The discovery of “chromosome fossils” by a team of scientists with Spanish participation is a milestone for science. Intact DNA was recovered from a female that died 52,000 years ago in Siberia. It appeared in 2018 in the Siberian permafrost. The recovery of intact DNA from mammoths opens up unimaginable possibilities.
It was not the first time that remains of this animal, which became extinct just 3,700 years ago, had been found. But the fascinating thing was that they were “extraordinarily well preserved.” “It is probably the best preserved sample I have ever found,” explained Swedish researcher Love Dalén. Specifically, what was found was an ear, which had undergone various procedures that have allowed intact DNA to be recovered.
Complete DNA
There they found an impressive piece of genome. Normally it is represented as a kind of line with all kinds of letters. And until now, almost all the fragments recovered had about a hundred characters. However, the mammoth ear has hundreds of millions. This is how geneticist Marc Martí Renom, one of the leaders of the study, published this Thursday in the journal Cell.
The reason the chromosomes were so well preserved was because the ear was so cold and desiccated. Its skin cells were trapped, which prevented the DNA fragments from scattering. The chromosomes were compared to modern elephants. They shared many features, including chromatin loops. These are important because they bring activating DNA sequences closer to their genetic targets. “They not only show us which genes were active, but also why.”
Resurrection of mammoths
Fossil chromosomes change everything. Knowing their shape makes it possible to assemble the complete DNA sequence of extinct creatures. In this case, the number of chromosomes was identified. “We found that they have 28 pairs of them. This is what modern elephants have, and they are the closest living relatives of the woolly mammoth,” says Juan Antonio Rodríguez, co-lead author and CNAG researcher.
The rescue of intact DNA from mammoths opens the door to a possible “resurrection” of these animals. In 2022, the company Colossal was looking for investors to carry out this work. It is not about creating photocopies, but genetically modified substitutes, say those involved. They say they are not in favor of creating any theme park with them. Do we believe them?