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Frontiers
NSF in the News

October 1997

ADVANCES IN MALE BIRTH CONTROL

Biochemist Joseph Hall is putting blindfolds on sperm and closing in on a possible birth control method for men. Hall, of the North Carolina State University in Raleigh, is supported by NSF's Division of Integrative Biology and Neuroscience. In the last decade, Hall has learned how sperm make their way toward the eggs and what compounds can safely and effectively stop that progress.

He recently developed a synthetic compound that "blinds" rat sperm. "I've worked on this for more than 10 years," he says, "and now I feel that we're getting close to identifying a beginning point for sperm-targeted contraceptive development."

Hall found that the compound, a sugary substance, inhibits 98 percent of the enzymatic activity needed for rat sperm to recognize an egg without altering the rat's hormonal balance. He's now testing the compound on bull and human sperm.

"The sugar analog appears to have a short onset of action, negligible effects on the libido, and no residual effect on fertility after the dosage has been discontinued," says Hall.

His analog works by inhibiting the activity of the B' form of the N-acetyl-beta-D-hexosaminidase enzyme, which is secreted and inserted into sperm cells after they leave the testis. The sperm then move into a long, tubelike organ called the epididymis. The enzyme is in most other cells in both the A' and B' forms, but sperm carry only the B' variant.

"The B' variant gives sperm their 'eyes,' so to speak," he says. "When you inhibit it, you essentially create blind sperm that cannot recognize eggs. But because you are not inhibiting the A' variant, you are not preventing the enzyme from performing its necessary physiological function on the rest of the body."

In addition to the 98 percent inhibition found when the experiments were performed on rat sperm in test tubes, Hall's analog blocks fertilization by about 90 percent when given to rats orally.

Additional work is needed before scientists will know for sure whether the analog is safe and effective on humans, but Hall's recent discoveries take researchers one step closer to a male contraceptive.


FORESTS AND STREAMS

Most people already know that trees are beneficial to ecosystems. Soon, this simple notion may lead to new public policy. Scientists at the Stroud Water Research Center, a field station funded by NSF, will spend the next three years studying the effects of forestation on stream life in Pennsylvania and Maryland. If the results are demonstrative enough, replanting may begin along the banks of streams that have been barren for centuries.

Streams with forested banks have channels that are two to four times wider than deforested streams, Bernard W. Sweeney, Director of the Center, told the New Britain, Conn. Herald. "By restoring the width, you increase the capacity to ... sustain life." The NSF study will focus on the effects of creating "forest buffers" around streams, with researchers measuring stream size, temperature and increased numbers of life forms.

So far, the response from landowners experimenting with reforestation has been overwhelmingly positive. The streams are healthier, they report, and bird populations have visibly increased.

 


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