FYI, from a colleague....
Jaro
> Subject: Circling the DNA wagons against radiation...
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> Posted on today's CBC site (http://cbc.ca/stories/2003/01/09/bacteria_rad030109)
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> Strong ring of DNA helps microbe resist radiation
> Last Updated Thu, 09 Jan 2003 19:50:01
> REHOVOT, ISRAEL - Bacteria that can eat up nuclear waste protect their DNA from radiation damage by packing the genes into a tight ring, researchers have found.
> Deinococcus radiodurans is not only the world's most radiation-resistant organism, but it can also survive extreme cold and dryness.
> For decades, researchers have been trying to figure out how the bacterium resists radiation. Most organisms have enzymes to repair DNA, but Deinococcus' enzymes didn't show anything special.
> Now Israeli chemists think the key could be its dense ring of tightly packed DNA.
> Radiation causes pieces of DNA to break off. The researchers suspect Deinococcus' tight ring keeps the bacterial DNA fragments in place and in order until they come back together.
> Prof. Avi Minsky of the Weizmann Institute of Science's Organic Chemistry Department and his colleagues also found the bacteria have four copies of DNA.
> The backups allow one copy to do its job of moving around to produce proteins while the three others remain packed in the protective ring.
> Unfortunately, human DNA is structured very differently so we won't benefit directly from the finding, Minksy said.
> As for how the bacteria developed an appetite for radiation, no one knows. A team of Russian scientists believes Deinococcus originated on Mars, where radiation levels are higher.
> Others, including Minksy, believe the bacteria evolved the resistance to cope with harsh, dry environments on Earth.
> The study appears in Friday's issue of the journal Science.
>
> Bacterial DNA ring is stained blue
> Courtesy: Avi Minsky
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