2015年6月4日 星期四

The Secret To Living 200 Years? Ask A Whale【長壽】

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The Secret To Living 200 Years? Ask A Whale

The late Henry Allingham, the oldest British man ever, once told Brighton’s Argus newspaper that the secret of his longevity was “cigarettes, whisky and wild, wild women”.
It’s not the orthodox prescription. But the latest ideas about how to extend human life are even more iconoclastic.
Scientists studying longevity have for the first time sequenced the genome of the bowhead whale (Balaena mysticetus) and have found some intriguing differences to its DNA which may explain how it manages to live as long as 200 years − making it the longest-lived mammal.
And they hope that this knowledge will eventually allow them to grant humans much longer life-spans too.

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A bowhead whale can live for 200 years (Photo credit: AnimalSpot.net)
“We believe that different species evolved different ‘tricks’ to have a long lifespan,” said Joao Pedro de Magalhaes of the University of Liverpool, who led the team. “We may be able to apply these findings to humans in order to fight age-related diseases.”
People have been searching for a way to beat death, or at least delay it, for countless centuries.
Spanish explorer Juan Ponce de Leon is said to have discovered Florida while searching for a fountain of youth, though scholars note that this motive wasn’t attached to him until after his death.
Scientific advances have been more successful at pushing average life expectancy to higher levels than the Conquistador was. However, most of the gains have come by cutting the number of infant and child deaths.
Even with the best of modern medicine, few people become “super-centenarians”, passing the 110-year mark. (Allingham was 113 when he died in 2009.) Bowheads pass that mark as gracefully as they would swim by an Arctic iceberg.
The whales are known for the huge bony skulls, which they use to break through the polar ice. They are the world’s second largest animals after their more famous cousins the blue whales. An adult typically measures 15 metres (50ft) and weighs 60 tonnes. (Their tongues alone way a tonne each.)
And that means they have lots of cells — about a 1,000 times as many as humans have. It would be reasonable to conclude that this gives them 1,000 times as many chances to get cancer. But it isn’t so.
“Given their large size and longevity, their cells must have a massively lower chance of developing into cancer when compared to human cells,” theresearchers said.
Moreover, the animals show few signs of other diseases until they get to advanced ages compared to humans.
Dr Magalhaes’s team identified mutations in the whales’ genes linked to cancer and aging, and the gain or loss of genes associated with DNA repair and cell-cycle regulation.
“Our results expand our understanding of the evolution of mammalian longevity,” the authors say in the paper published in Cell Reports.
The researchers are also looking at adaptations that helped the whales grow to such a huge size.
“Whale cells have a much lower metabolic rate than those of smaller mammals,” Dr Magalhaes said. “We found changes in one specific gene involved in thermoregulation [called UCP1] that may be related to metabolic differences in whale cells. This might allow us to see how and why bowhead whales and other similar creatures have sustained such an enormous size.”

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