Tortie Cats & the Limits of Cloning

[azulai]

io9: How Tortoiseshell Cats Show the Limits of Cloning


photo credit: Ben J Gibbs on Flickr.

When we first discovered the structure of DNA, it looked like all of life's mysteries were at our fingertips. We could control life and death! But soon enough, we started to run up against the limits of our awesome power over genetics — and one of the harshest taunts comes from the simple tortoiseshell cat.

Find out why this kitty evades the destiny of its own genes.

In the early days of genetics, society had a pie-eyed optimism about the power it would soon wield. We thought everything about a creature could be catalogued in one string of information. This data could be translated, switched out, copied, and duplicated at will. It was just a matter of gathering enough information. We were wrong.

Genetics has thrown us for a loop over and over. Mutations, junk genes, extreme variation, and epigenetics have made it very clear that nothing was as easy as it first appeared. One of the most interesting limits of cloning is exemplified by the housecat. Some pets are clonable — and there have been businesses set up for just that — but tortoiseshell cats cannot be replicated, because part of their genes simply aren't there anymore.

Tortoiseshell cats are the result of two different genes teaming up. One gene will turn the cat red, a nice solid ginger. The other will make it a black cat. Each gene is inherited from one of the tortoiseshell's parents. Each is on one of the tortie's X chromosomes. The tortoiseshell look is produced because of a process called ‘X-linked inactivation.' The cells of developing embryo of the tortoiseshell cat randomly shut off one of the X chromosomes. And there's no general consensus among the cells about which one to switch off, so each cell simply picks one. This random shut-off is why tortoiseshells have an unpatterned mix of black and red hair over their bodies.

Cloning a tortoiseshell involves taking the DNA from one cell. Since each of the cells have only one active X chromosome, when a new tortoiseshell embryo is developing using the borrowed DNA, it only has one gene affecting its coloration.

Thus, a cloned tortoiseshell kitten will generally be either black or red. Even if someone were to nab a cell from a developing embryo before the X-linked inactivation happened, the new cloned kitten would also randomly inactivate its X chromosomes, leaving two cloned siblings that don't have the exact same color pattern. No matter how advanced the technology, there is no way to clone a certain kind of animal. Life is sometimes determined to be unique, in spite of our best efforts to make it predictable.

photo credit: Bill Kuffrey/Flickr.

[mrk2010]

So even though the female cats have two X chromosomes they get the mutation, due to the x chromosome chromosome inactivation? Cause usually with an x linked disorder the females are just carriers and the males get the trait. I hope that's the gist of what u were meaning, I find it fascinating. Personally my background is microbiology, plasmids, vector cloning and bacterial taxonomy, I've never been a fan of eukaryotes and animals and the like, but I find this interesting. :-)

[Rainbowmum]

I have two torts.
That is amazing stuff.

[OrphanPip]

So even though the female cats have two X chromosomes they get the mutation, due to the x chromosome chromosome inactivation? Cause usually with an x linked disorder the females are just carriers and the males get the trait. I hope that's the gist of what u were meaning, I find it fascinating. Personally my background is microbiology, plasmids, vector cloning and bacterial taxonomy, I've never been a fan of eukaryotes and animals and the like, but I find this interesting. :-)

It's not an X-linked recessive allele, like say color blind trait in humans. X-linked inactivation occurs in the human beings as well, lyonization is a basic process of mammalian genetics. The tortoiseshell pattern occurs because they are heterozygous for black and red coat colours. The lyonization during embryotic development can result in 2 germ lines of erythrocytes, one expressing red coat pigment and one expressing black coat pigment. Their ultimate positioning in the skin is random.

[azulai]

So even though the female cats have two X chromosomes they get the mutation, due to the x chromosome chromosome inactivation? Cause usually with an x linked disorder the females are just carriers and the males get the trait. I hope that's the gist of what u were meaning, I find it fascinating. Personally my background is microbiology, plasmids, vector cloning and bacterial taxonomy, I've never been a fan of eukaryotes and animals and the like, but I find this interesting. :-)

This isn't my area either. Like you, I find it fascinating. I'm in biomedical engineering concentrating on prosthetics/motorized prosthetics and hopefully eventually neurological sensory feedback. mile:

I have two torts.
That is amazing stuff.

I love torts! My mom and I volunteer at a shelter (cleaning cages!) and they had the sweetest juvenile tortie. My mom kept looking at me with that -- 'don't even think about it!' look. I'm so easy! We already have a tabby and a ginger. Happily, the little cat eventually was adopted.

It's not an X-linked recessive allele, like say color blind trait in humans. X-linked inactivation occurs in the human beings as well, lyonization is a basic process of mammalian genetics. The tortoiseshell pattern occurs because they are heterozygous for black and red coat colours. The lyonization during embryotic development can result in 2 germ lines of erythrocytes, one expressing red coat pigment and one expressing black coat pigment. Their ultimate positioning in the skin is random.

I was going to answer with: I think this is one for Pip! :tongue:

[mrk2010]

It's not an X-linked recessive allele, like say color blind trait in humans. X-linked inactivation occurs in the human beings as well, lyonization is a basic process of mammalian genetics. The tortoiseshell pattern occurs because they are heterozygous for black and red coat colours. The lyonization during embryotic development can result in 2 germ lines of erythrocytes, one expressing red coat pigment and one expressing black coat pigment. Their ultimate positioning in the skin is random.

I think I'll stick to bacteria and phylogenetic analysis :p

[zeon]

slightly confused about the whole cloning stuff i mean it happenned with sheep and i dont see more lamb chops on the sheleves at asda so cloning a cat produces BIG MASSIVE CHUNKY MAKE ME PURRRRRRR EYES like the top photo

[mrk2010]

slightly confused about the whole cloning stuff i mean it happenned with sheep and i dont see more lamb chops on the sheleves at asda so cloning a cat produces BIG MASSIVE CHUNKY MAKE ME PURRRRRRR EYES like the top photo

There are still alot of issues with cloning mostly of an ethical nature thats all

[Sylph]

I've made a discovery as well!

I've discovered there are some intelligent gay scientists on here :3 .

All this mumbo jumbo isn't my thing :p (I'm a Musician...Doh ), but Zoology is something that I'm interested in and so naturally this interests me. Is this the only animal this happens to? What about Cows and Zebras?

And are they studying this in the hopes of cloning humans, cause personally and no offense, I think humans are alittle more complex than cute little kitties , plus it took thousands of years to get to where we are now as humans, so wouldn't it take twice as long to analyze and reproduce us, if at all possible?

(Ps- I got an A- in GCSE Biology :x , so I'm not a smartypants )