Half-Life of DNA is 521 Years, Jurassic Park Impossible After All

another random user writes with this quote from Nature News: "Few researchers have given credence to claims that samples of dinosaur DNA have survived to the present day, but no one knew just how long it would take for genetic material to fall apart. Now, a study of fossils found in New Zealand is laying the matter to rest — and putting paid to hopes of cloning a Tyrannosaurus rex (abstract). After cell death, enzymes start to break down the bonds between the nucleotides that form the backbone of DNA, and micro-organisms speed the decay. In the long run, however, reactions with water are thought to be responsible for most bond degradation. Groundwater is almost ubiquitous, so DNA in buried bone samples should, in theory, degrade at a set rate. Determining that rate has been difficult because it is rare to find large sets of DNA-containing fossils with which to make meaningful comparisons. To make matters worse, variable environmental conditions such as temperature, degree of microbial attack and oxygenation alter the speed of the decay process. By comparing the specimens' ages and degrees of DNA degradation, the researchers calculated that DNA has a half-life of 521 years. That means that after 521 years, half of the bonds between nucleotides in the backbone of a sample would have broken; after another 521 years half of the remaining bonds would have gone; and so on."

Re:Someone forgot to tell these guys

[dpilot]

That just says that they're going to inject the DNA - it doesn't say that they're going to get viable embryos out of it.

No water, no air, no bonds broken?

[Doofus]

So in amber, or some other similar impermeable substance, the chemical reactions requiring water or air might well be prevented or dramatically slowed, thus the degradation of DNA might be substantially slower than the 521 years described in the summary.

Not necessarily the end of the Jurassic Park idea.

Question...

[Savage-Rabbit]

If the half-life of DNA is 521 years how are scientists able to sequence 30.000 year old Neanderthal DNA? Presumably this applies to regular DNA, did Svante Pääbo and his team sequence mtDNA?

Uh, what?

[Daetrin]

Wikipedia seems to have a page all about doing what this article says is impossible: http://en.wikipedia.org/wiki/Ancient_DNA [wikipedia.org]

It claims there are multiple cases of Neanderthal DNA being sequenced, and a couple quick google searches seem to indicate there are many other similar situations where DNA was recovered.

So i'm wondering, did this study perhaps prove that if nothing is done to preserve the DNA after death then... surprise! The DNA isn't preserved?

Re:Someone forgot to tell these guys

[busyqth]

Why do they need to know? 10,000 years is roughly 20 half-life periods, so they should expect roughly 1-millionth of the DNA to remain.

Since the wooly mammoth genome is approximately 4.7 billion in 58 chromosomes, for an average of 81 million base pairs per chromosome, the DNA fragments would be, on average 81 base pairs long, which should be enough to figure out the original sequence after duplicating and matching. So a full reconstructed mammoth genome should be possible.

"Impossible After All"

[jlv]

One of the best ways to make it happen is to declare it's "impossible". It gives people something to strive for.

Re:Someone forgot to tell these guys

[gewalker]

Even more importantly, this ignores a previous published article on "DNA Sequence from Cretaceous Period Bone Fragments" -- Science 266 (5188) 1229-1232, here is a PDF [myweb.dal.ca] of the article in Science. Either 80 mya (Cretaceous) is horribly wrong, the 521 year half-live of DNA is horribly wrong, Woodruff, et al were horrible deceived (or frauds) or some combination of these.

You would hope evidence would be the deciding factor, but scientists are human too, and the interpretation of evidence is often more important than the actual evidence -- it is very hard to upset to prevailing opinion (as it should be when the opinion is well founded)