SEX-DEPENDENT MEIOTIC RECOMBINATION FREQUENCY IN THE TELOMERIC REGION OF MOUSE CHROMOSOME

利用PCR-SSCP方法，利用微卫星标记，在15号染色体远端[(B6^X_XMSM)_X MSM]N_2 （n=595）和[B6_X(B6^X_XMSM)]N_2 （n=325）两个亚种间回杂交板上，发现雄性的重组频率是雌性的10倍。这表明在该染色体区域存在着性别依赖的重组热点或冷点。为了研究这一区域是冷还是热，我们通过与BAC克隆进行物理制图，估算了微卫星标记d15mit40和D15Mit15在该区域的物理距离。由此产生的物理距离约为1兆碱基对。如前所述，遗传距离为0。在这些标记之间，雌性为17cM，雄性为5.23cM。将小鼠基因组每物理距离的平均重组频率与观察到的遗传距离进行比较，发现该区域雌性存在一个冷点，雄性存在一个热点。一些小鼠品系的杂交表明，重组频率的性别依赖性差异取决于所使用的品系。

We found that the male' s recombination frequency was as ten times much as the female' s one on the distal part of chromosome 15 by PCR-SSCP method with microsatellite markers on two intersubspecific backcross panels,[(B6^X_XMSM)_X MSM]N_2 (n=595) and [B6_X(B6^X_XMSM)]N_2 (n=325).This shows that a sex-dependent recombination hot or cold spot exists on this chromosome region. To investigate whether this spot is hot or cold, we estimated the physical distance between microsatellite markers, D15Mit40and D15Mit15, on this region by physical mapping with BAC clones. The resultant physical distance was about one mega-base pair. As previously reported the genetic distance was 0. 17cM in female and 5.23cM in male between these markers. A comparison of an average recombination frequency per physical distance on mouse genome with the observed genetic distances indicated that a cold spot exists in female, a hot one in male on this region. Several crosses of mouse strains suggested that this sex-dependent difference of recombination frequency depended on strains used.