Differential Regulation of Hsp70 Expression in Six Lizard Species under Normal and High Environmental Temperatures.

Ambient temperature is an especially important factor associated with the development and survival of ectotherms. To minimize the effect of temperature variation, ectotherms have developed specific physiological and biochemical adaptations. Heat shock proteins and other molecular chaperones play specific physiological roles in such thermal adaptation. Here, we analyzed heat shock protein 70 (Hsp70) expression in six lizard species to investigate the variation in Hsp70 response contributing to thermal adaptation. At first, we collected three lizard species of the genus Takydromus from different geographical locations. We found that either the constitutive expression pattern in different organs or the inducible expression pattern under higher ambient temperature were the same. The expression of Hsp70 was higher in the muscles. In liver, Hsp70 expression significantly increased after 38°C heat shock. We then collected other three lizard species, Plestiodon chinensis, Sphenomorphus indicus, and Scincella modesta, from geographical locations near each other, but with different microhabitats. We observed considerable variation in Hsp70 expression; the constitutive Hsp70 expression varied between organs and between species under heat shock. P. chinensis began to express Hsp70 significantly at 39°C and with the maximum expression at 41°C. S. indicus and S. modesta began to express Hsp70 significantly at 35°C, and a temperature above 37°C resulted in fatality for some individuals. Taken together, these results indicated that both microhabitat and active temperature range contributed to the differences in Hsp70 expression in lizards at normal and elevated ambient temperatures. [ABSTRACT FROM AUTHOR]