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Old 05-13-2007, 11:34 AM   #436
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Originally posted by yolland

Actually, good thing for me I said "about 90% certain" before, because I just finished reading about what causes whiteness in cats, and it turns out that almost all white cats are white because they have either at least one dominant white 'masking' gene ('masking' meaning overrides other genes for color), or else two recessive genes for albinism (which makes other genes for color unable to function). So really, the rest of their coloring genes could potentially code for just about anything, and their offspring could definitely express those traits as long as they don't also wind up with a genetic combination causing whiteness.

I also read that what causes Calicos is that when kittens are forming their coat patterns in utero, all the possible colors are present and one (or one including white) takes over and some enzyme shuts down the other color from manifesting itself. Calicos lack that enzyme, so any or all colors or patchwork patterns of all of them come out in the coat. Because the gene that lacks the enzyme is almost always on the X chromosome, and it needs to be doubled on both X chromosomes to come out, that's why calicos are always girls. In the rare cases where a male is calico, he has an extra X chromosome in addition to his XY.
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Old 05-13-2007, 12:07 PM   #437
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What about adding pictures from just this thread?
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Old 05-13-2007, 01:28 PM   #438
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Originally posted by U2Kitten
I also read that what causes Calicos is that when kittens are forming their coat patterns in utero, all the possible colors are present and one (or one including white) takes over and some enzyme shuts down the other color from manifesting itself. Calicos lack that enzyme, so any or all colors or patchwork patterns of all of them come out in the coat. Because the gene that lacks the enzyme is almost always on the X chromosome, and it needs to be doubled on both X chromosomes to come out, that's why calicos are always girls. In the rare cases where a male is calico, he has an extra X chromosome in addition to his XY.
Right, I read about that in the info on whiteness I was looking at, too. In calicos (which are genetically just torties with white spots; never realized that before) a different gene is at work, the 'white spotting' gene, as opposed to the 'white masking' gene or the albinism gene. (This is the same gene that creates tuxedo cats, magpie cats, 'van-' pattern cats, etc. in non-torties.) It works similarly though to the 'white masking' gene, just like you describe--all the other colors their genes code for are still produced; they just never make it up to the skin layer during fetal development, and so don't take effect (whereas two recessive albinism genes shut down pigment production altogether). In the case of 'white masking' this effect is total, in the case of 'white spotting' it's only partial. A somewhat similar process is involved in the brindling that both torties and calicos show, only there it's more of a competition between colors (X-linked ones in that case) for which gets to which area of skin first, rather than 'masking' of the other colors. Apparently it does occasionally happen that a cat with two dominant 'white spotting' genes will express that by appearing all-white, however I don't think that's a possibility in U2Fanatic4ever's case, as a cat with only dominant copies of that gene to pass on couldn't possibly produce solid black and tortie kittens. Then there are also wholly separate 'browning' genes (double recessive turns black pigment brown); 'dilution' genes (double recessive turns black into gray or 'blue', dark browns--if the browning gene is present too--into light browns or 'lavenders', and ginger into buff or cream); and 'rufism' genes (affecting the intensity of any ginger pigment present), further affecting the end result in some cats. Technically there are only two true 'base' colors--black and ginger (just as in human hair) and those are on the X chromosome, in cats anyhow.

:slinksbackintoarmchairgeekdom:
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Old 05-13-2007, 03:33 PM   #439
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Turtle vs Cat ( A real life teenage mutant ninja turtle)

http://break.com/index/a-real-ninja-turtle.html
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Old 05-13-2007, 05:07 PM   #440
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Quote:
Originally posted by yolland

