Fancy goggles, a swimming cap or the latest high-tech suit won’t help human sperm power through their race to fertilize an egg. Instead, the tiny cells rely on a proton-shedding pore to speed toward their target, a study in the Feb. 5 Cell finds.
The study also reports that a compound similar to the active ingredient in marijuana might interfere with this channel, offering a molecular link between habitual marijuana use and male infertility. Finding other compounds that open or close the channel may offer new ways to control reproduction, the authors say.
Researchers knew that powerful sperm swimming depends on protons leaving the sperm cell, thereby lowering its acidity. The concentration of protons inside a sperm is roughly 1,000 times higher than outside, says a coauthor of the new study, Yuriy Kirichok, a biophysicist at the University of California, San Francisco. As protons flood out of the cell like air let out of a balloon, a host of changes kick the sperm’s swimming into high gear. But just how the protons escaped was a mystery.