For Vene ~ Kitties

[antichrist]

I didn't want to derail the thread you had this on, but I was curious about the Xx_male syndrome.

I'm not sure how much you know about tri-colored cats, but is this where male tortoiseshells come from? Because the tri-colors are supposed to be a female trait, but I have seen 2 tri-color males in my life.

Just wondered what you knew about that, and if this was the same thing.

[cagnazzo]

Edit:I totally made this way longer than I intended. Skip to the last line for a summary. I bet the only person who'll enjoy this monster is, somewhat ironically, Vene.

Hey, Vene isn't the only one who knows the dark voodoo that is science.

Wikipedia says that tortoiseshells/calicos are male at a rate of 1:3,000

Yes, male tortoiseshells can be XX (pre-emptive point; tortoiseshell usually refers to orange and black cats, tri-color or calico refers to orange, black and white ones). I'm gonna go into a semi-detailed explanation, hopefully it isn't too deep. Ask if you need clarification:

Cat coat color is complex. Black and orange coloring is coded for on the X chromosome. An animal with a Y chromosome turns out male, under normal circumstances. Usually, that means that the creature in question is XY, unless something has gone wrong in meiosis (the splitting of cells that makes the sperm/egg). Thus it only has one X chromosome, so it can only have the black gene or the orange gene.

Now let me explain something about female mammals: They don't express both the X chromosomes they have everywhere. One is turned into something called a barr body, which doesn't get transcribed. Basically, one is turned off when they're an embryo, so they only express one of their X chromosomes. This happens when the embryo only has a few cells, and every patch of the body descended from one of those cells expresses the same X. That's why there are patches on tortoiseshells. It's really cool, if you're nerdy =P. Each black patch is descended from a specific cell, that turned off one of its X chromosomes, Same with each orange.

I'm gonna interject that I'm sorry this is turning out so technical, but I love this stuff and find it fascinating and can't write about it simply ><.

Anyway, that's why females can be patched and males can't. Males only have one spot for the color gene. If meiosis screws up, they can get two X chromosomes, and have the black-and-orange coloring.

You've probably noticed that I haven't said anything about white. The white genes are actually different. There are a few of them - there's one that's recessive and if both copies are inherited, the cat is completely white, no matter what other color genes it has. That one's also linked to deafness.

The important white gene is the one that leaves white spots. One copy children have a few, and two-copied children are mostly white. This gene is the one that can turn a tortoiseshell into a calico cat.

So to summarize: A cat can only be tri-colored if it inherited at least one copy of the white gene, and a copy of both the black and orange genes. Because the black and orange genes are on the X chromosome, a cat must be XX to be black and orange. For males this usually only happens if there's an error and they end up being XXY, which is called klinefelter's syndrome. Because these males are infertile, and this is basically an error in reproduction, they are rare.

There are also a few brown genes, and a lot more, but they're rarer and not really worth going into.

Also, in case anyone asks about gray and tan cats, there's another color gene that causes the dilute color pattern. A cat who inherits two copies of the dilute gene will have its black spots be gray, and its orange spots be tan.

Ok, that's one explanation of how a male can be orange and black. It's... the less common reason -_-. Chimerism, which Firefox claims isn't a real word, is the usual reason for a male tortoiseshell. Basically, the cat has two distinct cell populations inside it. In the case of chimerism, the embryo basically fused with its fraternal twin, at least usually. So it could be XY throughout, but if it had a black X gene, and its brother had an orange X gene, it would have cells that express black and cells that express orange, and be a tortoiseshell. Also, it would be fertile, but its children wouldn't be able to inherit it, because its sperm would all be descended from a specific cell, and there is no individual cell that has both the orange and black genes.

Oh my, I totally lied about making this brief, I'm sorry ><. To answer your question briefly, XX_ males can indeed be black and orange, though there are other ways that that can happen.

[antichrist]

Thanks

That is pretty brief for a gene description.

As I said I've seen two in my life, and one was at a cat show. The judge said that the person kept entering into the housecat division because some judges would automatically give it the ribbon due to it's rareness. Then again, he's the one who said it was 1:1,200 for male tortoiseshells.

The second one, I was taking the owners word that it was a male, so maybe I shouldn't count that one.

Oh, and have a kitty

[Vene]

KITTIES AND SCIENCE! Two of my favorite things.

Nice post cagnazzo, I really don't have anything to add to it.

[antichrist]

So is it possible for a male tortie not to be a mule?

