Freeze-dried jerky with remarkably well-preserved mammoth DNA.

The woolly mammoth, which died 52,000 years ago, has been so well preserved that it’s now possible to sequence its entire genome and reconstruct the three-dimensional structure of its chromosomes. This information provides unprecedented details about how the animal’s genes moved throughout its life. This incredible feat was made possible because the animal’s remains were naturally freeze-dried, preserving its DNA in a glass-like state.

Scientists discovered the remains of a mammoth preserved in permafrost in a Siberian cave in 2018. The mammoth’s tissue was dry, but “not as dry as commercial beef jerky,” the researchers said. Olga Dudchenko “It was, in fact, hairy,” says a researcher at Baylor College of Medicine in Texas. Wanting to find out what genetic information they could find, Dudchenko and his colleagues took a sample of flesh from behind the mammoth’s ear and sequenced its DNA.

“Until now, scientists have only been able to find small parts of the mammoth’s genome because DNA molecules begin to degrade when an animal dies, but to the researchers’ surprise, the animal’s chromosomes were completely preserved. “This was quite a surprise, as it doesn’t match anything we’ve analyzed so far from 52,000 years ago,” the researchers say. Juan Antonio Rodriguez Members of a research team from the University of Copenhagen in Denmark.

They also found that mammoths had 28 pairs of chromosomes, the same number as their closest living relative, the Asian elephant. The three-dimensional structure of the chromosomes was also preserved, which helps distinguish active from inactive genes. For example, the genes responsible for hair growth in mammoths were more active than in elephants, allowing the researchers to determine why they have such thick fur.

Identifying whether mammoth or elephant genes are more active could aid in so-called de-extinction efforts, he said. Hendrik Poyner “To get as close as possible to a real mammoth, [genetic] “The skeleton of a mammoth is different from that of an Asian elephant,” he says. Understanding which genes to tweak, such as the one that produces lots of hair, could help create a more realistic-looking and sounding animal that, while not a bona fide mammoth, more closely resembles the ancient pachyderm.

But how did this DNA remain intact for more than 50,000 years? The researchers attribute it to the cave’s ideal conditions, which cooled and dried the animal. “The sample lost much of its moisture during the cold, dry Siberian winter,” says Dudchenko. She adds that a similar drying process occurs during the production of foods such as prosciutto.

To test their theory, the researchers put fresh and freeze-dried beef liver through a series of rigorous tests. After three days at room temperature, the fresh beef’s DNA had fragmented; but the freeze-dried version still retained its nanometer-scale chromosome structure after a year. “At that point, we wondered, rather than time killing it, what is killing it?” Dudchenko says.

So the team tried to destroy the DNA of the mammoth jerky replica by shooting it with a shotgun, running it over with a car, and having a former professional baseball player throw a fastball at it. Each time, the dried beef liver crumbled into pieces, but its microscopic structure remained intact, preserving the DNA inside. “We found that this method worked, and that it survived,” Rodriguez says.