- MOSCOW (Sapa-DPA) -- A microbe
which is resistant to radiation may have come from Mars, Russian scientists
say.
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- The researchers suggest the bug may have begun life on
the red planet before being blasted to earth by an asteroid.
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- Deinococcus radiodurans can withstand a thousand times
the dose of radiation that would kill a human being. To find out how this
resistance was acquired, Anatoli Pavlov and his team from St Petersburg's
Ioffe Physico-Technical decided to blast another microbe, E.coli, with
gamma rays, according to New Scientist magazine.
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- The bugs were exposed to enough radiation to kill 99,9
percent of them and the remainder were left to recover before being exposed
to an increased dose.
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- 'It's certainly a mystery how this trait has developed
and why it persists'After 44 cycles it took 50 times the initial dose to
kill the same proportion of the bugs, but the researchers found it would
take thousands more cycles for E.coli to build up the same level of resistance
as Deinococcus.
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- On earth, that could take up to 100 million years, but
on Mars the bugs could receive the same exposure in only a few hundred
thousand years. This led the researchers to speculate that the bugs evolved
on Mars before being knocked into space by an asteroid and falling to earth
in meteorites.
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- However, Nasa astrobiologist David Morrison said it was
unlikely the bug came from Mars, as its genome was very similar to other
Earthly bacteria. Nonetheless he could not explain why Deinococcus was
so resistant to radiation.
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- "It's certainly a mystery how this trait has developed
and why it persists," he told New Scientist. - Sapa-DPA
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- http://www.itechnology.co.za/index.php?click_id=118&art_id=qw1036394640584B252&set_id=1
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