Genetic Variation Of Kaps Gene In Five Sheep Populations Of China

Keratin-associated proteins(KAPs) are main structural components of wool fibre, which are encoded by KAPs gene families. KAP11-1 and KAP15-1 belong to the member of high-sulfur KAPs gene, and few reports were published about these two genes in sheep and goat. In order to study the genetic variation of KAPs gene, 749 sheep samples, including Tibetan sheep(Oula type), Gansu Alpine Merino, Tan sheep, Hu sheep and Qinghai Merino were chosen as investigate objectives and, KAP11-1 gene and KAP15-1 gene were used as candidate gene to detect nucleotide and amino acid sequences variations, genetics characteristics such as allele frequency, genetic heterozygosity, effective number of alleles and polymorphism information content(PIC) using PCR-SSCP techniques in this study. The nucleotide sequences homology between sheep and other species of KAP11-1 and KAP15-1gene were compared. The main research results are:(1) Four SNPs(c.93C>T, c.240G>A, c.285C>G/A and c.331A>G) were discovered at the coding sequences of the KAP11-1 gene, and the former three were synonymous substitutions and c.331A>G was non-synonymous substitution, which would potentially result in an amino acid change(p.Ser111Gly). Seven SNPs were detected at the coding sequences of the KAP15-1 gene, these SNPs were c.133A>G, c.171C>T, c.229C>T, c.245T>C, c.267A>T,c.323G>A and c.339T>C, respectively. And c.133A>G, c.323G>A, c.245T>C and c.229C>T were non-synonymous substitutions that resulted in four amino acid changes(p.Thr45 Ala,p.Phe77 Ser, p.Phe82 Ser and p.Ser108Asn) in the putative peptide of KAP15-1.(2) Four alleles A, B, C and D were identified in the KAP11-1 gene of 5 sheep breeds, and A was the most common allele with the frequency of 87.70%. Four alleles A, B, C and D were identified in the KAP15-1 gene of Tibetan sheep(Oula type), Gansu Alpine Merino, Tan sheep and Hu sheep, while three alleles A, B and C were observed in Qinghai Merino. Allele A, among four alleles, was the most common allele with the frequency of 87.10%.(3) Population genetics analysis suggested that the polymorphism of KAP11-1 gene in Tan sheep was abundant and moderate, whose genetic heterozygosity, effective number of alleles and polymorphism information content were 0.17, 1.38 and 0.26. The polymorphismof KAP15-1 gene in Hu sheep was more abundant than the other four sheep breeds, and the effective number of alleles, heterozygosity and polymorphism information content of Hu sheep were 1.98, 0.27 and 0.44, respectively.(4) The nucleotide sequences of KAP11-1 gene and KAP15-1 gene in five sheep populations had the greatest homology with those of goat and cattle, and they existed in the same branches in the phylogenetic trees.