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San Francisco Chronicle
15-05-2025
- Science
- San Francisco Chronicle
Why are some cats orange? Stanford scientists solve century-old mystery
Orange cats are special — and not just because of notoriety for silly behavior. They have also been a longtime genetic enigma. Scientists have now cracked the cat color code. Two studies, published in tandem Thursday, pinpointed the gene responsible for orange cat fur. One study was led by Stanford University's School of Medicine and scientists based in the United States; the second was led by researchers in Japan. 'Over the past hundred years or so, it was recognized that orange cats kind of fall outside of the genetic rules for how coat color in mammals is determined,' said author Christopher Kaelin, a geneticist at Stanford University's School of Medicine. The investigation of felines' orange coat color addresses broader questions about animal evolution and how gene regulation is encoded in the genome, Kaelin said. Past studies pointed to the orange mutation as being on the X chromosome. By analyzing sequencing data, the American scientists further mapped the mutation to a DNA deletion near a gene called Arhgap36. In humans, increased expression of this gene has been implicated in brain tumors and endocrine cancer, according to the study. The researchers found cats with the orange mutation expressed higher levels of RNA from the Arhgap36 gene, specifically in pigment cells. They propose that the protein produced by this gene limits a step in the middle of the biological pathway behind coat color. In male cats, who typically have one X chromosome, the orange mutation means more Arhgap36 protein in pigment cells and activation of a pathway to produce reddish yellow pigment. By contrast, in male cats without the mutation, and less Arhgap36, pigment cells produce a different pigment that's black or brown. This switch recapitulates a molecular pathway in humans, in cells that make pigment that causes red hair, said author Gregory Barsh, a geneticist at Stanford University's School of Medicine and HudsonAlpha Institute for Biotechnology. Coat color is more complicated with female cats, who have two X chromosomes. A random process, known as X-chromosome inactivation, turns off one X chromosome in each cell. If a female cat has the orange mutation on just one X chromosome, this random inactivation results in a mixed tortoiseshell or calico pattern. Like the American team, the Japanese researchers identified Arhgap36 as the reason for orange cats' coat color. They additionally confirmed that the gene experiences chemical modifications that indicate it undergoes X-chromosome inactivation. 'The orange gene was a long-standing mystery for scientists,' said study author Hiroyuki Sasaki, a geneticist at Kyushu University's Institute of Bioregulation and Institute for Advanced Study, by email. 'It is a great joy for me to have finally cracked it with my colleagues.' The two studies were originally posted as preprints last year. The Japanese results were posted on Nov. 21, 2024; the American results were posted on Nov. 22, 2024. 'It's fantastic that not only one group, but two groups have published on this,' said Leslie Lyons, a feline geneticist at the University of Missouri College of Veterinary Medicine, who wasn't involved with the new studies. Lyons still wants to know more about how the genetic findings translate into the ginger hues of orange cats. One step could be quantifying how much reddish yellow pigment is produced, compared with other pigments. Another could be probing how much pigment is put into feline hairs. The U.S.-based researchers found the orange mutation specifically affected pigment cells, suggesting Arhgap36 isn't involved in orange cats' reputation for goofy behavior. Potentially, their friendly demeanors could just be a byproduct of orange cats typically being male. But there also could be linkage with some other genes, Lyons said. Scientists say orange cats' personalities could be an area for future study. 'There's a lot of anecdotal stories about orange cats and behavior, or orange cats and appetite, but those aren't well-documented in the scientific literature,' Kaelin said. 'I do think there's opportunities using citizen science approaches to make those types of associations.'
Yahoo
03-04-2025
- Science
- Yahoo
A Strange Glitter Gene Is Making Some Cats Sparkle Like Diamonds
Bengals are one of the most sought-after cat breeds in the world, in part due to a genetic trait that gives many of them shiny, almost 'glittery' coats. It turns out that this trait is a deviation of the Fibroblast growth receptor 2, and actually comes from the domestic part of the genetic tree rather than the wild Asian leopard half. As the costs of bengals skyrocketing, breeding these creatures is rife with exploitation, and the animals remain illegal in some municipalities. Having been domesticated 30,000 years ago, dog breeds display a remarkable amount of genetic diversity—after all, Great Danes and chihuahuas are somehow the same species. Cats, on the other hand, all look relatively similar to their wild ancestors (long hair and smooshed noses, aside). But while many cat breeds look similar to one another in both size and overall coloring, some breeds hide absolutely fascinating genetic secrets. And one of the most sought-after cats—the Bengal cat—may hide one of the most dazzling secrets of all. Although their leopard-esque coats hint at an ancient ancestry, Bengal cats are genetic newcomers. Created by a California cat breeder in 1963, the Bengal is a cross-breed between the domestic cat (Felis catus) and the Asian leopard (Prionailurus bengalensis). Although the Asian leopard looks remarkably similar to your average feline, the two species' common ancestor lived some six million years ago—that's more genetic distance than humans and chimpanzees (don't Google 'humanzee'). After two decades, the The International Cat Association (TICA) officially recognized the breed in 1986. However, after cross-breeding Bengals, a peculiar trait began to emerge—some of their coats sparkled like glitter (which you can see up-close here). To dig into exactly why this special shine showed up, scientists from the HudsonAlpha Institute for Biotechnology studied 3,000 DNA samples from Bengal cats and determined that this derived from an alteration of the Fgfr2 (Fibroblast growth receptor 2) gene. Contrary to what you might expect, this trait doesn't come from the wild Asian leopard, but is instead a very rare condition in domestic cats. They published their work last year in the journal Current Biology. 'Fgfr2 is a gene found in all mammals that is important for embryonic development and organogenesis,' geneticist Kelly McGowan, a co-author of the study, said in a press release in 2024. 'Our results show that while a complete loss of Fgfr2 is lethal, a moderate reduction causes a desirable trait to manifest mainly in the hair.' This trait isn't present in all bengal cats. According to the pet DNA site Wisdom Panel, of the millions of cats in its database, only 5,513 carry this altered 'glitter' gene. But, as McGowan and her team explain in their research, the gene is present in around 60 percent of the Bengal population. And this isn't the only trait that sets Bengals apart from other cats. For one, bengals tend to be much more active than other types of cats. They also tend to eschew the typical feline aquaphobic stereotype and instead love to play with water, similar to other savannah cats and hybrid breeds. Of course, with Bengal breeds runnings thousands of dollars, the Bengal breeding industry can be ripe for abuse, and because of their more wild origins, some experts believe keeping Bengals as pets isn't such a good idea due to their increased need for stimulation (compared to domestic cats). In New York City, for example, a Bengal cat needs to be six generations removed from its wild ancestor to be a legal pet. Bengal cats may be incredible creatures with glittering coats, but the jury's out if they're really suitable companions for a human's more sedentary, indoor lifestyle. You Might Also Like The Do's and Don'ts of Using Painter's Tape The Best Portable BBQ Grills for Cooking Anywhere Can a Smart Watch Prolong Your Life?
