Scientists have discovered genes for hibernation in humans.
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- The discovery could pave the way for human hibernation
of the kind foreshadowed for astronauts in the 30-year-old film 2001: A
Space Odyssey.
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- Human hibernation would make ultralong-haul space travel
feasible, with crews effectively put to sleep for months, or even years,
by triggering the hibernation genes that man's distant ancestors used
millions of years ago to sleep through hostile winters.
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- The American army, which has been funding the research,
is interested in the concept of inducing protective hibernation in battlefield
casualties to keep them alive when medical help is not at hand.
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- Researchers in Britain are also investigating the role
of genes in the mini-hibernation of Siberian hamsters, with the aim of
triggering similar genes in humans to help people lose weight.
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- But the first use of hibernation technology is likely
to be in transplant surgery, where donor organs would be preserved on shelves
for weeks or months by putting them into a state of deep sleep.
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- After a five-year project, Matthew Andrews, associate
professor of genetics at North Carolina State University has identified
two genes - PL and PDK-4 - which appear to mastermind hibernation.
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- One stops carbohydrate me-tabolism, which ensures that
the glucose that animals have stored in their body from their last meal
is preserved for use by the brain and central nervous system. The second
gene controls the production of an en-zyme that breaks up stored fatty
acids, and converts them into usable fats for fuel. As a result, the animal
can tick over on its stored fat.
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- Hibernation in animals is characterised by huge drops
in heart rate, body temperature and metabolism, resulting in long-term
dormancy. In this state, body temperature is only a few degrees above freezing,
oxygen consumption is down to 2% of normal, and the heart rate drops from
up to 300 beats a minute to just three or four.
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- Researchers found the genes can be made to work in similar
ways in humans. The PDK-4 gene, for example, is switched on by starvation,
when its job is to conserve glucose.
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- The next target is to track down the triggers which start
the genetic process that leads to the seasonal shutdown. One theory is
that melatonin, the hormone whose production responds to light, may be
involved.
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- At the Rowett Institute in Aberdeen, director Dr Peter
Morgan and his team have been working on the role of melatonin in the mini-hibernation
of the Siberian hamster.
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- "We think that the central mechanisms which regulate
body weight are finely tuned by melatonin, that they respond to the changes
in the length of day, the photo period, and make the changes that control
food intake, body weight, and energy expenditure," he says.
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- The research aims to identify what genes are involved
in triggering the loss of body fat, and to find a way of kick-starting
the same genes in humans as a way of losing weight.
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