[Vene]

Antichrist, I assume by "mule" you mean infertile rather than a cross-species hybrid. If so, cagnazzo already answered it with chimerism.

Apr 28, 2009 2:32:34 GMT -5 cagnazzo said:

Ok, that's one explanation of how a male can be orange and black. It's... the less common reason -_-. Chimerism, which Firefox claims isn't a real word, is the usual reason for a male tortoiseshell. Basically, the cat has two distinct cell populations inside it. In the case of chimerism, the embryo basically fused with its fraternal twin, at least usually. So it could be XY throughout, but if it had a black X gene, and its brother had an orange X gene, it would have cells that express black and cells that express orange, and be a tortoiseshell. Also, it would be fertile, but its children wouldn't be able to inherit it, because its sperm would all be descended from a specific cell, and there is no individual cell that has both the orange and black genes.

[antichrist]

I thought mule was the standard term for infertile for genetic reasons. Mule GM plants, etc.

Maybe I'm wrong.

And I appologize for missing that part about the fertility.

[antichrist]

So going back to the genes.

When they cloned CopyCat (C.C.) it came out a different color than it's mother. I've heard people say that that was because mom was a tri-color. Can you explain that one?

[cagnazzo]

Apr 28, 2009 12:44:48 GMT -5 @antichrist said:

So going back to the genes.

When they cloned CopyCat (C.C.) it came out a different color than it's mother. I've heard people say that that was because mom was a tri-color. Can you explain that one?

When an animal is cloned, it basically has one cell taken from it, and the clone is entirely descended from that cell. In most cases that doesn't make anything weird visible, but if the animal has two X's, the clones cells will all have the same X form the barr bodies. This means, basically, that if you take an orange-expressing cell from a multicolor cat and clone it, the clone will only express the orange-gene chromosome. All its cells have orange and black potentially, but because the same X is always shut down, the clone will appear monocolor. This occurs regardless of the sex of the cloned cat.

A chimera will also have a one color clone, but not because of barr bodies - it has two populations of cells, and the clone would only have one of those sets of chromosomes.

Edit: A article on copycat is here. There's a picture on the right. Really it doesn't need the caption - the clone is obvious the one who isn't both orange and black. It's also a nice demonstration of what I was saying about the white genes - they can be transmitted because they're set up differently from the black/orange genes, and because they're in a different place on a different chromosome, they are not mutually exclusive to black or orange.

[Vene]

Well, I looked up the paper in Nature. Their explanation was as follows.

As with other genetically identical animals with multicoloured coats, the cloned kitten's colour patterning is not exactly the same as that of the nuclear donor — this is because the pattern of pigmentation in multicoloured animals is the result not only of genetic factors but also of developmental factors that are not controlled by genotype.

Something that I like saying about genetics is that it's more probabilistic and deterministic. The presence of a gene doesn't guarantee that it's expressed, it just means that it's possible. If I was to speculate, I'd say that due to how they extracted the nucleus the reason the clone is not tri-color is because of the Barr bodies already mentioned. After fertilization of a female embryo the X chromosome inactivated is random. But, once one has been stored as a Barr body, it stays there. Since they extracted the nucleus from an adult, she already had an X stored as a Barr body. So, all cells that are a result of division should retain the same coat color as the original cell.

Edit: I see I was beaten to it, with the same conclusion no less.

[antichrist]

I really find this stuff interesting, I hope you don't mind me grilling you like this.

1. Ah-ha, they have different personalities! I read a Cat Fancy article many years ago that stated that personality in cats had a relation to color, and it was discussing a possible genetic link. I've been poo-poo'd over it, even by vets, but I believe it to be true.

2. Even though the cats share the same DNA, each uses it differently
Okay, say I want to clone my RottiXShepherd because he's the best dog ever (I've considered this) Would I get the same dog back? Could I end up with something way more rottie or shepherd?

3. The stuff about Dolly having old age diseases at a young age, does this mean that the genes determine the age of the cellular structure? Do genes get old and tired?

[Vene]

Apr 28, 2009 13:53:42 GMT -5 @antichrist said:

2. Even though the cats share the same DNA, each uses it differently
Okay, say I want to clone my RottiXShepherd because he's the best dog ever (I've considered this) Would I get the same dog back? Could I end up with something way more rottie or shepherd?

Differences in development would mean that the dog would be phenotypically (physically) different. I can't say the degree because I don't have enough details, nor do I have enough knowledge on the specifics of dog genetics. It would probably be best to think of a cloned dog as either the offspring or a sibling of the original. He would be close, but not identical.

