Bikchurina Tatiana I, Tishakova Katerina V, Kizilova Elena A, Romanenko Svetlana A, Serdyukova Natalya A, Torgasheva Anna A, Borodin Pavel M
Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Department, Novosibirsk 630090, Russia.
Novosibirsk State University, Novosibirsk 630090, Russia.
Genes (Basel). 2018 Apr 25;9(5):227. doi: 10.3390/genes9050227.
Hybrid sterility is an important step in the speciation process. Hybrids between dwarf hamsters and provide a good model for studies in cytological and genetic mechanisms of hybrid sterility. Previous studies in hybrids detected multiple abnormalities of spermatogenesis and a high frequency of dissociation between the X and Y chromosomes at the meiotic prophase. In this study, we found that the autosomes of the hybrid males and females underwent paring and recombination as normally as their parental forms did. The male hybrids showed a significantly higher frequency of asynapsis and recombination failure between the heterochromatic arms of the X and Y chromosomes than the males of the parental species. Female hybrids as well as the females of the parental species demonstrated a high incidence of centromere misalignment at the XX bivalent and partial asynapsis of the ends of its heterochromatic arms. In all three karyotypes, recombination was completely suppressed in the heterochromatic arm of the X chromosome, where the pseudoautosomal region is located. We propose that this recombination pattern speeds up divergence of the X- and Y-linked pseudoautosomal regions between the parental species and results in their incompatibility in the male hybrids.
杂种不育是物种形成过程中的一个重要步骤。矮仓鼠之间的杂种为杂种不育的细胞学和遗传机制研究提供了一个良好的模型。先前对杂种的研究检测到精子发生的多种异常以及减数分裂前期X和Y染色体之间的高频解离。在本研究中，我们发现杂种雄性和雌性的常染色体与它们的亲本形式一样正常配对和重组。雄性杂种在X和Y染色体的异染色质臂之间出现联会异常和重组失败的频率明显高于亲本物种的雄性。雌性杂种以及亲本物种的雌性在XX二价体处显示出着丝粒错排的高发生率及其异染色质臂末端的部分联会异常。在所有三种核型中，位于假常染色体区域的X染色体异染色质臂中的重组被完全抑制。我们认为这种重组模式加速了亲本物种之间X和Y连锁假常染色体区域的分化，并导致它们在雄性杂种中不相容。
