<div>Background: Heat shock proteins (HSPs) are molecular chaperones that play a critical role in recovering cells from stress and form a primary system for intra cellular self defense. They are highly conserved and play a crucial role in cellular thermo tolerance and heat stress response. Though there are many HSP genes, thermo tolerance is mainly correlated with HSP70 and HSP90 genes in Livestock species. Polymorphisms in these genes have shown an association with heat tolerance, milk production, fertility and disease susceptibility in livestock. They can be used as genetic markers for the selection of animals with better climate resilience, immune response and superior performance. 
 
Methods: The present study was carried out in Sahiwal (n=50) and Crossbred cows (n=50) with the objective to identify polymorphisms in HSP90AA1 gene. A 450 bp fragment of bovine HSP90AA1 gene covering exon3 was subjected to Polymerase Chain Reaction-Single-Strand Conformation Polymorphism (PCR-SSCP) technique to identify the polymorphism. PCR-SSCP patterns were correlated with the physiological, productive and reproductive traits in Sahiwal and crossbred cows using the univariate GLM model of SPSS 25. 
 
Result: The PCR-SSCP of exon 3 of HSP90AA1 gene yielded two conformational patterns AA and AB corresponding to two allelic variants A and B in both Sahiwal and crossbred cows. The allele frequencies of A and B were 0.78 and 0.22 and 0.84 and 0.16 in Sahiwal and crossbred cows, respectively. The association analysis of SSCP patterns revealed that genotype AA had higher lactation length in Sahiwal cows and higher total lactation milk yield and peak yield in crossbred cows.&nbsp;</div>

​Genetic Polymorphism within Exon 3 of HSP90AA1 Gene&nbsp;and its Association Studies in Sahiwal and Crossbred Cows

Heat Shock Proteins (HSPs) are group of proteins which are synthesized during heat stress. HSP genes have been reported to be associated with heat tolerance and production performance in cattle. HSP90AA1 gene has been mapped on Bos taurus autosome 21 (BTA 21) and spans nearly 5368 bp comprising 11 exons out of which first exon does not translate. The present study was carried out in Sahiwal cows (n=100) with the objectives to identify SNPs in targeted regions (exon 3, 7, 8 &amp; 11) of HSP90AA1 gene and to analyze their association with heat tolerance traits in Sahiwal cows. Respiration rate (RR) and rectal temperature (RT) was recorded once during probable extreme hours in winter, spring and summer season. Further, heat tolerance coefficient (HTC) also calculated to see the adaptability of the animals during the period of heat stress. On the basis of comparative sequence analysis, total five SNPs were revealed at position of A1209G, A3292C, T4935C, T5218C and A5224C in the targeted region of HSP90AA1 gene. Out of these, only two SNPs at A1209G and A3292C loci were found significantly associated with heat tolerance traits in Sahiwal cows. Whereas, THI has a highly significant associated with RR, RT and HTC in all the seasons. At A1209G locus in Sahiwal cows for traits RR, genotype AA (18.40&plusmn;0.46a), AG (19.60&plusmn;0.85b) and GG (21.18&plusmn; 0.64ab) and trait HTC AA (1.78&plusmn;0.04a), AG (1.85&plusmn;0.03b) and GG (1.91&plusmn; 0.02c) differ significantly (p&lt;0.01) while trait RT, AG (38.32&plusmn;0.10b) and GG (38.27&plusmn;0.08ab) didn&rsquo;t differ significantly. For a locus A3292C for traits RR, genotype AA (21.55&plusmn;1.01a), AC (19.66&plusmn;1.59b) and CC (18.40&plusmn;1.03c) differ significantly (p&lt;0.05), while traits RT, genotype AA (38.41&plusmn;0.12), AC (38.28&plusmn;0.20) and CC (37.96&plusmn;0.15) didn&rsquo;t differ significantly. For trait HTC, AA (1.93&plusmn;0.04a), AC (1.85&plusmn;0.06b) and CC (1.79&plusmn;0.05c) found significantly (p&lt;0.05) differ with each other. Our study indicated that Sahiwal cows of AA and AC genotype had better thermo-tolerance capacity, which had been useful for genetic improvement of Sahiwal cattle for heat tolerance traits.

Genetic Polymorphism within Exon 3 of HSP90AA1 Gene and its Association Studies in Sahiwal and Crossbred Cows

Single nucleotide polymorphisms in Heat Shock Protein (HSP) 90AA1 gene and their association with heat tolerance traits in Sahiwal cows

​Genetic Polymorphism within Exon 3 of HSP90AA1 Gene and its Association Studies in Sahiwal and Crossbred Cows

Single nucleotide polymorphisms in Heat Shock Protein (HSP) 90AA1 gene and their association with heat tolerance traits in Sahiwal cows

Genetic Polymorphism within Exon 3 of HSP90AA1 Gene and its Association Studies in Sahiwal and Crossbred Cows