Ancient DNA unleashed in ice melts
Ice holds the potential to unlock ancient DNA
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Tuesday, 07, Aug 2007 08:29
Ancient DNA locked in ice could return to life as glaciers melt, a new study has found.
Researchers behind the study claim it is the first to show that ancient frozen DNA could be revived.
US scientists melted five samples of ice ranging from 100,000 to eight million years old to find the micro-organisms trapped inside and then attempted to grow them.
"First, we asked, do we detect micro-organisms at all," said Kay Bidle, assistant professor of marine and coastal sciences at Rutgers, the State University of New Jersey.
"And we did – more in the young ice than in the old. We tried to grow them in media, and the young stuff grew really fast. We recovered them [the micro-organisms] easily; we could plate them and isolate colonies. They doubled every couple of days."
Micro-organisms from the oldest ice samples grew very slowly, doubling about every 70 days.
DNA appeared to decline with age; the DNA in the five samples showed an exponential decline after 1.1 million years.
In the old ice the DNA consisted of 210 pairs, whereas the average genome size of a bacterium is three million base pairs.
Writing in the Proceedings of the National Academy of Sciences journal, the scientists claim the findings illuminate how life on Earth could have started.
"Given the extremely high cosmic radiation flux in space, our results suggest it is highly unlikely that life on Earth could have been seeded by genetic material external to this solar system," the researchers conclude.