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　　Longevity Gene Debate Opens Trans-Atlantic Rift

　　A trans-Atlantic dispute has opened up between two camps of researchers pursuing a gene that could lead to drugs that enhance longevity. British scientists say the longevity gene is “nearing the end of its life,” but the Americans whose work is under attack say the approach remains as promising as ever.

　　The dispute concerns genes that make sirtuins, proteins involved in controlling cells’ metabolism. Because of their metabolic role, the sirtuins may mediate the 40-percent-longer life enjoyed by laboratory rats and mice put on a very low-calorie diet.

　　People cannot keep to such a low-fat diet, but drugs that activate sirtuin would in principle be a painless way for humans to add years of lean and healthy life. This idea took wing when resveratrol, a substance found in trace quantities in red wine, was reported to activate sirtuin. In 2008 the pharmaceutical company GlaxoSmithKline paid $720 million for Sirtris, a start-up company trying to develop resveratrol-mimicking drugs that activate sirtuins.

　　Since then, several aspects of the sirtuin story have come under scientific

　　challenge, including doubts as to whether resveratrol’s effects are really exercised through sirtuin, and whether the sirtuins are the real or only mediators of the longevity increase linked to a low-calorie diet.