Polymorphisms in Hsp90ab1 gene and their association with heattolerance in Sahiwal and Karan Fries cows

Heat shock protein functions as a molecular chaperone and plays an important role in thermotolerance. The study was undertaken to identify single nucleotide polymorphisms (SNPs) of Hsp90ab1 gene by comparative sequencing and to analyze their association with thermo-physiological parameters, viz. respiration rate (RR), rectal temperature (RT) and heat tolerance coefficient (HTC) in different seasons, viz. winter, spring and summer, at probable extreme hours of the day in Sahiwal and Karan Fries cows. The RR, RT and HTC in summers were significantly (P£0.01) higher than the other two seasons. Polymorphism of Hsp90ab1 gene, evaluated by comparative sequencing revealed six SNPs, viz. T17871421C, C17871485del, C17872061T, T17872112C, T17872148G and A17872199C, two each located in exon 8, intron 10 and exon 11. SNP loci T17871421C and C17871485del were found to be monomorphic for allele C and Deletion (-) respectively in experimental population. Individuals with AA genotype showed significantly (P £0.01) lower RR than AC genotype. While, individuals with CT genotype recorded significantly (P £ 0.01) lower RT than CC genotype. Therefore, it is inferred that propagation of AA and CT genotypes may be an aid to selection and breeding programmes to enhance thermo-tolerance in dairy cattle.