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Color Genetics Question

post #1 of 7
Thread Starter 
I was just recently thinking about an article I read a long time ago, about a cloned cat. It was (if I'm remembering right) the first cloned cat, and was named Copycat. However, it was a different coloration from the cat it had been cloned from. Something about influences in the womb causing a different coloration? I think the clone was a tabby and the original was not.

At the time, I think I was in middle school. Years later and with a biology/microbiology major in process, I remembered this and am now curious about it.

Does anyone remember this? And/or can anyone explain or direct me to a website that explains the science behind this?
post #2 of 7
I don't remember anything about it, but there is more than one type of cloning.

The one that can't really be done well is reproductive cloning - a complete clone of an animal, with the complete DNA from the original. This has been achieved a few times with horses and cattle, the first and most famous was Dolly the Sheep who was born in 1997. This method of cloning has an extremely low success rate. It involves huge trauma to the egg cell which is used for the transplant of genetic material - the nucleus is removed and the new genetic material injected into it. As a result, most of the egg cells die, Dolly was the 277th attempt to clone a sheep. Animals cloned in this way often have huge problems due to the damage done to the egg cell - growing too large, developing arthritis at an early age, and organ failure. Dolly was euthanised in 2003 due to her ongoing health problems. As far as I know, there has not yet been a completely successful clone of this type, it is still very much an experimental technology and is hugely expensive and most of the experiments have involved agricultural livestock as this is the area in which (should cheap, successful cloning ever come about) most profit could potentially be made, with the patenting of individual creatures.

The more common type of cloning is where rather than transplant the entire DNA, just a small gene sequence is introduced into the egg cell of the 'host'. This sort of genetic engineering could have major applications in medicine (although I do query the motives, as once you have done this you can patent the resulting gene sequence and it can generate a huge profit for a drug company and profit is generally a much larger motivator than welfare!) such as inserting the gene for human insulin into say a corn plant, so that insulin for treatment of diabetes can be grown and harvested cheaply.

So if anyone knows about this Copycat, I would be very interested to read about it! The tabby pattern is controlled by a number of genes, not conditions in the womb, so I would be very interest to find out how that happened - unless the cat was not a full reproductive clone I cannot imagine how it could happen.
post #3 of 7
I just read an article about Copycat giving birth. So yes I have heard of Copycat.


that is just one link of many news article from a google search.
post #4 of 7
Cheers, I don't think my google search was specific enough
post #5 of 7
We taught about Cc in my genetics class so I can give you a quick explanation.

Cc's cloned mom Rainbow is a calico, as is Cc herself. The two look different because one of the genes that affects color in a calico is located on the X chromosome. Since males have one X chromosome, while females have two, one chromosome is randomly inactivated in females during their development in the womb.

In calicos, one X allows for black coloration, and another for orange. So depending on which X is inactivated, you will get a patch of black, or a patch of orange. The inactivation takes place fairly early on, so that one area of the body will be black, and another orange.

Since its a "random" process (I'm sure there are lots of little factors that determine which one is done) Cc and her mom, despite being genetically identical, physically look different.
post #6 of 7

I didn't know the background to this case, but if they are both calico that explanation would be spot on (if you'll excuse the pun!)

One thing I haven't been able to find out is the stage when X-inactivation occurs in cats, do you know whether this has been determined yet? I know in mice it's at the 2 cell stage, and the best I've been able to come up with is that it's later than that for cats, but not by much!
post #7 of 7
Thread Starter 
Ohhhh! Okay, that makes perfect sense. I learned about X-Inactivation last quarter, actually. Thinking she was a tabby while the mother was something else was baffling. Two calicos with different patterns is different. X-inactivation makes most female mammals mosaic. Each originating cell inactivates an X at random, so clone or not it would be pretty much impossible to ever get two identical calicos. I wonder, then, why they chose a calico to clone? Unless perhaps they were studying X-mosaics. I know you can see it on people too, since there is a gene for sweat glands that is on the X-chromosome. Women who get the rare gene for no sweat cells will have patches of skin with and patches without.

Another random fact about mosaicism for anyone who finds it interesting ... in most mammals inactivation is random. In marsupials, all cells inactivate the father's X, so female Wombats--for example--are not mosaic.
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