2024-07-13 07:45:58
52,000 years ago, the skin of a Siberian woolly mammoth was exposed to icy conditions to the point that it spontaneously lyophilized, preserving fragments of DNA. Scientists have now used this sample to reconstruct the animal’s genome in three dimensions, AFP reported, quoted by BTA.
The breakthrough could help better understand extinct species and even spur efforts to bring them back to life.
Ancient DNA samples found so far have generally been in the form of incomplete fragments, greatly limiting the amount of information researchers can extract from them.
“We have now shown that under certain circumstances not only these DNA fragments are preserved, but also their original arrangement,” Olga Dudchenko, a geneticist at Baylor College of Medicine and co-author of the study published in the journal Cell, told AFP. ).
Understanding the three-dimensional architecture of the genome—the complete set of DNA—is critical to identifying active genes associated with specific organs. This will contribute to understanding, for example, how its brain cells allow it to think, how its heart cells allow it to beat, and how its immune system cells allow it to fight disease.
For a long time it was believed that due to the rapid degradation of the very small particles, this information would inevitably be lost.
About ten years ago, an international team of scientists set out to find an ancient specimen with the 3D organization of DNA almost intact to the point where it could be completely reconstructed using a new technique.
The search led to an exceptionally well-preserved woolly mammoth specimen found in northeastern Siberia in 2018.
It remains unclear whether the animal, a female, died naturally or was killed by humans. However, it appears to have been dismembered, with the skin around the head, neck and left ear remaining intact.
The researchers hypothesize that the skin froze, dehydrated, and went into an almost glassy state, preserving its molecules and preserving the shape of the chromosomes, the structures that contain the strands of DNA.
Long story short, researchers come across a piece of dried woolly mammoth meat.
To study its durability, they subjected pieces of modern dried meat – prepared in a laboratory and purchased commercially – to a series of tests simulating the kind of damage ancient samples are likely to have suffered over the millennia.
“We shot him with a rifle. We ran him over with a car,” said study co-author Cynthia Perez Estrada.
Each time the dried meat fell apart into small pieces. “However, at the nanoscale, the chromosomes were intact, unchanged,” explains the researcher from Rice University.
One of the researchers’ major findings is that mammoths had 28 pairs of chromosomes — the same number as elephants, their closest living relatives.
However, before the current research, everyone could make their own assumptions, notes Olga Dudchenko.
Scientists have also identified several genes that could be the ones that give woolly mammoths their characteristics, such as the gene responsible for long, thick eyelashes.
And while the research group’s goal was not to bring the mammoths back to life, the information gathered could help, the scientists said.
A Japanese team plans to clone woolly mammoths, and an American group is trying to create genetically “mammothized” elephants.
The authors of the study hope that it could open a new chapter in paleogenetics if other specimens of this type are found.
According to Olga Dudchenko, the permafrost of the Arctic remains a promising place to search for DNA, but the mummification processes of some ancient civilizations, for example domestic animals, could also preserve their DNA very well.