Seasonal variation and freezing response of glucose transporter 2 in liver of the wood frog: implications for geographic variation in freeze tolerance

摘要: Subarctic populations of the wood frog Rana sylvatica survive freezing to temperatures at least 10–13°C below those more southerly conspecifics. This profound freeze tolerance is due in part an enhanced glucosic cryoprotectant system that requires rapid mobilization glucose from hepatocytes during early hours freezing. To determine if transporter 2 (GLUT2) liver contributes geographic variation tolerance, we examined changes protein’s abundance seasonally and response experimental frogs Interior Alaska southern Ohio, USA. Using immunoblotting techniques, found GLUT2 increased preparation for winter both populations, but tests with Ohioan showed altered temperature alone does not cause these seasonal changes. In frogs, expression apparently was regulated transcriptionally, as mRNA levels, assessed using quantitative real-time polymerase chain reaction, changed accordance protein abundance. However, this pattern observed Alaskan suggesting other mechanisms regulation are important phenotype. Overall, constitutively greater responsive R. sylvatica, substantively extreme subarctic frogs.