Gene expression profiling of diapause termination in E and Z strains of the European corn borer moth, Ostrinia nubilalis
In order to understand evolved differences in the length of larval diapause termination for Z and E-strain European corn borers (Ostrinia nubilalis), we sampled three time points along the photoperiodically-initiated and terminated diapause developmental pathway. The first sampled time point occurred when both strains were in the diapause maintenance phase under short-day diapause inducing conditions (12:12 L/D). The second sampled time point occurred on day 1 after long-day exposure (16:8 L/D), but before a physiological change in respiratory metabolism in either strain ("day 1"). The final time point was sampled on day 7 after long-day exposure and after physiological divergence between strains ("day 7"). Head tissues were sampled to capture changes in major neuroendocrine glands and the primary endogenous clock. Five individuals were pooled for each of 5 replicates per strain per time point. Total RNA was extracted with the Qiagen RNeasy kit and prepared for next-generation sequencing using the TruSeq RNA Prep kit. Six libraries were multiplexed per lane and subjected to single-end 50 bp sequencing on an Illumina HiSeq 2000.