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A new study may have uncovered what makes orange cats something special – although this may not be the reason that they are thinking about.
Ingregation are known among cat owners to be particularly friendly and lively. For geneticists, however, the uniqueness of these domestic cats comes from the unusual way they get their color. Scientists now say that they have dissolved a long -term puzzle by identifying the specific DNA mutation that is responsible for this golden color – and the variant has not been found in any other animal.
The genetic variant is first described in a paper that was published on May 15 in the magazine Current Biology.
“This is a really unusual kind of mutation,” said Christopher Kaelin, a senior study author, a senior scientist in genetics at Stanford University in California.
The vast majority of the fully orange -colored cats are male, which caused scientists decades ago that the genetic code for orange color is transmitted on the x -chromosome. As with other mammals, female cats have two x chromosomes, while men have an X and a Y. Every male cat that carries the orange characteristic on its an X chromosome will be completely orange. A woman would have to inherit the feature of both X chromosomes (one of each of her parents) to be completely orange, which it makes less likely. Instead, most female cats with orange fur have stained patterns – Calico or tortoise – that can include black and white.
But where the mutation exists on the x chromosome and how it causes orange color, so far there was a mystery. Typically, mutations that lead to yellow or orange fur in animals (and red hair in humans) occur within genes that control the color. And these genes are not transferred to the X chromosome. “This suggested that we could learn something new and interesting by identifying the molecular cause, which turned out to be the case,” said Greg Barsh, Emeritus of Professor of Genetics and Pediatrics in Stanford.
The results not only explained the special origins of the charismatic color of some cats, but also showed new insights into a familiar gene.
Genetic error behind orange cats
Female cats who carry the genetic code for the orange color on an X chromosome are not ginger. You will be shield skin (left) or Calico. – Laurie Laporte/Moment RF/Getty Images
Scientists have known about this gender -related mutation for a long time. However, the mutation itself confused geneticists. – Ping Shu/Moment RF/Getty Images
Step one was to identify genetic mutations that are unique for orange cats and may lead to their color. For a decade, Kaelin has visited cat shows and asked the owners of inginger -colored cats whether he could take samples of the animals of the animals with a cheek smear. (He is also interested in patterns that resemble those in wild cats such as leopards and ocelots who are common in popular breeds such as Bengalian cats and toygers.)
He and his research team compares his collection of DNA with cat genemenes that have been sequenced in the past five to ten years, and found 51 genetic variations of the X -chromosome, which were shared by orange men. But 48 were also found during non -orange cats, which left three likely candidates for the difficult mutation.
One was a small 5,076-base pair deletion, which had removed about 0.005% of the X chromosome in a region that did not seem to be encoded for a certain protein. The deletion was not within a gene where mutations are normally found. However, the mutation was between two places that are associated with a nearby gene called Arhgap36 and regulated an important hormone signal path that is used by almost all mammalian cells and tissues. There was no connection to pigmentation. The gene is not even switched on in pigment-producing cells.
In order to find out how the gene affects the color, Kaelin examined his actions in living tissues, which were collected in spay and neutrum clinics that would otherwise have been rejected. The experiments showed that the deletion somehow activates Arhgap36 in pigment cells, where it blocks the production of black pigment so that the cells produce orange instead.
The variant was not found in other animals, including the wild cats that led to domestic cats.
“It is a genetic exception that was noticed over a hundred years ago,” said Kaelin in a press release from Stanford University. “It is really the comparative genetic puzzle that has motivated our interest in gender orange.”
This singularity suggests that the mutation probably occurred during the domestication and was then selectively bred, said Kaelin. “We see the same mutation in all orange cats that we looked at about a wide geographical area. Therefore a single mutation has taken place,” he said. “And we know that mutation is quite old because in Chinese art there are representations of Kaliko katzen that date up to the 12th century.” He added that specialists in prehistoric DNA could possibly use the new results to determine when and where the mutation was originally created.
“The identified variants could serve as valuable instruments in the population genetics to pursue the evolutionary history of domestic cats,” said Hannes Lohi, professor of veterinary bioschiens and genetics at the University of Helsinki in Finland. Lohi was not involved in the study.
In the meantime, Kaelin and his employees want to find out how a small deletion that is not in a gene can change the activity of a nearby gene.
“The goal is certain that we will get to know the mutation,” said Barsh. He pointed out that there are many conditions in people that are considered genetically, but no genetic mutation was identified. Perhaps, in such a way, the problem is not only that we have not found the mutations, but that we do not understand all possibilities how mutations can cause disease characteristics.
And could the unusual genetics of the orange cats possibly explain their respective personalities? So far, Kaelin says that he and his colleagues have no reason to think of this, although other researchers could use the results of the new study to look for associations between behavior and shift color. “I think orange cats really convinced their owners that they are different, but they haven’t convinced us yet,” he said.
Amanda Schupak is science and health journalist in New York City.
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