The siamese rat, a biological view

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Originally Posted by littleindiangirl

I wonder about the fawn gene on a blue point siamese? Has that been bred?

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I can't think of anyone who has bred one off the top of my head, but it wouldn't be any different to a non-dilute RED Siamese. All the dilute gene would do is further dilute the pigment, which is already paled out to white ...

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Originally Posted by littleindiangirl

I wonder why the pigments failed to produce at all when that second dilute was introduced. Was the tyrosinase too fragile, and made completely unfunctional with the second dilute? I guess I will have to differentiate between the functions of the pp and rr gene's compared to the dilute dd gene. Very interesting!

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I think a lot of it is just the fact that the pigment colour in rr and pp rats is so pale that it's just not possible to see on a Siamese rat. Consider that even black can only express itself to a dark brown seal colour, and you can see how hard it would be for the extremely deformed melanin in a PED or RED rat to express itself at all when restricted by the Himalayan gene. The eyes on a RED Siamese will be darker than the eyes on a PED Siamese though.

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Originally Posted by littleindiangirl

[edit] another thought also, does being agouti with the c(h) rr make any difference? You didnt really specify. I think if it were a self, the beige/buff would then be completely cancelled out. I'm just mowing over why it didnt work.

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From the limited breeding I did, it doesn't appear to make a difference if the rats are agouti or non-agouti based with Siamese. You might see a small amount of agouti banding on a really nice agouti point, but once you add the dilutes in it's impossible to see.

I thought the link didn't work ... but then I remembered I did add a forwarding page earlier. I will probably put some sort of main site back on the domain, leaving the varieties/genetics at the varieties.asp link in the future though.

It must just be too fragile then. That has to be it. I'm just confused why the blue comes through so well, but any other dilutes just pale it out so much. That bites, I would have liked to see a nice topaz/fawn point.
Thanks for all the great information! I do really love the site, I go there quite often, its such a great listing. ;)

You know what else I just thought of, the brown mutation. Its a very warm color when agouti, not quite chocolate, not quite cinnamon. That sound plausible at all? LOL, tell me when to stop, I'm just overly excited when I think of new ways to get around the complete dilution.

Not sure what relevance brown has here? Adding more colour modifying genes will only ever make the rat lighter, not darker...