Study On The Correlation Between Polymorphism Of The SNP Site Of Callipyge Gene And Five Microsatellite Loci With The Hindquarter Development In Meat Sheep

This study focused on the influence of the SNP site of Callipyge gene (CLPG) on the development in meat sheep hindquarter by varied methods of molecular genetic marker in order to have a better reasonable selection and new variety breeding of sheep. In this study, Poll Dorset, Suffolk adult rams were selected as the test material, from which jugular vein was collected to extract genomic DNA, and measured the hindquarter width and hip circumference on the spot.1. Experiment 1: Five microsatellite loci (OY3, MCMA26, UWCA4, TGLA122, BM3413) possiblely related with SNPCLPG were selected and analyzed on the Genetic variation (gene frequency, heterozygosity, PIC and effective numbers of alleles). The results showed that the five microsatellite loci had polymorphisms both in group of Poll Dorset and Suffolk sheep; the numbers of alleles were more than 8. Based on the correlation analysis of five different genotypes and hindquarter width ,hip circumference in Poll Dorset and Suffolk sheep, it was found that different genotypes of microsatellite OY3, MCMA26, UWCA4 had significant effects on hindquarter development of Suffolk sheep (P <0.05), and different genotypes of microsatellite OY3, MCMA26, UWCA4, TGLA122, BM3413 had significant effects on hindquarter development of Poll Dorset sheep (P <0.05). Meanwhile, some alleles related with hindquarter development of Poll Dorset and Suffolk closely were detected. The results preliminary showed that there was a linkage relationship between the selected microsatellite markers loci and hindquarter development of sheep; these markers perhaps have some efforts during assisted selection and earlier breeding in practice.2. Experiment 2: Single nucleotide polymorphisms (SNPs) of CLPG was analyzed by PCR-SSCP in Poll Dorset and Suffolk sheep, and thereby studied the effect of this SNP on hindquarter development. The results showed that, a polymorphism was detected in the SNP site of CLPG and three genotypes (AA, AB and BB) were observed both in Poll Dorset and Suffolk sheep. Compared with genotype AA, the mutation of G-A at amplified fragment 118 of genotype BB was identified by sequencing. In the group of Poll Dorset, the frequencies of genotypes AA, AB and BB were 0.7391, 0.2174 and 0.0435 respectively; and in the group of Suffolk, the frequencies of genotypes AA, AB and BB were 0.6667, 0.2667 and 0.0666 respectively. The least square mean of hindquarter width and hip circumference in Poll Dorset and Suffolk sheep by correlation analysis showed that no matter in group Poll Dorset or in group Suffolk, there was significant difference between genotype AB and genotype AA (P<0.05); a significant difference between genotype BB and AA was also detected (P<0.05). These results demonstrated that the SNP site of Callipyge gene to affect hindquarter development of sheep is notable , may be a QTL linked closely with CLPG.3. Experiment 3: the SNP site of Callipyge gene in Poll Dorset and Suffolk sheep was studied by PCR-RFLP . The results showed that, a polymorphism was detected in the SNP site of CLPG gene and three genotypes (AA, AB and BB) were observed both in Poll Dorset and Suffolk sheep. Compared with genotype AA, the mutation of C-T at amplified fragment 62 of genotype BB was identified by sequencing. In the group of Poll Dorset, the frequencies of genotypes AA, AB and BB were 0.7391, 0.2174 and 0.0435 respectively; and in the group of Suffolk, the frequencies of genotypes AA, AB and BB were 0.6000, 0.3333 and 0.0667 respectively. Based on correlation analysis, the least square mean of hindquarter width and hip circumference was greatest for BB, followed by AB and AA genotypes. The results indicated that the SNP site of Callipyge gene allele B may be correlated with the hindquarter development positively.