Latest news with #GregBarsh
Yahoo
23-05-2025
- Science
- Yahoo
What's so special about orange cats? Turns out they're freaks of nature
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. A new study may have uncovered exactly what makes orange cats special — though it might not be for the reason you think. Ginger kitties are known among cat owners for being particularly friendly and feisty. To geneticists, however, the uniqueness of these house cats comes from the unusual way they get their color. Now, scientists say they have unraveled a longstanding mystery by identifying the specific DNA mutation responsible for that golden hue — and the variant has not been found in any other animal. The genetic variant is described for the first time in a paper published May 15 in the journal Current Biology. 'This is a really unusual type of mutation,' said lead study author Christopher Kaelin, a senior scientist in genetics at Stanford University in California. The vast majority of fully orange cats are male, which led scientists to reason decades ago that the genetic code for orange color is carried on the X chromosome. As with other mammals, female cats have two X chromosomes, while males have one X and one Y. Any male cat carrying the orange trait on its one X chromosome will be entirely orange. A female would need to inherit the trait on both X chromosomes (one from each of her parents) to be completely orange, which makes it less likely. Instead, most female cats with orange fur have patchy patterns — calico or tortoiseshell — that may include black and white. But where the mutation exists on the X chromosome, and how it gives rise to orange coloration, has been an enigma until now. Typically, mutations that lead to yellow or orange fur in animals (and red hair in humans) occur within genes that control for color. And those genes aren't carried on the X chromosome. 'That suggested to us that by identifying the molecular cause, we might learn something new and interesting, which turned out to be the case,' said senior study author Greg Barsh, a professor emeritus of genetics and pediatrics at Stanford. The findings not only elucidated the peculiar origins of some cats' charismatic coloration, but also revealed new insights about a familiar gene. Step one was to identify genetic mutations that are unique to orange cats and might give rise to their color. For a decade, Kaelin has frequented cat shows, asking owners of ginger-colored cats if he could take samples of the animals' DNA with a cheek swab. (He's also interested in patterns that are similar to those found in wild cats such as leopards and ocelots, which are common in popular breeds like Bengal cats and Toygers.) Comparing his collection of DNA with feline genomes that have been sequenced in the past five to 10 years, he and his research team found 51 genetic variations on the X chromosome that were shared by orange males. But 48 were also found in non-orange cats, which left three likely candidates for the elusive mutation. One was a small, 5,076-base pair deletion that removed about 0.005% of the X chromosome in a region that didn't appear to code for a particular protein. The deletion wasn't located within a gene, where mutations usually are found. However, the mutation lay between two sites associated with a nearby gene called Arhgap36, which regulates an important hormone signaling pathway used by nearly all mammalian cells and tissues. There was no known connection to pigmentation. The gene isn't even turned on in pigment-producing cells. To find out how the gene affects color, Kaelin studied its actions in live tissues collected at spay and neuter clinics that otherwise would have been discarded. The experiments showed that, somehow, the deletion activates Arhgap36 in pigment cells, where it blocks production of black pigment so the cells produce orange instead. The variant has not been found in other animals, including the wild cats that gave rise to domestic cats. 'It's a genetic exception that was noticed over a hundred years ago,' Kaelin said in a news release by Stanford University. 'It's really that comparative genetic puzzle that motivated our interest in sex-linked orange.' That singularity suggests the mutation probably occurred once during domestication and then was selectively bred for, Kaelin said. 'We see the same mutation in all orange cats that we've looked at over a wide geographic area, so there's a single mutation that occurred,' he said. 'And we know that mutation is quite old because there are depictions of calico cats in Chinese art that dates to the 12th century.' He added that specialists in prehistoric DNA might be able to use the new findings to pinpoint when and where the mutation originally arose. 'The variants identified could serve as valuable tools in population genetics to trace domestic feline evolutionary history,' said Hannes Lohi, a professor of veterinary biosciences and genetics at the University of Helsinki in Finland. Lohi was not involved in the study. In the meantime, Kaelin and his collaborators want to figure out how a small deletion that's not itself within a gene can change the activity of a nearby gene. 'The goal is, sure, that we'll learn about the mutation,' Barsh noted, 'but we also want to learn more about mutational mechanisms in general: Why is this so unusual and might the same mechanism occur in other genes that cause other phenotypes in other animals?' He pointed out that there are many conditions in humans that are thought to be genetic, but for which no genetic mutation has been identified. Maybe, he posits, the problem isn't just that we haven't located the mutations, but that we don't understand all the ways that mutations can cause disease traits in the first place. And could orange cats' unusual genetics possibly explain their particular personalities? So far, Kaelin says he and his colleagues have no reason to think so, though other researchers could make use of the new study's findings to look for associations between behavior and coat color. 'I think orange cats have really convinced their owners that they're different, but they've yet to convince us,' he said. Amanda Schupak is a science and health journalist in New York City.
