UW Today

August 9, 2011

Study of abalone spawning could have implications for human reproduction

News and Information

For the first time, scientists have been able to study interactions between individual sperm and eggs of red abalone in conditions similar to its ocean surroundings and made precise chemical measurements and models of the interactions. The work could have implications for improving fertilization in humans and other mammals.

The red abalone, seen above, is a large edible sea snail commonly found in California waters. Below, two red abalone are seen in the act of spawning.

The red abalone, seen above, is a large edible sea snail commonly found in California waters. Below, two red abalone are seen in the act of spawning.Ignacio Vilchis, U. of Washington

The science team, including Jeffrey Riffell, a University of Washington assistant professor of biology, used a laboratory simulation of an abalones natural habitat to determine conditions in which sperm were most likely to encounter eggs and fertilization was most likely to occur.

The work, led by Richard Zimmer at the University of California, Los Angeles, was published recently in the online edition of the Proceedings of the National Academy of Sciences.

Abalone spawn all year long, with females releasing several million eggs and males sending billions of sperm directly into the ocean. The scientists found that tryptophan, a molecule released from abalone eggs to attract sperm, actually forms a plume around an egg that increases the size of the sperms target by as much as five times.

As the sperm float and disperse on natural eddies and currents in the water, the plume “makes it much easier for sperm to locate the egg, and that enhances fertilization,” Riffell said.

“The same kind of fluid motions occur in the mammalian reproductive tract,” he said.

Trypotophan is an amino acid that plays a key role in organism development and growth. But an egg has to release very little of its tryptophan reserve to create the plume that attracts sperm.

Riffell noted that abalone dont seem to suffer the same stuporous effect from tryptophan as do humans who have enjoyed a little too much Thanksgiving turkey.

“In our case, the tryptophan makes us drowsy, but for the sperm cells it actually increases their activity,” he said.

The research is funded by the National Science Foundation, the National Institutes of Health, the National Oceanic and Atmospheric Administration and UCLAs Council on Research.

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For more information, contact Riffell at 206-685-2573 or jriffell@uw.edu.