Temporal gene expression profiles in a palaearctic springtail as induced by desiccation, cold exposure and during recovery

P>1. Cryoprotective dehydration is a cold tolerance strategy used by small permeable invertebrates overwintering in frozen habitats. Even though an increasing number of species using this strategy have been described, little is known of the functional genomics of cryoprotective dehydration. 2. Megaphorura arctica is a northern palaearctic springtail (Collembola) which survives extreme low temperatures by cryoprotective dehydration. The massive loss of body water associated with this strategy requires a fine tuned physiological adaptation to both desiccation and cold exposure. 3. We investigated the temporal gene expression profile of six candidate genes, and compared gene expression responses to desiccation and cold separately, as well as both factors combined. 4. The major responses were found in Heat shock protein 70 (HSP70) and Trehalose-6-Phosphate-Synthase (TPS). TPS expression followed water loss closely, while HSP70 was induced after considerable water loss. HSP70 transcript response in M. arctica was induced by desiccation and rehydration, but not by exposure to cold. 5. The data suggest that cold and water loss induce partly different responses and that temporal sampling is important for uncovering the dynamics of gene responses to cryoprotective dehydration.