在蟒和蚺中发现 XY 性染色体。

The Discovery of XY Sex Chromosomes in a Boa and Python.

机构信息

Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA; Bell Museum of Natural History, University of Minnesota, St. Paul, MN 55108, USA.

Department of Biology, University of Texas at Arlington, Arlington, TX 76019, USA.

出版信息

Curr Biol. 2017 Jul 24;27(14):2148-2153.e4. doi: 10.1016/j.cub.2017.06.010. Epub 2017 Jul 6.

DOI:10.1016/j.cub.2017.06.010

PMID:28690112

Abstract

For over 50 years, biologists have accepted that all extant snakes share the same ZW sex chromosomes derived from a common ancestor [1-3], with different species exhibiting sex chromosomes at varying stages of differentiation. Accordingly, snakes have been a well-studied model for sex chromosome evolution in animals [1, 4]. A review of the literature, however, reveals no compelling support that boas and pythons possess ZW sex chromosomes [2, 5]. Furthermore, phylogenetic patterns of facultative parthenogenesis in snakes and a sex-linked color mutation in the ball python (Python regius) are best explained by boas and pythons possessing an XY sex chromosome system [6, 7]. Here we demonstrate that a boa (Boa imperator) and python (Python bivittatus) indeed possess XY sex chromosomes, based on the discovery of male-specific genetic markers in both species. We use these markers, along with transcriptomic and genomic data, to identify distinct sex chromosomes in boas and pythons, demonstrating that XY systems evolved independently in each lineage. This discovery highlights the dynamic evolution of vertebrate sex chromosomes and further enhances the value of snakes as a model for studying sex chromosome evolution.

摘要

50 多年来，生物学家一直认为，所有现存的蛇类都拥有相同的 ZW 性染色体，这些性染色体源自一个共同的祖先[1-3]，不同的物种表现出不同分化阶段的性染色体。因此，蛇类一直是动物性染色体进化的一个很好的研究模型[1,4]。然而，对文献的综述并没有令人信服地支持蟒和蚺类具有 ZW 性染色体[2,5]。此外，蛇类的兼性孤雌生殖的系统发生模式和球蟒（Python regius）的性连锁颜色突变，最好用蟒和蚺类具有 XY 性染色体系统来解释[6,7]。在这里，我们通过在这两个物种中发现雄性特异性遗传标记，证明了蟒和蚺确实具有 XY 性染色体。我们使用这些标记，以及转录组和基因组数据，在蟒和蚺中鉴定出了不同的性染色体，证明了 XY 系统在每个谱系中独立进化。这一发现突显了脊椎动物性染色体的动态进化，并进一步提高了蛇类作为研究性染色体进化模型的价值。