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Cats of all colors

Cats, especially purebred ones, have a great many of colors. All are divided into some groups.

1. Solid color - all hairs are colored uniformly from the roots to the tips.

2. Aguthy - all hairs are ring-colored (alternation of dark and light color).

3. Tabby -pattern on an aguthy-colored hair - striped (mackerel), marmoreal, spotted.

4. Silvery (smoky group) - every hair has a dark tip and light base.

5. Color-point, or Himalayan - the whole body is of rather light tone; mask, ears, limbs and tail are painted.

6. Tortoise and blue-cream (blue tortoise) - these colors can't be regarded as independent groups for they concern female cats solely and not male cats. Along with complete colors they are considered as "classic".

7. Particolor - all former groups in combination with white color. The special subgroup is bicolor, that is, solid color in combination with white.

However it should be noted that a cat might have a color, which is among several mentioned groups simultaneously. This is because apart from the fact that all genes influence each other, they are coherent within a color group sometimes (for example the Siamese color is coherent with blue eyes; white color - often with deafness; homozygous Scottish lop-eared, as a rule, have some deformations of skeleton and so on).

Let's examine groups of colors in detail:

1. Solid colors.

Every domestic cat in any case represents tabby color, practically is never free from it, if only there's no masking. The difference between tabby and solid colors from the genetic Point is that solid gene has a code "aa" (non-Aguthy), which due to epistasis prevents display of tabby color. Epistasis is masking of one gene by the other that is very clearly expressed in gene W. Yet one should remember that gene "aa" doesn't affect red and cream color therefore virtually there's no pronounced genetic difference between red and red tabby color. They are genetically identical. Differentiation into solid red and red marmoreal is a merit of holders, the result of their purposeful selection. The development of a pattern in red colored animals (especially in childhood) is independent of a presence of "aguthy" or "non-aguthy" gene, whereas in animals of other colors (except for white) it's obligatory for this gene to be part of genotype to provide a pattern.

Speaking about a white color we can say there're several genetic variants:

- Entirely white, conditioned by a dominant gene W. This gene provides a color that due to epistasis masks all other color variations. Thus there may occur very different colorings in a litter that were hidden in a genotype of this certain color. However "colored" kittens from white parents may occur if only one of parents - female or male - is homozygous by the gene of white color. If both parents are homozygous by a "white" gene (WW) than they will certainly have white kittens. Heterozygous couple (Ww) may have both either white (more likely) or "colored" kittens.

- Foreign White -gene W in their genotype is supplemented with a Siamese gene "cs", that is "csWW" or "csWw", therefore they can have only blue eyes.

- Recessive white albino ("c") - kind of a white color, that is occasionally met in cats. In this case a cat has no pigment at all, even in a retina that becomes pink, for blood vessels appear through it.

- Siamese albino ("ca") - a kind of a white in an animal that has lost a point-color and whose eyes are extremely pale.

- White particolor - this variant is represented by a gene of white spotting - Piebald spotting ("S"). This gene is dominant, and may occur heterozygous. As a rule, mating with a particolor cat gives particolors, but not necessarily. The appearance of solid colored kittens is accounted for by a heterozygosity of by gene "S" of a particolor parent. Remember one thing: coupling with particolor may give rise to solid colored kittens, a mating of two solid colored animal never gives particolors.

One more peculiarity of a white coloring is that standards of most of breeds (Persian, short-haired Britain, Turkish angora) admit a white color if accompanied with a certain color of eyes: red (copper), blue or diverse (one eye is blue, another is yellow).

2. Aguthy

I hairs of a cat of a solid color the, so-called, eumelanin (or feomelanin) accumulates and distributes evenly during the process of synthesis. Thus there's always the same amount of pigment per unit of length. As for hairs of aguthy there takes place quite another process that causes alternation of light and dark stripes. These stripes appear in a following way: at the moment when hairs begin to grow there accumulates the maximum amount of pigment inside. Then the concentration of pigment reduces and its' amount per unit of length decreases accordingly. Owing to a permanent growth light and dark stripes appear on hairs. One of the components of melanin - aminoacid Tyrosine, is very sensitive to temperature. By its' increase Tyrosine looses its' efficiency (critical temperature is about 38'c). This is why the warmest parts of a cat's body are light-colored. Color of colder regions is darker.

