Don't pull the plug! the Drosophila mating plug preserves fertility

Abstract

Mating plugs are hardened structures--typically a coagulation of seminal fluid components--that are transferred to, or formed within, the female reproductive tract of numerous animal species (both mammals and insects). Analysis of the role(s) of the mating plug in reproduction has been conducted in a wide array of diverse species. These structures have been proposed to have a multitude of functions, which include altering female re-mating rate, acting as a barrier to re-mating and being required for sperm storage or sperm movement to occur in mated females. A recent analysis of the Drosophila melanogaster mating plug has shown that proper formation of the structure is required for optimal fertility in flies: the Drosophila mating plug is required to retain the ejaculate within the female reproductive tract once mating has terminated. Here, we discuss the possible implications of the Drosophila mating plug in the fertility of this species in light of these new results.

Keywords: Drosophila reproduction; PEBme; mating plug; sperm storage.

Figure 1.

Diagram of the mating plug in the Drosophila melanogaster female lower reproductive tract. The uterus is shown containing the mating plug (AMP + PMP; for anterior + posterior mating plug, respectively). The figure also shows the sperm storage organs (seminal receptacle (SR), spermathecae (ST)), the parovaria (Pa), and the lower common oviduct (Ov). The upper reproductive tract (ovaries, lateral oviducts, upper common oviduct) is not shown, for simplicity.

Figure 2.

A schematic of the PEBme open reading frame, above a graph of amino acid sequence conservation. The protein is drawn to-scale, with the black bar indicating the predicted signal sequence. PEBme's ends (blue) are more highly conserved in sequence than its central region (red), which contains the repeated motifs. Conservation scores were annotated using the physico-chemical scores of Livingstone et al., as implemented in JalView. The graph was generated in R. Scores range from 0 (no conservation) to 11 (full conservation among all species).