# Wait, is this actually s/s?



## cirrutopia (Mar 8, 2010)

So today I was reading from this site, and found this:



> The "k" complex has been analyzed further by Dunn ( 1942) and it seems to consist of a large number of genes which, individually, have very small effects. At least one of these genes is dominant since when spotted mice from a " k" stock were crossed with DBAs, a strain devoid of spotting and putatively devoid of " k" genes, all F1 animals were spotted either on the tail, belly, or both.


My first mouse was from a friend, who got him from pet shop stock. I'm fairly certain they were feeder bin mice. All were black. I always figured the different amounts of white on their tails were just... well I didn't really know what they were, but this quote makes me wonder if they were actually s/s mice with a very small number of k factors? Was that actually the case?

My mouse, was, of course, never bred. I thought he might have had a tiny little white chest patch, too, but not more than a few hairs, and I could have been mistaken even about those.

Can anyone tell me a little about the cause of white tail patches?


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## thekylie (Mar 6, 2010)

I equate white tail spots, teeny tiny belly spots, and white toes with mice that are S/s. The F1 of the mice in the study would have been S/s.

I recently crossed a buck who was 90% for sure S/S with a s/s doe. All the offspring should have been S/s, and all the offspring had white tail tips and toes, and a couple had belly spots.

So, it could be argued that just the presence of k factors period affects the tail tips/bellies. Their presence could be also be why it's such a pain to breed white tail tips and toes out of mice that have a genetically mixed background, but eventually they can be eliminated as the mice that are bred are selected for their minimal or lack of k factors.

I have, however, had mice that were supposed to be s/s have only white tails and bellies spots and "gloves", but usually that's more than just a couple white hairs. They would be considered minimally marked pied, where my S/s offspring just had pale tips and toes and a few stray white hairs across the belly.

So, my guess would be that your mouse was S/s.


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## Rhasputin (Feb 21, 2010)

I have bred mice together with tail spots, and white toes, and never had them produce piebald mice. :| 
Though other people have. Hmm.


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## thekylie (Mar 6, 2010)

But it's entirely possible your S/s didn't produce their 25% s/s they would in a perfect world. :lol: Lord knows those punnet squares are loose guidelines at best!

And I'm not saying that ALL mice with toes/tips are S/s. Somewhere down the line the k factors could have just been introduced and even if the mouse is S/S they could still be minimally expressed. It's just that the most likely explanation would be that the mouse was S/s.


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## candycorn (Oct 31, 2011)

The thing to always keep in mind with percentages and punnet squares is that those odds are PER baby not per litter. So each individual baby has a 25 % chance of s/s. Not 1 out of 4 babies will have it. 
I learned that the hard way watching people breeding snakes!


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## thekylie (Mar 6, 2010)

You know... I've never really thought of it that way... but that makes a lot more sense! I use the squares as a prediction tool, but I don't put any stock in the percentages. I just tend to think in terms of "possible, likely, & not likely".


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