More than molting: Ecdysone signaling in adult Drosophila
Authors: Zachary Drum; Joseph Coolon
Affiliation: Wesleyan University
Keywords: d. evolution of gene expression; m. adaptation
Ecdysone signaling is critical for successful life-cycle transitions in developing holometabolous insects, but the role of ecdysone signaling in adult insects is understudied. Previous work in adult Drosophila melanogaster has found roles for ecdysone signaling in many different processes like stress responses, courtship behavior, reproduction, and lifespan, but the ecological relevance of ecdysone in adults is not well understood. Our work examining the transcriptional response of Drosophila sechellia to the toxic volatiles found in its host plant Morinda citrifolia has predicted both the ecdysone receptor (EcR) and the ecdysone induced transcriptional repressor blimp-1 to be involved in the transcriptional response to these compounds. Altering the expression of these genes in adult D. melanogaster alters survival from octanoic acid (OA) toxicity. When D. melanogaster and D. simulans flies are fed food containing the active form of ecdysone (20E), their survival significantly increases and when D. sechellia flies are fed 20E, their survival on OA significantly decreases. The expression of genes involved in ecdysone response and biosynthesis are significantly different in these different fruit fly species, so examining basal ecdysone titers, 20E titers in response to OA exposure, and the genome wide transcriptional response to 20E by RNA-sequencing will help us understand if the ecdysone signaling differs in these species. Understanding how ecdysone signaling relates to OA resistance in D. sechellia may help elucidate how D. sechellia has adapted to specialize on the fruit of M. citrifolia and provide an ecologically relevant role of ecdysone in adult Drosophila.