Why are some cats orange? Stanford scientists solve century-old mystery
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Diverging Reports Breakdown
Orange Cats Are Genetically Unlike Any Other Mammal and Now We Know Why
Orange male cats are uniformly colored, but female cats often have a patchwork of orange and black fur, commonly referred to as tortoiseshell or calico patterns. In most mammals, orange or yellowish fur results from mutations in one of two specific pigment genes. But these genes aren’t sex-linked and show up in both males and females alike. In orange cats, its unexpected activation in pigment cells throws a wrench into the cellular machinery responsible for melanin production. It blocks a late step in the pigment pathway — effectively flipping the fur’s palette from dark to bright orange. The mutation alters gene activity instead of disrupting the gene itself, and the affected gene codes for a protein that functions differently from what we could infer without experimentation, the researchers say. They scanned non-skin tissues and found no difference in Arhgap36 expression between orange and non-orange cats, based on our observations, this is highly specific to pigment cells, they say. Still, orange cats often come with big personalities — at least, according to their owners, who actually explored the genes behind their hue more than we think they do. The researchers found a tiny deletion on the X chromosome that causes a gene to turn on in
The mystery of orange cats is solved: A gene explains why most are male
U.S. and Japanese scientists have analyzed the genetic origin of the color in these cats. The orange fur of cats results from genetic variations on the X chromosome, one of the two sex chromosomes. What makes this trait unique is that it is sex-linked — something not observed in any other mammal. Males, possessing only one X chromosome (paired with a Y), will display orange coats if they inherit a copy of the ARHGAP36 gene from one parent. Females, with two X chromosomes, must inherit both copies of the gene to have a fully orange tabby coat, which is why they are much less common. The gene is not deleted, but it is located near the deletion site, which can alter the reading of the DNA sequence. This is a harmless mutation, in an area where it is not expected to have an negative effect, like fur. It is normally expressed in neuroendocrine cells, where it can cause tumors, but in human studies it was being investigated by scientists in the fields of cancer and developmental biology. The genetic puzzle was being solved by scientists at the National Institute of Agricultural and Food Research and Technology in Spain and the University of Kyushu in Japan. The study was published in
Orange cat mystery solved, unique gene identified by scientists
Unlike other mammals, orange coloration in cats is strongly linked to sex. Any male cat inheriting the “sex-linked orange” mutation will be entirely orange. However, a female cat needs to inherit this mutation on both of her X chromosomes to be fully orange, which is a much rarer occurrence. The cat’s orange secret lies elsewhere – on the X chromosome. Just like in most mammals, female cats have two X chromosomes (XX) while males have one X and one Y (XY). This explains why any male cat inherit the ‘sex- linked orange’ mutation will have entirely orange skin.
Decades-long mystery of ginger cats revealed
Scientists from Kyushu University in Japan and Stanford University in the U.S. have uncovered the DNA mystery that gives ginger cats their colouring. They discovered that ginger cats are missing a section of their genetic code, which means the cells responsible for their skin, eye and fur tone produce lighter colours. The breakthrough has brought delight to the scientists but also the thousands of cat lovers that originally crowdfunded the research. The scientists hope solving the puzzle could also help shed light on whether orange coloured cats are at increased risk of certain health conditions. It has been known for decades that it is genetics that gives orange tabby cats their distinctive colouring, but exactly where in the genetic code has evaded scientists till now. The ARHGAP36 gene is found in humans and has been linked to skin cancer and hair loss. The researchers think it is possible that the DNA mutation in the gene could cause other changes in these parts of the body linked to health conditions or temperament. For decades scientists have observed that cats with completely ginger colouring are far more likely to be male. This tallies with the fact that the gene is carried on the X chromosome. In comparison female cats have two X chromosomes so the DNA needs to be missing in
This Strange Mutation Explains the Mystifying Color of Orange Cats
In house cats, orangeness appears to be sex-linked. It almost always occurs in males because of a mutation on the sex-determining X chromosome. Scientists have long been unable to pinpoint any specific gene responsible for pumpkin-colored cats. Now two papers reveal a remarkably unique genetic pathway that has never been seen in other felines—or any other mammals.. A tiny deletion in a cat’s X chromosome increased the activity of a gene called Arhgap36, which scientists had never previously associated with pigmentation. In this case, it appeared to be coaxing the cat’s melanin-producing cells to shift orange. That meant that the mutation didn’t disrupt the cat�’s expression of melanin. The study adds to the knowledge about this gene and how it functions, says a Stanford scientist who was not involved in the study but was thanked for contributing to the genomic resources in the paper. “The candidate region had more than 10 genes, none of which was known for pigment regulation,” says Hiroyuki Sasaki, a geneticist and senior author of the Kyushu University study.“Everything you need to know about genetics, you can learn from your cat
Global Perspectives Summary
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Sources
- Orange Cats Are Genetically Unlike Any Other Mammal and Now We Know Why
- The mystery of orange cats is solved: A gene explains why most are male
- Orange cat mystery solved, unique gene identified by scientists
- Decades-long mystery of ginger cats revealed
- This Strange Mutation Explains the Mystifying Color of Orange Cats
Source: https://www.sfchronicle.com/science/article/orange-cat-gene-century-old-mystery-20317602.php