Studies On Candidate Genes BMPR-IA,BMP15 And GDF9 For High Prolificacy Of Small Tail Han Sheep

Based on the genetic polymorphism of BMPR-IA, BMP15 and GDF9 genes, respectively, I tried to link these candidate genes with the high productivity of Small Tail Han sheep, to provide scientific evidence for the basic genetic research on high productivity of Small Tail Han sheep.Single nucleotide polymorphism(SNP) of BMPR-IA gene was detected in both high fecundity sheep breeds (Small Tail Han and Hu sheep, respectively) and low fecundity sheep breeds (Dorset, Texel and German Mutton Merino sheep, respectively) by PCR-SSCP. The results indicated that both AA and AB genotypes were detected in Small Tail Han sheep. BB genotype was only detected in Hu sheep. AA genotype was found in Dorset, Texel and German Mutton Merino sheep, respectively. In Small Tail Han sheep, frequency of A-allele was 0.964 and frequency of B-allele was 0.036. The sequencing results showed that BB genotype had six single nucleotide mutations as compared with AA genotype. The BMPR-IA genotype distributions were significantly different (P<0.01) between Hu sheep and Small Tail Han sheep. The BMPR-IA genotype distributions were significantly different (P<0.01) between Hu sheep and low fecundity sheep breeds. The BMPR-IA genotype distributions were not different (P>0.05) between Small Tail Han sheep and low fecundity sheep breeds. The ewes with genotype AB had 0.15 (P>0.05) lambs more than those with genotype AA in Small Tail Han sheep. The chi-sequare test (x2) showed that fragment amplified by primer P3 was in a state of Hardy-Weinberg Equilibrium (HWE). These results showed that BMPR-IA gene may not be a major gene for high fecundity of Small Tail Han sheep, but may likely be a major gene for high fecundity of Hu sheep.Restriction fragment length polymorphism (RFLP) of BMP 15 and GDF9 gene were detected by PCR-RFLP. The results showed that the G8 mutation (C—T) of GDF9 gene and the B4 mutation (G-*-T) of BMP 15 gene were absent in the five sheep breeds. There was the same B2 mutation (C—*T) of BMP 15 gene in Small Tail Han sheep so also in Belclare and Cambridge ewes, respectively. The same B2 mutation was lacking in the other four sheep breeds. Concerning the B2 mutation of BMP 15 gene, AA and AB genotypes were detected in Small Tail Han sheep, frequency of A-allele was 0.734 and frequency of B-allele was 0.266. The BMP 15 B2 genotype distributions were significantly different (PO.01) between Small Tail Han sheep and the other four sheep breeds. The ewes with heterozygous mutant AB had 0.62 (P<0. 01) lambs more than those with wild homozygous type AA in Small Tail Han sheep. The chi-sequare test (x2) showed that fragment amplified by primer P6 of Hu, Dorset, Texel and German Mutton Merino sheep, respectively were in a state of Hardy-Weinberg Equilibrium.But the fragment amplified by primer P6 of Small Tail Han sheep was not in Hardy-Weinberg Equilibrium. These results indicated that the B2 mutation of BMP 15 gene had significant effect on the fecundity of Small Tail Han sheep, then the possibility was that the fecundity of Small Tail Han sheep was not affected by the G8 mutation of GDF9gene and the B4 mutation of BMP 15 gene, respectively.