DIFFERENT CHROMOSOMAL LOCALIZATION OF THE CLCN4 GENE IN MUS-SPRETUS AND C57BL 6J MICE/

We report the unprecedented finding of a gene with a different map pos ition in two mouse strains. The Clcn4 gene was found to map to the X c hromosome in the wild Mediterrean mouse, Mus spretus but to chromosome 7 in the inbred strain of laboratory mouse C57BL/6J. These data indic ate that a recent evolutionary rearrangement occurred on the mouse sex chromosomes, very close to the pseudoautosomal region, Our data provi de molecular evidence for a major divergence near the pseudoautosomal region, consistent with the hypothesis that hybrid sterility in these species results from abnormal pairing of sex chromosomes during male m eiosis.