Meiotic pairing and double-strand break formation along the heteromorphic threespine stickleback sex chromosomes
Meiotic pairing and double-strand break formation along the heteromorphic threespine stickleback sex chromosomes
复制标题
异形三刺刺鱼性染色体减数分裂配对和双链断裂形成
DOI：
10.1007/s10577-022-09699-0
复制
发表时间：
2022
影响因子：
2.6
通讯作者：
White, Michael A.
中科院分区：
文献类型：
--
作者：
Nath, Shivangi;Welch, Lucille A.;Flanagan, Mary K.;White, Michael A.
减数分裂期间的双链断裂修复通常使用同源染色体作为修复模板来实现。异形性染色体的序列同源性很小，对双链断裂的修复提出了独特的挑战。我们对异形性染色体在减数分裂过程中的行为的理解一直集中在古老的性染色体上，其中X和Y在整体结构和基因内容上有显着差异。目前还不清楚最近进化的性染色体如何彼此配对并形成双链断裂。一种可能性是配对的障碍迅速演变。或者，最近进化的性染色体可能表现出配对和双链断裂修复，更接近于它们的常染色体祖先。在这里，我们使用最近进化的X和Y染色体的threespine棘鱼（Gasterosteus aculeatus）研究模式的配对和双链断裂形成的分子细胞遗传学。我们发现三棘鱼的性染色体并不完全在假常染色体区域配对。相反，染色体以非同源的方式完全配对。为了实现这一点，X染色体在粗线期进行突触调整，以匹配Y染色体的轴长。双链断裂的形成和修复率也与常染色体相匹配。我们的研究结果强调，最近进化的性染色体表现出减数分裂行为，这让人想起常染色体，并主张进一步的工作，以确定用于修复X和Y染色体上的双链断裂的同源模板。
Double-strand break repair during meiosis is normally achieved using the homologous chromosome as a repair template. Heteromorphic sex chromosomes share little sequence homology, presenting unique challenges to the repair of double-strand breaks. Our understanding of how heteromorphic sex chromosomes behave during meiosis has been focused on ancient sex chromosomes, where the X and Y differ markedly in overall structure and gene content. It remains unclear how more recently evolved sex chromosomes that share considerably more sequence homology with one another pair and form double-strand breaks. One possibility is barriers to pairing evolve rapidly. Alternatively, recently evolved sex chromosomes may exhibit pairing and double-strand break repair that more closely resembles that of their autosomal ancestors. Here, we use the recently evolved X and Y chromosomes of the threespine stickleback fish (Gasterosteus aculeatus) to study patterns of pairing and double-stranded break formation using molecular cytogenetics. We found that the sex chromosomes of threespine stickleback fish did not pair exclusively in the pseudoautosomal region. Instead, the chromosomes fully paired in a non-homologous fashion. To achieve this, the X chromosome underwent synaptic adjustment during pachytene to match the axis length of the Y chromosome. Double-strand break formation and repair rate also matched that of the autosomes. Our results highlight that recently evolved sex chromosomes exhibit meiotic behavior that is reminiscent of autosomes and argues for further work to identify the homologous templates that are used to repair double-strand breaks on the X and Y chromosomes.