ORIGINAL PAPER Cellular thermotolerance is independent of HSF 1 expression in zebu and crossbred non-lactating cattle Jaspreet Kaur Gill 1 & J. S. Arora 1 & B. V. Sunil Kumar 1 & C. S. Mukhopadhyay 1 & Simarjeet Kaur 1 & Neeraj Kashyap 1 Received: 23 May 2016 /Revised: 3 February 2017 /Accepted: 31 March 2017 # ISB 2017 Abstract Heat stress is an important domain of research in livestock due to its negative impact on production and disease resistance. The augmentation of stress in the body stimulates the antioxidative activity comprising various enzymes (viz., catalase, superoxide dismutase), metabolites (reduced gluta- thione, etc.), vitamins, minerals, etc. to combat the situation. The major key players involved in regulation of heat shock response in eukaryotes are the transcription factors, called as heat shock factors (HSF). They activate the heat shock protein (HSP) genes by binding to their promoters. Lymphocytes are considered to be the best model to evaluate the immunity in any living body as it contains plethora of white blood cells (WBCs).In this study, the peripheral blood mononuclear cells (PBMC) obtained from non-lactating Sahiwal vis-à-vis cross- bred (Holstein Friesian × Sahiwal) cattle with 75% or more exotic inheritance were subjected to heat shock at 39, 41, and 43 °C in three different incubators, in vitro. The cell count and viability test of pre and post heat stress of concerned PBMCs indicated that the crossbreeds are more prone to heat stress as compared to Sahiwal. The reverse transcription PCR (qRT– PCR) expression data revealed an increment in HSF1 expres- sion at 41 °C which subsequently declined (non-significantly) at 43 °C in both breeds post 1 h heat shock. However, the association between the HSF 1 expression and antioxidative activity through correlation analysis was found to be non- significant (P < 0.05), though enzymatic activity appeared to behave in a similar fashion in both breeds at 5% level of significance (P < 0.05). This rule out the role of HSF1 expression level on the activity of enzymes involved in oxi- dative stress in vitro in zebu and crossbred cattle. Keywords PBMC . HSF1 . Antioxidativeenzymes . Invitro . Heat shock . Sahiwal . Crossbred Introduction Hyperthermia adversely affects the dairy animals by lowering its milk yield, reproductive regime, immunity to fight against diverse pathological and environmental diseases, growth, con- ception rate, feed intake, etc., which imposes a major threat to livestock industry, and it also raises the chances of mitochon- drial dysfunction leading to reduction in ATPs which further lower the immunity of any living system. Ruminants have an ability to regulate their body temperature and maintain ho- meostasis in a breed and species-specific manner with indig- enous breeds (Sahiwal/zebu) having higher thermotolerance than the crossbreds (Holstein Friesian × Sahiwal). Also dairy breeds are more susceptible to heat stress as compared to meat breeds leading to reduced milk yield in former which has always been an important issue worldwide (Kishore et al. 2013a, b). Different breeds of zebu viz. Sahiwal, Gir, Ongole, etc. exhibit varied inherent capabilities like higher thermotolerance, hardiness, and survival under diverse stress- ful conditions. There have been many studies which showed that indigenous breeds are hardier and much tolerant to harsh climate (Hansen 2004). Reactive oxygen species (ROS) are the main culprits of oxidative stress. Although they play a pivotal role in body’ s self-defense, under stressful conditions, they exceed their threshold levels and initiate rapid destruction of polyunsatu- rated fatty acids (PUFA) (Victor et al. 2000 and Halliwell and Gutteridge 1990). To combat this situation, body begins to * J. S. Arora drarora2003@gmail.com 1 Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab, India Int J Biometeorol DOI 10.1007/s00484-017-1350-0