 11β水酸化酵素 / 抗体 / 性ステロイドホルモン / は虫類 / 11-ケトテストステロン / ステロイド代謝酵素遺伝子 / エストラジオール-17β |
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| Research Abstract |
This international collaborative research is to combine a variety of approaches and animal systems to the study of sex determination and sexual differentiation. Sex change in the endemic, Hawaiian wrasse Thalassoma duperrey provides an ideal model system to investigate mechanisms of sex determination and sexual differentiation. We first used immunocytochemical methods to detect gonadal sites of P450 cholesterol side-chain cleavage enzyme (P450scc) in the wrasse at different stages of in the sex change process. P450scc cells were predominantly in the theca layr of normal females. As females underwent sex change, P450scc localization shifted from the theca layr to the interstitium. P450scc cells appeared to increase in number midway through sex change. The gonad's ability to produce estrogens, however, is permanently lost in the earliest stages of sex change. The levels of aromatase mRNA and protein, the enzyme responsible for converting androgens to estrogens, was undetectable in testes
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and transitional gonads. In contrast, protein levels of 11beta-hydroxylase, the enzyme responsible for 11-ketotestosterone production increase towards the end of sex change process.
In this collaborative research, we also examined immunocytochemically the initial differentiation and development of steroid-producing cells during gonadal sex differentiation in tilapia Oreochromis niloticus using polyclonal antibodies against four steroid-metabolizing enzymes (P450scc, 3beta-HSD,P450c17, P450arom). Immunoreaction for P450scc, 3beta-HSD,P450c17, and P450arom became evident for the first time in gonads of genetically females examined at several days before morphological sex differentiation. In contrast, positive immunostaining for all four steroidogenic enzymes was not easily identified in the testes during sex differentiation. A weak staining for P450scc, 3beta-HSD and P450c17, but not P450arom, was present in the tissue surrounding the efferent duct in testes 30 days after hatching. The number of immunoreactive cells as well as the intensity of staining ware increased in testes just before the onset of spermatogenesis. Taken together, these findings suggest that estrogens play an important role in ovarian differentiation in fish. The results of this collaborative research also suggest an important role of estrogens in temperature-dependent sexual differentiation in reptiles. Less
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