BMP-signalling inhibition inDrosophilasecondary cells remodels the seminal proteome, and self and rival ejaculate functions

Abstract

51Seminal fluid proteins (SFPs) exert potent effects on male and female fitness. Rapidly evolving 52 and molecularly diverse, they derive from multiple male secretory cells and tissues. In 53 Drosophila melanogaster, most SFPs are produced in the accessory glands, which are 54 composed of ~1000 fertility-enhancing 'main cells' and ~40, more functionally cryptic, 55 'secondary cells'. Inhibition of BMP-signalling in secondary cells suppresses secretion, 56 leading to a unique uncoupling of normal female post-mating responses to the ejaculate: 57 refractoriness stimulation is impaired, but offspring production is not. Secondary cell 58 secretions might therefore make a highly specific contribution to the seminal proteome and 59 ejaculate function; alternatively, they might regulate more global -but hitherto-undiscovered 60 -SFP functions and proteome composition. Here, we present data that supports the latter 61 model. We show that in addition to previously reported phenotypes, secondary cell-specific 62 BMP-signalling inhibition compromises sperm storage and increases female sperm use 63 efficiency. It also impacts second male sperm, tending to slow entry into storage and delay 64 ejection. First male paternity is enhanced, which suggests a novel constraint on ejaculate 65 evolution whereby high female refractoriness and sperm competitiveness are mutually 66 exclusive. Using quantitative proteomics, we reveal a mix of specific and widespread changes 67 to the seminal proteome that surprisingly encompass alterations to main cell-derived proteins, 68indicating important cross-talk between classes of SFP-secreting cells. Our results demonstrate 69 that ejaculate composition and function emerge from the integrated action of multiple secretory 70 cell-types suggesting that modification to the cellular make-up of seminal fluid-producing 71 tissues is an important factor in ejaculate evolution. 72 73 74 75 76

The evolution of sex peptide: sexual conflict, cooperation, and coevolution

“…However, there is no evidence that SP influences ejaculate processing. Drosophila melanogaster females can eject sperm after mating (Lüpold et al ., 2013; Lee et al ., 2015; Hopkins et al ., 2019a), but there is no evidence that SP influences this process: females mated to SP ‐null males store equivalent sperm quantities to females mating with SP‐transferring males (Avila et al ., 2010).…”

Experimental evolution under varying sex ratio and nutrient availability modulates male mating success in Drosophila melanogaster

“…Both suppression of female remating and the ability of a male's sperm to resist displacement by subsequent ejaculates are strongly driven by the transfer of seminal fluid proteins [32,33]. Previous work revealed that female remating propensity and sperm competitiveness are independent and possibly under the regulation of different glandular cell types and a distinct set of proteins [34]. Our results are consistent with the hypothesis that populations that evolved on a protein-restricted diet have altered seminal fluid composition and transfer, with changes limited to a subset of ejaculate functions.…”

Octopaminergic/tyraminergicTdc2neurons regulate biased sperm usage in femaleDrosophila melanogaster

“…Females were later dissected in 1X PBS to examine the presence of mating plugs in the bursae. 2) Immediately after mating, females were transferred to custom-designed mating plug ejection chambers (Hopkins et al . 2019) that were then covered with a piece of coverslip and secured with tape on diagonal corners.…”

“…Females were later dissected in 1X PBS to examine the presence of mating plugs in the bursae. 2) Immediately after mating, females were transferred to custom-designed mating plug ejection chambers (Hopkins et al 2019) that were then covered with a piece of coverslip and secured with tape on diagonal corners. Mating plug ejection chambers measure 34 mm × 33 mm × 9 mm with a concave depression of 20 mm × 20 mm × 7 mm, and were 3D-printed with black PLA filament at MannUfactory at Cornell University.…”