Cloning and expression of caprine KIT gene and associations of polymorphisms with litter size

Abstract

The full coding region of KIT mRNA was cloned from the caprine ovary. The results showed the caprine KIT cDNA (GenBank accession number KF364483) contained a 2925-bp open reading frame encoding a protein with 974 amino acid residues. BLAST analysis revealed that the caprine KIT protein had high similarity with that of four species: Ovis aries (99%), Bos taurus (99%), Sus scrofa (94%) and Homo sapiens (90%). The KIT mRNA expression pattern showed that KIT mRNA was expressed highly in kidney, ovary, uterus and breast. Two single nucleotide polymorphisms (g.88430T > A and g.120466G > A) in the caprine KIT gene were detected by PCR–restriction fragment length polymorphism (RFLP) and DNA sequencing in 735 goats of Xinong Saanen, Guanzhong and Boer breeds. The g.88430T > A mutation was a missense mutation (Tyr > Asn at position 409 amino acid of KIT). The association study has been done by jointly analysing all data in one analysis. The result showed that individuals with TT and TA genotypes had their litter size increased by 0.11 and 0.09, respectively, compared with those with AA genotype at the g.88430T > A locus for three goat breeds (P < 0.05). Further analysis revealed that combined genotype TTAA was better than the others for litter size in three goat breeds. Therefore, the biochemical and physiological functions, together with the results obtained in our investigation, suggest that the KIT gene could serve as a genetic marker for litter size in goat breeding.