Nature Genetics：研究破译比目鱼——半滑舌鳎全基因组序列图谱

近日，我国水产科学研究院黄海水产研究所、深圳华大基因研究院、哥本哈根大学、德国维尔茨堡大学、法国农业科学研究院和新加坡国立大学等机构联合破译比目鱼——半滑舌鳎全基因组序列图谱。文章发表在2月2日的《Nature Genetics》期刊上。

硬骨鱼类基因组进化

研究揭示了半滑舌鳎性染色体起源机制和比目鱼底栖适应的分子机制，同时为后续半滑舌鳎的遗传改良、新品种培育奠定基础。

此外，研究人员还揭示了半滑舌鳎温度控制下的性别逆转现象的表观遗传调控机制，并发现了在这种表观遗传调控下的性别逆转的稳定遗传现象，该成果也同时在线发表于《基因组学研究》。

科研人员对半滑舌鳎雌雄鱼分别进行了高深度全基因组测序、从头组装和分析。通过性染色体在雌雄鱼基因组测序覆盖深度的不同，并结合高密度遗传连锁图谱，构建了Z染色体的精细图谱和对应的W染色体序列图谱。

对于遗传和环境因素是如何相互作用来决定性别，目前还知之甚少。研究人员发现正常雌鱼性逆转成伪雄鱼之后，全基因组的DNA甲基化模型几乎变得跟正常雄鱼一模一样。而且，性逆转后发生的甲基化改变，显著富集于跟性别决定通路有关的基因。另外，通过对亲本和子代样品进行比较，研究人员发现亲本伪雄鱼相对于雌鱼发生的甲基化改变，能够被后代继承，这可能解释了为什么伪雄鱼后代不需要温度诱导就能自然发生性逆转。

原文链接：

Whole-genome sequence of a flatfish provides insights into ZW sex chromosome evolution and adaptation to a benthic lifestyle

Genetic sex determination by W and Z chromosomes has developed independently in different groups of organisms. To better understand the evolution of sex chromosomes and the plasticity of sex-determination mechanisms, we sequenced the whole genomes of a male (ZZ) and a female (ZW) half-smooth tongue sole (Cynoglossus semilaevis). In addition to insights into adaptation to a benthic lifestyle, we find that the sex chromosomes of these fish are derived from the same ancestral vertebrate protochromosome as the avian W and Z chromosomes. Notably, the same gene on the Z chromosome, dmrt1, which is the male-determining gene in birds, showed convergent evolution of features that are compatible with a similar function in tongue sole. Comparison of the relatively young tongue sole sex chromosomes with those of mammals and birds identified events that occurred during the early phase of sex-chromosome evolution. Pertinent to the current debate about heterogametic sex-chromosome decay, we find that massive gene loss occurred in the wake of sex-chromosome 'birth'.