Yahoo
22-05-2025
- Science
- Yahoo
Scientists solve the mystery of ginger cats – helped by hundreds of cat owners
After decades of mystery, new research has shed light on a question that has long stumped scientists and cat lovers alike – what exactly makes orange cats, well … orange? Two studies published in Current Biology last week by separate teams at Stanford University and Japan's Kyushu University at last provided some answers. Scientists have known for more than a century that orange cats inherit coloring differently from other mammals. Now – with help from hundreds of cat owners – researchers have identified the genetic mutation that gives orange cats their signature hue. 'From the time we started working on genetics of hair color, we have been fascinated to know what causes orange hair color in cats, and we know based on its inheritance that it must be different from what causes it in humans or dogs or mice or other animals,' said Greg Barsh, a professor of genetics at Stanford and the paper's senior author. 'What wasn't known is what the mechanism was.' To find out, the Stanford team began by collecting hundreds of cat DNA samples, visiting cat shows from California to Maryland and as far as Brazil. Researchers approached cat owners to ask whether they were willing to contribute and people were eager to participate, said Christopher Kaelin, a geneticist at Stanford and the study's lead author. 'Cat owners and breeders are really open to genetic studies and contributing to genetic studies,' Kaelin said. 'They're very interested in their cats, and they're very interested in talking about their cats and sending pictures, which is another big part of this study. All of that interest made it really easy to connect and collect samples.' Collecting a sample involved sticking a cotton swab in a cat's mouth and rubbing its cheeks to collect a small bit of DNA, Kaelin said. It's much more challenging to collect a cheek swab from a cat than a dog, due to felines being particularly resistant to having things placed in their mouths. But researchers have learned specific techniques to distract the cats, including scratching their heads. Talking them through the process seems to help, he added. 'After doing several hundred cats, you learn what you can get away with and when you need to back off quickly,' Kaelin said. As the study progressed, cat owners began reaching out in hopes of contributing, and mailed in brushes to the researchers. Several spay-and-neuter clinics contributed tissue samples from feral cat populations. 'Then in the lab, we could extract DNA from those samples and compare. We would then sequence portions of the genome and compare the sequences within those regions between orange and non-orange cats, looking for differences that might be the mutation that causes orange coat color,' Kaelin said. Researchers collected about 200 samples for use in the study, and in total have collected more than 3,000 samples for their research. After sequencing the DNA, they compared the sequence of orange cats to non-orange cats, which helped them locate the precise alteration: a small piece of missing DNA responsible for the orange mutation, Barsh said, near the gene known as ARHGAP36. The mutation activates that gene, which gets specifically turned on in pigment cells where it is not normally active. 'It intersects with the same pathway that is responsible for red hair in humans, but it affects that pathway in a completely different way,' Barsh said. 'That's why the study is important. This is a pathway that is required for hormonal signaling in many different cell types in many different animals, including humans. We've learned this pathway can be modulated in a new way to, in this case, affect hair color. But we think that that applies broadly to all cells and all tissues.' The fact that the samples were obtained in partnership with cat lovers in the community has allowed them to have greater engagement with the public, Barsh said: 'Both of those examples with cat shows and working with spay-neuter clinics are examples of how partnering with the community helps science and science education. More broadly, it advances science and no cats are harmed.' Kaelin has attended nearly 100 cat shows, he said, and presented research dozens of times so that cat owners have the opportunity to learn about what the team is doing. Feline color genetics are a useful scientific tool for discovery, and allow researchers to communicate scientific concepts to non-scientists. 'It really bridges an important gap,' Kaelin said.
