A Genetic Mutant?

According to genetics it is virtually impossible for a male cat to be carry the multi-color tortoiseshell coloring of this female cat.

According to genetics it is virtually impossible for a male cat to have the multi-color tortoiseshell coloring of this female cat.

Male cats can not carry the tortoiseshell markings—that is a genetic fact. This is based on very scientific principals, mainly that male cats only have one X chromosome. And, cats have this weird DNA twist: their sex chromosomes are directly linked to their fur color! (For more on this see this article)

It is important to recognize that multi-patterned calicos and tortoiseshell cats are already a result of a mutation process. This mutation occurs during the formation of the embryo. In order for this to transpire a female must start off with the Xb (black chromosome) and an Xo (orange chromosome) combination. While the embryo is developing a random switch between the Xb and Xo occurs resulting in a patchy coat pigmentation.

This means that a male tortoiseshell would actually be a double-mutant since he would need to inherit both the Xb and Xo chromosomes PLUS one Y (for him to be male). Quite a feat! Yet, mutations can occur but they are rare and the male is rendered sterile.

Now, imagine the excitement when a British veterinarian came across one of these wonders during a routine day in her practice. A client brought three tortoiseshell kittens to Dr. Karen Home’s clinic in Harpenden, Herfordshire for routine vaccinations. While examining the kittens, Dr. Home was happily surprised to discover that one of them was a male!

She immediately recognized that this kitten was indeed something special and adopted the little guy into her family of five cats, four dogs, and three children. They named him Eddie, after Eddie Izzard, the comedian because as Dr. Home said, “…. he is essentially a boy dressed as a girl.”

Demystifying the Sex/Color Connection in Cats

Why Does Color Affect the Sex of a Cat? Or Vice-Versa?

You always knew your cat was special, unusual, and certainly unique. But there are even more fascinating facts about the cat that have stumped people for some time. I am referring to what most cat lovers already know: cats of a certain color will be predominantly one sex or another. This has been common knowledge but back in the “dark ages” no one actually knew why. Happily, advances in the field of genetics have uncovered this feline mystery.

It all begins with a very unique genetic twist embedded into the chromosome code of the feline. This is an oversimplification but for the sake of this explanation lets just state that certain chromosomes determine gender (male or female). For example, females have two X chromosomes (XX) and males have only one X chromosome and one Y (XY). Now here comes the twist: a cat’s X chromosome coding is directly linked to the color of its coat! This unique coding is called a sex-linked gene.

Sex-linked gene determines color of cats

Sex-linked gene determines color of cats

Again this is an oversimplification, the coat color in all cats is an X-linked gene for black and orange-brown colors. So the color-coding would be Xb (for black) and/or Xo (for orange-brown). A female cat has two X chromosomes so she is able to “display” two colors at the same time: black AND brown-orange—and all the variations in between (the white color is a separate gene). A female cat with two Xb Xb chromosomes would be black. A female cat with two XoXo chromosomes would be orange-brown.

A male cat on the other hand will only receive his color designation from the one X chromosome and this chromosome would render a monochromatic coat. (The Y chromosome is a “blank.”) For a male to display BOTH red and black he would have to have two of the X chromosomes described above PLUS one Y (for him to be male). This could happen but it would be a mutation (abnormality) that would render him sterile.

The explanation gets a little more complicated when it comes to multi-patterned calicos and tortoiseshell cats (multi-colors of orange, brown, black, gray, cream, or white without patches). These coat colors and patterns are the result of a mutation that occurs during the forming of the embryo. For this to transpire the female will need start off with the Xb Xo combination. During embryonic development some cells randomly—through the process of mitosis (cell division)—will turn off the Xb or Xo gene. This in turn will produce patchy coat pigmentation that results in either a tortoiseshell or patterned calico cat.

As for the orange tabby cat being predominantly male that is true. However female cats can also be orange. It’s mostly a matter of probability. As explained above a male cat has only one color gene and that is located in his X chromosome. So, whatever color that X chromosome has attached to it is what he will be. The X chromosome inherited by the male will either be Xo (brown-orange) or Xb (black)—keep in mind that the white color is an entirely different gene. Therefore the odds are that male cats will be either orange/white; solid orange; brown/dark-brown; brown/dark-brown/white; black/white; solid black; or a dilution of black resulting in gray/white; or solid gray.

