Zhang Na, Xu Fei, Guo Ximing
National & Local Joint Engineering Laboratory of Ecological Mariculture, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong 266071, China Haskin Shellfish Research Laboratory, Institute of Marine and Coastal Sciences, Rutgers University, Port Norris, New Jersey 08349 University of Chinese Academy of Sciences, Beijing 100049, China.
National & Local Joint Engineering Laboratory of Ecological Mariculture, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong 266071, China.
G3 (Bethesda). 2014 Sep 11;4(11):2207-17. doi: 10.1534/g3.114.013904.
Despite the prevalence of sex in animal kingdom, we have only limited understanding of how sex is determined and evolved in many taxa. The mollusc Pacific oyster Crassostrea gigas exhibits complex modes of sexual reproduction that consists of protandric dioecy, sex change, and occasional hermaphroditism. This complex system is controlled by both environmental and genetic factors through unknown molecular mechanisms. In this study, we investigated genes related to sex-determining pathways in C. gigas through transcriptome sequencing and analysis of female and male gonads. Our analysis identified or confirmed novel homologs in the oyster of key sex-determining genes (SoxH or Sry-like and FoxL2) that were thought to be vertebrate-specific. Their expression profile in C. gigas is consistent with conserved roles in sex determination, under a proposed model where a novel testis-determining CgSoxH may serve as a primary regulator, directly or indirectly interacting with a testis-promoting CgDsx and an ovary-promoting CgFoxL2. Our findings plus previous results suggest that key vertebrate sex-determining genes such as Sry and FoxL2 may not be inventions of vertebrates. The presence of such genes in a mollusc with expression profiles consistent with expected roles in sex determination suggest that sex determination may be deeply conserved in animals, despite rapid evolution of the regulatory pathways that in C. gigas may involve both genetic and environmental factors.
尽管有性生殖在动物界普遍存在，但我们对许多分类群中性别是如何决定和进化的了解仍然有限。软体动物太平洋牡蛎（Crassostrea gigas）表现出复杂的有性生殖模式，包括雄性先熟雌雄异体、性别转变以及偶尔的雌雄同体现象。这个复杂的系统受到环境和遗传因素的控制，但其分子机制尚不清楚。在本研究中，我们通过对雌性和雄性性腺进行转录组测序和分析，研究了与太平洋牡蛎性别决定途径相关的基因。我们的分析鉴定或确认了关键性别决定基因（SoxH或Sry样基因以及FoxL2）在牡蛎中的新同源物，这些基因曾被认为是脊椎动物特有的。在一个提出的模型中，新的睾丸决定基因CgSoxH可能作为主要调节因子，直接或间接与促进睾丸发育的CgDsx和促进卵巢发育的CgFoxL2相互作用，它们在太平洋牡蛎中的表达谱与性别决定中的保守作用一致。我们的研究结果以及之前的结果表明，诸如Sry和FoxL2等关键脊椎动物性别决定基因可能并非脊椎动物所特有。这些基因在一种软体动物中的存在，且其表达谱与性别决定中的预期作用一致，这表明尽管调控途径在快速进化，在太平洋牡蛎中可能涉及遗传和环境因素，但性别决定在动物中可能是高度保守的。
