Hsp70 expression and metabolite composition in response to short-term thermal changes in Folsomia candida (Collembola)

In the present study the joint transcriptomic and metabolomic responses in Folsomia candida (Collembola) to temperature changes on a short-term scale were studied. Change in heat tolerance was examined as survival after a 35 °C heat shock (2 h) in the course of either a fluctuating temperature regime (8 to 32 °C; pre-treated) or a constant temperature (20 °C; control) over a period of 24 h. Exposure to a temperature increase from 20 to 32 °C (2.4 °C min−1) induced a significantly increased heat tolerance which continued throughout the experiment. Expression of the gene encoding heat shock protein Hsp70 was assessed at the mRNA level using real time quantitative polymerase chain reaction (QPCR). Hsp70 was rapidly induced and significantly increased by the temperature increase. The relative concentrations of low molecular weight metabolites were analysed in F. candida using nuclear magnetic resonance spectroscopy (1H NMR). A significant metabolomic divergence between pre-treated and control collembolans was evident; partly due to a significantly reduced relative concentration of five free amino acids (arginine, leucine, lysine, phenylalanine and tyrosine) in pre-treated collembolans. These results, obtained from ecological transcriptomics and metabolomics jointly generated insight on various levels into the combined responses to a changing environment.