Thank Trav! EVERYTHING is perfectly clear now! And if you believe that - I have a bridge I want to talk to you about. [img]confused.gif[/img] [img]confused.gif[/img] [img]eek.gif[/img] [img]confused.gif[/img]
<font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Aurora Leigh:
Then why is my cat BLUE?
Pigmentation
The colors in hair, skin, and eyes are caused by the presence of melanin. Melanin is deposited in the hair shafts in the form of microscopic granules which vary in shape, size, and arrangement, giving a variety of colors.
There are two chemically different kinds of melanin: eumelanin and phaeomelanin. Eumelanin granules are thought to be spherical in shape and absorb almost all light, giving black pigmentation. Phaeomelanin granules are thought to be elongated "footballs" in shape, and reflect light in the red-orange-yellow range.
Several genes can cause variation in the density of the the melanin granules, so other colors can be produced. The most variation is found in the black-based (eumelanistic) colors. The following table lists the commonly accepted names for the basic colors, by genotype
Mutations of the gene for Black give rise to Chocolate and Cinnamon. These colors are thought to be due to a smaller number of eumelanin granules in the hair shaft. The Chocolate color is a medium to dark brown color; it is sometimes called chestnut. Cinnamon is a terra-cotta or burnt sienna color. These are alleles at the (B) locus; Chocolate is recessive to Black, and Cinnamon is recessive to Chocolate.
A mutation of the gene for Dense coloration produces Blue, Lilac, and Fawn. These colors are due to clustering of the particles of pigment in the hair shaft. This is called dilution or Maltesing. Blue is the dilute form of Black; it is commonly seen as various shades of gray. Lilac is the dilute form of Chocolate; it is described as dove or light taupe gray, and is sometimes called frost or lavender. Fawn is the dilute form of Cinnamon; it is described as "coffee and cream" or caramel color. Dilution is a mutation at the (D) locus; dilution is recessive to dense coloration.
In comparison, the red-based (phaeomelanistic) colors have much less variation. Red is usually described as orange or "marmalade", but some red cats have rather pale pigmentation and so people may describe them as yellow. Cream is the dilute form of Red, and is described as a buff color. The symbol for the gene for Red/Cream is (O); Black is recessive to Red.
The Red gene (O) is carried on the X chromosome; for this reason it is sex-linked. Males normally only have one X chromosome and so if a male carries the Red gene at all, he will be Red. Females have two X chromosomes; if both X chromosomes carry the Red gene, then the cat will be Red. However, many females carry the Red gene on only one chromosome, which allows the black-based pigmentation to show through in patches. This combination of red and black is called Tortoiseshell.
A typical Tortoiseshell is a patchwork of black and orange, usually in a random pattern. Some "Torties" have large patches of orange, others are mostly black. The Tortoiseshell can be modified by dilution, which gives a patchwork of blue and cream rather than black and orange. Such dilute Torties are usually called Blue-Cream. Finally, the black patches of a Tortie may actually be any of the black-based colors, so you may see a Chocolate Tortie or a Cinnamon Tortie, and, if dilution is also present, a Lilac-Cream Tortie or a Fawn-Cream Tortie.
The mutations described above have been seen and described in cats in Europe and and the Western Hemisphere for hundreds of years. Another set of mutations of color has been introduced with the Siamese and Burmese cats from Asia. The Burmese carries the gene for Sepia color (cb) and the Siamese carries the gene for Pointed color (cs). These are alleles at the albino (C) locus; when they are combined (cb/cs), as in the Tonkinese, "mink" colors are produced.
Ticking and Tabby Patterns
All of the foregoing discussion has described solid colors. However, the solid or "self" colored cat is not the most common. More cats have ticked fur than solid color, and in most of them, the ticked fur alternates with the solid color in some sort of pattern, which is called tabbying.
First, ticking is the result of the agouti gene (A) which causes the individual hairs to have bands of light and heavy pigmentation. The agouti gene allows full pigmentation when the hair starts to grow, then slows down the synthesis of pigment for a while, and then turns it on for a while. As the hair approaches its normal length and stops growing, pigment synthesis stops. The result is a hair shaft that has dense pigment at the tip, then a band of yellow to orange, then a band of dense pigment, fading to yellow to orange at the root.
The agouti band can be seen in both the eumelanistic (black-based) and phaeomelanistic (red-based) colors. In both cases, the agouti band marks the period where the production of melanin has slowed down. It is fairly well accepted that the color in the agouti band of a eumelanistically-pigmented hair shaft is still eumelanin, not phaeomelanin, but it is the fact that the granules are sparse and "shredded" that gives them the yellow to orange color. The agouti band is not an alternation of eumelanin production with phaeomelanin production in the same hair shaft.
