Polymorphism of the promoter region of Hsp70 gene and its relationship with the expression of HSP70mRNA, HSF1mRNA, Bcl-2mrna and Bax-AMrna in lymphocytes in peripheral blood of heat shocked dairy cows

The blood samples were collected from dairy cows at the same milking stage. The single-strand conformation polymorphism (PCR-SSCP) method was used to analyze for polymorphism at the 5'-flanking region of the hsp70 gene. The mRNA expression levels of HSP70, HSF1, Bcl-2 and Bax-alpha at different daily-mean-temperature were analyzed by relative quantitative RTPCR. The DNA content, cell phase and the ratio of apoptosis of lymphocytes in peripheral blood of dairy cattle at different daily-mean-temperature were determined by FCM. The PCR-SSCP products of primer pair I showed polymorphisms and could be divided into four genotypes: aa, ab, ac, cc, with the cis-acting element (CCAAT box) included. Mutations in the hsp70 5'-flanking region (468-752 bp) had different effects on mRNA expression of HSP70, HSF1, Bcl-2 and Bax-alpha. The ac genotypic cows showed higher expressions of HSP70mRNA, HSF1mRNA and Bcl-2mRNA/Bax-alpha mRNA and lower ratio of apoptosis. These mutation sites can be used as molecular genetic markers to assist selection for anti-heat stress cows.