So, let’s think about temperature-sensitive albinos for a sec Notice this kitten’s nose is darkest? Big breathing holes there! And at this stage, his paws are just beginning to get their dark brown color. Siamese kittens are born with white fur their markings (points) develop later. All those cavities in the head account for enough of a drop in temperature to let the color kick in. True, but we have a lot of holes in our faces: eyes, ears, nose, mouth (the same argument my dad used when I was a kid and wanted to pierce my ears: “You don’t need another hole in your head!”). Someone questioned why the face - that’s not an extremity. Once they hit that critical temperature, those alleles that have been inhibiting the enzyme responsible for pigment turn off and color begins to develop - on the ears, paws, tail, and face. They pop out as white kittens too, but once exposed to atmosphere, their extremities begin cooling. It’s pretty warm in the womb, so all kittens with this special modifier allele are white throughout gestation. Kinda cool, huh? Why are these cats born lighter and then darken as they age? In essence, these cats are walking heat maps. Anything lower than that and the mutation is blocked and the color gene can then do its color thing.īecause a cat’s body is cooler around his ears, paws, and tail, that’s where the color begins to kick in. This modifier starts sending out its “stop the color!” message around 100.4-102.5 F (38-39.2 C), which is a cat’s standard body temperature. It inhibits pigment - in other words, it causes albinism.īut that modifier signal only gets through to a kitty’s fur if it’s above a certain temperature. And then there are modifier genes - these can cause a cat’s fur to be patterned in a certain way, or mask the color altogether, like you’d see in the white bib-and-spats on your classic tuxedo kitty.īut Siamese and similar cat breeds have a special modifier gene called a Siamese allele that mutates the color gene. They’re what tell a black cat to be black, or an orange cat to be orange. See, a cat’s coloring is determined by a set of eight different genes. But Siamese - and similar breeds - aren’t stark white, so what gives? Siamese are temperature-sensitive albinos because of genetics Photography © 2014,. When we think of an albino, we usually think of someone without pigment. It’s all thanks to a special gene they have in common: an albino gene. And anyone owned by a Siamese could do the same thing. But I really could get his fur to change color. If my cat wore socks, his fur would change color.
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