Large (>10 kb), nearly identical (>99% nucleotide identity), palindromic sequences are enriched on mammalian sex chromosomes. Primate Y-palindromes undergo high rates of arm-to-arm gene conversion, a proposed mechanism for maintaining their sequence integrity in the absence of X–Y recombination. It is unclear whether X-palindromes, which can freely recombine in females, undergo arm-to-arm gene conversion and, if so, at what rate. We generated high-quality sequence assemblies of Mus molossinus and M. spretus X-palindromic regions and compared them with orthologous M. musculus X-palindromes. Our evolutionary sequence comparisons find evidence of X-palindrome arm-to-arm gene conversion at rates comparable to autosomal allelic gene conversion rates in mice. Mus X-palindromes also carry more derived than ancestral variants between species, suggesting that their sequence is rapidly diverging. We speculate that in addition to maintaining genes’ sequence integrity via sequence homogenization, palindrome arm-to-arm gene conversion may also facilitate rapid sequence divergence.

中文翻译：

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大型 X 连锁回文在 Mus 谱系中进行臂对臂基因转换。

大型 (>10 kb)、几乎相同 (>99% 核苷酸同一性)、回文序列在哺乳动物性染色体上富集。灵长类 Y 回文序列经历了很高的臂对臂基因转换率，这是一种在没有 X-Y 重组的情况下保持其序列完整性的拟议机制。目前尚不清楚可以在雌性体内自由重组的 X-回文串是否会进行臂对臂基因转换，如果是，以何种速率发生。我们生成了Mus molossinus和M. spretus X-回文区域的高质量序列组合，并将它们与直系同源M. musculus X-回文区域进行了比较。我们的进化序列比较发现了 X-回文臂对臂基因转换率与小鼠常染色体等位基因转换率相当的证据。Mus X-回文在物种之间也携带比祖先变种更多的衍生，这表明它们的序列正在迅速发散。我们推测，除了通过序列同质化来维持基因的序列完整性外，回文臂对臂基因转换也可能促进快速的序列分歧。