Control of pheromone production by ovaries in Drosophila

Drosophila pheromones are long chain hydrocarbons (CHCs) produced by specialized epidermal cells, the oenocytes. Here we were explored the role of ovaries in CHC regulation. We studied tudor, a grandchildless-like mutation, resulting in progeny without ovaries and three alleles of ovoD, resulting in ovarian defects depending on the strength of the allele. We show here that these mutant flies with no or abnormal ovaries have a decrease in C29 length CHC ratio, balanced by an increase in C23 and C25 length ratio; this effect is dependent on the strength of the mutation. An increase in the amount of CHCs also occurred but was not related to the strength of ovoD alleles. As ovaries are the main site of ecdysone production in females, we knocked down the receptor to ecdysone EcR in the oenocytes and obtained increased amounts of CHCs and inhibition of long chain CHC synthesis, showing that the lack of an ecdysone signal arriving into the oenocytes is responsible for these defects. We then investigated the role of follicular cells and oocyte on CHC regulation: we RNAi-knocked down the LPR receptors in the oocyte to hinder vitellogenesis without significantly modifying CHC profile. We then expressed apoptosis genes within the follicle cells or within the ovocytes and obtained less long chain and more short chain CHC levels in the former case and an enhanced CHC production in the latter case. Together, these results support the notion of an interaction between oocyte and follicular cells, which send an ecdysone signal to the oenocytes to regulate CHC synthesis.