![\"Legs](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2024\/07\/10182937\/SEI_212224679.jpg\")
<\/div>The legs of a 39,000-year-old woolly mammoth<\/p>\n
Love Dal\u00e9n\/Stockholm University<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
A woolly mammoth that died 52,000 years ago is so well preserved that it is possible both to read its full genome and to reconstruct the three-dimensional structure of its chromosomes<\/a> \u2013 information that can provide unprecedented details about how the animal\u2019s genes behaved during its life. The extraordinary feat was possible because the animal\u2019s remains were naturally freeze-dried, preserving its DNA in a glass-like state.<\/p>\n Scientists found the mammoth remains in a cave in Siberia in 2018 where they had been preserved in the permafrost. The mammoth\u2019s tissues were dry, \u201cbut not as dry as commercial beef jerky\u201d, says Olga Dudchenko<\/a> at Baylor College of Medicine in Texas, \u201cand it was actually woolly\u201d. Eager to see what genetic information they could glean, Dudchenko and her colleagues sampled flesh behind the mammoth\u2019s ear and sequenced the DNA.<\/p>\n Because molecules of DNA begin to break down when an animal dies, scientists have previously only been able to find tiny snippets of the woolly mammoth genome \u2013 but to the researchers\u2019 surprise, the animal\u2019s chromosomes were perfectly preserved. \u201cThis does not match with anything that we have analysed before that was 52,000 years old, so that was very surprising,\u201d says Juan Antonio Rodr\u00edguez<\/a> at the University of Copenhagen in Denmark, a member of the research team.<\/p>\n <\/p>\n They also found that the mammoth had 28 pairs of chromosomes \u2013 the same number as their closest living relative, the Asian elephant. The chromosomes\u2019 three-dimensional structure was also preserved, which helps distinguish active genes from inactive ones. The researchers found, for example, that the gene responsible for hair growth was more active in the mammoth<\/a> than in elephants, explaining their shaggy coats.<\/p>\n Identifying which genes are active in woolly mammoths versus elephants may boost so-called de-extinction<\/a>\u00a0efforts, says Hendrik Poinar<\/a> at McMaster University in Canada, who was not involved in the work. \u201cTo get as close to a real mammoth as possible, one needs to know how the [genetic] architecture differs from an Asian elephant,\u201d he says. Understanding which genes to tweak \u2013 such as those that produce lots of hair \u2013 could help create more realistic-looking and sounding animals that closely resemble the ancient pachyderms, though they would not be true woolly mammoths.<\/a><\/p>\n But how did this DNA stay intact for more than 50,000 years without unravelling? The researchers credit the ideal conditions of the cave, which simultaneously chilled and desiccated the animal. \u201cThe sample lost much of its water into the cold and dry Siberian winter,\u201d says Dudchenko. She adds that a broadly similar drying process occurs during the production of foods like prosciutto.<\/p>\n To check their theory, the researchers put fresh and freeze-dried beef liver through a series of tough tests. After three days at room temperature, the DNA in the fresh beef was in fragments. But the freeze-dried stuff kept its chromosome structure on the nanometre scale even after a year. \u201cAt that point, we were like, okay, time doesn\u2019t kill it \u2013 what does?\u201d says Dudchenko.<\/p>\n So they fired a shotgun at the mock mammoth jerky, ran over it with a car and had a former professional baseball player throw a fastball at it, all to try to destroy its DNA. Each time, the dried beef liver shattered into small pieces but maintained its microscopic structure, preserving the DNA inside. \u201cWe found out that it works \u2013 it survives,\u201d says Rodr\u00edguez.<\/p>\n Topics:<\/p>\n<\/section><\/div>\n