Induction of Heat Shock Proteins (HSPs) in the Process of Heat Tolerance

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The aim of this study is to identify the inductions of HSPs (heat shock proteins) and CSPs (cold shock proteins) in weak heat-and strong cold-tolerant pika in order to clarify the mechanism of its character of weak heat-tolerance and to examine the physiological correlation between thermotolerance and HSPs, or CSPs (1) HSP 70 in rats and HSP 68 in rabbits were induced by the heat-shock. In pika rabbits, the induction of HSP by the heat-shock was not detected by 10% SDS-PAGE not only in liver tissue but also in those tissues such as kidney, adrenal gland, spleen, brain and skeletal muscle. According to previous research, tissues of liver, kidney, adrenal gland and spleen have relatively large ability of inducing HSP 70 than other tissues in hyperthermia of rat. In further study, Western blotting method with anti-HSP 70 antibody was performed. HSP 70 was detected in liver tissue of all rats under heat shock, but only one showed positive in all pikas. These results suggest that the diffic … More ulty of induction of HSPs somewhat relate no the characteristic of weak heat-tolerance in pika rabbits. (2) Induction of HSP 68 by chronic heat load instead of heat-shock was observed on 10% SDS-PAGE. In the experiment of Western blotting method with anti-HSP 70 antibody, the 68 kD protein responded to anti-HSP 70 antibody but the spot of staining showed smaller M. W. size. This discrepancy may be explained as a gradation of proteins including 68 kD protein. (3) Contrarily in cold-shock experiments, induction of CSP was not identified in rat, rabbit or pika. But one result was found that 32 kD protein in cytosol fraction vanished in one rat after cold-shock. Four kinds of plasma proteins (55, 27, 25, 20 kD) vanished in chipmunk, a hybernator, during and after the period of hybernation has been reported in previous paper. Therefore, the present finding showed the similarity to the previous report of chipmunk and suggests that not only hybernation but also short term of cold-shock may lead to the similar result. Furthermore, physiological significance of HSP and CSP was discussed from the viewpoint of thermal acclimation. Less