Orange cats are fat and silly? This may be because there are more male orange cats

When it comes to orange cats, the keywords that come to mind are often "good at eating" and "easy to gain weight"... However, this may not really be a stereotype!

Recently, scientists have discovered the genetic secrets of orange cats, which may explain the impression that "big orange cats are the most important" - there are more male orange cats than female orange cats , and male cats tend to be more gluttonous and larger in size.

Who are you calling fat? | Pixabay

It all starts with the color of the orange cat.

What does the “Orange” in Orange Cat mean?

The "orange" in orange cat refers to the orange color of the cat's fur .

This may sound like nonsense, but in fact many people confuse coat color, coat pattern, and breed. The color and pattern together make up the color of a cat's coat, and the color is one of the appearance characteristics to determine a cat's breed; but to determine a cat's breed, it is also necessary to consider a variety of appearance characteristics such as the shape of the body and head, eye color, etc. Therefore, "orange cat" is not a breed, but can refer to any cat with orange hair.

Judging from the color of its fur, Garfield is also an orange cat | Movie "Garfield"

For example, many people think that Cow Cat, Golden Gradient Cat, Garfield Cat, and Persian Cat are all breeds. But in fact, only " Persian Cat " is a breed; the rest:

Garfield is an exotic shorthair cat named Garfield, but now many people use "Garfield" to refer to this breed; in terms of coat color, Garfield is an orange cat.

Golden gradient is a kind of color, which usually appears on British shorthair cats. The most common color of British shorthair is blue (it looks more like gray to the naked eye). Later, people bred silver gradient color, and then some individuals had gene mutation, and golden gradient color appeared.

A cow cat refers to a cat whose coat has black and white patterns similar to a cow.

Cow Cat ⬆️ For a detailed interpretation of cat colors, click on the image to view the old article: After reading this article, I realized that the fur ball is actually a "black cat with a large white spot"?

Using clothing as an analogy, if a cat is a black and white plaid shirt, then black and white are colors, plaid is the pattern, black and white + plaid is the pattern, and the shirt is the variety.

There are many colors of cat fur, in addition to orange, the most common ones are white, black, blue, etc. However, there are only two main pigments that regulate cat fur color: Eumelanin can regulate black, brown and some derivative colors; Phaeomelanin can regulate red, orange, yellow and some derivative colors. A few breeds, such as the Norwegian Forest Cat, have unique colors.

The blue frame is the eumelanin regulatory area, the red frame is the phellogen regulatory area, and the area below is the Norwegian Forest Cat's fur color area｜messybeast.com/self-solid.htm; Translation: Xiaoyi

White is different from the above colors. It is not produced by pigments, but is controlled by a masking gene . Therefore, the cow cats we usually see are actually black cats with white spots. Even if there is only a small black spot on the cat, it is still a black cat with a large patch of white spots.

How the color of orange cats is formed

The orange color of domestic cats' fur is controlled by the pigment eumelanin; but why pigment cells produce eumelanin rather than melanin has always been a mystery.

It has long been speculated that the genes that control a cat's coat color are linked to sex, and this is especially true for tortoiseshell (black and orange) and calico (black, white and orange) cats, which are the offspring of black and orange cats and are almost always female .

The left one is tortoise shell, and the right one is calico. Generally speaking, cats of these two colors are female cats; the special case is a mutant male cat with XXY sex chromosomes, which is infertile｜Pixabay

Like humans, male cats have XY sex chromosomes, while female cats have XX sex chromosomes. However, each cell randomly inactivates one X chromosome and only expresses the information of the other. People speculate that the key gene that determines whether a cat expresses melanin or true melanin is located on the X chromosome , and the Y chromosome does not carry genes that control color.

In the offspring of black cats and orange cats, males only inherit one X chromosome from their mothers, so they can only be black or orange; plus the white masking gene, we have cow cats or orange and white cats. Female offspring inherit two different X chromosomes from their parents, which are randomly inactivated, and eventually black and orange patterns appear in different areas of the body, that is, tortoise shell; plus the white masking gene, we have calico cats.

Among the offspring of orange cats and black cats, orange ones are mostly male cats, and tortoiseshell ones are mostly female cats｜reddit.com

But what is this key gene, located on chromosome X? After 60 years of searching, geneticists may have finally found it.

The team from Stanford University compared skin samples from four orange cat embryos and four non-orange cat embryos and found that the RNA expression of the gene Arhgap36 in orange cats was very high, 13 times that of non-orange cats, and the gene was located on the X chromosome. The researchers speculated that Arhgap36 is the key gene regulating the orange coat of cats . When the expression of the Arhgap36 gene increases, it inhibits the ability of protein kinase A, reduces the expression of genes that produce eumelanin, leads to a decrease in the synthesis of eumelanin and an increase in the synthesis of pheomelanin, thus showing red or orange hair.

