Expression of heat shock protein genes in Simmental cattle exposed to heat stress

Abstract

Objective: In tropical, subtropical and arid zones, heat stress is the main cause of productivity reduction in cattle. When climate stressors occur, animals become thermal adapted through differential expression of some genes, including heat shock proteins (<i>HSP</i>) family. The aim of this study was to determine levels of expression of <i>HSP60</i>, <i>HSP70</i>, and <i>HSP90</i> genes in Simmental cattle raised in tropical environments of Mexico.Methods: In this study, expression of <i>HSP60</i>, <i>HSP70</i>, and <i>HSP90</i> genes was analyzed in 116 Simmental cattle from three farms with tropical climate located in western Mexico. Animals were sampled twice a day, in the morning and noon. Gene expression was evaluated by quantitative polymerase chain reaction using probes marked with fluorescence. The MIXED procedure of SAS with repeated measures was used for all statistical analysis.Results: <i>HSP60</i> gene expression differences were found for sex (p = 0.0349). <i>HSP70</i> gene differences were detected for sampling hour (p = 0.0042), farm (p<0.0001), sex (p = 0.0476), and the interaction sampling hour×farm (p = 0.0002). Gene expression differences for <i>HSP90</i> were observed for farm (p<0.0001) and year (p = 0.0521). <i>HSP70</i> gene showed to be a better marker of heat stress than <i>HSP60</i> and <i>HSP90</i> genes.Conclusion: Expression of <i>HSP70</i> gene in Simmental herds of the tropical region of western México was different during early morning and noon, but the expression of the <i>HSP60</i> and <i>HSP90</i> genes was similar. Identification of resilient animals to heat stress will be useful in the genetic improvement of the Simmental breed.