Half-Life of DNA is 521 Years, Jurassic Park Impossible After All 315
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by
Soulskill
from the unless-you-have-a-time-machine dept.
from the unless-you-have-a-time-machine dept.
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."
Cryogenics (Score:4, Interesting)
Does this have any bearing on cryogenics or would that preserve the DNA?
What about the 30,000 year old seed that sprouted? (Score:2, Interesting)
Re:No water, no air, no bonds broken? (Score:5, Interesting)
Also worth mentioning, what about the tar pits? If an animal is surrounded by tar and sealed in, what happens to the DNA degradation?
So what did MarySchweitzer find? (Score:5, Interesting)
Is this why we haven't heard much from Mary Schwietzer [discovermagazine.com] lately? Six years ago she isolated soft tissue remnants from inside a T-rex femur.
More recently, Charlotte Oskam (Biologist at Murdoch University in Australia) identified DNA in fossilized egg shells [metro.co.uk].
We've always known that DNA was unlikely to survive the passage of aeons, this just puts a number to it. Specific conditions could still allow better than typical preservation, and so I dislike making an absolute statement that we'll never find it. Hopefully those who are still looking for the elusive ancient DNA will take this study as a way to focus their search rather than have their funding cut.
Jurassic Park still possible (Score:4, Interesting)
Re:Someone forgot to tell these guys (Score:5, Interesting)
Heck, 81 base pairs would save you a lot of time chopping strands for PCR, you would already have the pieces. :)
Seriously though, given those numbers are for a single cell, how many do you have with a mammoth carcass? More than 1, in fact more than 1 million. If you can find a lab blender big enough to stuff a mammoth carcass in to, the rest should be trivial. I would also venture that after a while, the fact that a dinosaur bone didn't degrade to dust means that it is better preserved than your average thing stuffed in to the ground so the half life would, after a point, extend.
Given a few dinosaur samples, you could probably get enough to reassemble most of the genome. With some not all that complex math, you can compare it to a few key reptile sequences and likely get some strong hints or even direct sequences that are missing. Some things change a lot over time, others do not or can not.
And yes, I did do this in college. No, not on dinosaurs though, that would have been a bit more fun to talk about at the bars.
-Charlie
the mammoth DNA is frozen (Score:5, Interesting)
the assumptions in the 521 year half life number is that we are above freezing temperatures. so mammoth DNA has a different experience
there are arguments to make that frozen water would lengthen the half life (frozen water is not as chemically active) or shorten it (ice crystals shredding the dna physically rather than chemically)
i'm not knowledgeable enough to guess if the frozen effect would save the DNA better or shred it even worse, but i think it is a valid to say that the half life would be a lot different if you are dealing with a corpse that was frozen at death and stayed that way in permafrost the entire thousands of years time before getting to a modern biotech lab