Institute for Applied Ecology, University of Canberra, Bruce, ACT 2617, Australia.
Australian National Wildlife Collection, Commonwealth Scientific and Industrial Research Organisation, Crace, ACT 2911, Australia.
Proc Natl Acad Sci U S A. 2022 Jan 25;119(4). doi: 10.1073/pnas.2116475119.
has female heterogamety (ZZ/ZW), but the master sex-determining gene is unknown, as it is for all reptiles. We show that (Nuclear Receptor Subfamily 5 Group A Member 1), a gene that is essential in mammalian sex determination, has alleles on the Z and W chromosomes (Z- and W-), which are both expressed and can recombine. Three transcript isoforms of Z- were detected in gonads of adult ZZ males, two of which encode a functional protein. However, ZW females produced 16 isoforms, most of which contained premature stop codons. The array of transcripts produced by the W-borne allele (W-) is likely to produce truncated polypeptides that contain a structurally normal DNA-binding domain and could act as a competitive inhibitor to the full-length intact protein. We hypothesize that an altered configuration of the W chromosome affects the conformation of the primary transcript generating inhibitory W-borne isoforms that suppress testis determination. Under this hypothesis, the genetic sex determination (GSD) system of is a W-borne dominant female-determining gene that may be controlled epigenetically.
（）具有雌性异配性（ZZ/ZW），但主要的性别决定基因与所有爬行动物一样尚不清楚。我们发现，（核受体亚家族 5 组 A 成员 1），一种在哺乳动物性别决定中必不可少的基因，在 Z 染色体和 W 染色体上都有等位基因（Z-和 W-），这两个等位基因都可以表达和重组。在成年 ZZ 雄性的性腺中检测到了 Z-的三种转录本异构体，其中两种编码具有功能的蛋白质。然而，ZW 雌性产生了 16 种异构体，其中大多数含有提前终止密码子。由 W 染色体携带的等位基因（W-）产生的转录本阵列可能产生截短的多肽，这些多肽含有结构正常的 DNA 结合域，并可能作为全长完整蛋白的竞争性抑制剂。我们假设 W 染色体的结构改变会影响初级转录本的构象，从而产生抑制睾丸决定的抑制性 W 染色体携带的异构体。根据这一假设，（）的遗传性别决定（GSD）系统是一个 W 染色体携带的显性雌性决定基因，可能受到表观遗传控制。
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