Sex chromosome differentiation and the W- and Z-specific loci in Xenopus laevis.
Sex chromosome differentiation and the W- and Z-specific loci in Xenopus laevis.
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DOI：
10.1016/j.ydbio.2016.06.015
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发表时间：
2017-06
影响因子：
2.7
通讯作者：
Shuuji Mawaribuchi;Shuji Takahashi;Mikako Wada;Y. Uno;Y. Matsuda;M. Kondo;A. Fukui;N. Takamatsu;M. Taira;Michihiko Ito
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文献类型：
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作者：
Shuuji Mawaribuchi;Shuji Takahashi;Mikako Wada;Y. Uno;Y. Matsuda;M. Kondo;A. Fukui;N. Takamatsu;M. Taira;Michihiko Ito
脊椎动物的遗传性别决定系统包括两种基本类型的异配子体：XX（雌性）/XY（雄性）和ZZ（雄性）/ZW（雌性）类型。非洲爪蟾（Xenopus laevis）具有ZZ/ZW型性别决定系统。在这个物种中，我们以前确定了一个W-特异性性别（女性）决定基因，并指定了W和Z染色体，这可能是形态上无法区分的（同态）。除dmw基因外，我们最近还发现了两个基因，分别命名为scanwn和ccdc 69 w，以及一个基因，分别命名为capn 5，位于W和Z特异区域。在这项研究中，我们揭示了W/Z特异性位点和基因的详细结构。序列分析表明，在染色体2Lq 32 -33上的278 kb W特异性序列和83 kb Z特异性序列之间几乎没有序列相似性，这两个转座因子在染色体2Lq 32 -33上都很丰富。同线性和同源性分析表明，所有的W/Z特异性基因可能是独立出现的。表达分析表明，scanwandccdc 69 worcapn 5 z在早期分化的ZW性腺或睾丸中表达，从而分别暗示了在雌性或雄性发育中的可能作用。重要的是，性别决定基因（SDG）dmw可能是在异源四倍体化后产生的，从而表明新的性别决定系统是在物种杂交后建立的。此外，通过直接基因分型，我们证实了二倍体WW胚胎发育成正常的雌性青蛙，这表明Z特异性区域是不必要的雌性发育。总的来说，这些发现表明性染色体分化已经开始，尽管在X中还没有明显的异形性染色体。光滑。同源重组抑制可能促进了突变和转座因子的积累，并扩大了W/Z特异性区域，从而导致W/Z染色体的分化。
Genetic sex-determining systems in vertebrates include two basic types of heterogamety; XX (female)/XY (male) and ZZ (male)/ZW (female) types. The African clawed frogXenopus laevishas a ZZ/ZW-type sex-determining system. In this species, we previously identified a W-specific sex (female)-determining genedmw, and specified W and Z chromosomes, which could be morphologically indistinguishable (homomorphic). In addition todmw,we most recently discovered two genes, namedscanwandccdc69w, and one gene, namedcapn5zin the W- and Z-specific regions, respectively. In this study, we revealed the detail structures of the W/Z-specific loci and genes. Sequence analysis indicated that there is almost no sequence similarity between 278 kb W-specific and 83 kb Z-specific sequences on chromosome 2Lq32-33, where both the transposable elements are abundant. Synteny and phylogenic analyses indicated that all the W/Z-specific genes might have emerged independently. Expression analysis demonstrated thatscanwandccdc69worcapn5zare expressed in early differentiating ZW gonads or testes, thereby suggesting possible roles in female or male development, respectively. Importantly, the sex-determining gene (SDG)dmwmight have been generated after allotetraploidization, thereby indicating the construction of the new sex-determining system bydmwafter species hybridization. Furthermore, by direct genotyping, we confirmed that diploid WW embryos developed into normal female frogs, which indicate that the Z-specific region is not essential for female development. Overall, these findings indicate that sex chromosome differentiation has started, although no heteromorphic sex chromosomes are evident yet, inX. laevis. Homologous recombination suppression might have promoted the accumulation of mutations and transposable elements, and enlarged the W/Z-specific regions, thereby resulting in differentiation of the W/Z chromosomes.