对日本稻米鱼(rice fish)所做的新的实验显示，fox13基因看来是决定一个生殖细胞究竟是变成卵子还是精子的转换器。该发现可帮助研究人员更多地了解脊椎动物生殖细胞的最终性别在发育中是如何决定的。Toshiya Nishimura和同事证明，fox13会给出一个分子暗示来阻止精子形成的启动;fox13会在稻米鱼生殖器官内的生殖细胞中表达，但却不会在生殖细胞周边的细胞中表达。当研究人员在有2个X染色体(雌性状态)的成年稻米鱼中将fox13破坏后，该雌鱼的卵巢内竟形成了精子。这些精子是有功能的，它们能正常地令卵子受精。这些结果表明，为了转变成精子，稻米鱼(可能也包括其他的脊椎动物)的生殖细胞无需处于雄性的生殖器官环境之中。

    原文链接：foxl3 is a germ cell-intrinsic factor involved in sperm-egg fate decision in medaka

    原文摘要：Sex determination is an essential step in the commitment of a germ cell to a sperm or egg. However, theintrinsic factors that determine the sexual fate of vertebrate germ cells are unknown. Here we show thatfoxl3, which is expressed in germ cells but not somatic cells in the gonad, is involved in sperm–egg fatedecision in medaka fish. Adult XX medaka with disrupted foxl3 developed functional sperm in the expandedgerminal epithelium of a histologically functional ovary. In chimeric medaka, mutant germ cells initiated spermatogenesis in female wild-type gonad. These results indicate that a germ cell–intrinsic cue for the sperm–egg fate decision is present in medaka and that spermatogenesis can proceed in a female gonadal environment.