Right, I read about that in the info on whiteness I was looking at, too. In calicos (which are genetically just torties with white spots; never realized that before) a different gene is at work, the 'white spotting' gene, as opposed to the 'white masking' gene or the albinism gene. (This is the same gene that creates tuxedo cats, magpie cats, 'van-' pattern cats, etc. in non-torties.) It works similarly though to the 'white masking' gene, just like you describe--all the other colors their genes code for are still produced; they just never make it up to the skin layer during fetal development, and so don't take effect (whereas two recessive albinism genes shut down pigment production altogether). In the case of 'white masking' this effect is total, in the case of 'white spotting' it's only partial. A somewhat similar process is involved in the brindling that both torties and calicos show, only there it's more of a competition between colors (X-linked ones in that case) for which gets to which area of skin first, rather than 'masking' of the other colors. Apparently it does occasionally happen that a cat with two dominant 'white spotting' genes will express that by appearing all-white, however I don't think that's a possibility in U2Fanatic4ever's case, as a cat with only dominant copies of that gene to pass on couldn't possibly produce solid black and tortie kittens. Then there are also wholly separate 'browning' genes (double recessive turns black pigment brown); 'dilution' genes (double recessive turns black into gray or 'blue', dark browns--if the browning gene is present too--into light browns or 'lavenders', and ginger into buff or cream); and 'rufism' genes (affecting the intensity of any ginger pigment present) further affecting the end result in some cats. Technically there are only two true 'base' colors--black and ginger (just as in human hair) and those are on the X chromosome, in cats anyhow.

:slinksbackintoarmchairgeekdom:


well, after all that..

All I can say is that Isabella came from one black parent and a cream parent thus producing 2 white/or cream kittens, 2 black kittens and her. This is just how the genetics worked out in her case I guess.
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Old 05-13-2007, 06:54 PM   #441
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Right, that's the bottom line... My guess is her 'white' parent was carrying one dominant 'white masking' gene (which s/he passed along to two of its kittens) and therefore was white, even though s/he also carried the dominant ginger gene, 'O' (which Isabella inherited). As an outside possibility, s/he could've been a double recessive albino instead (that would still allow for the presence of a ginger gene), but that's a lot less likely statistically. (Or even less likely, my initial guess--a very heavily diluted ginger with no 'white masking' or albinism expressed at all.) Then those two black kittens, whether female ('oo'--double recessive, X-linked black) or male ('o'--single recessive, X-linked black), missed out on the 'O' ginger gene...either because one or both of them were girls and mom was genetically a 'white tortie', so to speak ('Oo' + either 'white masking' or albinism) with a spare 'o' to pass along, or else because they were both boys, in which case mom could've been either 'Oo' ('white tortie') or 'oo' (black)--since dad had only a Y chromosome to offer, and the Y doesn't carry either 'O' or 'o'. Who knows what the 'white' kittens may have been carrying genes for--if they did have either one dominant 'white masking' gene or two recessive albinism genes, then it's quite possible that if they ever produced any offspring, there were some Isabella-type 'surprises' in the litter, depending on what the other parent looked like.

For contrast, here's a pic of one of our cats, Lucia--less elegant-looking than Isabella, but as you can see, also a tortie:





Lucia's an adopted stray, so we don't know anything about her parents, but anyhow, as with any tortie, what you're seeing when you look at her is alternating patches of (recessive/'o'), black-based color from one parent, and (dominant/'O') ginger-based color from the other. Lucia isn't as diluted as Isabella is, so her black isn't grayed down, and her ginger looks redder than Isabella's. Isabella's 'gray' had to come from her black parent though, as it could only have had one (or two, if female) recessive genes for black ('o' or 'oo') to offer in order to be black, and 'gray' can't be produced by the ginger gene, no matter how diluted it is. Whereas her 'ginger' patches appear 'brownish' because they're diluted (and she probably also has less 'rufism' than Lucia does)--rather than the sort of 'brown' that comes from black pigment under the influence of 'browning' genes. Neither of them seem to show much browning of their black patches.

OK, I really will shut up now, I promise...
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Old 05-13-2007, 07:04 PM   #442
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Hmm, I wonder what Marijke's parents are. She's a mix of torti (not dilute), tabby, and has one orange calico-esque patch on her face and a few cream spots on her feet. Most of her fur is ticked, solid black or brown, but the fur on her belly is a solid cream.

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Old 05-13-2007, 07:11 PM   #443
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Wow. All that was really interesting and really informative.

I was working on a paper last night and one of my cats, Pokey, wanted to sleep in my desk chair (he thinks it is his bed). When I wouldn't move, he squeezed in where he could, using my leg as a pillow.

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Old 05-13-2007, 08:03 PM   #444
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Quote:
Originally posted by ylimeU2
Wow. All that was really interesting and really informative.

