An international research team has successfully assembled the entire genome and 3D chromosomal structure of a 52,000-year-old woolly mammoth. 

This groundbreaking achievement marks the first time such detailed genetic information has been reconstructed from an ancient DNA sample.

The team was able to extract DNA from a remarkably well-preserved woolly mammoth, which had undergone a natural freeze-drying process shortly after its death. 

This preservation method kept the DNA in a glass-like state, allowing for an unprecedented level of detail in the genetic reconstruction.

“This is a new type of fossil, and its scale dwarfs that of individual ancient DNA fragments - a million times more sequence,” said Dr Erez Lieberman Aiden, Director of the Center for Genome Architecture at Baylor College of Medicine.

“It is also the first time a karyotype of any sort has been determined for an ancient sample.”

The research team used the Hi-C method to detect spatial proximities and interactions within DNA sections in their natural state. 

This technique, combined with DNA sequencing, enabled the team to create an ordered map of the mammoth’s genome. 

By using the genomes of present-day elephants as a template, they identified the interacting DNA sections and successfully reconstructed the mammoth’s genomic architecture.

The analysis revealed that woolly mammoths had 28 chromosomes, the same number as present-day Asian and African elephants. 

The fossilised chromosomes retained a high degree of physical integrity, including nanoscale loops that connect transcription factors with the genes they control.

The team’s research also provided insights into the gene activity within the mammoth’s skin cells. 

They identified distinct gene activation patterns compared to the skin cells of its closest relative, the Asian elephant. This included genes potentially related to the mammoth’s woolly coat and cold tolerance.

“For the first time, we have a woolly mammoth tissue for which we know roughly which genes were switched on and which genes were off,” Dr Marti-Renom noted. 

“This is an extraordinary new type of data, and it’s the first measure of cell-specific gene activity of the genes in any ancient DNA sample.”

The research has implications beyond the study of woolly mammoths. 

According to M Thomas Gilbert, a paleo-genomicist at the University of Copenhagen and the Norwegian University of Science and Technology, the methodology used in this study could be applied to other ancient DNA specimens, such as Egyptian mummies and more recently preserved museum specimens. 

The full study is accessible here.