Sperm can adapt to sexually transmitted microbes

Researchers at the Technical University of Dresden (TUD) and the University of Sheffield have discovered that male fertility can adapt to microbes. These findings shed new light on the importance of sperm ecology and could have significant implications for evolutionary biology and medical research, particularly in understanding and treating infertility.

The work has now been published in the journal Evolution Letters.

Sperm are considered to be the most morphologically diverse cell on earth. This form of rapid evolution probably arose from competition between males for the best sperm. Now researchers at TUD and the University of Sheffield (UK) have discovered that sperm function, technically known as male fertility, adapts to sexually transmitted microbes.

The study was carried out on an insect species, the notorious bed bug. “This species was a model that we could handle very well, but we think that the results will be similar in humans,” explains Dr. Oliver Otti from TUD, who led the study.

By exposing sperm to microbes in women’s bodies, researchers found that fertility decreased by one-fifth when sperm and microbes had no prior contact. However, fertility remained unchanged when sperm and microbes were familiar with each other.

“We know that some microbes damage sperm and thus reduce fertility, but this study shows for the first time that sperm adapt to them,” explains Oliver Otti.

“We had expected a small effect,” adds Klaus Reinhardt, Professor of Applied Zoology at TUD, “but the fact that sperm function was reduced by more than a fifth was really surprising.”

“Perhaps our results can explain why some studies find no influence of microbes on human male fertility, but others do – the studies may differ on whether sperm and microbes have a common evolutionary history or not.”