The female orange tabby has received two Xo chromosomes. And this does happen, producing females with varying degrees of ginger colors that can be accompanied by white markings. However, she is more likely to receive two different types of X chromosomes such as the XoXb combination. And because of the double X sex-linked color chromosome it is safe to say that female cats will display more color combinations than males.

Simba's unique brown coat is the result of his Xo chromosome that produces the brown-orange color. The white is a separate gene not attached to the X chromosome. Many breed specific cats such as the Siamese and Burmese have specific color-coded genes not related to their gender. Simba's tabby-stripes are visible in his brown coat and reveals the fact that all cats are tabbies, even the "solid" color ones.

Ezra has inherited the sex-linked chromosome Xb resulting in a black coat. A white gene adds a touch of class to this handsome gent.

Ezra has inherited the sex-linked chromosome Xb resulting in a black coat. A white gene adds a touch of class to this handsome gent.

Leon has inherited the sex-linked gene Xo producing a nice red tabby male with alert green eyes.

Leon has inherited the sex-linked gene Xo producing a nice red tabby male with alert green eyes.

Diamond is a lovely blue-cream and apricot medium hair calico. She inherited the sex-linked chromosomes XoXb resulting in the two colors. The pattern she displays is the result of cell mitosis and random shutting off of Xo and Xb resulting in a "pattern." Although she is not a black/red/white she is still considered a calico due to the white markings. She is indeed a wonderful example of genetic color diversification.

Diamond is a lovely blue-cream and apricot medium-hair tortoiseshell. She inherited the sex-linked chromosomes XoXb resulting in the two colors. The pattern she displays is the result of cell mitosis and random shut down of chromosome Xo and Xb resulting in a "pattern." She is indeed a wonderful example of genetic color diversification.

This little calico displays the traditional orange/black/white coloring of a calico cat. She inherited the XoXb sex-linked chromosomes and cell mitosis produced a lovely pattern on her coat. The white is a requirement for the calico color designation. Keep in mind that a calico cat is not breed. It is a distinct color.

This little calico displays the traditional orange/black/white coloring of a calico cat. She inherited the XoXb sex-linked chromosomes and cell mitosis produced the classic calico pattern on her coat. The white is a requirement for the calico color designation. Keep in mind that a calico cat is not breed. It is a distinct color.

Gracie displays the another variation of the chromosome XoXb sex-linked gene. This time the result is a tortoiseshell cat with a tabby stripe pattern, particularly around her head. Her coat coloring is called a dilute tortoisehell because the colors are muted.

Gracie displays another variation of the chromosome XoXb sex-linked gene. The result is a tortoiseshell cat with a tabby stripe pattern, particularly around her head. Her coat coloring is called a dilute tortoiseshell because the colors are muted.

Finding the Purrfect Kitty for Your Family!

July 31, 2008 by Editor  
Filed under ALL ABOUT CATS, Cat Characteristics

The following article content is provided with the permission of the ASPCA

SecurePet Pet Sitter Services of Wimberley, Texas Presents: The ASPCA Feline-Ality Test

A love match made in heaven? Well it can be if you select the right feline personality to suit your lifestyle. The ASPCA (with the sponsorship of IAMS) has developed what they consider a sure-fire method of finding that perfect “feline-ality.” You could say it is a personality test for cats. The purpose is to match potential adopters with their perfect kitty.

How does this program work? It assesses the behavior of felines along with the expectations of potential adopters. Cats are assessed on two major scales of behavior: One is the “valiant” scale, the other is the “independent-gregarious” scale. And adopters participate in a survey that helps match them to their perfect kitty mate. The two feline behavioral scales are the valiant scale and the independent-gregarious scale.

The valiant scale is based on the feline’s response to novel stimuli. In other words, the valiant scale determines the degree of comfort a cat displays in new situations. A low valiant cat, for example, would be apprehensive in a new situation while a high valiant cat would display little or no nervousness if placed in a novel circumstance.

