[Relationship between microsatellite DNA polymorphism and hind-quarter development in sheep chromosome 18]

Ten highly polymorphic microsatellite loci possibly linked to or correlated with the Callipyge gene were selected, according to the genetic map and linkage map of sheep chromosome 18. They were ILSTS54, TGLA337, HH47, TGLA122, BP33, OB2, BM3413, MCM38, MCMA26 and CSSM18. Polymorphisms of these microsatellites were detected in 61 Dorset (male) x Xinjiang fine wool sheep (female) samples and 76 Suffolk (male) x Xinjiang fine wool sheep (female) samples. Results showed that the number of alleles for the 10 microsatellite loci, heterozygosity and PIC (polymorphism information content) in the Dorset population were 8-16, 0.8370-0.9252, and 0.8221-0.9167, respectively. The same parameters in the Suffolk population were 5-10, 0.7603-0.8913 and 0.7176-0.8809, respectively. The effect of these loci on hindquarter width was analyzed in a generalized linear model. Results showed that, in the Dorset group, BM3413, MCMA26 and CSSM18 each had a significant effect on hindquarter width (P<0.05), while the other seven loci had no effect on it (P>0.05). In the Suffolk group, TGLA122, BM3413, MCM38 and CSSM18 had a significant effect on hindquarter width (P<0.05), while the other six loci did not (P>0.05). Our results also indicated that the cause of hindquarters hypertrophy in Xinjiang meat sheep may be different from the A-to-G mutation between the region of DLK1 and GTL2 . There may be other genes or QTL (quantitative trait loci) that affect hindquarter muscle development on chromosome 18 in Xinjiang meat sheep.