Left: When Arhgap36 gene expression is not increased, the cells eventually produce eumelanin; Right: When Arhgap36 gene expression is increased, melanin synthesis increases, and the coat is orange | Reference [1]

What causes the increased expression of the Arhgap36 gene in orange cats? Researchers found that this gene does not have a mutation in orange cats, but a section of DNA is missing near it . It may be this missing DNA that affects the amount of protein expressed by the gene.

A research team from Kyushu University in Japan recently discovered a similar gene deletion. They also found that in calico cats, the RNA expression of Arhgap36 in the orange area is higher than that in the black area.

Interestingly, in other animals, over- or under-expression of the Arhgap36 gene can cause developmental problems; but in orange cats, this gene is only over-expressed in developing and mature pigment cells (i.e., melanocytes), so it does not cause developmental problems for orange cats. Currently, both papers have been published on the preprint platform bioRxiv and have not yet been peer-reviewed .

What does this have to do with the orange cat being fat and greedy?

The Arhgap36 gene, located on the X chromosome, not only explains why tortoiseshell and calico cats are mostly female, but also why there are more male than female orange cats .

Because the Y chromosome does not carry genes that control color, for a male cat, as long as the X chromosome carries the gene that controls the production of brown pigment, it will appear as an orange cat; but a female cat needs both X chromosomes to carry genes that control the expression of brown pigment to appear as an orange cat. Therefore, male orange cats are more common than female cats.

Conversely, it can also be inferred that the mother of this litter of kittens has orange hair｜Pixabay

In addition to gender, temperature can also affect the color of certain cats .

Siamese cats carry a mutated gene that encodes tyrosinase, which promotes the production of melanin. Tyrosinase is very sensitive to temperature, so the coat color of Siamese cats changes with the temperature - when the temperature reaches 38°C, tyrosinase is inactivated and the body no longer produces melanin. The paws, tail and face of Siamese cats are better at dissipating heat than the trunk, so their body temperature is relatively low and dark. During the pregnancy of Siamese cats, the temperature around the fetus is stable at 38°C, making it difficult to produce melanin, so kittens are milky white at birth, and their limbs, tail and face will gradually turn dark as they grow.

Just came back from coal mining, my face and limbs are all black｜Pixabay

Many of our impressions of orange cats, such as greedy, fat, and stupid, may be caused by gender.

Previous studies have found that male cats have a higher average weight than female cats . Whether they are neutered or intact, male cats are more likely to be overweight than female cats. There are more male cats among orange cats, which may be the source of the impression that "big orange cats are the heaviest."

Both are British shorthair, the 1-year-old brother is bigger than the 2-year-old sister｜SamKakeru

Orange cats look "stupid", which is also an illusion caused by male cats. Cat owners who have raised cats of different genders may have the experience that male cats are "stupid" than female cats. In fact, this is because male cats are generally braver, less sensitive to external sounds, vibrations and other stimuli, and will not be nervous or afraid when meeting strangers; while female cats are relatively timid, so their eyes will look more alert and more sensitive to external stimuli.

In general, a cat's appetite, body size, and IQ are largely affected by gender, and the effect of fur color is extremely limited. Orange cats eat a lot, are large in size, and look silly, probably because most orange cats are male.

People, how can you say Mimi is stupid｜Mai Mai

Moreover, each cat is a different individual . Their childhood experiences, growing environment, and interactions with humans will all affect their personality and state. Don’t assume that orange cats are fat just because “big orange cats are heavy” - if your cat is really overweight, humans still have to help them control their weight!

References

doi: 10.1101/2024.11.21.624608. PMID: 39605675; PMCID: PMC11601623.

[2] Hidehiro Toh, Wan Kin Au Yeung, Motoko Unoki, Yuki Matsumoto, Yuka Miki, YumikoMatsumura, Yoshihiro Baba, Takashi Sado, Yasukazu Nakamura, Miho Matsuda, HiroyukiSasaki. A deletion at the X-linked ARHGAP36 gene locus is associated with the orange coloration of tortoiseshell and calico cats. bioRxiv [Preprint]. 2024.11.19.624036; doi: https://doi.org/10.1101/2024.11.19.624036

[3] Ellen Kienzle* and Katja Moik. A pilot study of the body weight of pure-bred client-owned adult cats. 2011. The British journal of nutrition 106 Suppl 1(S1):S113-5. DOI:10.1017/S0007114511001802

Author: SamKakeru

Edited by: Yellowtail Pollock

This article comes from GuokrNature (ID: GuokrNature)

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