Hoge Carla, de Manuel Marc, Mahgoub Mohamed, Okami Naima, Fuller Zachary, Banerjee Shreya, Baker Zachary, McNulty Morgan, Andolfatto Peter, Macfarlan Todd S, Schumer Molly, Tzika Athanasia C, Przeworski Molly
Dept. of Biological Sciences, Columbia University.
The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health.
bioRxiv. 2023 Jul 11:2023.07.11.548536. doi: 10.1101/2023.07.11.548536.
In vertebrates, there are two known mechanisms by which meiotic recombination is directed to the genome: in humans, mice, and other mammals, recombination occurs almost exclusively where the protein PRDM9 binds, while in species lacking an intact , such as birds and canids, recombination rates are elevated near promoter-like features. To test if PRDM9 also directs recombination in non-mammalian vertebrates, we focused on an exemplar species, the corn snake (). Unlike birds, this species possesses a single, intact ortholog. By inferring historical recombination rates along the genome from patterns of linkage disequilibrium and identifying crossovers in pedigrees, we found that PRDM9 specifies the location of recombination events outside of mammals. However, we also detected an independent effect of promoter-like features on recombination, which is more pronounced on macro- than microchromosomes. Thus, our findings reveal that the uses of PRDM9 and promoter-like features are not mutually-exclusive, and instead reflect a tug of war, which varies in strength along the genome and is more lopsided in some species than others.
在脊椎动物中，已知有两种机制可将减数分裂重组导向基因组：在人类、小鼠和其他哺乳动物中，重组几乎只发生在蛋白质PRDM9结合的位置，而在缺乏完整[相关内容未明确]的物种中，如鸟类和犬科动物，重组率在类似启动子的特征附近会升高。为了测试PRDM9是否也能在非哺乳动物脊椎动物中指导重组，我们聚焦于一个典型物种——玉米蛇（）。与鸟类不同，该物种拥有一个完整的[相关内容未明确]直系同源基因。通过从连锁不平衡模式推断基因组上的历史重组率，并在谱系中识别交叉，我们发现PRDM9确定了哺乳动物以外的重组事件位置。然而，我们也检测到类似启动子的特征对重组有独立影响，这种影响在宏观染色体上比在微观染色体上更明显。因此，我们的研究结果表明，PRDM9和类似启动子特征的作用并非相互排斥，而是反映了一场拉锯战，其强度在基因组上各不相同，在某些物种中比其他物种更不平衡。
