Abstract

We have recently developed a set of tools in Drosophila to identify and then characterise microcarriers and their association with Sex Peptide. These now allow us to study this interplay and the roles of other interacting proteins in seminal fluid signalling and the induction of female LTR. We will use a range of assays to: a. Assess the regulation of microcarrier production, structure and release from secretory cells; b. Investigate the loading of Sfps on microcarriers, using GFP-fusions such as SP-GFP, and the subsequent dispersal of these cargos in females; c. Identify novel microcarrier cargos through a proteomics approach; d. Determine the effect of mating on different long-term post-mating responses in females, namely egg laying, sperm competition and reduced receptivity to remating, and combine these assays, most of which are quantifiable, to assess the effects of knocking down specific gene transcripts expressed in the accessory gland, which we hypothesise play a role in SP-dependent microcarrier signalling. Using these approaches, we will: i. Determine how the SP network genes regulate SP and microcarrier function, particularly the release and relocalisation of SP in the female reproductive tract; ii. Test how SP and microcarriers co-operate together to regulate microcarrier structure and delivery of Sfps, and promote fertility; iii. Identify other microcarrier regulators and cargos from proteomics screens and determine their roles in microcarrier biology and reproductive signalling. These studies will provide the most comprehensive picture to date of how specific proteins and signalling structures function together in seminal fluid to enhance the fertility of females and suppress competition from other males. Since many proteins we study are evolutionarily conserved or members of conserved protein classes, our findings should be relevant to fertility in other animals and the technologies employed to modulate it.