The seminal fluid extracellular matrix: a new paradigm in reproductive biology?

In many animals, females store sperm from multiple males for weeks, months or years. This enhances female reproductive choice but can also create a “war of the sexes”, where males rapidly evolve reproductive traits that promote paternity and reproductive success.

Drosophila melanogaster is the foremost system for studying these phenomena. Male Drosophila seminal fluid contains a small protein called the “sex peptide”. The sex peptide ensures paternity of the offspring by inducing changes in female post-mating behaviour. These changes last for around 2 weeks and include increased egg laying and loss of receptivity to courting males.

The sex peptide binds to sperm stored inside the mated female. The bound sex peptide is cleaved from the sperm over a period of ~10 days, releasing a bio-active fragment that triggers and maintains the female long term post mating response.

How the sex peptide binds to sperm and how it is released are unknown. In this project, working jointly between the Cockburn and Isaac labs at the Astbury Centre, University of Leeds, you will use cutting-edge cryoEM and cryo-electron tomography with focussed ion beam millling to study the structure and function of seminal fluid complexes that mediate sex peptide signalling inside the mated female. You will relate these structures to the post-mating behaviour of mated females using experiments with transgenic flies.

This will train you in the most up-to-date structural biology methods, providing an excellent platform for your future career. It will fill an important knowledge gap in reproductive biology, and inform development of new insecticides against closely related insect pests e.g. D. suzukii, which feeds on fresh fruit and costs the agricultural industry ~$500m annually.