In vivo and in vitro heat shock proteins gene expression in cattle.

Abstract

The main purpose for this study was the quantification of the heat shock proteins HSPA1A and HSP90AA1, in cow lymphocytes, when subjected to heat stress directly - in vivo, or indirectly - in vitro. The aim was to identify differences between HSP expression in vitro and in vivo. The experiment was conducted in the Biometeorology and Ethology Laboratory of FZEA-USP. Were used three female Holstein Frisian, which were subjected to heat stress, by sun exposure. The blood samples were collected after sun exposure, with a temperature of 40 ± 2 º C, during three days. For in vitro tests, blood of the same animals was collected and placed for a period of 4 hours in a water bath at 40 º C, thus simulating the thermal stress. Total RNA of lymphocytes was extracted, treated with DNase I and submitted to cDNA synthesis for gene expression quantification of HSPA1A and HSP90AA1, by real time PCR (qRT-PCR). The data were tested for normality by Kolmogorov-Smirnov test and for homocedasticity by Levene test. Data were analyzed according to a general linear model procedure with 2 fixed factors treatment and genes expression. Significantly different means were submitted to post-hoc comparisons of means (LSD test) and regarded as significantly different when P<0.05. The results showed that there are no significant differences between the in vitro and the in vivo treatments,