3. Tabby

This coloring consists of two components:
- gene Aguthy, that dominates non-aguthy (that is solid colors);
- gene of a pattern on a cat's body, which is irregularly recessive towards the gene "of the absence of pattern"

There are following kinds of "pattern": Abyssinian, striped (mackerel), spotted, marmoreal (classic).

As well as there are genes of coloring aguthy/non-aguthy there exist other genes and alleles that are responsible for the pattern tabby. As a rule during the process of cell division new cells with chromosomes and genes situated on the same places as in old ones appear. But sometimes during the process of formation and development of new cells some alterations in a gene position and its' characteristics may take place. This process is called modification, a modified gene is a mutant and a result of a process is a mutation.

Genes controlling tabby color have also been exposed to mutation. The original gene gives a striped coloring, mackerel, with thin stripes. A mutant gene gives Abyssinian coloring as well as marmoreal (classic). As a rule, the original gene is dominant and mutant genes are recessive. However there are exceptions: a mutant Abyssinian color of tabby presents an example of incomplete dominance. The sequence of dominance of tabby patterns is: Abyssinian - striped - marmoreal, where Abyssinian is incompletely dominant over striped. So-called spotted tabby is nothing else but the effect of polygenes of striped tabby.

4. Silvery (Smoky group)

The coloring in this group is very special. Hairs are entirely or almost depigmentated at the roots, while tips are colored brighter. This is accounted for by "I" gene (inhibitor; Lat. "inhibere" - restrain, stop). The greater is gene's activity the softer is the color. "I" gene cooperates with "A" gene (Aguthy) in the case of "chinchilla" and shaded silvery, and works with "a" gene (non-aguthy) in the case of smoky colors. The group is quite widespread and numerous.

5. Color-point, or Himalayan color.

The American name is "Himalayan". The core of the phenomena causing this coloring is that the color drifts to a mask, limbs and tail, forming so-called "points". Gene ("cs"), responsible for such coloring is recessive and shows itself only if both parents have it. It is inseparably linked with blue eyes. This kind of linking is called monogenetic variation. Different kinds of this coloring are named by the color of "points".

Kittens at birth are almost white; points develop gradually during the first year of life. Ears become colored in the period between three first hours and four first weeks. The color of mask develops slowly -from the nose and up; it is possible that during first two months only the tip of nose is colored.

Color-points (Siamese scheme) regard as a kind of albino that control the distribution of color by the whole body. They include:
- uniform coloring of the whole body - "C" gene;
- Burma color (the tone of trunk is more pale) - "cb" gene;
- Siamese color (only "points" are colored) - "cs" gene;
- Blue-eyed albino (white color, blue eyes) - "ca" gene;
- True albino (white color, pink retina) - "c" gene.

One may to be confused by the names of "Siamese" and "Burma" colors because they concern not only the breeds by which they are called. The drift of color itself (to a mask, limbs and tail) is more pronounced in a Siamese scheme than in Burma case. Colors of type "cs" and "cb" are represented in different breeds with different skeleton patterns and hair length: consider American "Cimbur" breed arisen on mating Burmas and color-points (they themselves are the result of mating solid-colored Persians and Siamese cats).

It's possible to say that in groups every latter gene is recessive towards the former one. This is not absolutely true as far as albinos are concerned. All four mutant genes are recessive to original gene "C" but the relationships among them are still not clear. This is neither a dominance of one gene to another nor their equivalence. In both cases an entirely pigmented cat ("C") can be a carrier of one of recessive genes - "cs" or "cb", or "cs" on one allele and "cb" on another. In this case we deal with a light variant of Burma, or Tonkinic color (once again, the color can be related not only to Tonkinic cats but other breeds as well).

Another phenomena - gene "C" causes total black or red coloring of whole body. But these colors can be changed in the following manner: "cb" gene turns black into seal (dark-brown) and red into light- mandarin. Kittens have trunk more colorless then limbs, but in adult cats this difference is not pronounced. Gene "cs" alters colors in the same manner as "cb", however more dark parts of body occur more contrasting than in Burmas.

