Fifty-two thousand years ago, the skin of a Siberian woolly mammoth was exposed to freezing conditions, causing it to freeze-dry and trap fragments of its DNA. Scientists used it to reconstruct the animal's 3D genome.
This breakthrough could help us better understand extinct species, and even boost efforts to bring them back to life.
Until now, ancient DNA samples found 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 conditions, not only are these DNA fragments preserved, but also their original arrangement,” said Olga Dudchenko, a geneticist at Baylor College of Medicine and co-author of the study presenting these findings, which was published Thursday in the journal Cell.
dried meat
Understanding the three-dimensional structure of the genome – its complete set of DNA – is crucial to identifying the active genes associated with particular organs and thus understanding, for example, how brain cells allow it to think, heart cells allow it to beat, and immune system cells allow it to fight disease.
It is not clear whether the female elephant died naturally or was killed by humans. However, it appears that individuals dismembered her, leaving the skin around the head, neck and left ear intact.
The researchers hypothesized that the skin had frozen and dried, turning into an almost glassy state that trapped its molecules and preserved the shape of its chromosomes, the structures that contain the strands of DNA. In short, the researchers found themselves with a piece of dried woolly mammoth meat.
One of the main discoveries of this work was the proof that mammoths have 28 pairs of chromosomes. This is consistent with the 28 pairs of elephants, the closest living relatives of mammoths. But “before this study, everyone could guess for themselves,” says Olga Dudchenko.
Scientists have also identified several genes that could give the woolly mammoth its characteristics, including the gene responsible for its long, thick eyelashes.
Erez Lieberman-Aydin, who also led the study, said that although the group of researchers did not aim to bring the mammoth back to life, the information collected could help.
A Japanese team plans to clone a woolly mammoth, while an American team seeks to create genetically “mimetic” elephants.
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