Meeting Abstract
The physiological responses to long-term, ecologically relevant temperature stress are poorly understood. In insects, long-term low temperature exposure can lead to chill injury. However, periodically increasing temperatures during chilling has been shown to increase survival. The transcriptomic response for this increase in survival have never been characterized. Here we present the first transcriptome-level analysis of increased longevity under fluctuating temperatures during chilling. Overwintering post-diapause quiescent alfalfa leafcutting bees, Megachile rotundata, were exposed to a constant temperature of 6°C or 6°C with a daily fluctuation to 20°C. RNA-seq was performed at two different time points, before and after mortality rates began to diverge between temperature treatments. Expression analysis identified differentially regulated transcripts functioning in ion homeostasis, metabolic pathways, and oxidative stress response. The exact timing of these gene expression changes was determined by measuring expression of selected transcripts at two-week intervals. Taken together, these results provide genetic support for the hypotheses that fluctuating temperatures protect against chill injury by reducing oxidative stress and returning ion concentrations and metabolic functions to favorable levels. In addition to these established mechanisms, we identified additional mechanisms, immune response and neurogenesis, that are associated with increased longevity during chilling in M. rotundata.
