A photo of a mammoth foot in a permafrost environment.
Researchers assembled the genome and 3D chromosomal structures of a 52,000-year-old woolly mammoth, the first time ever done in ancient DNA sampling, according to a press release.
The woolly mammoth “Yuka” froze immediately after it died. The permafrost preserved its chromosomes in a state more like glass. A remarkable and unusual fossilized creature provided the most “alive” picture ever captured of ancient DNA. Most samples found are in fragments or pieces.
“Our study shows that the morphology of ancient chromosomes is preserved in mammoth permafrost samples from 52,000 years ago, enabling the genome assembly and transcriptomic analysis of extinct species,” researchers stated.
“This is a new type of fossil with a million times more sequence,” Erez Lieberman Aiden, a corresponding author of the study said. “It is also the first time a karyotype [a complete set of chromosomes] of any sort has been determined for an ancient sample.”
Mapping the woolly mammoth’s DNA was almost like solving a puzzle with “three billion pieces,” corresponding author Marc A. Marti-Ronom analogized. Researchers had to evaluate which sections of the DNA matched up in a skin sample taken from behind its ear.
They didn’t have a picture of the completed puzzle to reference, but they could approximate it using the genomic analysis technique (Hi-C). With Hi-C analysis and DNA sequencing combined, they mapped out 28 chromosomes using the modern elephant as a model, which also has 28 chromosomes.
The most stunning aspect of the study concerns the preservation state of the fossilized chromosomes. As they “retained a huge amount of physical integrity and detail, including the nanoscale loops,” as per the press release, researchers could tell which genes were active and inactive in its skin cells. They will apply that knowledge in the next step of their research: epigenetics, or gene expression.
“For the first time, we have a woolly mammoth tissue for which we know roughly which genes were switched on and which genes were off,” corresponding author Marti-Renom says. “This is an extraordinary new type of data, and it’s the first measure of cell-specific gene activity of the genes in any ancient DNA sample.”
They offer a glance into the genome inside living cells and which genes were active. In comparison with its modern-day relatives, researchers can say that their genes had distinct patterns of behavior most likely related to its “woolly-ness” and cold tolerance.
They even believe this research could help bring back the species.
“These results have obvious consequences for contemporary efforts aimed at woolly mammoth de-extinction,” corresponding author M. Thomas Gilbert concludes.
They published their paper, “Three-dimensional Genome Architecture Persists in
a 52,000-year-old woolly mammoth skin sample,” in Cell.
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Maria Mocerino Originally from LA, Maria Mocerino has been published in Business Insider, The Irish Examiner, The Rogue Mag, Chacruna Institute for Psychedelic Plant Medicines, and now Interesting Engineering.
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