MOLECULAR EVOLUTION OF A Y-CHROMOSOMAL REPETITIVE SEQUENCE FAMILY IN THE GENUS MUS

A 522-base-long Y-chromosomal sequence was isolated from a BALB/c geno mic library and was designated ''BF046.'' It is repeated about 200 tim es in the male genome, and a difference was detected between the Mus m usculus musculus and the M. m. domesticus type Y chromosomes. BF046-re lated sequences were present over the entire length of the Y chromosom e as visualized by in situ hybridization. Southern blot analysis again st DNAs isolated from eight species in the genus Mus showed that BF046 -related sequences were amplified in the Y chromosomes of three closel y related species: M. musculus, M. spicilegus, and M. spretus. To gain insight into the stability of the BF046 sequence family, we isolated 18 additional clones from these three mouse species and compared their sequences. The M. musculus sequences differed from the M. spicilegus and M. spretus sequences by two indels. The remaining parts of the seq uences were very similar, but both parsimony and distance-based analyt ical methods divided the sequences into the same four subgroups, with each species having its own subgroup(s). Thus, the Y chromosomes of M. musculus, M. spicilegus, and M. spretus can be distinguished from one another.