PDF(Pubmed)
Abstract：
Most vertebrates develop distinct females and males, where sex is determined by repeatedly evolved environmental or genetic triggers. Undifferentiated sex chromosomes and large genomes have caused major knowledge gaps in amphibians. Only a single master sex-determining gene, the dmrt1-paralogue (dm-w) of female-heterogametic clawed frogs (Xenopus; ZW♀/ZZ♂), is known across >8740 species of amphibians. In this study, by combining chromosome-scale female and male genomes of a non-model amphibian, the European green toad, Bufo(tes) viridis, with ddRAD- and whole genome pool-sequencing, we reveal a candidate master locus, governing a male-heterogametic system (XX♀/XY♂). Targeted sequencing across multiple taxa uncovered structural X/Y-variation in the 5\'-regulatory region of the gene bod1l, where a Y-specific non-coding RNA (ncRNA-Y), only expressed in males, suggests that this locus initiates sex-specific differentiation. Developmental transcriptomes and RNA in-situ hybridization show timely and spatially relevant sex-specific ncRNA-Y and bod1l-gene expression in primordial gonads. This coincided with differential H3K4me-methylation in pre-granulosa/pre-Sertoli cells, pointing to a specific mechanism of amphibian sex determination.
摘要：
大多数脊椎动物发育不同的雌性和雄性，性别是由反复进化的环境或遗传触发因素决定的。未分化的性染色体和大型基因组在两栖动物中引起了主要的知识空白。只有一个主性别决定基因，雌性异类爪蛙（非洲爪鱼；ZW‰/ZZ‰）的dmrt1-paralogue（dm-w），在>8740种两栖动物中已知。在这项研究中,通过结合非模型两栖动物的染色体尺度的女性和男性基因组，欧洲绿蟾蜍,Bufo(tes)viridis,使用ddRAD和全基因组池测序，我们揭示了一个候选的主基因座，管理男性-异型系统(XX‰/XY‰)。多个分类单元的靶向测序揭示了基因bod1l的5'-调控区的结构X/Y变异，其中Y特异性非编码RNA（ncRNA-Y），只在男性中表达，表明该基因座引发了性别特异性分化。发育转录组和RNA原位杂交显示原始性腺中及时和空间相关的性别特异性ncRNA-Y和bod1l基因表达。这与前颗粒细胞/前支持细胞中的差异H3K4me甲基化相吻合，指向两栖动物性别决定的特定机制。
