不同绵羊品种FGF5基因的多态性分析

根据人和小鼠成纤维细胞生长因子5（FGFS）基因的同源序列设计引物对绵羊基因组进行PCR扩增，将扩增片段进行克隆和测序，并与人和小鼠的成纤维细胞生长因子5基因序列进行同源性比较，确定扩增的片段为绵羊的FGF5基因片段。采用PCR-SSCP技术分析了FGF5基因外显子在小尾寒羊、湖羊、藏羊、中国美利奴等4个绵羊品种的多态性。结果表明：FGF5基因在P1和P2引物扩增片段中存在PCR-SSCP多态性。经克隆测序分析，位于外显子1的引物1扩增产物存在G→T突变，该突变位点使编码的氨基酸发生A→S的改变；引物2扩增产物发生了碱基序列C→T的突变，这一突变位点没有引起编码氨基酸的改变，属于同义突变。对不同绵羊品种的基因型和基因频率统计结果表明，引物1扩增产物小尾寒羊、湖羊、藏羊以等位基因A为主，而中国美利奴羊则以等位基因B为主，且各群体均处于Hardy-Weinberg平衡；引物2扩增产物小尾寒羊、湖羊、中国美利奴羊均以等位基因E为主，而藏羊的基因型频率与其它品种有显著差异，中国美利奴羊在引物2位点的基因频率处于Hardy-Weinberg不平衡状态。

PCR-SSCP Analysis of FGF5 Gene in Different Sheep Breeds

FGF5 is a member of the FGF superfamily.It is specifically expressed in hair follicles cells and functions as a negative regulator of follicle anage.This study was designed and aimed to identify the single nucleotide polymorphisms(SNPs) of FGF5 gene by PCR-SSCP(single-strand conformation polymorphism) in various sheep breeds including Small Tail Han sheep,Hu sheep, Tibetan sheep,Chinese Merino sheep.The 3 pairs of primers for FGF5 gene were designed based on the human and mouse genomic sequence.Two SNPs were identified in the sheep FGF5 gene by PCR-SSCP and sequencing.They were in the exon 1 region in different sheep lines.The result of these analysis indicated that the polymorphisms are due to two single point mutation G to T and C to T at base position 122 and 385,respectively.Population genetic analysis indicated that genotype frequency of the P1 SNPs in Chinese Merino sheep were quite different from other tested sheep breed.Frequency of the BB genotype was much higher in Chinese Merino sheep while the AA genotype was much lower than other breed.The genotype frequency of P1 was significantly different in the tested sheep lines(P<0.01).All the population were in Hardy-Weinberg equilibrium state.For primer 2,frequency of the EE genotype in Tibetan sheep was higher than those in the other lines,Frequency of allele E in primer 2(P2) in Tibetan sheep was higher than that of other breed.All the population were in Hardy-Weinberg equilibrium state except Chinese Merino sheep.