Author : Ramneek Kaur, Ankita Sharma, Monika Sodhi, Vijay Lakshmi Sharma, Parvesh Kumari and Manishi Mukesh

Na+/K+-ATPase gene is known to maintain the electrochemical gradient of Na+ and K+ ions across the plasma membrane and regulates the transport of metabolites and nutrients. Recently, this gene has been linked with thermotolerance trait in dairy animals. Several anatomical and physiological evidences for adverse impact of summer stress on riverine buffaloes have been reported. In contrary, the information related to molecular and cellular mechanism involving heat stress is not well defined in riverine buffaloes. In the present study, an attempt was made to assess the expression pattern of four isoforms namely ATP1A1, ATP1A2, ATP1A3, and ATP1A4 of Na+/K+-ATPase gene in heat stressed buffalo mammary epithelial cells (MECs). The MECs were exposed to heat stress at 42°C for 1 hour. The cells were subsequently allowed to recover at 37°C and harvested at different time points. The qPCR data was normalized using RPL4, RPS23 and EEF1A1 reference genes that were identified previously for similar experimental condition. The buffalo MECs data showed induction of ATP1A1/ATP1A2 isoforms immediately post heat stress and reached to maximum level (4.65/1.84 folds) at 4 hr post stress. The expression pattern of ATP1A1/ATP1A2 mRNA in heat stressed buffalo MECs at different time points was also compared to that of HSP70, HSP90 and HSP60 transcripts. Among all, HSP70 gene was most responsive to heat stress, followed by ATP1A1 gene and the expression pattern of ATP1A1/ATP1A2 mRNA were positively correlated with HSPs expression data. The differential induction of ATP1A1/ATP1A2 mRNA post heat stress in MECs showed these isoforms to be heat responsive and could be utilized in future as an additional marker to understand the cellular tolerance of dairy animals to heat stress.

Keywords: Na+/K+-ATPase, Electrochemical gradient etc.