Inhibitor Gene: Smoke, Shaded, Shell
Explaining the difference between Smoke, Shaded, and Shell is a tad bit complicated. But once you know the basics it really not as confusing as you might think. If you would like the most simplified explanation these three types are all caused by the “inhibitor gene” sometimes called the “silver gene”. Each varies in the amount of color left to the coat.
What color is your cat?
1/8 of hair length colored at tip – shell
1/4 of hair length colored at tip – all shaded
1/2 of hair length colored at tip – all smoke
Tarnishing
When the Inhibitor gene fails to completely block pigment (it is more effective at blocking black-based pigment than blocking red-based pigment) and there is a breakthrough of reddish color known as "tarnishing". Tarnishing is common on the muzzles of random-bred silver tabbies, but rare on pedigree silver tabbies due to selective breeding and refinement.
“Wide Band” Effect
For convenience, breeders talk of Wide Band as a single gene, but there appear to be multiple interacting genes that determine the width of the pale band between the pigmented tip and the follicle. The presence or absence of the Inhibitor (silver) gene does not affect the Wide Band effect. Golden Shaded lacks the Inhibitor gene but has a shading pattern comparable to Silver Shaded cats.
Non-agouti + Wide Band = Solid Color
Non-agouti + Wide Band + inhibitor gene= Smoke Pattern
Agouti + Wide Band = Golden series
Agouti + Wide Band + inhibitor gene = Silver series
The extreme wide-banding effect is very rare and at first, the look will appear to be “Shaded” instead of “Smoke” due to the high level of white. A solid color nose is indicative of non-agouti (Smoke), this can be confirmed by DNA testing.
Melanin inhibitor gene is a dominant gene. This means a non-expressing cat can not carry this gene . Offspring can receive this gene from either parent but only if one or both parent has the gene. The Inhibitor gene has a greater affect on the yellow pigment phaeomelanin than on black pigment eumelanin.
Silver Maine Coon
Silver Maine Coons have dark “eyeliner”, that is the black outline that surrounds the eyes, and sometimes the nose. A silver kitten’s nose will always be a rosy pink or wine color.
White Maine Coons will have soft pink noses and no eyeliner. White kittens paw pads will also be light pink in color.
Blue Maine Coons their shimmering coat appears almost silver and they're considered to be a long-haired variety of the Russian Blue.
Smoke Maine Coon
Smoke Maine Coons are a solid color cat that carries the inhibitor gene which suppresses the color in the hair shaft. This means that the cat's hairs are dark (usually black) at the tips but have much lighter colored bands near the bottom. All solid colors can be affected by the inhibitor gene which labels them “Smoke” plus the underlining solid color. A young non-smoke cat has a kitten coat that is often a lot lighter than the base color of the cat. The cat can look like a smoke, but because neither parent cat has a white undercoat, the kitten cannot be a smoke. The kitten coat will darken as the cat gets older.
Smoke Maine Coon Cats have more than 33% of the hair ends colored.
Solid Blue + Inhibitor Gene = Blue Smoke Maine Coon
Solid Red + Inhibitor Gene = Red Smoke Maine Coon
Shaded Maine Coon
Shaded Color Maine Coon Cats have 33% or 1/3 of the hair ends are colored. This is the second to lightest degree of “tipping” within the Maine Coon Breed. In other breeds such cats maybe refereed to as “Shaded” or “Chinchilla” Lesser degree of wide-band than a “shell” and more than a smoke.
Inhibitor + Wide-Band = Shaded
Shell Maine Coon
Shell Maine Coon Cats have 12% or 1/8 of the hair ends are colored.
Smoke Maine Coon | aa I- | - | For "I-" you can either have II (homozygous for silver) or Ii (heterozygous for silver) |
Shaded Maine Coon | A- I- |
plus genes for tabby | For "A-" you can either have AA or Aa. For "I-" you can have II or Ii. Note that silver tabby, shaded and shell have the same genetic code for their coat colour. |
Shell Maine Coon | A- I- |
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Silver Maine Coon | A- I- Ta- ticked |
For "Ta-" you can have TaTa, or
Tata. You find TaTa f.e. in the Somali or Abyssinian. |
|
A- I- Mc- mackerel |
For "Mc-" you can have McMc or
Mcmc. Note: You may add Ta- or tata to this code. |
||
A- I- mcmc blotched |
Resources
http://www.mat.uniroma2.it/~picard/Cats/Feline_genetics_notes.pdf (Old Theory)
http://www.mainecooneducation.com/