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

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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.