Old DNA

[arcticpenguin]

We had a thread while back about recovering DNA from fossils, but I can't find it. Anyway, there is a new study which claims to have identifed plant DNA between 300 and 400 thousand years old.

http://news.bbc.co.uk/1/hi/sci/tech/2949629.stm

They also claim to have found DNA from vaious animals like lemmings, mammoth, reindeer, bison and horse.

So how did they do it, did they use a new extraction technique on old fossils? No! They didn't use fossils. They dug up some dirt from the permafrost.

I am rather skeptical of this. So far I have not seen the original article, just descriptions of their findings. I would like to know what safeguards and controls they used. I'd also like to know what they didn't find - for example, did they try searching for kangaroo DNA? If they had found that in Siberia I would doubt their other findings as well.

[Goshawk]

Well, AP, if you mean you're wondering about contaminated samples, you're not the first one, apparently.The researchers, led by Eske Willerslev of the University of Copenhagen, have tried to avoid any dispute in this case by getting researchers in other laboratories to verify their work. The Ancient Biomolecules Centre is a serious institution and not some crackpot organization (which was my first thought when I read their name, LOL.)

http://evolve.zoo.ox.ac.uk/projects.html
http://abc.zoo.ox.ac.uk/
http://abc.zoo.ox.ac.uk/Facilities/fac.html
The Ancient Biomolecules Centre consists of two facilities - an Ancient DNA Facility situated in the Oxford University Museum of Natural History (NHM) and a Molecular Analysis Facility in the Department of Zoology.

The physical separation of the two facilities is critical because ancient DNA research can only be performed in a physically isolated environment, free of contaminating DNA. The amount of DNA preserved in old specimens is vanishingly small, because it is broken down by oxidation and hydrolysis over time. Consequently, even innocuous sources of modern DNA such as human skin flakes and exhaled cells can easily act as contaminants. The risk of contamination is enormously magnified in modern biology buildings where research often involves the amplification of DNA to huge concentrations (e.g. trillions of copies). Consequently, extreme measures must be taken to protect ancient DNA research from being swamped in a sea of contamination.So they appear to be aware of the problem, and if Thomas Gilbert says it's the real thing, then I guess it must be.

[BillHoyt]

I'd like to look over the research article(s) myself. Does anybody know where it is to be published?

Contamination isn't the only problem. I see at least three others:
o Dating - unlike fossils in rocks, those tiny cells will migrate great distances. Just because you find the DNA 2,000 feet down doesn't mean it dates to anything by which it is surrounded

o Unknowns - the focus here was on the easy ones, the matches that could be made to verify the technique. To apply that technique to identify unknowns will be tricky.

o Evolutionary timeline - because of the dating problem, it will be a while before we may be able to see our way to using this to reliably ID intermediate changes.

The problems notwithstanding, this is a great breakthrough.


Cheers,

[shemp]

Didn't you know? DNA has a born-on date, like Budweiser!

[BillHoyt]

Originally posted by shemp
Didn't you know? DNA has a born-on date, like Budweiser!

You know, I'm so busy when I'm in the midst of -uh - it -- that I never did look! Couldn't tell you if I smoke afterwards either.

Cheers,

[Goshawk]

Originally posted by BillHoyt
I'd like to look over the research article(s) myself. Does anybody know where it is to be published? Dunno, but I found an e-mail addy for Eske Willerslev of the University of Copenhagen, you could ask.

http://www.talkorigins.org/faqs/homs/mungonhm.html

Eske Willerslev, email: ewillerslev @ zi.ku.dk