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DNA and coat pattern

post #1 of 9
Thread Starter 
Does the DNA of a cat completely determine the coat pattern? I'm thinking of tabby stripes, or the exact mix of orange and black on a tortoiseshell, or the exact placement of white on a cat with the white spotting gene, etc.

I.e. if you have two cats with the same DNA (identical twins -- does that happen in cats?), would they look identical? Or would their patterns vary in some random way?
post #2 of 9
I'm not really sure other then if they are identical twins, they would have to look exactly alike. In the case of a tortie where it would be the egg splitting, they might not look the same in colors.

Good question, maybe someone would know the answer. I don't think DNA really has anything to do with color. Maybe some patterns like tabby, but not sure.
post #3 of 9
Their coat patterns would probably vary, especially in the case of torties/calicos.

I'm not sure how tabby striping is translated to stripes on the outside, but the black and orange color in torties/calicos is controlled by the X chromosome. In a black and orange cat, one X causes the black color to become orange, while the other X does not contain this mutation.

In female animals, one X is randomly turned off, so that a female animal only has one active X chromosome in each cell, just like a male animal (who is XY, instead of XX). Since the inactivation of X is random, even genetically identical cats will have different patterns of color.

This can be seen really well in Cc, the cloned cat, and her clone mother, Rainbow.
You can read about that and see pictures in the following links.
http://learn.genetics.utah.edu/units.../cloningmyths/
http://www.mun.ca/biology/scarr/Cloned_Cat.html
post #4 of 9
Thread Starter 
Interesting. Thanks for the pictures and info on the cloned cats. I also note that the amount and distribution of the white fur is slightly different (although similar).

I wonder what would have happened if they had cloned a cat that was not a tortie/calico?
post #5 of 9
Quote:
Originally Posted by tigerlily0 View Post
Does the DNA of a cat completely determine the coat pattern? I'm thinking of tabby stripes, or the exact mix of orange and black on a tortoiseshell, or the exact placement of white on a cat with the white spotting gene, etc.

I.e. if you have two cats with the same DNA (identical twins -- does that happen in cats?), would they look identical? Or would their patterns vary in some random way?
A calico has been cloned and her clone did NOT get the same color distribution as the original. Obviously there are other factors than DNA only that determines the distribution of calico colors and white spotting.
post #6 of 9
Quote:
Originally Posted by tigerlily0 View Post
Interesting. Thanks for the pictures and info on the cloned cats. I also note that the amount and distribution of the white fur is slightly different (although similar).

I wonder what would have happened if they had cloned a cat that was not a tortie/calico?
I suppose that would depend on the color's recessiveness... If it was recessive there'd have to be two copies, so it would likely show up anyway? But beyond that... could you bring out a recessive through cloning? *ponder*
post #7 of 9
No, this can only happen for calicos. One of the articles had a good explanation. CC is still, genetically, a calico. She has one X chromosome with the red gene and one without. However, her red is inactive. When a calico is conceived through normal means, some of the cells "inactivate" the X chromosome with the red gene, and some inactivate the other one. CC was cloned from one of Rainbow's cells that had already inactivated the red X, so ALL of CC was inactive red. Technically, she could have given birth to a red kitten. She's still got the red X.

I remember reading somewhere that white spotting is something that occurs while the kitten is in the womb. Basically, the gene for white spotting says how fast or slow the white spotting comes in, but random chance in the womb can change where exactly the spotting ends up. So cloning won't ever cause white spotting to be identical.
post #8 of 9
I heard that the white spotting gene works from the bottom upwards and the color from the top down. Depends on how fast one is then the other - you can get the white to cover most of the cat with little color or reverse.

That is why you won't see a white cat with a colored belly and legs (reverse bicolor) - white will always be at the bottom of the cat (feet, legs, belly, etc.)
post #9 of 9
It's not really understood how the white spotting gene works exactly, as there are a number of factors involved during early fetal development and cell specialisation/migration, an area which is not fully understood.

It's known that during early fetal development in mammals the melanoblasts, which go on to develop into melanocytes - the pigment producing cells, emerge from the neural tube and are 'called' by a complex chemical signalling system to move to the right place within what will become the skin and the nervous system (melanin also plays a role in neural development). The white spotting gene responsible for the white in calicos and bicolours/tuxedo in cats, and similar genes in other mammals such as mice, seems to work by somehow disrupting that signalling system, so the melanocytes do not end up distributed all over the body - either the signal is too weak and does not reach the neural tube from the furthest areas such as the cells that will form the abdominal skin, or the signal is received but movement of the melanoblasts is disrupted, or they move too slowly to make it there by the time the skin has started to form.

Either way, you can imagine that there are a number of influences besides DNA which could affect where white/coloured areas end up - the position of the nubs that will become limbs, conditions in the uterus, whether the foetus is tightly or loosly curled up and its position, etc. - except to say that it is the areas furthest from the neural tube that are most likely to end up white. DNA codes for the manufacture of proteins which make bodies function, but other factors can also play a role in development. Another example of this is the tortoishell cat, the process of X-inactivation has already been described earlier in the thread, so I won't repeat it other than to reiterate that it is a random factor that occurs at an early stage of fetal development, and 2 tortie twins who have identical DNA can end up looking quite different, at least in terms of red/black distribution in the coat.
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