|Faraday (left) and Maxwell|
|Gratuitous shot of Faraday using his lungs|
Interestingly, that pointed coat is a form of albinism.
Wait...da boyz are albinos? Say it isn't so!
Okay, it's not so – at least not the way an albino is traditionally understood. When we think of an albino, we usually think of someone without pigment. Well, da boyz aren’t stark white, so what gives?
scientific post ahead!
scientific post ahead!
Well, it’s kind of a genetic thing. See, a cat’s coloring is determined by a set of eight different genes. They're what tell a black cat to be black, or an orange cat to be orange. But Siamese, Burmese and Tonkinese cats have something funky going on with one of those genes!
|Pointed cats have alleles that determine their coat pattern|
One special set of alleles in Siamese type breeds sends a command that inhibits pigment – in other words, albinism.
Not funky enough for ya? Well, that signal only gets through to a kitty's fur if it's above a certain temperature.
So basically what this means is that Siamese, Burmese and Tonkinese cats are temperature-dependent albinos. Kinda cool, huh!
How does it work?
Well, the alleles start sending out their "Stop the Color!" message around 38-39.2°C, which is a cat’s standard body temperature. Anything lower than that and the alleles’ message is blocked and the color gene can then do its color thing. Since a cat’s body is cooler around his ears, paws and tail ... that’s where the color begins to kick in.
How come these cats are born lighter and then darken as they age?
|Ryker at 4 months|
Someone questioned why the face – does that really compute? Surely the face is warmer than the extremities! True, but we have a lot of holes in our faces: eyes, ears, nose, mouth (that was my dad’s big argument, by the way, when I was a kid and wanted to pierce my ears: “you don’t need another hole in your head!”).
All those cavities in the head account for enough of a drop in temperature to let the color kick in. Notice Ryker's nose is darkest? Big breathing holes there! And at this stage, his paws were just beginning to get their dark brown color.
So let’s think about this for a second. If all it takes to make these cats “go albino” on you is to increase their temp, what if you made Maxwell wear socks? Would his paws turn white?
First…good luck with that experiment. Be sure to let me know how that worked out for ya, ‘k?
If you followed Ryker’s medical condition during his last year, you may have seen his “Bikini wax”, as we called it (he called it The Great Indignity, but I digress.)
|Ryker, immediately after being shaved|
The vet shaved a 4 inch swath around his lower abdomen for a sonogram, and it happened right before we dove into one of the coldest winters on record in Kansas City. His fur grew back a shade darker. (He didn’t think it was very funny.) Fortunately, as spring turned into summer, his coat lightened once again.
|Ryker, early summer. Dark area is beginning to lighten.|
True. And all of this information can be applied to them as well: Himalayan, Colourpoint, Javanese, Balinese, etc. So why specifically focus on Siamese, Burmese and Tonkinese in this article?
Blame the scientists. It’s in the naming.
See, the scientists discovered two different alleles (TYR-G301R and TYR-G227W).
One is more efficient at turning color off than the other.
|Natural Mink Burmese: Wikimedia Commons|
This makes total sense if you look at pics of both breeds.
Siamese have the most contrast whereas Burmese can sometimes have very little contrast.
That’s why many Burmese – and half of the Tonkinese – aren’t described as points, as in “seal point” or “blue point”.
They’re known as minks instead. See how little contrast the guy in the picture on the right has? He's considered a mink, not a point.
Back to the other breeds for a sec: they also have allele pairs. Himalayans, for example, have the Siamese (cs cs) allele. Some Ocicats carry the Burmese allele.
And as far as Tonkinese go – well, guys like Faraday (a platinum mink) fall in the middle. They have one of each, so a pointed Tonk will have a Siamese dominant allele pair (cs cb), whereas cats like Faraday who are minks will have a Burmese dominant allele pair (cb cs).
|Faraday's coloring isn't as extreme: he's a Platinum Mink|
(Platinum name comes from coat sheen)
Oooookay. Done with the hard science. Back to the cool stuff.
What if da boyz didn't have that allele pair? If you ignore the funky, temperature-dependent albinism thing going on...
Genetically, Maxwell's a solid grey kitty. Faraday's silver. And Ryker? He'd be dark brown.
|Caleb: Seal Point Siamese = black cat (with alleles)|
Caleb, Ryker's older brother and a seal point Siamese – well, genetically he was a black cat... with alleles. Interesting to think about, no?
Albinism and Eye Color
Anim Genet. 2005 Apr;36(2):119-26. Tyrosinase mutations associated with Siamese and Burmese patterns in the domestic cat (Felis catus). Lyons LA;Imes DL;Rah HC;Grahn RA. Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA. email@example.com http://www.ncbi.nlm.nih.gov/pubmed/15771720
"Ocular pigmentation in white and Siamese cats," Investigative Ophthalmology & Visual Science, 1980 May;19(5):475-86.
Published by NationalInstitute of Health's PubMed site