PDF(Pubmed)
Abstract：
According to Mendel\'s second law, chromosomes segregate randomly in meiosis. Non-random segregation is primarily known for cases of selfish meiotic drive in females, in which particular alleles bias their own transmission into the oocyte. Here we report a rare example of unselfish meiotic drive for crossover inheritance in the clonal raider ant, Ooceraea biroi, in which both alleles are co-inherited at all loci across the entire genome. This species produces diploid offspring parthenogenetically via fusion of two haploid nuclei from the same meiosis. This process should cause rapid genotypic degeneration due to loss of heterozygosity, which results if crossover recombination is followed by random (Mendelian) segregation of chromosomes. However, by comparing whole genomes of mothers and daughters, we show that loss of heterozygosity is exceedingly rare, raising the possibility that crossovers are infrequent or absent in O. biroi meiosis. Using a combination of cytology and whole-genome sequencing, we show that crossover recombination is, in fact, common but that loss of heterozygosity is avoided because crossover products are faithfully co-inherited. This results from a programmed violation of Mendel\'s law of segregation, such that crossover products segregate together rather than randomly. This discovery highlights an extreme example of cellular \'memory\' of crossovers, which could be a common yet cryptic feature of chromosomal segregation.
摘要：
根据孟德尔第二定律,染色体在减数分裂中随机分离。非随机隔离主要用于女性的自私减数分裂驱动的情况，其中特定的等位基因偏向它们自己传递到卵母细胞中。在这里，我们报告了一个罕见的无私减数分裂驱动的例子，用于克隆掠夺者蚂蚁的交叉遗传，Ooceraeabiroi,其中两个等位基因在整个基因组的所有基因座上共同遗传。该物种通过融合来自同一减数分裂的两个单倍体核，孤雌生殖地产生二倍体后代。这个过程应该导致快速的基因型退化，由于杂合性的丧失，如果交叉重组之后是染色体的随机（孟德尔）分离，则会导致交叉重组。然而,通过比较母亲和女儿的整个基因组，我们表明杂合性的丢失是非常罕见的，增加了O.biroi减数分裂中不频繁或不存在交叉的可能性。结合细胞学和全基因组测序，我们证明交叉重组是，事实上,常见，但避免了杂合性的损失，因为交叉产物是忠实地共同遗传的。这是由于对孟德尔隔离定律的编程违反，这样交叉产品就会隔离在一起，而不是随机的。这一发现凸显了细胞“记忆”交叉的极端例子，这可能是染色体分离的一个常见但隐秘的特征。
