Temporal dynamics of transcriptome change in Drosophila S2R+ cells after a temperature shift from 25 to 14°C

Cells in ectothermic organisms often maintain homeostatic function over a considerable range of ambient temperatures. However, as temperature has pronounced effects on all biological processes, but not necessarily in a uniform manner on each of the myriad of distinct processes, cellular acclimation to distinct temperatures is predicted to involve complex regulation. To assess the effects of a temperature downshift from 25 to 14°C, i.e. from the optimal temperature to the lower limit of the readily tolerated range, on the transcriptome in a time-resolved manner, we have performed expression profiling with S2R+ cells, which are derived from the ectothermic organism Drosophila melanogaster. Aliquots of S2R+ cells were plated and incubated at 25°C for 36 hours before a temperature downshift shift to 14°C was applied. At 0, 4, 12, 24 and 72 hours after the temperature downshift, total RNA was isolated and processed for hybridization to microarrays. For control, an additional aliquot was maintained at 25°C for 12 hours rather than shifted to 14°C, resulting in a cell density comparable to that obtained after 72 hours at 14°C. The experiment was teplicated until at least three replicates of sufficient technical quality were available for each time point.