PROJECT SUMMARYThe male ejaculate of internally fertilizing organisms is a diverse mixture of components including sperm andnumerous other macromolecules that are transferred to females during mating. Research on male contributionsto fertility has mainly focused on sperm and more recently on proteins present in the seminal fluid. While thesestudies have greatly advanced our understanding of postcopulatory interactions the relatively high incidence ofidiopathic infertility suggests that investigation of understudied molecules in the ejaculate may yield novel insightsinto novel factors mediating reproductive outcomes. We previously discovered the transfer of RNA from malesto females during copulation in Drosophila arizonae. In this proposal we provide evidence gathered with fundingfrom our recent R21 award demonstrating translation of male RNA transcripts within cells of the D. arizonaefemale reproductive tract. Building off this work the goals of the proposed research are to establish functionaleffects of seminal fluid RNAs on the female postmating response (Aim 1) investigate how they function infemales (Aim 2) and identify the source and mechanisms by which they are packaged in males (Aim 3). Wecapitalize on unique aspects of our D. arizonae/D. mojavensis study system that combine to make a geneticallytractable manipulative experimental system that is particularly well suited to investigate the function of maleRNA within the female reproductive tract. With this powerful system we combine proteomic analyses using ourrecently developed Variant Assisted SILAC Proteomic Analysis (VASPA) approach with detailed investigationsof individual mdFTPs (male-derived female translated proteins). Given that RNA appears to be a conservedfeature of male ejaculates we expect our findings will have broad significance for better understandingpostcopulatory interactions across a range of species including humans.