European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
Genome Biol. 2011;12(4):R36. doi: 10.1186/gb-2011-12-4-r36. Epub 2011 Apr 11.
When mismatches in heteroduplex DNA formed during meiotic recombination are left unrepaired, post-meiotic segregation of the two mismatched alleles occurs during the ensuing round of mitosis. This gives rise to somatic mosaicism in multicellular organisms and leads to unexpected allelic combinations among progeny. Despite its implications for inheritance, post-meiotic segregation has been studied at only a few loci.
By genotyping tens of thousands of genetic markers in yeast segregants and their clonal progeny, we analyzed post-meiotic segregation at a genome-wide scale. We show that post-meiotic segregation occurs in close to 10% of recombination events. Although the overall number of markers affected in a single meiosis is small, the rate of post-meiotic segregation is more than five orders of magnitude larger than the base substitution mutation rate. Post-meiotic segregation took place with equal relative frequency in crossovers and non-crossovers, and usually at the edges of gene conversion tracts. Furthermore, post-meiotic segregation tended to occur in markers that are isolated from other heterozygosities and preferentially at polymorphism types that are relatively uncommon in the yeast species.
Overall, our survey reveals the genome-wide characteristics of post-meiotic segregation. The results show that post-meiotic segregation is widespread in meiotic recombination and could be a significant determinant of allelic inheritance and allele frequencies at the population level.
在减数分裂重组过程中形成的异源双链 DNA 中的错配如果未被修复，两个错配等位基因在后一轮有丝分裂中就会发生减数后分离。这会导致多细胞生物中的体细 胞镶嵌现象，并导致后代中出现意想不到的等位基因组合。尽管它对遗传有影响，但减数后分离仅在少数几个基因座上进行了研究。
通过对酵母分离子及其克隆后代的数万种遗传标记进行基因分型，我们在全基因组范围内分析了减数后分离。我们表明，减数后分离发生在近 10%的重组事件中。尽管单个减数分裂中受影响的标记数量很少，但减数后分离的速率比碱基替换突变率大五个数量级以上。减数后分离在交叉和非交叉中以相等的相对频率发生，并且通常发生在基因转换区的边缘。此外，减数后分离倾向于发生在与其他杂合性隔离的标记中，并且优先发生在酵母种中相对罕见的多态性类型。
总的来说，我们的调查揭示了减数后分离的全基因组特征。结果表明，减数后分离在减数分裂重组中广泛存在，可能是等位基因遗传和群体水平等位基因频率的重要决定因素。
