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，在任何形态的性别二型性之前，内源性雌激素的合成是卵巢分化所必需的。为了鉴定卵巢和睾丸分化过程中的下游基因产物，我们用来自正常和雌激素处理的XY性腺的mRNA进行了消减杂交。我们鉴定了10个调控基因产物，其中7个与卵巢分化有关，3个与睾丸分化有关。10个基因产物中有2个在生殖细胞中表达，其余在体细胞中表达。用甲基睾酮(MT)或芳香酶抑制剂(AI)处理30天后，遗传性别控制的雌性罗非鱼发生了性别逆转。在第12天(性别分化起始期)和第30天(仅af…)用改进的差异显示技术比较基因表达谱与对照组更多的性别分化完成)。在第12天，共鉴定出16个上调基因和21个下调基因；在第30天，鉴定出14个上调基因和19个下调基因。这些基因被克隆和测序，然后进行同源性搜索和基因表达分析。在这项研究中，我们利用一个雌雄同源的物种来研究鱼类性别变化的机制。人工智能诱导了从女性到男性的性别转变。相反，AI和雌二醇-17b(E_2)联合使用并没有引起性别变化。通过体外组织培养，我们成功地在3-4周内将重建的完整卵巢组织诱导为有精子的成熟睾丸组织。据我们所知，这是脊椎动物首次从卵巢组织到完整的睾丸进行“体外性别转变”的证明。这种在实验上诱导这种变化的能力对未来脊椎动物性别决定和性别分化的研究具有重要意义。较少

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