This study was conducted to identify the association of coding variations in the HSPA8 gene with heat stress in two different breeds of sheep. All the coding regions of the HSPA8 gene of Awassi and Arabi sheep were covered by amplifying nine exons. A single-strand conformation polymorphism (SSCP) was utilized to assess the genetic variations in both breeds. The possible association of the observed genotypes with rectal temperature (RT), respiratory rate (RR), and heat tolerance coefficient (HTC) was analyzed in different seasons. While all the coding regions of both sheep were monomorphous, a remarkable heterogeneity was observed in exon 4, of which two SSCP patterns, a normal TT and a mutant TG, were detected. The TG genotype was characterized by a missense variant of T177P with frequencies of 77% in Awassi and 54% in Arabi. Cumulative in silico tools indicated extremely deleterious consequences for T177P on protein structure, function, and stability. Results indicated that sheep with the TT genotype had significantly (P < 0.05) lower RT, RR, and HTC values than sheep with the TG genotype. Therefore, a significant association of T177P with a lower tolerance of Awassi to higher temperature conditions was revealed. In conclusion, the identified T177P may have damaging effects in the HSPA8, which affects the ability of Awassi sheep to cope up with elevated temperatures compared with Arabi sheep. This manuscript describes a novel description of a highly deleterious missense variant in the HSPA8 gene that may reduce the ability of sheep to withstand high-temperature conditions.

进行了这项研究，以鉴定两种不同品种的绵羊中HSPA8基因编码变异与热胁迫的关系。HSPA8的所有编码区域通过扩增九个外显子覆盖了Awassi和Arabi绵羊的基因。单链构象多态性（SSCP）用于评估两个品种的遗传变异。在不同季节分析了观察到的基因型与直肠温度（RT），呼吸频率（RR）和耐热系数（HTC）的可能关联。虽然两只绵羊的所有编码区都是单态的，但在第4外显子上观察到了显着的异质性，其中检测到两个SSCP模式，即正常TT和突变TG。TG基因型的特征是T177P的一个错义变异，Awassi的频率为77％，Arabi的频率为54％。累积的计算机软件表明T177P对蛋白质的结构，功能和稳定性造成了极其有害的后果。结果表明，具有TT基因型的绵羊显着（P  <0.05）比具有TG基因型的绵羊降低了RT，RR和HTC值。因此，揭示了T177P与Awassi对较高温度条件的较低耐受性的显着关联。总之，识别T177P可以具有在破坏作用HSPA8，这影响Awassi绵羊与升高的温度下与阿拉比羊相比应付起来的能力。该手稿描述了HSPA8基因中高度有害的错义变异体的新颖描述，该变异体可能会降低绵羊承受高温条件的能力。