雌性性别决定基因的筛选是国际鱼类遗传学领域的重要科学问题。半滑舌鳎是我国重要海水养殖鱼类，雌性比雄性生长快2-4倍，为ZW性别决定类型，ZW雌鱼可性反转为表型雄鱼，但ZZ雄鱼则难以性反转为表型雌鱼。因此，半滑舌鳎是筛选雌性性别决定基因的理想模型。本项目将在完成半滑舌鳎全基因组精细图谱并发现dmrt1基因为雄性决定基因的基础上，通过多层级基因组组装策略，绘制半滑舌鳎W性染色体精细图谱，揭示W染色体起源与进化机制，筛选W染色体特异基因；采用基因组编辑和转基因等技术研究雌性决定候选基因的功能，揭示其对雄鱼和雌鱼性别分化、性腺发育的影响机制；通过表观遗传学手段揭示甲基化对雌性决定基因表达及性腺分化的调控作用；最终揭示雌性性别决定与分化的分子机制；同时探索通过基因组编辑培育半滑舌鳎全雌苗种的新途径。本项目不仅对于鱼类雌性性别决定机制研究具有重要科学意义，而且对于半滑舌鳎全雌苗种培育具有重大应用价值。

The screening of female determination genes is a significant scientific issue in the research field of fish genetics. As an important mariculture fish in China, half-smooth tongue sole (Cynoglossus semilaevis) has ZW sex determination system and exhibits growth dimorphism, where females usually grow 2-4 times faster than males. Tongue sole is an ideal model for screening female determination genes because ZW fish can be sex-reversed to male, but ZZ fish is difficult to become females. Our previous study has deciphered the tongue sole genome and identified dmrt1 as the male determination gene. Based on these data, the project plan to construct the fine map of W chromosome via multi-level assembly strategy, in order to reveal its origin and evolution and screen W chromosome specific genes as female determination candidate genes; Subsequently, we will employ genome editing and transgenic technology to investigate the function of these genes, which would uncover the mechanism in sexual differentiation and gonadal development; Moreover, we will analyze the regulatory effect of methylation on gene expression and gonadal differentiation through epigenetic method. Through all these data, we will finally illustrate the molecular mechanism of female determination and differentiation. In the meanwhile, based on genome editing technology, we will also exploit new method to produce all female stock in the tongue sole. This project not only has great scientific significance for understanding female determination mechanism, but also has huge application potential for all-female fry breeding.