Point coloration

Pointed cats are cats whose body coat is lightened, while the cooler regions, the so-called. Points are like the face, ears, legs, tail and scrotum darker. The color of the points is determined by the genetic background color of the cat.

Cause

Cause of the discoloration of the body fur is a mutation that leads to a partial albinism, caused by the defective function of the enzyme tyrosinase, which is necessary for the production of the pigment melanin basic substance. Responsible for point coloration so is an inherited metabolic disorder. In this form of albinism with temperature-sensitive residual activity of tyrosinase is not functional at higher temperatures, so the colder parts of the body such as limbs, tail, ears and nose color dark gradually, while the fur near the warmer body core remains bright. Point Cats are so animals with albinism, their melanin production is not completely switched off (see also Genetic background ). In the cattery this is known colloquially as the so-called Colouration gene, including point- gene, called point-factor. Point cats are basically born almost white because it is so warm in the womb, no melanin can be formed. During the first weeks of life to the cooler air then form the points, the skin darkens. This Nachdunklungsprozess stops the whole life and then extends to the body coat. Old Point Cats can therefore be quite dark, but remain recognizable as pointed cat. The fact that the discoloration has actually something to do with the outside temperature, indicated by the fact that the pointed cats that are kept in warm countries, less darkening than those who live in a cooler environment. If a paw partially sheared, eg for a blood draw, and then put under a dressing, the hair growing on the dark paw in cropped area to light, because the temperature is increased under the dressing.

Other effects of partial albinism

Of the defective production of melanin, the pigment in the iris and other structures of the eye are affected, among other things. This applies primarily to cats with the Siamfaktor (see: Genetic variants). These cats always have blue eyes. Strabismus, strabismus, and nystagmus, nystagmus is used in all pointed cats very common, but is, unlike normal colored cats with them no independent hereditary diseases with private inheritance is, but are a result of albinism oculocutaneous type 1.Due causal link between desired Point staining and adverse visual defects are the breeding suggestibility limits. The Teilabinismus the pointed cats is mentioned in the report as to the interpretation of 5 11 b of the Animal Welfare Act. Although the Siamese cats have problems with fixation and likely to have an impaired binocular vision, their hunting ability is not seriously affected. The two cats on the example photo above to the right show a slight squint.

Genetic variants

In cats, there are two different genetic variants, denoted by cs or cb. cs stands for Siamfaktor, cb for Burma factor. One of the few intermediate modes of inheritance in the color genetics of cats (cs cb) provides a further variant, the Tonkinese. In general parlance, but the point-factor is equated with the Siamfaktor usual.

Cats that are homozygous for the gene cs ( Siamese and their descendants ), always have blue eyes. Cats that are on the gene cb homozygous ( Burmese and their descendants ), however, have yellow eyes. Point Cats that the intermediate devolution cb cs have ( Tonkinese and their derivatives ), have green - blue to blue -green eyes. Also in the race of Bengal enters this color (cb cs) on; she says there seal mink.

Breeds

Well-known examples of the breed Siamfaktor are the already mentioned Siamese ( short haired ), Birman Cat ( semi longhair) and Persian Colorpoint ( long-haired ), Ragdoll Cat and the Neva Masquaradeals color variant of the Siberian cat. Cat Burma (Burma factor) and Tonkinese as a hybrid form are less known to us. The so-called Snow Bengal cats are genetically Point.

Point - colors

In principle, any coat color may also occur as point color, both the different variations of black and red, and their dilution blue and cream, as well as variants and chocolate- cinnamon along with their dilution lilac and fawn. Even gold and silver are possible. Not all colors are allowed but at every race. The classic Siamfarbe called Seal - Point and is derived from black. From Red to Flame Point derives, sometimes called red-point. For the other colors, the color name with the word point is combined (eg Chocolate Point or Blue Point ). Pointed cats can be monochrome or have tabby pattern, in the U.S. tabby pointed cats are called Lynx Point. Piebald spotting is excluded in many breeds with point- drawing unwanted and from the standard. In the Siamese cat wearing " Siamese with white " name Seychellois. In other breeds, such as the Neva Masquerade, there are no standard specifications for the amount of white. At all events, but did not see many judges like it when a high proportion of white destroys the point. The Birman contrast in size and shape well-defined white gloves to the breed standard include. Even with the Ragdoll in size and distribution of uncommitted amount of white part of a standard.

Street cat with tabby -point drawing

Point drawing with red paint: Flame Point

Ragdoll: Seal Point with white spots

(Brown spots, brightened by the Dilute gene) Siamese Cat, Lilac-Point

Siamese, Chocolate Point ( brown spots )

Siamese Blue Point

Siamkätzchen 4 weeks old (Lynx Point)

Genetic background

For the formation of point- coloring a form of albinism subgroup OCA 1B is responsible. OCA 1B based on mutations in the tyrosinase gene that produces an enzyme defect residual tyrosinase activity. The production of pigment is therefore not blocked completely, but it may be slightly pigment are formed by the residual function. More precisely, we have to do it at the point- coloring of the cat with the subgroup OCA 1B TS = temperature -sensitive OCA 1B. Here, the activity of the enzyme Tyrosynase, which is necessary for the synthesis of melanin, temperature-dependent.

Comparable mutations there are in man, in cattle ( White Park Cattle ) and in many Nagetieren.1 The mutation is inherited recessively. This means that both parents must be carriers of the mutation, so that the amendment takes effect. Point Cats are therefore always homozygous for the mutation and therefore have only point -colored offspring. If both parents are carriers only, so enter in the offspring pointed cats, normal colored carrier and animals free of this mutation in the ratio of 25 % to 50 % to 25% off.

Burma cat with black base color and the allele cb

Complete albinism in a cat ( allele c )

White Park Cattle

Swell

• 1 Krista Siebel; July 2001 Analysis of genetic variants of loci for the coat color and their relationships to Farbphänotyp and quantitative performance characteristics in pigs Inaugural Dissertation for the degree of Doctor of Veterinary Medicine; Department of Animal Sciences, Humboldt -Universität zu Berlin
• B. Käsmann Waiter & B. Seitz: Phenotype of the visual system in ocular albinism and okulokutanem, ISSN 0941- 293x
• B. Käsmann Waiter: pediatric ophthalmology, orthoptics, Paed. Low Vision, Campus, University Eye Hospital, Building 22, Homburg ( Saar) albinism, Far more than just blue eyes
• Kalil, R. E. et al. (1971 ) Anomalous retinal pathways in the Siamese cat: an inadequate substrates for normal binocular vision, Science 174:302-305

Other sources see the cat coat colors