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2 months ago
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Experts are a step closer to bringing the woolly mammoth back to life thanks to the first ever 3D reconstruction of chromosomes collected from ancient skin.
Around 52,000 years ago, a woolly mammoth happened to be freeze-dried by the weather just after it died, preserving its DNA in a glass-like state.
The unusually well-preserved specimen was excavated in northeastern Siberia in 2018, allowing a team of international scientists to analyse its skin tissue.
Now, they have successfully assembled a detailed reconstruction of the extinct species' chromosomes – thread-like structures that are made up of DNA.
This is the first time scientists have been able to do this from such an ancient sample.
Experts are a step closer to bringing the woolly mammoth back to life thanks to the first ever 3D reconstruction of chromosomes collected from ancient skin
Around 52,000 years ago, a woolly mammoth happened to be freeze-dried by the weather just after it died, preserving its DNA in a glass-like state. The unusually well-preserved specimen was excavated in northeastern Siberia in 2018, allowing a team of international scientists to analyse its skin tissue
And they said this could boost efforts to 'de-extinct' the woolly mammoth by allowing a comparison to the DNA to modern-day elephants.
Currently, a company called Colossal Biosciences are leading the drive to bring the woolly mammoth back to life.
Their strategy is to take an Asian elephant genome and introduce a large number of small edits to the DNA.
Then, an Asian elephant will carry that offspring to term, giving birth to an elephant with many of the adaptations that made woolly mammoths thrive in the cold.
The team behind the new discovery says the genetic information preserved in this fossil is far more detailed than most ancient DNA fragments that have been found.
They were able to see not just the genes present in the fossil, but also roughly which ones were active and which were 'switched off' – something they had never seen before.
Erez Lieberman Aiden, one of the study's authors from the Baylor College of Medicine in Texas, said this will aid efforts to de-extinct the mammoth as it helps scientists understand which genes and sequences they need to 'edit' in an elephant genome to turn it into something resembling the extinct species.
'Like DNA, whole chromosomes have been thought to be fragile objects, that cannot survive for very long outside a living organism,' he said.
The study could boost efforts to 'de-extinct' the woolly mammoth by allowing a comparison to the DNA to modern-day elephants
The team behind the new discovery says the genetic information preserved in this fossil is far more detailed than most ancient DNA fragments that have been found. They were able to see not just the genes present in the fossil, but also roughly which ones were active and which were 'switched off' – something they had never seen before
'But, under the right circumstances, chromosomes can, in fact survive for a long time.
'And this surprise makes many things possible, like assembling extinct genomes, or looking in a woolly mammoth tissue and seeing which genes were on and which were off, or examining the DNA loops that turn genes on and off.
'The general plan for de-extinction is to use what has been learned about the mammoth from DNA sequencing to engineer an elephantid life form that is similar, in important ways, to the mammoth. '
While versions of this plan have existed for some time, a 'potential monkey wrench' was large gaps in knowledge about the woolly mammoth genome – for example, how many pairs of chromosomes it has.
'The great news for de-extinction is that we don't have to worry about whole sets of potential monkey wrenches, because the global structure of the genomes of the two species is quite similar,' Dr Aiden said.
'It therefore really seems like local edits [to DNA] could take us very far.'
'The great news for de-extinction is that we don't have to worry about whole sets of potential monkey wrenches, because the global structure of the genomes of the two species is quite similar,' Dr Aiden said
He said their discovery also helps pinpoint exactly what edits are needed to transform an Asian elephant into a mammoth.
'For instance, we can look at the skin in woolly mammoth now, and using these fossil chromosomes we can see, for the first time, which genes were active in the skin of a woolly mammoth that were not active in elephants, and vice-versa,' he added.
'So now we can understand, in a deeper way, which genes and sequences we need to focus on to make an elephant woolly, and which sequences may be less important for that trait.'
Although the method used in this study hinges on unusually well-preserved fossils, the researchers are optimistic that it could be used to study other ancient DNA specimens such as Egyptian mummies.
Other authors include researchers from the University of Copenhagen, the Centre Nacional d'Anàlisi Genòmica and the Centre for Genomic Regulation in Spain.
The findings were published in the journal Cell.
WOOLLY MAMMOTHS EXPLAINED: THESE GIANT MAMMALS ROAMED THE EARTH DURING THE PLEISTOCENE 10,000 YEARS AGO
The woolly mammoth roamed the icy tundra of Europe and North America for 140,000 years, disappearing at the end of the Pleistocene period, 10,000 years ago.
They are one of the best understood prehistoric animals known to science because their remains are often not fossilised but frozen and preserved.
Males were around 12 feet (3.5m) tall, while the females were slightly smaller.
Curved tusks were up to 16 feet (5m) long and their underbellies boasted a coat of shaggy hair up to 3 feet (1m) long.
Tiny ears and short tails prevented vital body heat being lost.
Their trunks had 'two fingers' at the end to help them pluck grass, twigs and other vegetation.
The Woolly Mammoth is are one of the best understood prehistoric animals known to science because their remains are often not fossilised but frozen and preserved (artist's impression)
They get their name from the Russian 'mammut', or earth mole, as it was believed the animals lived underground and died on contact with light – explaining why they were always found dead and half-buried.
Their bones were once believed to have belonged to extinct races of giants.
Woolly mammoths and modern-day elephants are closely related, sharing 99.4 per cent of their genes.
The two species took separate evolutionary paths six million years ago, at about the same time humans and chimpanzees went their own way.
Woolly mammoths co-existed with early humans, who hunted them for food and used their bones and tusks for making weapons and art.
