鸡8个功能基因5′-侧翼区与内含子的SNP多样性比较

Comparison of SNP diversity between 5′-flanking regions and introns of eight functional genes in chickens

本研究旨在探讨鸡功能基因5′-侧翼区的单核苷酸多态性(SNP)水平。作者以白来航鸡、隐性白洛克鸡、杏花鸡、丝羽乌骨鸡、固始鸡、红色原鸡为材料,扩增了GH、DDBC1、RIKEN、RASGRP3、IGF1、THRSP、VIP及PRL共8个基因的5′-侧翼区DNA序列。扩增序列全长为8,399bp,SNP的总数为161个,平均每52bp出现一个SNP。8个功能基因5′-侧翼区核苷酸多样性的θ均值和π均值分别为0.00620±0.00110和0.00559±0.00100。比较检验表明,5′-侧翼区的SNP多样性显著低于内含子区域。5′-侧翼区是基因表达的一个重要调控区域,在分子进化和系统发生过程中承受着比内含子区域更大的选择压,其较低的SNP多样性是适应性较好的表现。Tajima检验与Fu和Li检验表明,与鸡繁殖性状显著关联的VIP基因和PRL基因很可能是人工选择或自然选择的目的基因。

The goal of this study was to explore the level of Single Nucleotide Polymorphisms （SNP） level of 5＇-flanking regions in chicken functional genes. The 5＇-flanking region of eight genes, including GH, DDBC1, RIKEN, RASGRP3, 1GF1, THRSP, VIP and PRL, were amplified and sequenced for White Leghorn, White Recessive Rock, Xinghua, Silkie, Gushi, and Red Jungle Fowl strains. A total length of 8,399 bp sequence was obtained and 161 SNPs were identified, with an average of one SNP per 52 bp. Watterson＇s estimate of 0 was 0.00620 ± 0.00110 and the average nucleotide diversity （π） calculated from the average number of pair-wise differences was 0.00559 ± 0.00100. The SNP diversity of 5＇-flanking regions was significantly lower than that of introns. Because of their importance in regulation of gene expression, the 5＇-flanking regions may have endured more selective pressure than introns during molecular evolution. A relatively low SNP diversity in 5＇-flanking region may be more adoptive. The Tajima test and Fu ＆ Li test showed that VIP and PRL, which are significantly associated with chicken productivity, are likely to be target genes for artificial and natural selection.