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Nature's Vacuum: A Fern That Sucks Up Arsenic


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Nature's Vacuum: A Fern That Sucks Up Arsenic

Arsenic cleanup is a top priority for the Environmental Protection Agency. In mid-January, federal regulators reduced the permitted level of arsenic in drinking water from 50 parts per billion to 10 ppb. To comply with this new standard, the American Water Works Assn. estimates at least 10% of the nation's water providers must do some serious cleanup.

To solve the problem completely, however, engineers also need to go to the source: hundreds of acres of soil contaminated by arsenic-laced waste from manufacturing plants and other businesses. Typically, that would entail carting away and storing thousands of tons of contaminated earth. New research published in the Feb. 1 issue of Nature suggests a better and cheaper way: enlisting the lowly brake fern.

The ability of plants and trees to vacuum up heavy metals such as zinc and nickel from soil has long been known. But until recently, no one had ever discovered a plant that could suck up arsenic. To find one that did so, Lena Q. Ma, a chemist at the University of Florida, collected 15 different plant species growing near arsenic-laden soil and tested them to see how much of the metal they had accumulated. Only the brake fern contained significant amounts of arsenic--as much as 7,500 parts per million, which is more than 200 times the level seen in the soil.

Ma notes that high levels of arsenic kill most plants, gumming up the inner workings of their cells. But the brake fern seems to thrive on the poison and actually grows better in its presence. Ma believes the plant actually stores the arsenic in a nontoxic form in its fronds. Once the metal is in the plant, it's no longer a hazard.Edited by Ellen LickingReturn to top

Bad News for Teeth Grinders

Grinding or clenching of teeth during sleep has long been linked to tooth loss, headaches, and jaw pain. An international team of sleep researchers has found a link between this syndrome, known as bruxism, and sleep apnea, which involves potentially deadly gaps in breathing during sleep.

The study, published in the January issue of Chest, hinges on interviews with more than 13,000 people in Britain, Germany, and Italy. The findings suggest that bruxism is not only a serious medical condition but also extremely common. About 8% of those surveyed reported grinding their teeth at least once a week, suggesting that 27 million Americans may be afflicted.

Both the exact cause of bruxism and its link to sleep apnea remain unclear. Dr. Maurice M. Ohayon, a sleep expert at the Stanford University School of Medicine and the study's lead researcher, suspects that bruxism and sleep apnea share the same anatomical cause, perhaps an abnormality of the jawbone or jaw muscles. He urges doctors and dentists who see signs of bruxism, such as unusual wear and damage to the teeth, to check for sleep apnea, which can be treated.By Mitch Nelin; Edited by Ellen LickingReturn to top

Biofilms: Getting a Grip on Slime

Pathogenic bacteria and fungi tend to travel in packs, forming slimy communities called biofilms. The implications add up to a medical nightmare: Doctors estimate that at least 5% of the patients who receive stents and catheters each year develop grave infections from biofilms growing on their devices.

Scientists are beginning to understand how and when bacteria form these sticky mats. But little is known about the colonies formed by Candida and other fungi. That may soon change, however, thanks to a new line of investigation described in the Feb. 2 issue of Science.

Todd B. Reynolds and Gerald R. Fink, both of the Whitehead Institute at Massachusetts Institute of Technology, have discovered a way to make ordinary baker's yeast form biofilms. When the yeast cells are grown on a mucus-like surface, they quickly form amazing, flower-like blooms.

With the blooms in hand, the researchers pinpointed genes that might play a role in the process. And they found that mutations in an adhesive protein called Flo11p, which is located on the yeast's outer cell wall, prevent biofilm formation. The next challenge is to identify compounds that gum up this protein and halt the formation of the films.Edited by Ellen LickingReturn to top


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