On the frozen tundra Sibirien about 50,000 years ago, a Wollmammut under mysterious circumstances. In rehearsals of the animal's skin, researchers have now discovered chromosomes that have been preserved in their original 3D configuration 1 -a service that has so far been considered impossible in DNA research at Fossil DNA.

The team also revealed the spatial organization of the Mammoth's DNA molecules and the active genes in its skin, including a gene that gives the animal its fluffy appearance. The work was published in Cell today.

The study is the first to report the 3D structure of an antique genome, says Ludovic Orlando, a molecular archaeologist at the University of Paul Sabatier in Toulouse, France that was not involved in research. Because the spatial structure of a genome-the complete set of the genetic material of an organism-provides indications of genetic activity, the understanding of this structure could offer deeper insights into the cell biology of the skin of the mammoth than the mere examination of the DNA sequence alone, he says. "This work is just unprecedented."

destruction by time

could survive distant past , including Egyptian mummies . It has become apparent since then that the DNA has been preserved in many ancient remains.

Since time flies, DNA degrades and suffers chemical damage, so that researchers had previously only received DNA fragments that had no coherent structure, says the study mitutor Erez Lieberman Aiden, a geneticist at the Baylor College of Medicine in Houston, Texas. A reconstruction of a 3D genome of such pieces is almost impossible: a mammalian genome is 30 million times larger than a typical fragment of ancient DNA, he says.

astonishing discovery

In the challenge of this assumption, Lieberman Aiden and his colleagues started a nine -year search for well -preserved antique rehearsals and finally found almost intact chromosomes in 52,000 -year -old skin samples of a woolly mammoth ( Mammuthus primigenius ), which came from the Siberian permafrost. The discovery was "just breathtaking", says the study mitachor Cynthia Pérez Estrada, a geneticist at the Baylor College of Medicine.

The legs of a juvenile female wooly mammoth, with a gloved hand holding a tuft of ginger hair at the foot

The researchers analyzed the structure of the chromosomes of the mammoth and unveiled the folding of the DNA molecule and its spatial organization in the cell nucleus-two characteristics that are crucial for which genes are switched on and how long.

Compare with Modern ELEFANTEN Living relatives of the mammoth , not only showed similarities in the number of chromosomes and structure, but also differences in the activity of genes that are involved in the growth of hair and the refrigeration.

freezer -dried DNA

The researchers suggested that the mammoth chromosomes were preserved in a glass -like state by a dehydrated process, similar to that for the production of beef joy. This technique leads to a tissue in which the DNA molecules are packed and immobile.

The team's experiments on freezer -dried beef -dried beef joy, which was subjected to extreme tests such as the shelling with a weapon and the run over with a car, confirmed the theory of the researchers: the Jerky broke like glass, but its chromosomes remained intact.

"Under no circumstances would one think that [old] DNA is preserved in its form," says Víctor Moreno Mayar, a specialist in genomics of ancient populations at the University of Copenhagen, which was not involved in the study. To see that she can, "is really cool," he says.

The results suggest that the potential for restoring old DNA beyond what is previously considered possible, provided the conditions are ideal, says Moreno Mayar.

The approach in the paper could also help the researchers to put together a complete mammoth genome, says eriona hysolli, head of the organic sciences at Colossal Biosciences, a biotechnology company in Dallas, Texas that works on the revival of the wool mammoth .

Hysolli, which was not involved in the study, says that a complete mammoth genome could help uncover features that could be relevant for the daring plan of the company- The production of an elephant mammoth hybrids , which could be introduced to the extinct animal and could be introduced again in its natural habitat.