Studies of Mecteinism of sex determination and sex diferentiation in fish.

我们的研究表明，内源性雌激素的生物合成发生在未分化的XX性腺，而不是XY性腺的外观之前的任何形态性二型性，和卵巢分化所需的内源性雌激素。为了鉴定卵巢和睾丸分化过程中的下游基因产物，我们使用来自正常和雌激素处理的XY性腺的mRNA进行消减杂交。我们确定了10个受调控的基因产物，其中7个与卵巢分化有关，3个与睾丸分化有关。用甲基睾丸酮（MT）或芳香化酶抑制剂（AI）处理30天，诱导遗传性别控制的雌性罗非鱼发生性逆转。在第12天（性分化起始期）和第30天（刚开始性分化），用改良的差异显示技术比较基因表达谱，并与对照组进行比较。 ...更多信息 性分化完成）。在第12天时，鉴定了16个上调和21个下调的基因，而在第30天时，鉴定了14个上调和19个下调的基因。本研究通过对这些基因进行克隆、测序、同源性检索和基因表达分析，以雌性先熟鱼类为研究对象，探讨了鱼类性别转变的机制。人工授精诱导了雌性向雄性的性别转变.相反，AI和雌二醇-17b（E2）联合使用不会引起性别改变。本研究利用体外组织培养技术，在3-4周内成功地将完整的卵巢组织用精子诱导重建为成熟的睾丸组织。据我们所知，这是第一次证明脊椎动物从卵巢组织到完整睾丸的“体外变性”。实验诱导这种变化的能力对脊椎动物性别决定和性别分化的未来研究具有重要意义。少

Our studies indicate that endogenous estrogen biosynthesis occurs in undifferentiated XX gonads but not XY gonads before the appearance of any morphological sexual dimorphism, and that endogenous estrogens are required for ovarian differentiation. To identify the down-stream gene products during ovarian and testicular differentiation, we performed subtractive hybridization using mRNA derived from normal and estrogen treated XY gonads. We identified ten regulated gene products, seven of which related to ovarian differentiation and three to testicular differentiation. Two out of the ten gene products were expressed in germ cells, whereas the others were expressed in somatic cells.Sex reversal was induced in genetically sex-controlled female tilapia by a 30 days treatment with methyltestosterone(MT) or aromatase inhibitor(AI). Gene expression profiles were compared with a control group by modified differential display at Day 12 (initiation period of sex differentiation) and Day 30(just af … More ter completion of sex differentiation). At 12,16 up-regulated and 21 down-regulated genes were identified, where at Day 30,14 up-regulated and 19 down-regulated genes were identified. These genes were cloned and sequenced, followed by homology searches and gene expression analysis.In this study, we examined the mechanism of sex change in fish using a protogynous species. AI induced compete a sex change from female to male. In contrast, AI and estradiol-17b(E2) in combination did not bring about the sex change. These results strongly suggest that endogenous E2 has critical role in sex change.Using in vitro tissue culture, we succeeded in inducing restructuring complete ovarian tissue to mature testicular tissue with sperm in 3-4 weeks. To the best of our knowledge, this is the first demonstration of "in vitro sex change" from ovary tissue to a complete testis in vertebrates. This ability to experimentally induce this change has important implication for future research on sex determination and sex differentiation in vertebrates. Less