Differential Expression Of PHK And GP And Changes Of Glycogen Content In Tissues Of Rana Dybowskii Under Low Temperature Stress

Rana dybowskii is mainly distributed in the suburbs,including northeastern China,inner Mongolia,the Korean Peninsula,eastern Mongolia and the far east of Russia.During the hibernation,the body is in a sustained low temperature condition,and accumulate high concentrations of glucose to resist freezing damage.Phosphorylated kinase(PHK)and glycogen phosphorylase(GP)are key rate-limiting enzymes in the process of glycogen metabolism.Therefore,the expression of PHK and GP(isoenzyme PYGL,PYGM,PYGB)mRNA and the change of glycogen content in the heart and liver were studied for understand the cold hardness mechanism of Rana dybowskii.In this experiment,the Rana dybowskii was collected from Yichun,Heilongjiang Province.Rana dybowskii at 4? was set as the control group and that of-1? was set as the stress group.The levels of PHK,PYGL,PYGM and PYGB in the heart and liver were detected by Real-time PCR at 4h,8h,12 h,12h,24 h,48h and 72 h.And the changes of glycogen content in myocardium and liver tissue were detected by PAS staining at each time point.Results:At-1?,The levels of PHK,PYGL,PYGM and PYGB transcription were significantly increased in the heart at all the time of stress(P <0.05),PYGM reached the peak value at 12 h,and the others reached th peak value at 24 h.The levels of PHK,PYGL,PYGM and PYGB transcription were significantly increased in the liver at 12 h,48h and 72h(P <0.05),PYGM reached the peak value at 12 h,and the others reached th peak value at 48 h.The results showed that PHK,PYGL,PYGM and PYGB were all involved in the metabolism of glycogen catabolism in the heart and liver under low temperature stress,so as to generate high concentration of glucose to enhance the antifreeze ability of the body.PAS staining and image analysis showed that,when at-1?,the content and distribution of glycogen in myocardium and liver tissue decreased with the increase of stress time.The distribution of glycogen in myocardium decreased at 24 h,and that of liver tissue decrease at 12 h.The results showed that glycogen was consumed under low temperature stress in myocardium and liver tissue,and it was involved in the high glucose production mechanism.In conclusion,the key mRNA levels of glycogen metabolism in myocardium and liver tissue glycogen content were studied in Rana dybowskii under low temperature stress.The results showed that PHK,PYGL,PYGM and PYGB were significantly increased,and the contents of glycogen in myocardium and liver tissue were significantly decreased.This result provided a theoretical basis for understanding the cold hardness of Rana dybowskii.