In eumelanistically-pigmented hair shafts, the agouti band is normally a drab yellow-beige color. However, the color of the agouti band can be a richer orange due to the effect of "rufousing" factors. These are polygenetic factors that have not been isolated and identified, but breeders have been able to select for them to produce "warm" background colors in the tabbies. In particular, the Brown Tabby patterns are genetically Black, but the selection of individuals with strong rufousing has produced a rich brown color in the ticked hairs.
The mutation that causes solid color is called non-agouti (a/a), and is recessive. The effect of non-agouti is to suppress the ticking, so the same density of pigment is found all along the hair shaft, except at the root, where it normally begins to fade in any case.
The tabby pattern is determined by the tabby gene (T), which causes the ticked hairs to alternate with stripes, blotches, or spots of hairs of solid color. The commonly-recognized types of tabby patterns have been given descriptive names:
Mackerel Tabby. Ticked hairs alternate with solid hairs in stripes, as on a tiger. This is the most common tabby pattern.
Classic Tabby. Ticked hairs alternate with solid hairs in a blotched pattern, often with a circular "bullseye" on the side, or a "butterfly" on the back. This is called a Blotched Tabby in the UK.
Ticked Tabby. Ticked hairs are found uniformly over the entire coat, giving a flecked or freckled appearance. This pattern is sometimes called the Agouti Tabby or Abyssinian Tabby.
Spotted Tabby. Ticked hairs alternate with spots or rosettes of solid color, as on a leopard or jaguar.
The agouti and tabby genes combine with the basic pigments to create the following patterns and colors:
<font color="#000002" size="1">[ September 18, 2004 06:56 AM: Message edited by: travelinman ]</font>
Thank Trav! EVERYTHING is perfectly clear now! And if you believe that - I have a bridge I want to talk to you about. [img]confused.gif[/img] [img]confused.gif[/img] [img]eek.gif[/img] [img]confused.gif[/img]
<font size="2" face="Verdana, Helvetica, sans-serif">That's what happens when you ask an Engineer a question.Originally posted by Sluggo:
Thank Trav! EVERYTHING is perfectly clear now! And if you believe that - I have a bridge I want to talk to you about. [img]confused.gif[/img] [img]confused.gif[/img] [img]eek.gif[/img] [img]confused.gif[/img]
Pssttt... Sluggo. Trav is the type of person who, if asked what time it is, will immediately provide detailed drawings and and a 100 page document outlining the correct way to build a watch.
Never, ever ask him to compare and contrast spice combinations! [img]eek.gif[/img]
gae - All I said was that I would like an ORANGE tabbie because the color looks "orange" to me. Had I known that the color is called red, even though it looks orange to MOST people , I would have called it "RED" just to avoid that explanation (if that was what it was). HOWEVER - I am still [img]confused.gif[/img] [img]confused.gif[/img] [img]confused.gif[/img] [img]confused.gif[/img]
Sluggo,
All was revealed in my very first post in this thread:
<font size="2" face="Verdana, Helvetica, sans-serif">Just looking at the pictures, aren't you? [img]smile.gif[/img]Being the sucker that I am, I've been feeding a stray blue. (To the normal eye, it looks like grey, but Trav assures me that the color is blue.) And then came the red, which to the normal eye looks like orange.
All the stuff Trav posted is just genetics, dominant and recessive genes. Reason 114 that I absolutely refuse to raise and show cats.
Well, I will NEVER believe science or biology again anyway! In high school we HAD to take biology and the ONLY thing I can remember is that brown eyes are dominate over blue or hazel. And that dark hair predominate over blond or red hair. I married a blondish guy and I had dark brown (almost black) hair so, I figured we would have, at the very least,, half dark eyed and dark haired kids. We have six kids. One boy has very dark brown hair and the rest of the kids have hair colored like their dad and there are NO, I will repeat, NO brown eyed kids NOR grandkids. Biology stinks!!!!!
Sluggo, and you managed to convince their Dad that he was the biological father? You sly fox, you!
[img]wink.gif[/img]
No, no, I don't know what biology they were teaching in the 1980s when you were in high school, but hair and eye color are not really that simple. For example, (warning! simplified!) you could have one blond and one dark haired gene, and the dark hair would show up in you, but you could pass on a blond gene.
And then we get into the mendelian characteristics of gray hair and baldness. Or let us not, that way lies madness.
<font size="2" face="Verdana, Helvetica, sans-serif">Although I could not have spouted it the way AL did, I'm distressed that I knew what she was talking about.And then we get into the mendelian characteristics of gray hair and baldness. Or let us not, that way lies madness.
I read too much. [img]eek.gif[/img]
A.L. - I thank you for the suggestion that I MAY have been in high school during the 70's OR the 80's!!!!!!! But, unfortunately, I graduated from high school in (for God's sake) 1956. You know? Back in the stone age. Or possibly it was the iron age. I have forgotten which. Anyway, did you not know that I am OLD???? [img]graemlins/martini.gif[/img] [img]graemlins/beer.gif[/img]
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