Amazing "chimera" cat still a mystery

Adam Khor

http://news.nationalgeographic.com/news/2012/08/120831-venus-two-faced-cat-genetics-animals-science/

Mickeroo

Very interesting, crazy even. Different DNA on each side of it's body? Didn't think that was even possible. Hadn't heard of the cat before.

steddyeddy

All tortoise shell cats with a normal ploidy (a normal number of chromosome sets) are female. Those that are toms often have an extra x chromosome as the allelles for coat color are on different x chromosomes. The tortoise shell color requires the expression of two x chromosomes so toms who usually have only a y and x chromosome only carry one color pattern.

Ziphius

And, amazingly, the cat's coat pattern is determined by one X chromosome being randomly turned off in each cell.

This means that a cloned tortoiseshell cat can have completely different pattern from the cat it was cloned from.

Have a look at CC and Rainbow.

The top pictures show Rainbow (left) and her clone CC ( right).
The bottom picture shows CC and her surrogate mother.

steddyeddy

Ziphius wrote: »

And, amazingly, the cat's coat pattern is determined by one X chromosome being randomly turned off in each cell.

This means that a cloned tortoiseshell cat can have completely different pattern from the cat it was cloned from.

Have a look at CC and Rainbow.

The bottom picture shows CC and her surrogate mother.

Yes indeed x inactivation is common in mammals (including humans). The lack x inactivation can be tremendous and often result in an unviable foetus. The other factor with clones is epigenetic factors. One cat could have the exact same genes as another but in the womb variables like blood flow could affect the switching on and on of certain genes.

Ziphius

steddyeddy wrote: »

. The lack x inactivation can be tremendous and often result in an unviable foetus. .

Do you know why this is? I remember reading that most cases of trisomy are fatal. Could this be related?

The area of epigentics looks fascinating but it's something I know next to nothing about.

steddyeddy

Well there is still huge amount of research on why one x chromosome is activated and one is not. We also know that unfortunatly it gets more complicated than just one particular x chromosome inactivated per organisim. In placental mammals (who have the xy system of sex determination)

Females either inherit their x chromosome from their mother or father. So fifty per cent of the the cells in the body of the female contain paternally derived inactive x chromosomes and the other 50 percent contains maternally derived inactive chromosomes. Thats why tortoise shell cats are patterned. The gene for color is on the x chromosome so the tom will be one color. The female will contain genes for both orange and black say and in 50% of hairs black is expressed and the other 50% orange is expressed. So you get a mottled look to your tabby!

Do you know why this is? I remember reasing that most cases of trisomy are fatal. Could this be related?

Yes well x inactivation is essential for survial. If you express an extra fifty per cent of genes than you should you code for double the number of protiens. Then the accumalation during pregnancy can cause problems and thats only part of it!

The area of epigentics looks fascinating but it's something I know next to nothing about.

Yes I love the area. It basically explains how a queen bee becomes a queen despite having the exact same genetics as her brothers and sisters.

steddyeddy

Ziphius you and anyone who is interested in Epigenetics should read the epigenetic revolution by Nessa Carey!

Ziphius

steddyeddy wrote: »

Ziphius you and anyone who is interested in Epigenetics should read the epigenetic revolution by Nessa Carey!

Thanks for the tip. I'll look it up.