AUSTRALIAN researchers have found a way to stop sperm swimming, opening another avenue for developing a male contraceptive pill and shedding light on possible causes of infertility in men.

The scientists were able to cut off the fuel supply to the ''motor'' that drives human sperm, so they are left twitching and not swimming.

Illustration: Matt Golding.

Professor Moira O'Bryan, of Monash University's School of Biomedical Sciences, led the research with scientists from the University of Newcastle, John Curtin School of Medical Research and Garvan Institute of Medical Research, and the University of Cambridge, in Britain. Their study has been published in the journal PLoS Genetics.

In laboratory tests using mice, the team engineered a mutation in a gene called RABL2, which delivers protein fuel to the engine in a sperm's tail, known as the axoneme.