Sunday, June 12, 2011

Calico Cats

Is there such thing as a male calico cat?
Because genetic determination of some coat colors in cats is linked to the sex chromosome, calicoes are nearly always female.

What is a calico cat?
Calico cats are domestic cats with a spotted or parti-colored coat, usually predominantly white with orange and black patches. Outside of North America the pattern is more usually called tortoiseshell-and-white. Other names include tricolor cat, mi-ke (Japanese for 'triple fur') and lapjeskat (Dutch for 'patches cat'); calicoes with diluted coloration have been called calimanco or clouded tiger. "Calico" refers only to a color pattern on the fur, not to a breed. Among the breeds whose standards allow calico coloration are the Manx, American Shorthair, British Shorthair, Persian, Japanese Bobtail and Turkish Van.



Japanese Bobtail

British Shorthair

American Shorthair


Turkish Van

As calico cats are not a breed, but a color pattern on the fur which occurs in a non-predictive manner, there is no true historical background concerning calico cats. However, the existence of patches in calico cats was traced to a certain degree by Neil Todd in a study determining the migration of domesticated cats along trade routes in Europe and Northern Africa. The proportion of cats having the orange mutant gene found in calicoes was traced to the port cities along the Mediterranean in France and Italy, originating from Egypt.

The beginning of serious study of calico cats seems to have occurred around 1948 when Murray Barr and his graduate student E.G. Bertram noticed dark, drumstick-shaped masses inside the nuclei of nerve cells of female cats, but not in male cats. These dark masses became known as Barr bodies. In 1959, Japanese cell biologist Susumo Ohno determined the Barr bodies were X chromosomes. In 1960, Mary Lyon proposed the concept of X-inactivation, that one chromosome inside a female mammal shuts off. Although study has continued and deepened, these were the major contributors in the discovery of X inactivation in the early days.

So is there a male calico?
Calico cats are almost always female because the X chromosome determines the color of the cat and a female cat has two X chromosomes. A common male cat has one X and one Y chromosome. Since the Y chromosome does not have any color genes, there is no chance he could have both orange and non-orange together. One main exception to this is when, in rare cases, a male has XXY chromosomes, in which case the male could have tortoiseshell or calico markings. Most male calico or tortoiseshell cats are sterile due to the abnormality of carrying two X chromosomes.
In the case of a calico cat, the feline’s parents passed on different versions of X chromosomes genes related to coat color. The color of calico or tortoiseshell cats is determined by the X chromosome(s).
Tortoiseshell and calico cats are almost always female because of X chromosome inactivation.

As Sue Hubble stated in her book Shrinking the Cat: Genetic Engineering before We Knew about Genes, "The mutation that gives male cats a ginger-colored coat and females ginger, tortoiseshell, or calico coats produced a particularly telling map. The orange mutant gene is found only on the X, or female, chromosome. As with humans, female cats have paired sex chromosomes, XX, and male cats have XY sex chromosomes. The female cat, therefore, can have the orange mutant gene on one X chromosome and the genes for a black or white coat on the other, and those can affect or modify the orange mutant gene. If that is the case, those several genes will be expressed in a blotchy coat of the tortoiseshell or calico kind. But the male, with his single X chromosome, has only one of that particular coat-color gene: he can be not-ginger or he can be ginger (although some modifier genes can add a bit of white here and there), but unless he has a chromosomal abnormality he cannot be a calico cat."

 The process is further complicated because the female carries 2 X chromosomes while the male has only 1. So in mammals, one of the two X chromosomes in females gets inactivated. This is why calico cats are virtually always female - one X chromosome carries the gold color and the other X chromosome carries the black color. If the gold chromosome is shut off, the fur is black. If the black is shut off, the fur is gold. A male could carry either the black or the gold chromosome, but not both since he's XY. So in males, there is no second X chromosome to shut off.

About one in 3000 tricolored cats are male.

       Male Calico Cat

Male calico kitten

So how do people pay for these rare cats?
In truth a lot find their way to homeless shelters. Some people claim they can sell them for a 1000 dollars, but this depends on the buyer you find. Most people will not pay over the normal price for a male domestic cat. It just happens to be a rare event in the chimeric genes of a cat. The male calico is always sterile, if someone claims to have a kitten by a male calico it will most likely be mosaic and not calico. The cat is pricless to the owner as always.

What people are doing

Cloning, it has been observed that it is impossible to produce the same patterns in calico cats by cloning. As Ann Peneople Tsernoglou discovered from a prominent cloning company in 2004, "Calico cats cannot be cloned identically when it comes to their coat coloring. This is due to an effect called x-linked inactivation which involves the random inactivation of one of the X chromosomes. Since all female mammals have two X chromosomes, one might wonder if this phenomenon could have a more widespread impact on cloning in the future."

Feminine studies, calico cats may have already provided some fundamental and significant findings relating to the differences physiologically between male and female mammals. This insight may be one day broadened to the fields of psychology, psychiatry, sociology, biology and medicine as more information becomes available regarding the complete effect of random X-inactivation in female mammal.

Cats of this coloration are believed to bring good luck in the folklore of many cultures.  In the United States, these are sometimes referred to as money cats. The Japanese Maneki Neko figurine is almost always a calico cat.

Wiki Calico cat
Free-pet-wallpapers breeders
mosaicism toms

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