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Molecule in male sperm suppresses female sex drive (in fruit flies)

8 August 2003

Female fruit flies have their sex drive reduced by a biologically active substance that is released from the male during the act of mating itself, according to new research from UCL, which may also have implications for human sexual activity.

The male seminal fluid contains a molecule - the sex peptide - that both makes females unwilling to mate again for several days and boosts their egg production, revealed Dr Tracey Chapman from the Department of Biology.

Using a technique called RNA interference the UCL team showed that the actions of the SP boost male paternity and act as a sort of remote 'chemical mate guard'. The results revealed that the response of females to the SP depends upon the presence of sperm, possibly because sperm themselves act as carriers to transport and stabilise the SP molecules.

"The semen of many organisms, including humans, is a similarly complex mixture of proteins, peptides and other substances," said Dr Chapman. "These results show that male sperm effectively suppresses the female sex drive reducing sexual receptivity and an elevation in egg production for up to 5 days. Further work is now necessary to discover the extent to which SP-like molecules exist in other species, particularly humans."

Notes for editors

  1. The sex peptide of Drosophila melanogaster: Investigation of post-mating responses of females by using RNA interference,' is published by PNAS.
  2. To interview Dr Chapman please contact Heidi Foden in UCL Media Relations, 020 7679 7678, h.foden@ucl.ac.uk