Thermotolerance in Domestic Ruminants: A HSP70 Perspective

Thermal stress is one of the most important factors limiting ruminant production and thermotolerance studies in domestic ruminants has lot of bearing on the identification of prospective biomarkers for thermal stress, especially the heat stress. Heat stress in ruminants is characterized by heat shock response, which is mediated by different types of Heat Shock Proteins (HSP) like HSP60, 70, 90, 110, 27 among which some play a critical role in the initial stages of heat stress and some in the later stages. Among all HSP, HSP70 is considered as cellular thermometer and is indicator of quantum of stress experienced by the cell. At a given amount of stress the expression of HSP70 varies with species, breed, age and type of tissue indicating the variations in thermotolerance. Members of HSP70 family have many homologues like HSPA1A, HSPA1B, HSPA1L, HSPA2, HSPA4, HSPA5, HSPA6 & HSPA8 of which some are constitutive and some are inducible. These genes are elevated with heat stress in different type of cells at variable rate. The differences in thermotolerance among species and breeds are correlated with variations in different HSP70 family members. HSP70 can be viewed as prospective biomarker for marker assisted selection in animals in order to have more thermotolerant animals in future as a strategy towards Climate resilient ruminant production.