The Guardian
22-05-2025
- Science
- The Guardian
Scientists solve the mystery of ginger cats – helped by hundreds of cat owners
After decades of mystery, new research has shed light on a question that has long stumped scientists and cat lovers alike – what exactly makes orange cats, well … orange? Two studies published in Current Biology last week by separate teams at Stanford University and Japan's Kyushu University at last provided some answers. Scientists have known for more than a century that orange cats inherit coloring differently from other mammals. Now – with help from hundreds of cat owners – researchers have identified the genetic mutation that gives orange cats their signature hue. 'From the time we started working on genetics of hair color, we have been fascinated to know what causes orange hair color in cats, and we know based on its inheritance that it must be different from what causes it in humans or dogs or mice or other animals,' said Greg Barsh, a professor of genetics at Stanford and the paper's senior author. 'What wasn't known is what the mechanism was.' To find out, the Stanford team began by collecting hundreds of cat DNA samples, visiting cat shows from California to Maryland and as far as Brazil. Researchers approached cat owners to ask whether they were willing to contribute and people were eager to participate, said Christopher Kaelin, a geneticist at Stanford and the study's lead author. 'Cat owners and breeders are really open to genetic studies and contributing to genetic studies,' Kaelin said. 'They're very interested in their cats, and they're very interested in talking about their cats and sending pictures, which is another big part of this study. All of that interest made it really easy to connect and collect samples.' Collecting a sample involved sticking a cotton swab in a cat's mouth and rubbing its cheeks to collect a small bit of DNA, Kaelin said. It's much more challenging to collect a cheek swab from a cat than a dog, due to felines being particularly resistant to having things placed in their mouths. But researchers have learned specific techniques to distract the cats, including scratching their heads. Talking them through the process seems to help, he added. 'After doing several hundred cats, you learn what you can get away with and when you need to back off quickly,' Kaelin said. As the study progressed, cat owners began reaching out in hopes of contributing, and mailed in brushes to the researchers. Several spay-and-neuter clinics contributed tissue samples from feral cat populations. 'Then in the lab, we could extract DNA from those samples and compare. We would then sequence portions of the genome and compare the sequences within those regions between orange and non-orange cats, looking for differences that might be the mutation that causes orange coat color,' Kaelin said. Researchers collected about 200 samples for use in the study, and in total have collected more than 3,000 samples for their research. After sequencing the DNA, they compared the sequence of orange cats to non-orange cats, which helped them locate the precise alteration: a small piece of missing DNA responsible for the orange mutation, Barsh said, near the gene known as ARHGAP36. The mutation activates that gene, which gets specifically turned on in pigment cells where it is not normally active. 'It intersects with the same pathway that is responsible for red hair in humans, but it affects that pathway in a completely different way,' Barsh said. 'That's why the study is important. This is a pathway that is required for hormonal signaling in many different cell types in many different animals, including humans. We've learned this pathway can be modulated in a new way to, in this case, affect hair color. But we think that that applies broadly to all cells and all tissues.' The fact that the samples were obtained in partnership with cat lovers in the community has allowed them to have greater engagement with the public, Barsh said: 'Both of those examples with cat shows and working with spay-neuter clinics are examples of how partnering with the community helps science and science education. More broadly, it advances science and no cats are harmed.' Kaelin has attended nearly 100 cat shows, he said, and presented research dozens of times so that cat owners have the opportunity to learn about what the team is doing. Feline color genetics are a useful scientific tool for discovery, and allow researchers to communicate scientific concepts to non-scientists. 'It really bridges an important gap,' Kaelin said.
