Re: [DIYbio] Information physics and theoretical limits of extremely old DNA?

I've been wondering about ancient DNA.

There is at least one claim from the panspermia folks that says, among other things, that DNA and microbes can travel on asteroids for millions of years. But at the same time, nobody has figured out a reliable PCR protocol for extracting DNA from million-year-old bugs trapped in ambers. We've successfully extracted DNA from "recently" deceased hominids and other creatures- say, those that have been living within 50 kya.

"Assuming physiological salt concentrations, neutral pH and a temperature of 15 C, it would take about 100k years for hydrolytic damage to destroy all DNA that could be reasonably retrieved (Hoxreiter et al., 2001)."

via: http://email.eva.mpg.de/~paabo/pdf1/HofreiterAncDNA_NatRev2001.pdf

which primary cites "Instability and decay of the primary structure of DNA" (too old to find a copy?).

Meanwhile.. the panspermia claim is over here from Wikipedia: "Studies of bacteria frozen in Antarctic glaciers have shown that DNA has a half-life of 1.1 million years under such conditions, suggesting that while life may have potentially moved around within the Solar System it is unlikely that it could have arrived from an interstellar source. [68]"

http://ur.rutgers.edu/medrel/viewArticle.html?ArticleID=5898

... ha, a "half-life". Anyway, their reference doesn't exist anymore, so if anyone knows the actual study in question, I'd like to know about it too.

I haven't seen any particular study about million year old DNA molecules. Gamma photons will probably screw it up over time, and the salt concentration has to play a role somewhat. But I would expect something like a theoretical study about the possible ways that DNA could be stored reliably, and then seek out fossilized or ancient DNA by looking for similar conditions. I am not convinced that "drill into amber, insert some buffer mix into a fly carcass, PCR the mix" is a reliable strategy for extracting old DNA. The DNA could be found first through some physical technique, like scanning probes or something.

Does anyone have some better documents I could look over?

- Bryan
http://heybryan.org/
1 512 203 0507

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