PgmNr D1148: Male proteins mediate the binding of sex peptide binding to sperm to prolong post-mating responses in D. melanogaster females.

Authors:
Akanksha Singh 1 ; Geoffrey D. Findlay 2 ; Mariana F. Wolfner 1


Institutes
1) Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA; 2) Department of Biology, College of the Holy Cross, Worcester, Massachusetts, USA.


Keyword: physiology of adult organs

Abstract:

Drosophila melanogaster seminal proteins induce several post-mating responses in mated females, some short-term and others lasting for days. The long term post-mating responses, which include elevation of egg-laying, regulation of sperm release from storage, and changes in mating receptivity and behaviour, are mediated by the seminal protein Sex Peptide (SP), which is retained in the female by its binding to sperm. To test whether male-derived proteins are sufficient for SP binding to sperm, we examined the extent of this binding in ejaculates (produced by fru-GAL4;UAS-dTRP-A1 males in the absence of females), compared to that seen in the bursa and seminal receptacle of mated female. By immunofluorescence and Western blotting we see that SP can bind to sperm in ejaculates, indicating that male contributions are sufficient for this step. However, the level and distribution of this SP-sperm binding differs a bit from that seen on sperm isolated from the bursa or seminal receptacle, suggesting possible assistance by female components. Some male-derived seminal proteins needed to bind SP to sperm are known. To identify the full suite, and any sperm proteins that are required for SP binding, we used a comparative genomic method to pinpoint proteins whose evolutionary rates across the Drosophila phylogeny co-vary with the SP network proteins. Twenty-six such candidates are being tested for effects on the persistence of post-mating response and for their effects on SP binding to sperm.