The second scale is the independent-gregarious measure. This measures a feline’s social behavior. It specifically measures the amount of time the cat will want to spend with the adoptive family. It determines whether the cat is independent, social or gregarious. This provides the potential adopter with a measure of how much family time their new cat will need, as well as other social requirements.

Each major color assignment is based first and foremost on the valiant scale. A low valiant score is a purple cat. A medium valiant score is an orange cat. And a high valiant score is a green cat. Secondly, the independent-gregarious scale is used to determine personality ranges withing each color category. A cat with a score of 5-13 is ranked independent. A cat with a score of 14-23 is considered social, while a cat with a score of 24-34 is considered gregarious.

The MYM program allows for three main feline-ality colors, with a total of three independent-gregarious scales within each color. This adds up to a total of nine distinct feline personality types.

Putting it all together, the potential adopter is asked to fill out an adopter survey card. The information from the survey provides specific points and the final score determines if the adopter falls in the purple, orange or green category. It is then up to the individual adopter to choose within each specific color range the most likely candidate for their home environment.

To take the adopter survey please visit the Cat Adopter Survey Test page.

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Private Investigator

Category: Independent/low valiant

“I’m working undercover to keep an eye on you and your household. You may not even know you’re under surveillance. I can vanish into thin air if anyone or anything interferes with my investigation. If you need a cat who knows how to stay out of trouble and will always keep your secrets, I just might be your case.”

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Secret Admirer

Category: Social/low valiant

” When it comes to relationships, I’m very level-headed. I don’t leap in paws first. If you know what I mean. But give me a little time, and then I’ll shower you with purrs, head-butts, and plenty of lap time. In the meantime, you may not see a lot of me—but I’ll be thinking of you.”

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Love Bug

Category: Gregarious/low valiant

” Do you seek affection? I do! If you also like petting, purrs, and paws kneading in your lap, I think we might have A LOT in common. I’m looking for “someone who enjoys quiet times and togetherness.” Could that someone be you?”

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The Executive

Category: Independent/medium valiant

“I have to say, I’m a busy cat. First, I’ve got to check out what’s happening out the window. Next, I’ll see if any closets or cupboards need looking into. And then there are my naps—can’t be late for those. I can fit a little socializing into my schedule. Shall we plan on breakfast and dinner? I hope you like kibbles.”

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The Sidekick

Category: Social/medium valiant

“Like all sidekicks, I’m just plain good company. I like attention, and I also like my solitude. I don’t go looking for trouble but I’m not a scaredy-cat, either. If you are looking for a steady companion to travel with you on the road of life, look no further.”

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Personal Assistant

Category: Gregarious/medium valiant

“You’re working on the computer? Let me press the keys. Reading the paper? I’ll hold the pages down for you. Watching TV? I’ll just plop on your lap so you can pet me. I love an orderly household, don’t you? I’ll help you with all your chores and I’ll help you relax when we’re done. You’ll be wondering how you ever managed without me.”

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MVP

Category: Independent/high valiant

“I’m a savvy cat who knows the score. I’m pretty unflappable, too. I don’t mind entertaining myself, but a human companion at the other end of the couch and a nice scratch behind the ears always make my day. If you’re looking for a resourceful addition to your team, think about signing this Most Valuable Pussycat.”

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Party Animal

Category: Social/high valiant

“I’m a cat on a mission: PARTY! I love to play and explore and test my limits. I’d love to play with you, but I can make a toy out of anything: pencils, post-it notes, potatoes. If you are looking for some laughs and someone to liven up the party,
think about inviting me.”

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Leader of the Band

Category: Gregarious/high valiant

“I’m a cat who does everything in a big way. I not only like to be in the middle of things—I like to lead the parade. I’m an adventurous cat, but I’ll still make plenty of time to show you my affectionate side. I’m the demonstrative type, you might say. Want a cat who’s brimming with confidence? That’s me.”

SecurePet Pet Sitter Services is located in Wimberley, Texas and provides pet sitting care for all types of animals: ranch animals, dogs, cats, birds, reptiles (but not gators!) and amphibians. This full-service petsitter company will ensure that all your pets receive lots of love and the best of care while you are away on business or pleasure.