3. The stuff about Dolly having old age diseases at a young age, does this mean that the genes determine the age of the cellular structure? Do genes get old and tired?

Yes, they do. The end of a chromosome is capped with telomeres. After every round of cell replication the length of the telomeres is shortened. There is an enzyme called telomerase which can add to the telomeres, but it's not expressed in somatic (body) cells. Typically, these regions are just nonsense, but it has been shown that shortened telomeres corresponds with shorter lifespan. Now, there is much more to aging than just these, but telomeres are a part of it.

[cagnazzo]

Apr 28, 2009 13:53:42 GMT -5 @antichrist said:

I really find this stuff interesting, I hope you don't mind me grilling you like this.

1. Ah-ha, they have different personalities! I read a Cat Fancy article many years ago that stated that personality in cats had a relation to color, and it was discussing a possible genetic link. I've been poo-poo'd over it, even by vets, but I believe it to be true.

2. Even though the cats share the same DNA, each uses it differently
Okay, say I want to clone my RottiXShepherd because he's the best dog ever (I've considered this) Would I get the same dog back? Could I end up with something way more rottie or shepherd?

3. The stuff about Dolly having old age diseases at a young age, does this mean that the genes determine the age of the cellular structure? Do genes get old and tired?

You're going to make me late to class. The Antichrist is evil.

Anyway, cats are mammals, and as such are raised by their parents. That's actually more likely to affect their personalities. Certain traits are probably hardwired, certain ones are probably mostly learned, but given how complex most of them are, it's doubtful that they're linked in any significant way to color, though I can't rule it out.

In terms of two, he would have more or less the same genetic makeup as your dog, being half rott half shepard. The important parts of fetal development are usually what "forms" an animal, so to speak. In this way, it's possible for it to end up completely different. Huge things can affect development, though they're rare - you can make XX males by injecting the proper hormones, and there's some evidence that human traits such as transsexualism is caused by the environment the fetus matures in. To summarize, he'd have the same genetic code and probably be similar to the other organism. However, even if he was born the exact same as the other one, at that point his life would diverge, and as smarter (especially social) mammals learn a lot from their environment, he'd be likely to be only vaguely similar, if that. He'd be predisposed to similar traits, but not necessarily have them. Basically, he wouldn't be the same dog. He'd just be like an identical twin, only with different raising, it's likely he'd be even more different than them. It's not the same dog, it's a completely new animal who happens to share the genome with its "father".

For the last question, I have to go into microbiology for a bit. Chromosomes have little tags on the end called telomeres. At the end of the chromosome, there is TTAGGG repeated over and over again. When DNA is being replicated, the enzyme that does it can't get the last bit of DNA. Picture it like you reading a sentence - only you can't see the first letter. You're trying to reproduce it, but you can only reproduce the last part. So if I write "Hey, telomere", you would copy it as "ey, telomere", then when you have to reproduce that as "y, telomere", ", telomere" and finally "telomere". You've lost important information. So by adding TTAGGG to the beginning, nothing useful is lost - you still have all the important information for a long time if instead I write "aaaaaaaaaaaaaaaaaaa Hey, telomere" - you only lose the spam "a"s. When the telomere runs out, stuff starts going wrong. Gene promoters get eaten, cells lose proteins, and things generally are not good. This is, I believe, one of the reason that clones get health problems often (among other things). If you were to clone me right now, my cells would have the telomeres of a 21 year old. Clone that at 21, the clone's cells would be 42 years old. Now, they are researching ways to reverse that using telomerase, but it's nothing you could get done - it's still all lab work. They're not so much applying it yet as poking it and seeing what happens (yay science).

I think that's the commonly accepted reason clones are unhealthy. Cloning is relatively new, however, so I wouldn't be surprised if it had less to do with it than I think and there were a lot of other factors. However, given the research I've seen, I think it's fair to say that telomeres certainly play a part in genetic decay for clones.

Also, Firefox doesn't recognize telomeres. Silly Firefox.

Now I'm late, screw you guys =P.

[Vene]

Apr 28, 2009 14:09:41 GMT -5 cagnazzo said:

For the last question, I have to go into microbiology for a bit.

I thought that was more cell biology or molecular biology. Last time I checked microbiology was microorganisms (and viruses and prions, but I really don't want to get into a discussion on what is or isn't alive).

[antichrist]

More kitties for cagnazzo & Vene

Rainbow & C.C.


Random kitty from photobucket


I will have more questions, but I've got a bunch of stuff to do right now and I have to absorb this.