So, in summary, we can't clone tortoiseshell cats because we can't clone their patterns?
In that case we can't clone anything - identical twins don't have identical fingerprints.
This also ignores the problem of "active" chromosomes (even though it relies on it). Well sure, you'll get one that's active, and that can't be used directly to clone a tortoiseshell cat into another tortoiseshell cat - but that will only be true until we can reactivate the inactive one.
A cursory glance through Wikipedia suggests X-inactivation isn't a well-understood area of genetics, so I propose it's not an actual limit, but that it lies beyond our current "limit of understanding". Calling it impossible is pure conjecture, but probably makes for a more link-baity article.
> Calling it impossible is pure conjecture, but probably makes for a more link-baity article.
It's probably right though, and would be received with an incredulous "well duh" by most (if not all) biologists: we've known for quite some time that there's a certain amount of plasticity in development.
So randomness is an inherent guaranteed feature of life itself. Imagine if this applied universally to skin color too. What would our prejudices be then? Cue 1960s Star Trek episode where one guy is white on left side while the other is white on his right side...
"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."
The different colour patterns part is true for any cloned cat's markings, not just clones of a tortoiseshell.
The cloned cat "Cc" who hit the news a decade ago was a tabby-and-white clone of a calico cat; calico patterns also result from having the black coat gene on one X chromosome and the ginger coat gene on the other, which is why calico and tortoiseshell cats are almost all female, and why ginger cats are three times more likely to be male than female. Trisomy does occur in cats but very rarely.
I can't help but be reminded of the various copy protection schemes they used with CD/DVD disks, such as SafeDisc. It feels like this is "nature's copy protection scheme", if you forgive the cliché.
We're still working with the primitives, the biological equivalent of machine code. Even when we get to genes we're talking about pre-defined functions which call external libraries (the epigenetic and environmental factors) that we are limited to splicing around.
The quantum shift will come when we are able to abstract the genetic and epigenetic functions. The metaphor has yet to shift.
I think the io9 author is striving here to emphasize a favored, romantic conclusion: "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."
I expect it's equally likely a way to reset the X-linked-inactivation within a single cell will be discovered, so while the coloring of the clone won't be a perfect copy, it will be a product of roughly the same random process as the template cat. (Perhaps the reset would even be possible in adult cells: give your cat a pill to rescramble its colors over the course of a shedding cycle, or force it one way or the other.)
Of course there are all sorts of other confounding influences, such as horizontal gene transfer and chimerism, both of which will probably turn out to be more important than usually assumed. But given a few hundred years, the error in 'cloning' an organism can likely be made almost imperceptibly small.
> I expect it's equally likely a way to reset the X-linked-inactivation within a single cell will be discovered, so while the coloring of the clone won't be a perfect copy, it will be a product of roughly the same random process as the template cat.
That's not the point of cloning, though. Scientists expect an exact replica - without that, what's the point? I can find you another tortoise shell cat that looks almost exactly the same in the real world, sans an expensive procedure. What you'd want is an exact copy of your beloved cat. I think what the article hinting at, but not saying, is that if something as simple as a hair pattern can't be copied then other more complicated systems, for example the brain, certainly have similar inconsistencies that arise during the cloning process.
Scientists don't value duplication unless it's also visually identical? This is a new bit of information to me. The people this likely matters the most to are people trying to clone their pets.
As for non-copyable attributes, we've known that for a long time - twin fingerprints, for instance. This discovery hasn't caused all funding for cloning to be withdrawn, so I doubt it matters as much as you seem to be implying.
Beautiful cat. I have a dilute calico female that is very sweet, but only to me and my wife. I think this might be more indicative of female cats in general. I find more than 1 female in a home is typically a problem, whereas multiple (neutered) males tend to get along better.
If I remember correctly, with the exception of genetic anomalies, calicos/tortoise shells are always female and orange tabbies always being male. The other interesting thing I read was that the more white on a calico, the larger the individual color 'splotches'. A calico with no white will have the black and red mixed all over (like your cat).
Our tortie of 14 years passed away last year. They can be really unique cats. She really only bonded with my wife and me. To everyone else, she was a sassy ball of attitude; but alone, she was the sweetest cat. No one believed us when we told them how affectionate she was.
That cat helped keep me sane through some crappy times. I miss that cat.
In that case we can't clone anything - identical twins don't have identical fingerprints.
This also ignores the problem of "active" chromosomes (even though it relies on it). Well sure, you'll get one that's active, and that can't be used directly to clone a tortoiseshell cat into another tortoiseshell cat - but that will only be true until we can reactivate the inactive one.
A cursory glance through Wikipedia suggests X-inactivation isn't a well-understood area of genetics, so I propose it's not an actual limit, but that it lies beyond our current "limit of understanding". Calling it impossible is pure conjecture, but probably makes for a more link-baity article.