2013年10月5日星期六

Why Do Naked Mole Rats Live So Long?

Joseph Stromberg in Smithsonian:
Mole-rat1That hairless, wrinkly, fanged rodent in the photo above? It’s a naked mole rat, and deep inside its cells, its molecular machinery might hold the secret to living a very, very long time. “They are an incredibly striking example of longevity and resistance to cancer,” says Vera Gorbunova, a biologist at the University of Rochester who studies the long-lived rodents, which have been shown to survive for up to 28 years—a lifespan eight times that of similarly-sized mice—and have never once been observed to develop cancer, even in the presence of carcinogens. In recent years, Gorbunova and her husband Andrei Seluanov have looked closely at the species, which lives in underground colonies in East Africa, hoping to figure out how exactly it manages to survive so long. As revealed in new research her team published today in Proceedings of the National Academy of Sciences, their team thinks they’ve found at least part of the answer: naked mole rats have strange ribosomes.
Every one of our cells (and, for that matter, every living organism’s cells) converts the genetic instructions present in our DNA into proteins—which control a cell’s overall operation—through a process called translation. Tiny microscopic structures called ribosomes handle this translation, reading genetic instructions that specify a particular recipe and churning out the protein accordingly. The ribosomes in almost every multicellular organism on the planet is made up of two large pieces of RNA, a genetic substance similar to DNA. But last year, one of the Rochester lab’s students was isolating RNA from cells taken from the naked mole rats when he noticed something unusual. When he separated the RNA pieces, instead of seeing two distinct pieces of ribosomal RNA, he saw three. “At first, we thought we were doing something wrong and it’d gotten damaged,” Gorbunova says. “Because for all mammals, you’d see two, but we kept seeing three.”
More here.
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