Aberration? Scientists discover the genetic origin of orange cat color

One new study may have discovered exactly what makes orange cats special “Although maybe it’s not for the reason you imagine.”

Radiv kittens are known among tutors because they are particularly friendly and personality full. For geneticists, however, the uniqueness of these domestic animals comes in the unusual way as they get their color.

Now scientists say they have unveiled a longtime mystery by identifying the specific DNA mutation responsible for this golden tone – a variant that was not found in any other animal.

The genetic variant was first described in an article published on May 15 in the magazine Current Biology.

“This is a really uncommon type of mutation,” said the study’s main author Christopher Kaelin, a senior scientist in Genetics at Stanford University in California.

Most totally orange cats are male, which led scientists decades ago to conclude that the genetic code for orange color is located on the X chromosome.

As with other mammals, females have two X chromosomes, while males have an X and an Y. Any male cat who carries the orange gene on their only X chromosome will be entirely of this color. Already a female would need to inherit the gene in both X (one of each parent) to be completely orange, which is less common.

Instead, most orange coat cats have stained patterns – Calica or Turtle Peel – which may also include black and white.

But where exactly the mutation is located on the X chromosome, and as it generates orange color, it was a puzzle so far. Normally, changes that lead to yellow or orange hair in animals (and red hair in humans) occur within genes that control pigmentation. And these genes are not on the X chromosome.

“This suggested to us that by identifying the molecular cause, we could learn something new and interesting – which actually happened,” said Greg Barsh, study co -author and emeritus teacher of Genetics and Pediatrics at Stanford.

The findings not only clarified the peculiar origin of the charismatic color of some cats, but also revealed new insights about a known gene.

The genetic failure behind oranges cats

The first step was to identify exclusive genetic mutations of orange cats that could cause their color. For ten years, Kaelin frequented cat exhibitions, asking red -haired feline tutors permission to collect DNA samples with a oral cotton swab. (He also has an interest in standards similar to those of wild cats, such as leopards and jaguatiric, common in popular races such as Bengal and Toyger.)

Comparing his DNA collection with sequenced feline genomes in the last five to ten years, he and his research team found 51 genetic variations on the X chromosome shared by orange male cats. But 48 of them were also present in non -orange animals, leaving only three mutations as probable candidates.

One of them was a small exclusion of 5,076 pairs of bases that removed about 0.005% of the X chromosome in a region that apparently did not encode any specific protein. Exclusion was not inside a gene, where mutations usually occur.

However, the mutation was between two places associated with a nearby gene called Arhgap36, which regulates an important hormonal signaling route used by virtually all mammalian cells and tissues. There was no known connection with pigmentation. The gene is not even activated in cells that produce pigment.

To understand how the gene affects color, Kaelin studied his action in living tissues collected in castration clinics, which would otherwise be discarded.

The experiments showed that, somehow, the exclusion activates the Arhgap36 in pigment cells, where it blocks the production of black substance, causing cells to produce the orange color.

This variant was not found in any other animal, including wild cats that gave rise to domestic cats.

“It’s a genetic exception that was noted for over a hundred years,” Kaelin said in a statement at Stanford University. “It is precisely this comparative genetic puzzle that motivated our interest in the gene linked to sex that causes orange color.”

This uniqueness suggests that the mutation probably occurred only once during domestication and was then selected by intersections, Kaelin explained. “We see the same change in all oranges cats we analyzed in a wide geographical area, so it was a unique modification,” he said.

“And we know that this mutation is quite old because there are representations of Cellic cats in Chinese art dating from the twelfth century.” He added that pre-historical DNA experts can use these new discoveries to identify when and where the change has arisen.

“Identified variants can serve as valuable tools in the genetics of populations to track the evolutionary history of domestic cats,” said Hannes Lohi, professor of veterinary and genetic bioscience at the University of Helsinki, Finland, who did not participate in the study.

Meanwhile, Kaelin and his collaborators want to find out how a small exclusion, which is not located inside a gene, can change the activity of a nearby gene.

“The goal is, of course, to learn about this mutation,” said Barsh, “but we also want to understand more about mutation mechanisms in general: because it is so unusual and whether the same mechanism can occur in other genes that cause other phenotypic characteristics in other animals.”

He pointed out that there are many conditions in humans considered genetic, but for which no mutation has been identified. Perhaps, he proposes, the problem is not just that we do not yet locate mutations, but we do not understand all ways in which mutations can cause disease.

And can the unusual genetics of orange cats explain their particular personalities? So far, Kaelin says he and his colleagues have no reason to believe it, although other researchers can use discoveries to seek associations between behavior and coat color.

“I think oranges cats have convinced their owners that they are different, but have not yet convinced us,” he concluded.

Japanese artist makes portraits of realistic cats in 3D

Liquid cats? PhD in physics viralizes with studies that say yes

Was this content originally published in aberration? Scientists discover the genetic origin of orange cat color on CNN Brazil.

Source: CNN Brasil