Genetic mapping of 10 microsatellites in the t complex region of mouse chromosome 17.

Abstract

A complete t haplotype consists of four large non-overlapping inversions of mouse Chromosome (Chr) 17 with respect to the wild-type homolog and is naturally occurring in wild mouse populations by recombination suppression and transmission ratio distortion (Silver et al. 1992). This t complex includes the major histocompatibility complex (H2), the loci of Brachyury (T) and tufted (tf), as well as several lethal mutations like tclw5 and tcl12 (Hamvas et al. 1997). The tclw5 mutation is an early acting embryonic lethal, recombinationally inseparable from H2-K (Shin et al. 1984). In an attempt to positionally clone tclw5, contigs of cosmids have been made, 18 genes have been identified, and a detailed description of the region is now available (Abe et al. 1988; Yeom et al. 1992; Lai et al. 1994). Unfortunately, the restricted polymorphism of probes and the size of the region to explore have made the approach particularly tedious. When the first microsatellites (Mits) became available (Dietrich et al. 1994), they proved to be extremely useful for our linkage analysis project: we refined the mapping of 12 Mits, using our panel of 140 t/t recombinants and narrowed down the genetic region containing tclw5 (Vernet and Artzt 1995). In the present report, using the same panel, we have refined the location of 10 new satellites from the second release of microsatellites and define now a new genetic limit to tclw5. Mit primer pairs for the polymerase chain reaction (PCR) were purchased from Research Genetics (Huntsville, Ala.); isolated DNA from recombinant mice was amplified under conditions described by Dietrich and co-workers (1994). Amplified bands were resolved on 6% denaturating polyacrylamide electrophoresis gels. Figure 1 shows a summary of the Mit map and the number of recombinants between each locus. The t recombinant crosses were able to separate several markers that previously were considered to be in the same bin. Additionally, D17Mit147 is the new telomeric limit for the region where tclw5 is located.