SCIENTISTS have sequenced the genome and chromosomal structures of a woolly mammoth for the first time in history.
The feat, published today in Cell, It is also the first of its kind for any ancient DNA sample.
And it could be the key to bringing the colossal creature back from the dead.
The research was made possible by a perfect storm of conditions that preserved the mammoth’s DNA in a glass-like state.
An international research team has removed chromosomes from 52,000-year-old remains discovered in northeastern Siberia six years ago.
The mammoth was “freeze-dried” shortly after death and was strangely well preserved, making it an ideal specimen.
Scientists soon discovered that the fossilized chromosomes were a million times longer than most ancient ones DNA fragments.
They were able to assemble a complete set of chromosomes, known as a karyotype.
This provided evidence of how the mammoth genome was organized within its cells and which genes were active in the tissue from which it originated. DNA was extracted.
“This is a new type of fossil, and its scale surpasses that of ancient individuals DNA fragments,” said corresponding author Erez Lieberman Aiden.
“It is also the first time that a karyotype of any type has been determined for an ancient sample.”
Researchers tested dozens of samples over a five-year period before landing on the “freeze-dried” woolly mammoth.
“Nuclear energy architecture in a dehydrated sample can survive for an incredibly long period of time,” explained corresponding author Olga Dudchenko.
To reconstruct the mammoth genome, researchers took advantage of DNA of a skin behind the creature’s ear.
They used a method called Hi-C that allows them to detect which sections of DNA are likely to be spatially close and interact with each other in their natural state in the nucleus.
3
Corresponding author Marc A. Marti-Renom compared the process to constructing a puzzle without having a picture of the end result to work with.
“Hi-C allows you to get an approximation of that image before you start putting the puzzle pieces together,” he explained.
Basing their work on mapping the human genome, the team combined the results of Hi-C analysis with DNA sequencing to identify the interacting sections of DNA and create a map.
It was revealed that woolly mammoths had 28 chromosomes, the same number as modern Asian and African elephants.
3
The remarkable fossil retained significant details, including the physical structures that allow for the control of genes.
This allowed researchers to identify previously active and inactive genes in mammoth skin cells.
Compared to its closest surviving relative, the Asian elephant, the mammoth’s cells showed distinct patterns of gene activation, possibly related to its woolly hair and cold tolerance.
“For the first time, we have a woolly mammoth tissue for which we know approximately which genes were turned on and which genes were turned off,” Marti-Renom said.
“This is an extraordinary new type of data and is the first measurement of the cell-specific genetic activity of genes in any ancient DNA sample.”
Woolly mammoth – the main facts
Here’s what you need to know…
- The woolly mammoth is an ancient creature that is now extinct
- The species first appeared 400,000 years ago in East Asia, when it “diverged” from the steppe mammoth
- Its closest living relative today is the Asian elephant
- Woolly mammoths are one of the best-studied prehistoric animals, due to the discovery of frozen carcasses in Siberia and Alaska
- We also have evidence of them in the form of skeletons, teeth, excrement and cave paintings.
- A woolly mammoth was similar in size to a modern African elephant
- Males were typically around 3.5 meters tall and weighed up to 6 tons.
- Females were smaller, 9.5 feet tall and weighing 4 metric tons
- A newborn calf weighed around 90 kilograms or 200 pounds
- Woolly mammoths adapted well to the frigid temperatures of the last Ice Age thanks to their fur coats.
- They largely disappeared from the mail about 10,000 years ago, thanks to habitat shrinkage and human hunting.
- Isolated populations survived on Arctic islands until 4,000 years ago
The team hopes that the methods used in the study can be replicated to examine other ancient DNA samples.
However, they note that their success depends on well-preserved fossils, which are few and rare.
The results also bring scientists closer to extinction, as the karyotype provides a potential model for genetic engineering.
Geneticists led by Harvard George Church of the Faculty of Medicine is among those leading the charge.
This story originally appeared on The-sun.com read the full story
