Association between polymorphism of GPR54 gene and litter size in Small Tail Han sheep

Abstract

A DNA fragment (4262 bp) of sheep GPR54 gene was obtained through PCR and DNA sequencing methods. One nucleotide transition mutation (A125G) and one 5 bp deletion/insertion (TTCTT) mutation at the 163–167 locus in 5´-regulatory region of sheep GPR54 gene were identified by sequence alignment between Small Tail Han and Corriedale sheep. The distributions of these two mutations were determined in high prolificacy breeds (Small Tail Han and Hu sheep) and low prolificacy breeds (Chinese Merino and Corriedale sheep) and their effects on litter size in Small Tail Han sheep were also evaluated. The results showed that the two mutations existed in all four sheep breeds tested. In Small Tail Han sheep, genotype frequency of AA, AG and GG was 0.250, 0.500 and 0.250, respectively. The differences of litter size between three genotypes were not significant in Small Tail Han sheep ( P > 0.05). Genotype frequency of CC, CD and DD was 0.175, 0.125 and 0.700, respectively. Small Tail Han sheep ewes with genotype CC had 0.66 ( P < 0.05) or 0.49 ( P < 0.05) lambs more than those with genotype DD or CD, respectively. The ewes with hap3/hap3 or hap2/hap3 had the most litter size in Small Tail Han sheep. And the inserted/deleted mutation may influence the binding of the transcription factor deltaE. These preliminary results indicated that allele C at the 163–167 locus in GPR54 gene may be a potential marker for improving litter size in sheep.