I was working on a paper last night and one of my cats, Pokey, wanted to sleep in my desk chair (he thinks it is his bed). When I wouldn't move, he squeezed in where he could, using my leg as a pillow.

x 1,000!
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Old 05-13-2007, 08:56 PM   #445
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Quote:
Originally posted by Liesje
Hmm, I wonder what Marijke's parents are. She's a mix of torti (not dilute), tabby, and has one orange calico-esque patch on her face and a few cream spots on her feet. Most of her fur is ticked, solid black or brown, but the fur on her belly is a solid cream.

What I found most helpful was starting with
Wikipedia's 'cat coat genetics' page,
then if you want more detail (but maybe slightly less scientific accuracy), try:
messybeast.com's Breeding & Genetics section (see 'Basics')

Any cat with two recessive 'dilution' genes will express whatever combo of base colors it has (black, ginger, or black + ginger) in diluted form--it doesn't have to be a tortie. Tabby is a group of pattern, rather than color, genes--all cats carry tabby genes, and if you know what you're looking for, you can detect some amount of tabby pattern in all but solid black, solid dilute black (gray/blue) or 'masked white'/albino cats...in the former two because a double recessive form of a gene called 'agouti' is suppressing the tabby pattern (whereas there's no such thing as a solid ginger or solid dilute ginger, i.e. cream--they can have the double recessive agouti, but the ginger gene always 'overrides' the suppression mechanism, resulting in at least a few tabby 'ghost marks'). Marijke's 'brown' patches are presumably in reality non-'rufous' ginger patches--as a tortie, it's guaranteed that she carries and expresses both black and ginger through 'brindling', even if the tabby patterning (e.g., the classic "M" design on her forehead) breaks them up into distinct ticked areas. Her 'cream' patches are probably caused by the 'white spotting' gene. Not sure how to account for that lone bright ginger patch--I suppose that's either a spot where 'rufism' is expressed particularly strongly, or else she is in fact somewhat dilute (is that gray on her cheeks and around her eyes?), and that spot is just less diluted than her other ginger patches. Neither rufism nor dilution are necessarily expressed wholly uniformly across the body; also, I'm not sure whether they might perhaps be 'incomplete dominance' traits--e.g., whether a 'Dd' (nondilute + dilute) cat might display some amount of dilution...just a whole lot less than a 'dd'.
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Old 05-13-2007, 09:05 PM   #446
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Quote:
Originally posted by yolland
Tabby is a group of pattern, rather than color, genes--all cats carry tabby genes, and if you know what you're looking for, you can detect some amount of tabby pattern in all but solid black, solid dilute black (gray/blue) or 'masked white'/albino cats.
So true. Posh is black and white and Beckham is solid gray, but in both you can see tabby stripes under the right lighting (Posh's stripes are visible on the parts of her that are black). I wonder if that's the same as a "black panther" still having visible spots...?
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Old 05-13-2007, 09:08 PM   #447
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Quote:
Originally posted by ylimeU2
Wow. All that was really interesting and really informative.

I was working on a paper last night and one of my cats, Pokey, wanted to sleep in my desk chair (he thinks it is his bed). When I wouldn't move, he squeezed in where he could, using my leg as a pillow.

That is so cute!!

Does anyone know if Peach Lily plants are dangerous for cats?
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Old 05-13-2007, 09:30 PM   #448
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I'm not familiar with a Peach Lily, but lillies in general are some of the most dangerous plants for cats. They are my favorite, but I've banned Phil from ever getting them for me (he used to before I had cats).
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Old 05-13-2007, 09:41 PM   #449
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Evil Chloe.

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Old 05-13-2007, 09:56 PM   #450
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Quote:
Originally posted by Liesje
I'm not familiar with a Peach Lily, but lilies in general are some of the most dangerous plants for cats. They are my favorite, but I've banned Phil from ever getting them for me (he used to before I had cats).
All lilies very dangerous for cats.

This site has a good list of poisonous to cat plants.

http://www.cfainc.org/articles/plants.html

And this page has plants and other toxins.

http://animalcare.lacounty.gov/poisons.asp

Both specifically list peach lilies.
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