Sex-chromosome pairing: evidence that the behavior of the pseudoautosomal region differs during male and female meiosis.
In humans, recombination in the pseudoautosomal region is approximately 10-fold higher in males than in females. This difference is thought to reflect the fact that, in females, there is opportunity for genetic exchange along the entire length of the X chromosome, resulting in a relative reduction in the likelihood of exchange in the pseudoautosomal region. In two instances in the laboratory mouse where X-chromosome pairing and exchange in females are limited to the pseudoautosomal region, a significant level of X-chromosome pairing failure was observed at diakinesis/metaphase I. Further analysis indicated that, in female meiosis, the inability of the X chromosome to consistently form a pairing configuration via the pseudoautosomal region alone is not a property of the pseudoautosomal region per se but is due to the fact that it resides on an X chromosome. Thus previously reported sex-linked differences in recombination rate in the pseudoautosomal region may actually reflect differences in pairing and/or recombination of the pseudoautosomal region on an X chromosome undergoing male versus female meiosis.
Hunt
P A
PA
Department of Pathology, Emory University, Atlanta, GA 30322.
LeMaire
R
R
D000818:Animals; D003433:Crosses, Genetic; D012734:Disorders of Sex Development / Q000235:genetics*; D005260:Female; D007621:Karyotyping; D008297:Male; D008540:Meiosis; D051379:Mice; D008810:Mice, Inbred C57BL; D011995:Recombination, Genetic; D012727:Sex Characteristics; D012729:Sex Chromosome Aberrations; D014960:X Chromosome / Q000502:physiology*; D014998:Y Chromosome / Q000502:physiology*