Meeting Abstract
Diapause, an alternative developmental pathway, provides animals a means to “escape” from hostile environments. This dormant state, defined by arrested development, depressed metabolism, and increased stress tolerance, is regulated endogenously, at least in part, by the endocrine system including ecdysone and insulin signaling pathways. Accumulating evidence suggests microRNAs regulate diapause and may work in conjunction with the endocrine system. Helicoverpa zea (i.e., the corn earworm) enters diapause during the pupal stage following exposure to short day-lengths during the larval stage. Diapause in this species is associated with downregulation of both the ecdysone and insulin signaling, and with significant changes in the miRNA abundances. High-throughput sequencing was used to identify and quantify microRNAs in diapausing and nondiapausing H. zea. Overall, 108 microRNAs were differentially regulated. Forty conserved (i.e. previously identified) and 20 putative, novel microRNA sequences were more abundant in diapausing pupae, and 31 conserved and 16 novel miRNAs were less abundant in diapausing pupae compared to nondiapausing pupae. Notably, miR-34 and miR-252 were, respectively, 3.87 and 1.79-fold more abundant in diapausing pupae. These miRNAs are involved in ecdysone biosynthesis and signaling in insects. Computationally predicted gene targets of miR-34 include ecdysone-induced protein 74EF and ecdysone receptor, and one target of miR-252 is cytochrome p307A1, a gene in the ecdysone synthesis pathway. In addition, miR-277 abundance was 60 % lower in diapausing pupae than in nondiapausing pupae. miR-277 regulates metabolism via insulin signaling in diapausing insects. Taken together, these changes in microRNA abundance provide preliminary evidence that microRNAs work in conjunction with the endocrine system to regulate diapause in H. zea and possibly other insects.
