Recent evolution of mouse t haplotypes at polymorphic microsatellites associated with the t complex responder (Tcr) locus

Abstract

Microsatellites closely associated with each member of the Tcp10 gene family were amplified simultaneously from t haplotype and wild-type forms of mouse chromosome 17, by PCR. The t complex responder (Tcr) locus, which plays a central role in transmission ratio distortion, maps within the Tcp10 cluster on the t haplotype. Thus the amplified set of microsatellite loci (referred to collectively as Tcp10ms) provides a direct marker for this central component of the meiotic drive system associated with all naturally occurring t haplotypes. A unique Tcp10ms pattern of microsatellite alleles was obtained for a number of independent, laboratory-maintained complete and partial t haplotypes. Independent t chromosomes found in wild mice from US populations also had unique patterns, even when they were classified within the same lethal complementation group. Wild and laboratory chromosomes in the tw5 group showed similarly-sized but non-identical Tcp10ms patterns, suggesting they share a recent common ancestor. These chromosomes are likely to have derived from an ancestral chromosome within the founding population of North American house mice. The Tcp10ms pattern was also shown to be useful in field studies for distinguishing among independent t haplotypes, when more than one is present within a single population.