t-Specific DNA polymorphisms among wild mice from Israel and Spain.

Lehrach and his coworkers have isolated a series of DNA probes that specifically hybridize with different regions of mouse chromosome 17 within the t complex. The probes display restriction fragment length polymorphisms, RFLPs, which are specific for the t haplotypes in all laboratory mouse strains tested thus far. Some of these probes have been used to test wild mice populations for these t-associated DNA forms. It is demonstrated that populations from Germany, Switzerland, Italy, Greece, Yugoslavia, Australia, Costa Rica, and Venezuela contain chromosomes in which all the tested DNA loci display the t-specific polymorphisms. The frequency of mice carrying these chromosomes is as high as 31%. Wild mice from Israel and Spain, on the other hand, carry chromosomes displaying t-specific DNA forms only at one or two of the probed loci, while the other loci carry the wild-type (+) forms. These chromosomes thus resemble the partial t haplotypes known from the study of laboratory mice. One possible interpretation of these findings is that these DNA polymorphisms contributed to the assembly of the complete t haplotypes and that these haplotypes may have originated in the Middle East.