Working with fruit-flies (Drosophila melanogaster), University of East Anglia scientists have observed “remarkable” changes in female gene expression after exposure to a protein in semen. The researchers say the effects, which may also exist in other species, include altered fertility, immunity, libido, eating and sleep patterns. Published in the journalProceedings of the Royal Society B, the new findings add to the growing list of intriguing physiological effects triggered by exposure to semen.
Lead researcher Tracey Chapman said that a single protein found in semen known as the “sex peptide” changes the expression of a “remarkable array of many genes in females – both across time and in different parts of the body.”
Specifically, the researchers observed significant alterations to genes linked to egg development, early embryogenesis, immunity, nutrient sensing, behavior and, unexpectedly, phototransduction (the neural pathways involved in vision).
Chapman says the semen protein is like a “master regulator” which means that males effectively have a direct and global influence on the behaviour and reproductive system of the female. She posits that such effects may well occur across many species.
She added that the effects of semen proteins can favour the interests of males whilst generating costs in females, resulting in sexual conflict. “For example, there can be a tug-of-war, where males employ semen proteins to ensure that females make a large investment in the current brood – even if that doesn’t suit the longer term interests of females,” she explained.
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