The genetic mutation that makes dogs small already existed in wolves

Scientists believed that dogs They started out big and got smaller around 20,000 years ago when they were domesticated. But a new study raises the possibility of a new evolutionary narrative.

A team of researchers at the National Institutes of Health (NIH) has identified a mutation in a growth hormone regulatory gene which corresponds to the small body size of dogs and was present in the wolves over 50,000 years agolong before domestication.

After ten years of research, the NIH team identified a mutation in a gene that regulates canine growth hormone.

NIH scientists had been looking for this mutation for over a decade. elaine ostrandera geneticist at that institution told his team to look for sequences around the gene that were positioned upside down and confirm if any were present in other canids and in ancient DNA.

Using this approach, the researchers found a reverse form of the insulin-like growth factor 1 (IGF1) gene with variants that correlated with size in the 200 dog breeds they examined.

“It’s not so much that the ‘gene’ is positioned backwards, but rather that a small piece of the IGF1 gene creates a complement on the opposite strand. This messenger RNA (mRNA) it can then bind to the true mRNA of IGF1 and affect its ability to make a protein. The reversed version is called long-chain non-coding RNA (lncRNA)”, explains Ostrander to SINC. The results are published this week in the journal Current Biology.

When researchers examined the DNA of a 54,000-year-old Siberian wolf, they found that it already had the growth hormone mutation.

The team then collaborated with evolutionary biologists Greg Larsonfrom the University of Oxford (United Kingdom), and Laurent Francisfrom Ludwig Maximilian University (Germany), to research the DNA of ancient wolves and find out when the IGF1 mutation first appeared.

This graph shows the distribution of the small body size mutation in different canid species. / Plassais et al.

“We tried to find the critical mutation for a decade and we failed. We look at the coding region, the regions between the genes, the ones that control gene regulation. We didn’t find out until we decided to look inside the gene and see if there was something interesting on the opposite strand. It helped a lot that there are now thousands of genes that we have the full genome sequence –of more than 250 races–. So we have a lot of big and small dogs to compare”, argues the scientist.

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A valid study for several species of canids

When the team examined the siberian wolf DNA (Canis lupus campestris) from 54,000 years ago, he discovered that he also had the growth hormone mutation. “It’s as if nature kept it in her pocket for tens of thousands of years until she needed it,” adds Ostrander.

The discovery holds true not only for dogs and wolves, but also for coyotes, jackals, African hounds and other members of the canid family. “This relates to many aspects of canine domestication and body size. What we thought was modern is actually very old,” he says.

“This is an important piece of the puzzle for understanding how the size in races. Dogs show more size variation than any other mammal on Earth. Learning how nature achieved this is a big step towards better understanding mammalian growth and regulation,” emphasizes Ostrander.

Now they will continue to study the genes that regulate the body size of dogs. “We would like to find the critical variants of some other genes that contribute to body size variation in canids. Usually only a few 25 genes they seem to regulate for the most part, between the major and minor races. We would like to understand how these genes work together to make the difference between being as small as a poodle toys and as big as a Newfoundland”, he concludes.

Source: SYNCHRONIZE

Rights: Creative Commons.

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