Possible question is: where's the difference between Burma and Siamese colors? In other words, should one refer the Burma color to Points or to solid colors? As is often happen the answer lies contrasting in the characteristic of Siamese scheme itself. If we regard Point colorings as animals with a light trunk and pigmented mask, limbs and tail, then Burma color comes upon this description all right. If we define Point colorings as inseparably linked with blue eyes then one is to refer "Siamese" cats to this group solely.

6. Tortoise, or blue-cream color.

Cats of these colorings represent a mixture of black, red and cream colors. Yet under no condition these cats are three-colored. Cream color actually is just broken red on a tabby pattern.

As is well known there's no gene of a Tortoise color. Both black and red colors in domestic cats are located in X-chromosome, not in Y, and both occupy the same site. If gene gives red color, it of cause can't give black color. The relation between red color and sex is considered as a linkage of color by a sex character. Thus a male has only one gene that defines color, that is it can be black or red but is unable to have both colors simultaneously. A female has two X-chromosomes, that is, two genes that give color. Hence, a female cat may have two black genes or two red genes, or one - black and another - red (tortoise color). Tortoise male cats are to be an occasional event. They almost always occur to be sterile (tortoise male cats have two X-chromosomes and one Y-chromosome).

This rule is valid for all kinds of tortoise colorings (blue, chocolate, lilac). Genes of black and red in blue tortoise (blue-cream) cats are in a depressed state - blue and cream, correspondingly. The derivatives of black are: seal, blue, chocolate, cinnamon. Lilac derives from blue. Background varies from cinnamon to blue. Cream derives from red. Speaking about linkage between red color and sex, again we remind the important rule to estimate colors and sexes in litter: " Males inherit mother's color".

The relationship between tortoise and tabby color is also worth mentioning. Combination "aa" (non-aguthy) doesn't influence red (cream) coloring. Holders alone using methods of selection and sorting of tribal animals have succeeded to reduce the display of tabby pattern in red and cream cats. That's why cats with tortoise color will always demonstrate residual tabby color (i.e. cream coloring in tortoise is nothing else but broken red in tabby pattern).

And now consider standards as they describe tortoise-colored cats. Governing Council Cat Fancy: "Black color is clearly splitted by spots of red color, distributed across whole body and limbs". However, as for broken variant of tortoise - blue-cream - standards turn out to be absolutely different: " blue and cream, both in light, pastel tone, evenly mixed across whole body and limbs" (as for chocolate tortoise: "chocolate and red are clearly splitted", as for lilac tortoise: "lilac and cream evenly mixed").

Tortoise coloring in Britain shorthaired breed: "the mixture of black and deep red; pale red spots may be displayed sometimes. Both colors display themselves across the body, never generating clear spots, except for muzzle". As for blue tortoise color, the characteristic is the same; colors are described as "middle blue and pale cream".

Oriental tortoise should go under the same standard: " The original color of oriental tortoise should remain to the roots of hairs and free from any tabby marks. On the original color there is a red (cream) color displayed disorderly or organized in clear spots and may carry some residual tabby. Head, trunk, tail and limbs should not have any clear stripes, but be of red (cream) color. The presence of red spot on the head is facultative". Blue oriental tortoise: "Blue color in range from light to middle, is mixed with cream or light-cream".

Seal-tortoi-point color: "seal (dark-crown) is splitted by spots or mixed with red, stripes allowed on big spots of red. Point-colored cats are obligatory to have one or more red spots of any size. The presence of red spot on the head is facultative". Other variants of tortoise coloring follow the same standard.

Tortoise Burma: "Hair demonstrates a mixture of brown and red without bright stripes". Blue tortoise Burma has the same characteristic and the colors are described as: "mixture of blue and cream". In that way, we get the following versions of description of tortoise colorings:
- splitted by clear spots;
- mixed evenly;
- combination of colors, scarcely mixed, without clearly outlined spots, except for head;
- splitted by clear spots and/or mixed disorderly; tabby is allowed;
- several spots on the original color;
- mixture of colors without stripes.

