Supplementary Material for: Higher Intercellular Variation in Genome-Wide Recombination Rate in Female Mice

Meiotic recombination affects fertility, shuffles genomes, and modulates the effectiveness of natural selection. Despite conservation of the recombination pathway, the rate of recombination varies among individuals and along chromosomes. Recombination rate also differs among cells from the same organism, but this form of variation has received less attention. To identify patterns that characterize intercellular variation in the genome-wide recombination rate, we counted foci of the MLH1 recombination-associated protein in oocytes and spermatocytes from a panel of wild-derived inbred strains of house mice. Females show higher intercellular variation in MLH1 focus count than males from the same inbred strains. This pattern is consistent across strains from multiple subspecies, including 2 strains in which the average MLH1 focus count is higher in males. The sex difference in genome-wide recombination rate we report suggests that selection targeting recombination rate will be more efficient in males than in females.

减数分裂重组（Meiotic recombination）会影响生物体生育能力、重塑基因组结构，并调控自然选择的作用效率。尽管重组通路具有进化保守性，但重组速率在不同个体间以及染色体全长上均存在差异。同一生物体的不同细胞间重组速率亦存在差异，但此类细胞间变异的研究尚未得到足够重视。为阐明全基因组重组速率的细胞间变异特征，本研究对一组野生起源近交系小家鼠的卵母细胞与精母细胞中，与重组相关的MLH1蛋白灶点进行了计数。相较于同一近交系小鼠的雄性个体，雌性个体的MLH1灶点数量的细胞间变异程度更高。这一规律在多个亚种的近交系小鼠中均成立，其中包括2个品系的雄性平均MLH1灶点数量高于雌性的情况。本研究报道的全基因组重组速率性别差异表明，针对重组速率的自然选择在雄性个体中会更为高效。