TheD17Tu5 locus in thet complex: implications for the origin oft haplotypes and inbred strains

The mouse × Chinese hamster cell line R4 4-1 contains only one mouse chromosome, the bulk of which corresponds toMus musculus chromosomes 17 and 18 (MMU17 and MMU18, respectively). A genomic library was prepared from the R4 4-1 DNA, and a mouse clone was isolated from the library, which—with the help of somatic cell hybrids-could be mapped to the MMU17. A locus defined by a 2.7-kb longBam HI probe from this clone was designatedD17Tu5 (Tu for Tübingen). The locus proved to be polymorphic among inbred strains and wild mice. By testing of recombinant inbred strains and partialt haplotypes, theD17Tu5 locus could be mapped to a position between theD17Leh66E andD17Rp17 loci within thet complex. Two alleles were found at this locus,D17Tu5 ^a andD17Tu5 ^b , defined byTaq I restriction fragment length polymorphism. Both alleles are present among inbred strains and wild mice of the speciesM. domesticus. All completet haplotypes tested carry theD17Tu5 ^a allele and all tested wild mice of the speciesM. musculus, with the exception of those bearingt haplotypes, carry theD17Tu5 ^b allele. Additional alleles are found in some populations of wild mice and in other species of the genusMus. The distribution of the two alleles among the inbred strains correlates well with their known or postulated genealogy. Their distribution between the two species ofMus and among the mice withT haplotypes suggests a relatively recent origin of thet haplotypes.