URBANA Who knew that male fertility depends on sperm-cell architecture? A University of Illinois study reports that a certain omega-3 fatty acid is necessary to construct the arch that turns a round, immature sperm cell into a pointy-headed super swimmer with an extra long tail.
"Normal sperm cells contain an arc-like structure called the acrosome that is critical in fertilization because it houses, organizes, and concentrates a variety of enzymes that sperm use to penetrate an egg," said Manabu Nakamura, a U of I associate professor of biochemical and molecular nutrition.
The study shows for the first time that docosahexaenoic acid (DHA) is essential in fusing the building blocks of the acrosome together. "Without DHA, this vital structure doesn't form and sperm cells don't work," said Timothy Abbott, a doctoral student who co-authored the study.
Men concerned about their fertility may wonder what foods contain DHA. Marine fish, such as salmon or tuna, are excellent sources of this omega-3 fatty acid.
The scientists became intrigued with DHA's role in creating healthy sperm when they experimented with "knockout" mice that lack a gene essential to its synthesis. "We looked at sperm count, shape, and motility, and tested the breeding success rate. The male mice that lacked DHA were basically infertile," Nakamura said.
But when DHA was introduced into the mice's diet, fertility was completely restored. "It was very striking. When we fed the mice DHA, all these abnormalities were prevented," he said.
The scientists then used confocal laser scanning (3D) microscopy to look at thin slices of tissue in progressive stages of a sperm cell's development. By labeling enzymes with fluorescence, they could track their location in a cell.
"We could see that the acrosome is constructed when small vesicles containing enzymes fuse together in an arc. But that fusion doesn't happen without DHA," he said.<
|Contact: Phyllis Picklesimer|
University of Illinois College of Agricultural, Consumer and Environmental Sciences