在鱼类性腺分化之前，未分化生殖细胞的增殖会促进雌性性腺的分化并阻碍雄性特征的维持。在前期研究中，我们建立了特异性标记生殖谱系细胞转基因斑马鱼品系Tg(piwil1:EGFP-3UTRnos3)。利用该品系对未分化性腺中的发育进行追踪观察后发现：未分化生殖细胞较多有利于卵子发生，而未分化生殖细胞较少有利于精子发生。Elovl2基因的突变导致斑马鱼雄性化。进一步我们发现elovl2突变体的未分化生殖细胞数目显著减少，并可能影响未分化生殖细胞的增殖。申报项目拟在此基础上，以Tg(piwil1:EGFP-3UTRnos3)转基因斑马鱼和elovl2突变体为工具，利用影像学、转录组分析、生殖细胞靶向敲除及靶向过表达等技术描述未分化生殖细胞的增殖过程，挖掘和鉴定生殖细胞增殖相关因子，并力图揭示这些因子调控原始生殖细胞增殖的分子机制。

Before gonad differentiation in fish, the high proliferating of germ cells promotes feminization while prohibits masculinization. In our previous study, we generated a transgenic line named Tg(piwil1:EGFP-3UTRnos3) which specifically labels germline lineage. Using this fish, we traced the early development of primitive gonad. It was found that the primitive gonad with extensive germ cells facilitates oogenesis, while one with relatively less germ cells facilitates spermatogenesis. In addition, the mutation of elovl2 led to masculinization. We further observed that the number of undifferentiated germ cell was significantly decreased in elovl2 mutant which might be due to the inhibition of proliferation of undifferentiated germ cell. In this proposal, using Tg(piwil1:EGFP-3UTRnos3) and elovl2 mutant as tools, we will characterize the proliferation of undifferentiated germ cell and identify regulating factors involved in this process by using combination of techniques including imaging, omics and germ cell targeted knock-out and over-expression. By doing these, we intend to reveal roles of those factors in germ-cell proliferation.