Comparison of mouse Y-chromosomal repetitive sequences isolated from Mus musculus, M. spicilegus, and M. spretus.

The mouse Y chromosome is rich in repetitive sequences. We describe a new highly male-specific BALB/c mouse sequence named 142-5. The distribution of 142-5 related sequences, which appeared to be repeated at least 100 times in the male genome of Mus musculus, was visualized on the Y chromosome by in situ hybridization. Their accumulation patterns in the genus Mus showed that the sequences evolved quickly and suggested that they might prove useful for detecting genetic differences between closely related species. To test this hypothesis, we isolated 20 additional sequences from three mouse species (M. musculus, M. spicilegus, and M. spretus) and compared their nucleotide sequences using three different computer programs. It was found that the sequences were remarkably similar but could be divided into four subgroups, and that each species had a distinct set or sets of sequences that were amplified in the Y chromosome.