Towards a molecular and functional analysis of the Drosophila mating plug. Frank W. Avila, Fatima S. Ameerudeen, Mariana F. Wolfner. Dept Mol Biol & Gen, Cornell Univ, Ithaca, NY.

   In many animals, a mating plug is formed in the female reproductive tract during and/or after mating. Mating plugs are composed of male seminal fluid proteins (SFPs), and have been shown to have a wide range of functions across numerous species. In insects, the structure has been shown to be required for the storage of sperm, acting as a physical barrier to re-mating, and decreasing female receptivity to re-mating (Avila et al., 2011). In the house mouse, proper mating plug formation is required for fertility, as malformation of the structure decreases the probability that sperm will reach the uterus (Murer et al., 2001). In D. melanogaster, a mating plug is formed within minutes after the start of mating and is comprised of two distinct parts: a posterior region (posterior mating plug, PMP) composed of proteins from the male ejaculatory bulb, and an anterior region (AMP) composed of proteins from the male accessory gland. In D. melanogaster, a handful of mating plug proteins have been identified to date (Peb, PebII, and Acp36DE), and at least one of them (PebII) has been reported to be necessary for a short-term decrease in sexual receptivity. To fully assess the structure and role of the mating plug in Drosophila reproduction, we used mass spectrometry to identify the most abundant proteins of mating plugs dissected from females at 1 hour post-mating. This analysis revealed >60 proteins. Using RNAi knockdown we removed individual mating plug candidates from the male ejaculate and examined for a role in mating plug formation and subsequent post-mating processes. Of the 10 candidates screened thus far, we have found two that reduce female fertility.