Showing posts with label agouti. Show all posts
Showing posts with label agouti. Show all posts

Wednesday 28 December 2022

'Agouti'. What does it mean?

You see the word "agouti" use quite a lot by the cat fancy and on cat websites. What does it mean? It's a reference to a type of coat which we know very well, a tabby coat. Specifically, it refers to the genetics of a tabby coat. Agouti is the name given to a coat in which each individual hair strand is pigmented with bands of black, brown and yellow.

The most typical agouti pattern is seen in the ticked tabby coat of the Abyssinian cat; an "all-agouti" cat. The classic tabby cat that we see has blotches of dark areas and so we have, in the words of Robinson's Genetics, a tabby pattern which "consists of two coexisting systems of pigmentation or, more likely, a background of agouti, with a superimposed system of stronger black pigmentation."

The background of agouti as they state are areas in which the hair fibres are banded or ticked with alternating black or yellow pigmentation as mentioned.

Superimposed on this are areas in which almost all-black hairs predominate in which the yellow band is reduced to the very base of the hairs.

If you look closely at a tabby cat at each individual hair strand, and if you follow the black areas i.e. the markings, you can see that the top of the hair strand is black whereas going down the hair strand towards the skin you can see light yellow.

My tabby cat
My tabby cat. He has a spotted tabby coat. Very wild cat looking.

It is the way these particular hairs are placed on the coat which provides the markings that we see which in addition to the blotch tabby mentioned, there is the spotted tabby and the striped or mackerel tabby.

The cat's genetics dictate the location of these hair strands that provide the markings.

The agouti coat is the original wild-type colouration by which I mean it is the coat of the wild cat ancestor of the domestic cat and other wild cat species.

Monday 14 September 2020

Agouti gene and tabby cat coat

The word "agouti" is rather confusing. It refers to a gene which creates a certain type of cat coat namely the tabby cat coat. It is signified by the symbol A. It is dominant. The recessive is non-agouti indicated by the symbol a. Dr Morris describes the word "agouti" as the name given to a coat in which each individual hair is marked with bands of black, brown and yellow. He is referring to the tabby coat in which each individual hair strand is banded, essentially striped. The striping is created by two types of colour pigment, eumelanin (black/brown pigment) and phaeomelanin (yellow/red pigment).

The toyger, a relatively rare cat breed has a striped tabby coat created by the agouti gene:

The glamorous Toyger has a tabby coat. Photos by Helmi Flick. Collage by Michael.

Tabby coats are marked with dark areas of swirling fur or stripes or spots. There is another version which is the ticked tabby, seen on the Abyssinian cat and also in another species of animal a large South American rodent called an agouti; hence the name. The Abyssinian cat is an all-agouti cat.

The agouti gene is very common and "highly conserved among all mammalian species". It produces a molecule called the "agouti protein". As the hair shaft grows within its hair follicle in the skin, eumelanin is produced by cells within the hair follicle called melanocytes. This pigment is deposited into the growing hair. As the amount of agouti protein increases within the melanocytes, eumelanin production is inhibited which results in a shift to production of phaeomelanin which is then deposited in the hair shaft to create this sandwich effect. In the ticked coat the band at the top is black with yellow at the base.

Another well-known animal that happens to be a cat but this time a wild cat species which has a very well-defined and strong ticked coat is the jaguarundi. The cat with the most pronounced ticked cat coat:

In short, when you think of the word agouti you should think of the tabby cat coat in all its varieties.

Note: the quote is from Robinson's Genetics.

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