A 52,000-year-old discovery reshapes our understanding of ancient DNA
The well-preserved body of a woolly mammoth from 52,000 years ago has allowed scientists to reconstruct its three-dimensional genome for the first time in history. The samples contained more information than was initially thought possible.
The latest research results, published on Thursday in the journal "Cell," indicate that ancient DNA samples may contain more information about the past than previously believed. This is all thanks to the mammoth found in Siberia. Scientists emphasize that it was preserved in excellent condition due to the dry and frosty winters.
While researching the skin samples taken, scientists discovered that they were practically intact. Further magnifications revealed that the chromosomes in each cell were still organized into distinct structures, which provided experts with insight into which genes were active at the time and which were turned off during the mammoth's life.
Knowing the structure of the genome, you can figure out which genes were active in that particular animal at the moment that it died and which genes were repressed – said Marc A. Marti-Renom, a co-author of the study and professor at the National Centre for Genomic Analysis in Barcelona, quoted by "The Washington Post".
As Olga Dudchenko, an assistant professor at Baylor College of Medicine who participated in the study, admitted, it was not known until now that ancient samples could be preserved in such good condition. Most of them were severely fragmented because DNA begins to degrade after an organism's death. Although the ancient DNA in the sample taken from the Siberian mammoth fragmented over the last 52 millennia, this process was relatively minor in the skin cells.
The authors discovered similar chromosome structure preservation in another woolly mammoth sample. It was a piece of skin taken from a mammoth named Yuka, who is 39,000 years old and is considered one of the best-preserved mammoths ever discovered.
The authors suspect that the chromosome arrangements were stabilized through a process known as vitrification, in which all material components are frozen in time due to appropriate temperature conditions.
This is what scientists learned from the samples taken
Research indicated that the mammoth had 28 pairs of chromosomes, similar to the elephant's closest living relative. Using information about the location of chromosomes in cells, the authors could detect genes responsible for differences between the mammoth and the elephant. This includes genes that lead to hair growth and the mammoth's ability to maintain warmth in a cold environment.
In addition to progress in genomics, this research's findings may play an important role in efforts to protect animals.
To assess how poorly or how well species are doing in terms of genetic diversity and their overall genetic health, it’s important to understand … what is ‘natural’ for them – said Patrícia Chrzanová Pečnerová, assistant professor of evolutionary genetics at the University of Copenhagen, who was not involved in the study.
Scientists want to find an answer to the mammoth population's appearance before the human species began hunting them or before climate changes occurred. Eriona Hysolli, head of the biological sciences department at Colossal Biosciences – a company working on reintroducing a version of the woolly mammoth to the Arctic – stated that the three-dimensional chromosome structures found by the authors "may reveal genome features that might have been significant in the extinction process of the mammoths".
