***Before taking the steps to participate in any of our research projects, please read the article here.
Silver and Gold
Lead contact: Lyons Lab – felinegenome@missouri.edu
At least two different genes are suspected of influencing the silver and golden coat colors found in many cat breeds.
Silver (a.k.a. Inhibitor (I,i)) appears to reduce or eliminate the production of pheomelanin or yellow pigment in the cat’s hair. Generally considered a dominant trait, one copy can cause the loss of pigment, but likely a cat with two copies of the mutation may have less “ruffusing” or “tarnishing” as well. On a tabby cat, the black banding will appear but the yellow bands are devoid of coloration. (Figure 1) Silver is seen in random bred cats and may be a very ancient mutation, pre-dating the development of breeds and the cat fancy. Many argue as to whether there may be a second – recessive type of silver mutation. I personally do not think this should be ruled out until we prove otherwise, but I think the majority of evidence (or cats) is for a single dominant mutation. There may be more than one mutation, we will see! Cats that are non-agouti (aa) and are solid, will appear as smokes, with white at the base of the hair when they have the silver mutation. Silver is a novel gene in cats, all the genes that cause silver colorations in other species have been eliminated as the cause.
Wide-band is the trait that affects the length of the band, displayed when the cat is agouti (AA or Aa). This gene seems to have extensive variation, causing many short bands or a few longer bands. The selection for longer and fewer bandings in the cats’ hair is likely due to selection by breeders and is less common in the feral cat population. Cats with extremely long bands appear as chinchilla’s when the cats are silver and goldens when the cats are non-silver. (Figure 2)
Click on image to enlarge
Figure 1. Banding (ticking) in cat fur. Left side is my cat Figaro – a normal, wildtype, brown tabby cat with ticked / banded fur. The drawing is the coloration in her fur, alternating bands of yellow (pheomelanin) and black (eumelanin) pigment. Far right is hair that is silver and is depleted of only yellow pigment. These are the effects of only the silver gene. The Silver cat also has a mutation at the gene called Ticked which removes the tabby patterns (Tabby Aby, Ta).
Click on image to enlarge
Figure 2. The effect of the Wide-band locus on cat hair. The Wide-band trait is less understood as extreme variation can be seen in the length of the banding in the cats fur. Breeders have selected for extremes, producing the chinchilla (left) and golden cats (right). Golden is the effect of only wide-band while chinchilla is the effect of wide-band and silver. I have no direct breeding evidence of wide-band, but the trait is suspected to be recessive.
How can you help??
- We need DNA samples – buccals swabs, blood or tissues. Any DNA source will be good for this project – see DNA sampling instructions.
- Silver cats, especially if you think you have homozygotes.
- Wide-band cats – looking for the extremes – the chinchillas and especially goldens!
- Send pictures of the cats and pedigrees. We very often refer back to pictures.
Please do not send samples that you are not certain of the coloration, hoping you will get an answer. We will not use these samples and we will put them aside. Research projects are not a free way to get DNA typing on your cats. Do not expect answers as we have a long way to go. Once we publish a manuscript, then if your cat got used – then we can provide the DNA type. You will get some “free” typing in the end, but do not expect answers in order to make breeding decisions – this happens all the time – sorry.
However – do you have cats with odd blotches / patches of what appear to be silver, maybe they have been called “merle”? Contact us as these cats may constitute an entirely different project!
References:
Genetics for Cat Breeders – Roy Robinson, Pergamon Press 3rd edition
Robinson’s Genetics for Cat Breeders and Veterinarians, Vella, Shelton, McGonagle, Stanglein, Butterworth-Heinemann
Funding:
The Winn Feline Foundation to Dr. Gandolfi – Miller Trust 2014 award