# Magical color changing mouse



## micurious (Nov 7, 2015)

So at some point in the past 48 hours my roan mouse - just past six weeks old - turned into a merle.

This is very exciting - my plan is to breed long haired merles - but extremely startling, because I have two other merles who have been merles since basically day three of their lives, it was obvious long before they grew hair that they had three different colors (they also happen to be pied, which as far as I can tell this one is not, although the modifiers in her siblings seem to tend toward very small pied markings.)

She's also darkened by at least one shade from her previous salt-and-pepper colors overall. It's very intriguing and I look forward to seeing where she ends up. I'll try to get a picture tonight.


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## Laigaie (Mar 7, 2011)

What you just experienced is the magic of T1 vs T2 merles! In the US at least, we have two main types of merle. One shows the roan vs merle patches when it first develops pigment (or at fur-up if the contrast isn't enough, like on red or pe merles). The other doesn't merle out until right around six weeks.

Right now, most show line US merles are T2 (late merling), but there's been some instances of vaginal atresia popping up in those lines (due to an outcross to California mice that are rife with the condition), so some folks are switching over to T1 merles and breeding them back up to good type and size.

Hillary (who goes by Frizzle here) is my number one US merle person to talk to, but the area west of the Great Lakes is thick with merle breeders right now.


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## micurious (Nov 7, 2015)

The epi/genetics lover in me is salivating a little.

Once everyone has aged up a bit I'm going to breed back the long-haired Siamese to his T1 merle mom - fingers crossed that I get my first long haired merle! Bonus points because they are both the sweetest tempered out of all the mice. The rest of F1 is still a little skittish.

I'm waffling on what to do with this T2 doe. I have a pied T1 tan boy (half brother) and a pied black tan (full brother), both with a nose spot I would LOVE to replicate long term. She also has a nice, social, curious temperament. The boys are a little skittish. I also have her sire, who is an absolute love if maybe a bit of an escape artist.

Ideally, I'd like to end with sweet tempered, long hair merles with more spots than she has, including both pied and not. And with other colors, if I can get my hands on them.

I'm just east of the Great Lakes, in NY. Perhaps they're migrating? My first three came out of a feeder bin at the sole local mom & pop pet store that didn't serve all albino all the time. I am now EXTREMELY curious about their sources...

Does anybody have a grasp on what controls T1 versus T2? Gene interaction or something more purely epigenetic? Is it the same base gene for roaning?


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## Laigaie (Mar 7, 2011)

Noooo idea. I am so not the person to ask. I do know that there are transitional merles, who aren't patterned up when they get skin pigment, but who develop the pattern before weaning. That sounds to me like two alleles of the same thing, but then I haven't been testbreeding it (I don't breed merle). It could also be that there's a spectrum from T1 to T2, but most are at those two poles. I'll see if I can drag Frizzle back onto the forums to chat with you about it, or maybe she can be convinced to write up an article.

RE: migrating, I know there was T1 in petshops for sure on the east coast. T2 was common in Ohio before that area lost a few of its show breeders. I wouldn't be surprised if T2 had made it into mom-and-pop shops as well from there.


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