Tortoiseshell cat

The tortoiseshell pattern is composed of red and black fur games and is found almost exclusively in female cats. In males it is very rare and almost always goes hand in hand with infertility. It is called in the jargon also Tortie ( tortoise shell " tortoise shell " of Engl. ). If at the same time before a tabby markings, one also speaks of Torbie ( contraction of tortie and tabby ).

The tortoiseshell pattern can also occur in conjunction with the gene for dilution; the colors are just blue and cream.

A three- colored cat with white-black- red patterned coat is referred to by breeders as tricolor, with Persian cats as Calico, as tortoiseshell with white or Tortoise with white. In Japan, this coloring is called Mi- ke (Japanese三毛, " three skins ").

Genetic background

The tortoiseshell pattern follows a simple X-linked codominant inheritance: Both the allele for red and for black coat color lying on each of the two X chromosomes; So the cat is heterozygous for red / black. Although red would be dominant over black; However, only one X - chromosome in a cell always active while the other is inactivated in the early embryonic development (X- inactivation). It can therefore be assumed with a high probability that a cat that is very red on both X chromosomes carries the allele for red ( homozygosity ).

Heterozygous cats there for a region of the skin where the allele for red active and the coat is then red, and other regions where the allele the fur is active for non- red and then black. The distribution of the red and black regions is not genetically determined, but is determined by the embryonic development. Three-color cats are therefore a good example of a genetic mosaic. In some cases, one of the two colors to be so prevalent that a tortoiseshell cat is first held for a single-color cat and only discover the offspring that it must be genetically a tortoiseshell cat.

If a tortoiseshell cat is cloned, thereby the X-inactivation of the donor cell remains. The clone so that the same inactivated X - chromosome in all cells so that it comprises either a only red or only black coat pattern. The first successfully cloned cat, CC the cat, emerged from a tortoiseshell cat with white.

If once a male tortoiseshell cat born yet, this is mostly barren. The cause of a tortoiseshell coloration in male cats Klinefelter 's syndrome ( XXY karyotype ), a genetic XX / XY mosaic, despite an XX karyotype male phenotype or an instability of the Farballels with XY karyotype come into question.

The white color of the three colored cats is not controlled by the X chromosome, but is due to different alleles for spotting, which are controlled by the autosomal c-kit locus ( leucism ).

Superstition

In Brehm's Animal Life from 1893 we find the following section to the popular belief about three colored cats:

" A three- colored cat protects the house from fire and other calamity, the people from the fever, also clears the fire, when thrown into the same and is therefore called " Fire Cat ". Who has drowned them out of luck or is seven years unhappy; who kills them henceforth no luck; who proposes to do it from behind. "

The Japanese lucky charm in shape of a cat, Maneki Neko are commonly portrayed Tortoiseshell.