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Genes resistant to damage. Healing powers. Very low risk of cancer. No, scientists do not describe Wolverine or Superman – these are the powers of the great white shark.
The blockbuster star of Steven Spielberg, whose scientific name is Carcharodon carcharias, has the reputation of being a sea monster that eats meat. But in fact, great white sharks can offer clues to the genetic underpinnings of self-healing DNA.
For the first time, scientists have successfully sequenced the entire genome of the Great White Shark. A genome is all the genetic material of an organism – its genes and its DNA. A new study reveals that these sharks have 4.63 billion bars on their DNA and 41 pairs of chromosomes compared to the 23 "humans.
So this sequencing effort took years.
But scientists believe the job will be worth it, Business Insider Mahmood Shivji, a biologist at Nova Southeastern University and co-author of the new shark genome study, told Business Insider.
"Sharks are well known for being able to heal wounds effectively, but nobody knows why," he said.
This new genome could reveal a plethora of genetic secrets that could explain why these animals are so good at healing and preventing disease.
"There is so much to learn from these evolutionary marvels with great success," said Shivji. "Their function and design represent 400 million years of extremely minute evolution."
The great white sharks heal quickly
Great whites and other sharks seem to be able to recover from serious injuries – injuries that can result from risky court behavior, fighting with other sharks or harpoon hunting – in just a few weeks.
Shivji and his co-authors have discovered that the big white has more genes dedicated to blood clotting, as well as various proteins that help stimulate new tissues and skin, more than any other mammal, fish or bird.
"They have dedicated a significant portion of their genome to wound healing," Wired Michael Stanhope, an evolution biologist at Cornell University, who directed the study with Shivji, told Wired.
In addition to this rapid healing, sharks do not contract cancer more often than humans, despite their large size. Scientists generally believe that the risk of developing cancer should increase with the size and lifespan of the body, since a larger number of cells and a longer lifespan increase the chances of damage. to the DNA causing cancer.
But "it is rare to find a shark" sick "in the wild," wrote scientists at the Mote Marine Laboratory in a study conducted in 2018.
Great whites can measure up to 20 feet long, weigh around 7,000 pounds and live between 40 and 70 years old. The fact that they do not have an increased risk of cancer suggests that something in their genome confers additional protection. (The typical causes of shark deaths involve interactions with humans or simply old age.)
According to the new study, one of the reasons could be that the genetic code of the big white hides an opposite DNA balance that makes the overall genome stable.
On the one hand, the genome contains a large proportion of "jumping genes": genes that copy themselves and then insert into various parts of the genome. Shivji said that scientists expect these genes to make the genome more unstable because they break the DNA strands during insertion, which increases the risk of errors and damage in the genetic code.
Such genomic instability is associated with a higher risk of human cancers, as well as other age – related diseases, such as Alzheimer 's disease.
But it turns out that the shark genome balances these jumping genes with stabilizing genes involved in DNA repair, damage response and damage tolerance.
So it seems that great white sharks have developed a way to keep their genomes stable despite their bulky bodies and long lifespans, Shivji said.
Genetic "superpowers" of sharks could have applications for human health
While the idea that sharks are at the test of cancer continues to circulate, animals can catch the disease. 44 cases of cancerous lesions were reported among 21 types of chondrichthyes, a class of species containing sharks and sting rays. According to a study conducted in 2016, about one third of these 44 cases were malignant.
This myth of cancer is the basis of shark cartilage pills, the sale of which continues to decimate shark populations around the world. The International Union for the Conservation of Nature has classified the Great White in the category "vulnerable to extinction".
Shivji pointed out that consuming shark-based products – such as cartilage pills or shark fin soups – will not improve the ability of your own genes to resist cancer.
"We want to avoid giving people the impression that if you eat sharks it will cure diseases," Shivji said. "It's as silly as saying," if you eat sharks, you'll be able to better hold your breath. "
But he added that the shark genome could provide scientists with "information that can be useful for human biomedical applications," including ways to "fight cancer and age-related diseases," and "to fight against cancer." improve treatments for wound healing ".
However, all treatments developed on the basis of these results are still far away. Stanhope told Wired that "it would take years of work".
"The sharks have had more than 400 million years to test their immune systems and develop this incredible ability," said Shivji. "We only touched the surface of the understanding of how they do that."
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