The Savannah Signal Final Issue 2011
www.savannahcatclub.com
Permissible Savannah colours/ patterns defined
F6C Clos du Chat Cats Silver – ―I‖
Silver is not actually a colour, but rather a gene that inhibits pigmentation of hairs. It has a greater abil- ity to suppress the warmer colours (phaeomelanin), such as reds or yellows, than the cool dark colours (eumelanin), such as dark brown and black. The Silver gene creates a hair that is white at the base, and dark at the tip. There is great variation in shades of silver, from very dark to almost white. This de- pends on the length of the white and dark band on each hair.
Silver is dominant to the Non-silver (brown or golden in savannahs) allele. So our cats, even if they are Brown(Black) Spotted Tabbies or Melanistics, have one form of this gene. They are either Silver or Non- silver.
The Silver gene is ―I‖ and the Non-silver allele is ―i‖. Agouti – ―A‖
The Agouti gene is rather complex but I will try to make this as simple and easy to understand as possi- ble.
In layman‘s terms, Agouti is the Tabby gene. This covers ticked tabby, classic (marble) tabby, mackerel tabby, and spotted tabby.
This gene controls how colour is deposited on the hair via the Agouti protein, which gives the fur its ticked appearance and creates a hair that is black at the tip, and yellow at the base. This produces the ticked tabby, as seen on the Abyssinian. For the other forms of tabby, there is a secondary system of pigmentation that produces dark or black hairs with no or minimal ticking at various points on the skin. However, they are all considered Agouti. With regards to Savannahs, both the Brown(Black) Spotted and Silver(Black) Spotted Tabbies are ―Agouti‖.
In addition to Agouti, there is the recessive allele ―Non-agouti‖ or Solid. In these cats, the protein re- sponsible for the bands or ticking on the hair shaft is defective, but the underlying tabby pattern (spotted in savannahs) is still present. This produces a hair that is all one colour, so it is solid. The solid colours accepted in the Savannah are Melanistic (Solid black) and Black Smoke (Solid Silver).
So, all our cats have one form of this gene, whether they are Tabby (Agouti) or Solid (Non-agouti). The Agouti gene is ―A‖ and the Non-agouti allele is ―a‖. 25
Now that we have covered the basic terminol- ogy, it‘s time to take a more detailed look at our permissible Savannah colours/patterns. There are dozens of different genes that affect the colours and patterns in our savannahs, even amongst our four permissible colours. However, we will only be dealing with two genes in this article: The Agouti gene and the Silver gene. Each of our cats has a variation of both of these genes, regardless of whether they are Brown(Black) Spotted, Melanistic, Sil- ver(Black) Spotted or Black Smoke. Therefore, the Agouti and Silver genes are at the very core of our Savannahs‘ colour/pattern.
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