Genetic mechanism in hybrid sterility of the mouse

我们在1992年的初步研究中观察到，不育（C57 BL/6 × Spretus）F_1雄性在第一次减数分裂中期（MI）出现了高频率的X-Y分离（X//Y），在回交后代中，X//Y性状分离为一个单基因，与X染色体上的一个远端位点Amg连锁。为了研究假常染色体区域（PAR）在X-Y配对和雄性育性中的作用，我们产生了在C57 BL/6（B6）背景上携带spretus PAR或在spretus宿主上携带B6 PAR的匡威的同源系。无论是高X//Y和小睾丸大小或低X//Y和大睾丸大小的后代分离几乎1：1，其双峰分布与远侧X染色体标记TeloXY的分离完全相关。此外，在雄性与雌性交配的后代中，也发现了低X//Y和PAR型纯合的可育后代。这一结果表明，PAR的遗传分化是 ...更多信息 在（B6 × M.macedonicus）F_1雄性中，精子发生在初级精母细胞的早期被阻滞，没有观察到任何第一次减数分裂中期。为了研究杂种雄性不育的遗传机制，我们研究了C57 BL/10与可育F1雌性杂交的回交雄性的X-Y解离和不育性。结果表明，该群体的后代可分为三种类型：无MI且精巢小的后代、高X-Y分离且精巢小的后代和低X-Y分离且精巢大的后代。用主要卫星DNA探针（pMR 196）对80个（B6 × M.spretus）F_1 × M.spretus和70个（B6 × M.spretus）F_1 × B6后代的染色体分离进行了FISH分析。结果表明，种间杂种F_1的减数分裂过程中，不存在对随机分配的初步偏离，因为190个配对比较几乎都没有偏离预期，而且相似的（C57 BL/6 × M.spretus）杂种F_1的正反交回交后代中，相同染色体的偏离模式也不一致。少

In our initial sutdies (1992) we observed high frequency of X-Y dissociation (X//Y) at first meiotic metaphase (MI) in sterile (C57BL/6 X M.spretus) F_1 males, and that in the backcross progeny the X//Y trait segregated as a single gene which was linked to a distal locus on the X chromosome, Amg. To examine the role of pseudoautosomal region (PAR) in X-Y pairing and male feritility we produced congenic lines that carried the spretus PAR on the C57BL/6 (B6) background or the converse of B6 PAR onto the spretus host. The progeny with either high X//Y and small testis size or low X//Y and large testis size segregated almost 1 : 1 in each succeeding backcross generation, and the bimodal distribution was completely correlated with the segregation of the distal X chromosome gene marker, TeloXY.Furthermore, fertile progeny with low X//Y and homozygous PAR-type were found in mating M.spretus males with female miece of the congenic line, this result showing that the genetic divergence of PAR is … More a major contribution to the male sterility observed in interspecific hybrid males.Spermatogenesis is arrested in earlier stage of primary spermatocytes and any first meiotic metaphase are not observed in (B6 X M.macedonicus) F_1 males. To examine genetic mechanism of male sterility in the hybrid, we examined X-Y dissociation and sterility in backcross males from fertile F1 females crossed with C57BL/10. Three types of progeny were found as follows : progeny with no MI and small testis size, high X-Y dissociation and small testis size, and low X-Y dissociation and large testis size. This result indicates that there are one or two autosomal factors, which controls hybrid sterility, in addition to the pseudoautosomal region.Chromosomal segregation was analyzed in 80 (B6 X M.spretus) F_1 X M.spretus progeny and 70 (B6 X M.spretus) F_1 X B6 progeny using FISH analysis with a major satellite DNA probe (pMR196). The results suggested that there was not primary deviation from random assortment during meiosis in the interspecific hybrid female, because nearly all of the 190 pair-wise comparisons did not deviate from expected and because there was no consistent pattern of deviation of the same chromosomes in the reciprocal backcross progeny from similar (C57BL/6 X M.spretus) F_1 hybrid females. Less