Cats

1 Cat hacks

Elizabeth Van Nostrand, Coping with cats.

2 Cat facts

Geneticists have finally solved the mystery of Garfield’s orange coat

Mammals have only two pigments, which are two colours of melanin: eumelanin (dark brown, blackish) and pheomelanin (yellowish, reddish or orange). Redheads only produce pheomelanin, while dark-skinned people accumulate mainly eumelanin. All other skin and hair colours fall somwehere in between, thanks to as many as 700 genes that regulate pigmentation in animals.

In primates, horses, rodents, dogs, cows and many other animals, melanin production and the decision to produce eumelanin or pheomelanin is in the hands of a membrane protein called MC1R.[…] However, cats are another matter altogether. […]

In cats, eumelanin or pheomelanin production is not controlled by the MC1R receptor. Instead, it is in the hands of a locus […] called “orange”.

One detail to note is that the orange locus is on the X chromosome. Female cats are XX and male cats are XY, like all other mammals. And as with all female mammals, all cells throughout development will randomly inactivate one of the two copies of the X chromosome. Oo female cats – carrying the O variant on one X chromosome and the o variant on the other – will generate areas of their body that are orange (in areas where they have inactivated the ‘o’ allele) and others that are black (when inactivating the ‘O’ allele).

This means that when we see a bicolour (black/orange) or tricolour (black/orange/white) cat, or one of its more diluted versions, we know that it must be a female, […] Male cats are either orange or black (they have only one X chromosome), but cannot be bicoloured or tricoloured,