Molecular Cloning and Induced Expression of Six Small Heat Shock Proteins Mediating Cold-Hardiness in (Coleoptera: Coccinellidae).

The main function of small heat shock proteins (sHSPs) as molecular chaperones is to protect proteins from denaturation under adverse conditions. Molecular and physiological data were used to examine the sHSPs underlying cold-hardiness in . Complementary DNA sequences were obtained for six sHSPs based on its transcriptome, and the expression of the genes coding for these sHSPs was evaluated by quantitative real-time PCR (qRT-PCR) in several developmental stages, under short-term cooling or heating conditions, and in black and yellow females of experimental and overwintering populations under low-temperature storage. In addition, we measured water content and the super cooling and freezing points (SCP and FP, respectively) of individuals from experimental and overwintering populations. The average water content was not significantly different between adults of both populations, but the SCP and FP of the overwintering population were significantly lower than that of the experimental population. Overall, the six sHSPs genes showed different expression patterns among developmental stages. In the short-term cooling treatment, and expressions first increased and then decreased, while and expressions increased during the entire process. Under short-term heating, the expressions of , and showed an increasing trend, whereas decreased and then increased. Under low-temperature storage conditions, the expression of decreased, while the expressions of and were higher than that of the control group in the experimental population. The expression of increased and then decreased, whereas expression was always higher than that of the control group in the overwintering population. Thus, differences in sHSPs gene expression were correlated with the forms, suggesting that the mechanism of cold resistance might differ among them. Although, , and regulated cold- hardiness, the only significant differences between overwintering and experimental populations were found for and .