HSF1 and HSPA6 as functional candidate genes associated with heat tolerance in Angus cattle

ABSTRACT The purpose of this study was to access and characterize single nucleotide polymorphisms (SNP) located within the HSF1 and HSPA6 candidate genes for adaptability in Angus breed raised in subtropical climate. Samples of DNA from 20 animals representing extreme phenotypes for adaptability traits were obtained. Sequence variations in the candidate genes were described by sequencing target regions. We identified 12 SNP located in the HSF1 gene. Moreover, four of the six SNP found in the HSPA6 gene cause amino acid substitutions in protein-coding regions. We also identified a representative SNP (called tag SNP) in a region of the HSF1 gene with high linkage disequilibrium (r2 = 0.87) that may represent 11 SNP located in this gene. Minor allele frequency observed for the SNP ranged from 0.10 to 0.50 and 0.02 to 0.21 for the HSF1 and the HSPA6 genes, respectively. Overall, almost all SNP analyzed showed significant deviation from the Hardy-Weinberg Equilibrium and half of the loci had heterozygosity greater than 0.50. The data suggest that there is sequence variability in these genes that could be exploited by breeding programs. There is genetic variation in HSF1 and HSPA6 genes in this populations of Angus breed, which is fundamental to obtain response to selection.

摘要 本研究旨在评估并表征亚热带气候下饲养的安格斯牛（Angus breed）适应性相关候选基因HSF1与HSPA6内的单核苷酸多态性（single nucleotide polymorphism, SNP）。本研究采集了20头具有极端适应性表型的安格斯牛的DNA样本。通过对目标区域进行测序，本研究对候选基因的序列变异进行了分析与阐释：在HSF1基因中鉴定出12个SNP位点；在HSPA6基因中发现的6个SNP里，有4个会导致蛋白质编码区发生氨基酸替换。此外，本研究还在HSF1基因的高连锁不平衡（r²=0.87）区域内鉴定出一个代表性SNP（称为标签SNP，tag SNP），该位点可代表该基因内的11个SNP。经检测，HSF1基因的SNP次要等位基因频率范围为0.10至0.50，HSPA6基因的SNP次要等位基因频率范围则为0.02至0.21。总体而言，本次分析的几乎所有SNP位点均显著偏离哈迪-温伯格平衡（Hardy-Weinberg Equilibrium），且半数位点的杂合度高于0.50。本研究数据表明，这些基因存在序列变异，可用于家畜育种计划。该安格斯牛群体的HSF1与HSPA6基因存在遗传变异，这是实现选择响应的核心基础。