Tuesday, December 2, 2008

Persistent Pollutant May Promote Obesity

“Tributyltin, a ubiquitous pollutant that has a potent effect on gene activity, could be promoting obesity, according to an article in the December issue of BioScience. The chemical is used in antifouling paints for boats, as a wood and textile preservative, and as a pesticide on high-value food crops, among many other applications. Tributyltin affects sensitive receptors in the cells of animals, from water fleas to humans, at very low concentrations - a thousand times lower than pollutants that are known to interfere with sexual development of wildlife species. Tributyltin and its relatives are highly toxic to mollusks, causing female snails to develop male sexual characteristics, and it bioaccumulates in fish and shellfish. The harmful effects of the chemical on the liver and the nervous and immune systems in mammals are well known, but its powerful effects on the cellular components known as retinoid X receptors (RXRs) in a range of species are a recent discovery. When activated, RXRs can migrate into the nuclei of cells and switch on genes that cause the growth of fat storage cells and regulate whole body metabolism; compounds that affect a related receptor often associated with RXRs are now used to treat diabetes. RXRs are normally activated by signaling molecules found throughout the body.”


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