Tao of Pooh

Why are only females calico?

Why are white cats with blue eyes deaf?

What's up with the double-pawed or multi-toed thingie that pops up ocassionally?


I know, I could probably google this stuff but you guys are sooo smart I bet you just know this shit right off the top of your heads




Some people see things that are and ask, Why?
Some people dream of things that never were and ask, Why not?
Some people have to go to work and don't have time for all that shit.

Codec

Sex linked gene. That is the gene combination for calico is on the same chromosome that determines sex. It needs two X's to get calico (and so female), although mutations (1/3000) can do it for males.

Don't know the rest.

Tao of Pooh

Well, I figured it was sex-linked but it seems odd to me that a fur-colour gene (?) would be sex-linked.





Some people see things that are and ask, Why?
Some people dream of things that never were and ask, Why not?
Some people have to go to work and don't have time for all that shit.

Codec

Why? A chromosome is like a book of recipes. It just happens in this case that the recipe for sex determintation is in the same book that has the recipe for fur colour.
The X chromosome has all sorts of things on it - in humans it has the genes for colour-pigments in the eye, such that males can often be colour blind when they are defective (females have a spare copy).

In this case, one X chromosome contains one of the colours for calico, and the paired other X contains the other colour. Hence males can't express it as they only ever have one X chromosome, except for rare mutations where the get an extra X such as XXY (which are usually sterile).

Have looked into your other questions (I like a challenge).
White/blue eared is a problem with the way the embryo tissues are formed apparently, giving both the blue colour and malformed ear parts.

Polydactyl cats are just a mutation, and it can be inherited. Its recessive though, so you need to polydactyls to breed more for certainty.

I love your end quotes BTW.

JonF

Polydactyls are quite common in the Boston area; we've had several and there's one in the room right now.

Jukia

Another living fossil. See, the creationists are right, science knows nothing.
Oh wait, that would be Pterodactyl. Sorry, mea culpa.

And Tao, I too love your end quotes. Just made copies for some of the others in my office.

Tao of Pooh

So the white & blue-eyed thing is a fallacy? I've never had a white cat so I didn't know that, I guess it's just one of those things you hear for so long you don't question it anymore...thanks.

Thanks again, I've rec'd several complimentary PMs about them.
I'm anticipating yet another not-complimentary PM from a mod/admin about them soon








Some people see things that are and ask, Why?
Some people dream of things that never were and ask, Why not?
Some people have to go to work and don't have time for all that shit.

Daisy

No, read the article. It said that there is a strong, well-known link BUT both blue eyes and white color can be caused by more than one gene combo, so it depends on the genotype not the phenotype.

doghouse

Deafness and white, blue eyed cats:

The cochlea of the inner ear is filled with fluid that is high in K+ and low in Na+. A structure called the stria vascularis maintains this ionic levels, a process that involves B melanocytes, the same cells that produce pigment in the skin, hair and iris.

The white gene in cats not only suppresses melanocytes in the skin, hair, and eyes but also in the inner ear. When the melanocytes are absent from the stria in the inner ear, the stria degenerates and collapses due to the ionic imbalance of the surrounding fluid. This causes the hair cells responsible for hearing to die.

This same mechanism accounts for deafness in dogs with the merle gene, piebald gene and white gene, such as dalmations and bull terriers.

The risk of deafness depends on how strongly the gene is expressed. For example, dalmatians with blue eyes (strong piebald expression) are statistically more likely to be deaf. Dalmatians with a patch (weak piebald expression) are statistically less likely to be deaf. Similarly, deafness is 3-5 times more common in cats with two blue eyes than cats without blue eyes, and two times more common in cats with one blue eye.

BTW, Darwin commented on deafness in blue-eyed white cats in The Origin of Species.

notta_skeptic

repeated information from post above