So far we were talking only about genes that define colors in cats. Yet we haven't discussed what affects the colors' quality (intensity and brightness) and what, in particular affects the way of color mixing in Tortoise colorings.

After analyzing tortoise colorings in total one should conclude that differences between them are not just due to differences between genes. Some other mechanism is probable to exist.

There are two ways of affecting Tortoise colorings. First of all, we'd mention the influence of "S" gene of white spotting. We'd say that blue-cream tortoise would always have the coloring of type "splitted by clear spots" and not "evenly mixed". The more is the part of white in a coloring the more clear spots will be outlined.

Another mechanism of affecting tortoise coloring is conditioned by polygenes. The genetic basis of colors and its' distribution is rather simple. Everyone is able to understand the principle of genetic code and its' relationship with outer display. One or two genes clearly distinguished control characters in organism. Phenotypic display of a cat depends on its' genotype.

It's quite difficult to explain what is responsible for the quality of colorings and the mixture of colors in Tortoise in particular. There are no strict boundaries - differences between colorings are not that clear and can't be explained only by presence or absence of a certain gene.

All above characters are controlled by a great number of genes that have an influence only when they are together. The group of these genes is called polygenes, so characters that they control are polygenetic.

We can say that cat with very pale hair should possess certain polygenes for a light coloring, as well there're polygenes that cause a dark tone. The difference between above mentioned tortoise colorings is the result of influence of such polygenes, each providing a certain variant of coloring.

7. Particolors

These are colorings or color combinations including white color in some proportion (white spotting). Particolors that have less then fifty percents of white mostly are heterozygous by "Ss". Particolors that have a bit more than fifty percents of white are homozygous ("SS"). Quantitative display of white spotting is reflected as a range from a small white spot to almost entirely white cat with a couple of colored spots (such cats may have eyes colored differently).

The history of Particolor recognition is very long. Since the standard implies a number of conditions for a holder to improve a breed, it should include only those characteristics that can be affected in the selection process. However standard recognize only two out of eight possible variants of white color distribution:
- not less then 1/3 and not more then 1/2 of white - particolors and bicolors;
- more then ninety percents of white - harlequins and vans (tail is always colored from the base and to the tip).

At first sight it's not very important but the consequences of such restriction are negative. Holders of particolors have noticed that next generations demonstrate more and more "whitening". Particolors displaying too little (by standard) of white color are required for breeding (on the assumption of a good state, of cause). However these very animals, as a rule, get bad marks at the shows.

Harlequin needs to have "one or two clearly outlined colored spots on the head, that might not be spread on ears; two or three spots on the trunk that might be round; tail is colored up to the tip". However these appear to be the requirements of aesthetics than that of genetics. For cat with such characteristics may be born from a couple with any degree of "whitening".

Unfortunately still there is no clear evidence of mechanism that is responsible for inheritance of "whitening" degree in particolors.

Series of genes of hair colors
(Dominant gene goes first)
Series
Influence
Gene code
Distribution of Pigment across the length of every hair aguthy A
non-aguthy a
Original color of hair black B
chocolate b
cinnamon b'
Distribution of color across the body body is entirely colored C
Burma color (trunk is to some extent more light) cb
Siamese scheme (trunk is light; mask, ears, limbs, tail are colored) cs
blue-eyed albino ca
true albino (retina is pink) c
Pigmentation intensity total, intense pigmentation D
broken, diluting into blue (*) d
Pigment presence or absence near the root of every hair silvery (smoky) color I
normal color i
White spotting white spots S
no white color s
Distribution of aguthy (non-aguthy) across the body (kinds of tabby patterns) Abyssinian ticking Ta
mackerel (striped) T
marmoreal Tb
Masking of all other color variants, colorings dominant (white) (epistasis) W
not white w
Original color is red (linked to sex) red O*
normal color (not red) o

* - blue chocolate - lilac (bbdd); blue cinnamon - background (b'b'dd); Genetic code of cream color - ddO, o - normal, not red color.

Translated by Tatiana Karpova (Moscow)
(MSU, Biology faculture, Dep. zoology and ecology).