中国和新西兰绵羊群体FABP4基因遗传特性比较分析

脂肪型脂肪酸结合蛋白(adipocyte fatty-acid binding protein,A-FABP)在家畜脂肪沉积中发挥重要作用,但在藏绵羊群体中的遗传特性和特异的作用机制尚不明确,研究不同生产方向绵羊品种的FABP4基因变异及分布有助于揭示藏绵羊独特的种质特性。应用PCR-SSCP(polymerase chain reaction-single strand conformation polymerase)和测序技术检测了中国和新西兰共10个绵羊群体(575只个体)FABP4基因编码区(外显子2和外显子3)的变异,并分析其连锁不平衡状态。结果表明,两多态区域共鉴定8处单核苷酸突变,两多态区域SNPs间呈弱连锁不平衡状态(D'=0.548,r~2=0.119),鉴定14种潜在的单体型。外显子2-内含子2区域A_1为优势等位基因(38.4%),A_1B_1为优势基因型;外显子3-内含子3区域B_2为优势等位基因(48.3%),A_2B_2为优势基因型。新西兰绵羊群体在两多态区域偏离Hardy-Weinberg平衡状态(P0.01),而藏绵羊处于Hardy-Weinberg平衡状态(P0.05)。罗姆尼与派仑代群体基因型分布无显著差异(P0.05),美利奴与考力代群体基因型分布差异显著(P0.05)。新西兰绵羊群体两多态区域均为高杂合度及高度多态,藏绵羊群体均为高纯合度及中度多态。聚类分析表明欧拉和甘伽羊、考力代和美利奴羊、罗姆尼和派仑代羊分别聚在一起。c.246+37AG和c.348+298TC位点多态性在藏绵羊和新西兰绵羊群体中分布差异较大,该两处SNPs可作为潜在的分子标记应用于藏绵羊肌内脂肪含量性状选育。

Comparative Analysis of FABP4 Genetic Characteristcs of Ovine Population from China and New Zealand

The adipocyte fatty-acid binding protein (A-FABP) plays an important role in fat deposition in livestock, but it is still not clear about the mechanism of genetic characters and specific function in Tibetan sheep. Studying FABP4 genovariation and their distribution in different sheep breeds with various production direction will reveal the unique characters of Tibetan sheep. This paper studied FABP4 variations and the linkage disequilibrium of SNPs across 2 regions (exon 2 and exon 3) using PCR-SSCP (polymerase chain reaction-single strand conformation polymerase) and sequencing technology in a total of 575 samples selected from 10 populations (Tibetan and NZ sheep). The results indicated that 8 SNPs and 14 haplotypes across 2 regions were identified and these SNPs across 2 regions were found to show weak linkage disequilibrium (D′=0.548，R2=0.119). Allelic A1 was showed to be preponderant (38.4%) and genotypic A1B1 was showed to be preponderant in exon 2-intron 2 region. Allelic B2 was showed to be preponderant (48.3%) and genotypic A2B2 showed to be preponderant in exon 3-intron 3 region. Allelic frequency in amplified regions were found to deviate Hardy-Weinberg (P<0.01) in NZ sheep, while which were found to conform to Hardy-Weinberg (P>0.05) in Tibetan sheep. Genotypic difference was not observed in Romney and Perendal breeds (P>0.05), but the remarkable genotypic difference was observed in Merino and Corriedal breeds (P<0.05). The higher heterozygosity and polymorphism information content (PIC) were found in NZ breeds, but the higher homozygosity and medium PIC were observed in Tibetan sheep. The cluster analysis indicated that Ola and Ganjia were found to be clustering together. These breeds (Corriedal and Merino) and the other 2 breeds (Romney and Perendal) were found to be clustering together, respectively. Big frequency differences of SNPs (c.246+37A>G and c.348+298T>C) were found between Tibetan and NZ sheep. And these SNPs might be used as molecular markers to improve the trait of intramuscular fat content in Tibetan sheep.