[moustress]

For those of you have interested in this subject, here's the skinny.

From hiiriforumi; I asked:

When one breeds in order to achieve a change in the color of fur, is there a genetic change that occurs along with the change of appearance of the mousie?

I think there must be some sort of change of genotype when there's a change of phenotype. Nothing else makes sense, considering what I know, however little that may be.

I've been reading about Cattanach's Translocation, absorbing it slowly since the material is highly technical. If nothing else, it will be educational. Thank you all for your help and encouragement. Knowledge is the ultimate gift that keeps on giving.

The mod answers:

So... If I understand correctly, you're asking whether the differences in colour / coat / etc. in mice have a background in genetics?

I have to make sure what you meant because what I think you're asking is kind of fundamental foundation in breeding mice and understanding how colours and many other things are inherited.

The answer is: Yes they do.

You should probably read Finnmouse's "colour varieties" -pages http://www.hiiret.fi/eng/breeding/varieties/index.html and then continue to Willys K. Silvers' The Coat Colors of Mice - A Model for Mammalian Gene Action and Interaction.

 

[WillowDragon]

Huh... I really don't understand your question there... of course mouses genetics change with coat colour. A chocolate mouse has different genetics to a blue mouse!

Willow xx

 

[moustress]

Of course they have very different genes, Willow, being totally different colors.

What we're hashing out here is whether or not there is a genetic change when you take mousies that have one kind of appearance, say, for instance, yellow mousies, but want to get fawn or red mousies. You select for deeper and deeper color in generation after generation until ou have the desired shade. The overall genotype of A^vy or A^y or ee remains the same in the larger view, but there are changes in the genotype, when seen in detail, or there would be no change in color.

The system fancy mouse breeders use to designate genotypes is relatively simple, the devil is in the details! There are probably hundreds, maybe thousands of modifiers at play in creating the actual appearance of a mousie.

 

[Jack Garcia]

I'm afraid what you're asking makes no sense to me either.

 

[moustress]

Okay, at least you are willing to admit it. That earns big respect. The very fundamental aspects of genetics seem so simple: Adednine, Cystosine,Thymine, Guanine; only four bases in the freakin' system, you'd think it would be easy, but they are complex molecules that can connect in many ways. And then at the far end of the subject We have seven or ten major things, the ABC's mousie genetics which also sounds so simple. There's a world of details in between. Sometimes you have to look into the details to get past the simpler stuff...like what exactly makes a mousie who is definitely champagne, genetically by the simple system, look like a dove. And then, of course there are all the other things that can alter the appearance of critters, diet, environment, etc. but al that stuff is based on genetics as well. Then there's RNA, which another great big ball 'o wax. And mtDNA. Oh, lordy, there's so much I don't know!

 

[Oakelm]

Im new to mice but actually think I get what your saying. Which to me is reading simply you have a various mice of one genetic colour but with the same genetic make up (that is currently known) actually look different to each other, so various shades of champagne from the really light to the really dark. And asking if we think there are possibly further genetic classifications or something else that this could be attributed too. Is that what your saying or have I completely mis read you.

Anyway if I think I have got what you mean then the way I currently look at it there are further genetics that havent been discovered or classified but fall more into the catergories of hypo and hyper melanism. In snakes (where I do understand genetics)there is an albino gene in the royal python that has both a tyrosinase postive and negative meaning the melanine to create the brown is for lack of a better word leaky so you get yellow and white albino ranging through to a darker caramel albino meaning with further selective breeding it could be possible to adjust the level to create a number of shades.

Not sure how much is truly transferable to mice and I hope that makes some sense.

 

[Lime Green Mouse]

RNA shouldn't be in the expressing mix at all, unless I'm misremembering my bio. Don't worry about anything but the plain DNA, everything else is for getting it from the strand to the skin.

I totally understand what you're asking, I tried to ask it before on a different topic, and I believe it boils down to "modifiers." You are only looking at ONE allele, one small (relatively) section of code, that says "be A(vy)." That will give you a basis to run with. Next up comes all the rest of the DNA that will affect how your final mouse comes out; there are all sorts of "on/off" switches rampant in DNA, something that seems completely unrelated could turn off some little section that makes your color look redder in mouse A than mouse B, and that's inheritable too. Therefore, selection is inheriting the small, important modifiers alongside the big, basic genes.

I hope I helped, hopefully I didn't miss your point entirely! XD (I am AWFULLY tired though, heh)

 

[WillowDragon]

Ohhh so this is like what I will be doing with my Lilacs, trying to breed for the right 'shade' of colour?

It will be like, all lilacs have the same basic genetic colour code, but there are lots of other stuff I don't know about working around that basic code to affect shade etc.

I guess its kinda the same thing with humans with blue eyes have different shades of blue! hehe

Willow xx

 

[moustress]

That's exactly right, Willow.

LGM, RNA does affect the appearance of color; there are factors that limit or allow color to appear in particular ways. This isi not an area I know in any detail, but I believe this is the mechanism that gives marked meeces that are clones of each other different markings. Also, from what I remember, there are many environmental and developmental factors that randomize that process, as if you were throwing dice. The two dice are identical but you are unlikely to roll sevens all the time, and less likely to roll snake eyes or boxcars. (2's and 12's) Other than those factors, which I learned from someone with a lot of experience breeding animals for show, there are probably many that I am nor aware of. Extranuclear genetics is one of those areas of inquiry where new discoveries happen on a weekly basis, and in the other areas as well. There's even an area of study to try to find out why, in certain pairings, genes are not expressed in an orderly recessive/dominant manner, but the mothers or fathers recessive is expressed even when there is a dominant gene in the mix.

 

[Lime Green Mouse]

That's exactly right, Willow.

LGM, RNA does affect the appearance of color; there are factors that limit or allow color to appear in particular ways. This isi not an area I know in any detail, but I believe this is the mechanism that gives marked meeces that are clones of each other different markings. Also, from what I remember, there are many environmental and developmental factors that randomize that process, as if you were throwing dice. The two dice are identical but you are unlikely to roll sevens all the time, and less likely to roll snake eyes or boxcars. (2's and 12's) Other than those factors, which I learned from someone with a lot of experience breeding animals for show, there are probably many that I am nor aware of. Extranuclear genetics is one of those areas of inquiry where new discoveries happen on a weekly basis, and in the other areas as well. There's even an area of study to try to find out why, in certain pairings, genes are not expressed in an orderly recessive/dominant manner, but the mothers or fathers recessive is expressed even when there is a dominant gene in the mix.

I definitely bow to your wisdom there; I'm a bit used to doing this stuff with bacteria, where there is no nucleus and extra DNA is always important :lol: Now I know something new, though, and I'm off to go research the heck outta it.

 

[moustress]

Learning should be a lifetime activity; if a day goes by where I learn nothing new I consider it a wasted day.

Today I stole off with the new issue of Time Magazine with the cover story being about a whole new level of genetic knowledge called epigenetics. I had heard of this as theory from several science magazines (Probably Science News) and I'm thrilled to see this past the theoretical and into the factual. It turns out that Lamarck wasn't completely off base after all! He's the guy that preceded Darwin (with his concept of the Origin of Species) with the idea that characteristics could be acquired in a parents lifetime that would be passed on to his offspring. Epigenes do that! They exist sort of camped out at the outside edge of the double helix and are turned on or off by conditions experienced by the parent, which can affect the function of that gene in the offspring. It appears that there are 125 times as many epigenes as there are genes in the human genome. Maybe more.

Exciting stuff!

 

[WillowDragon]

So these are the genes that lie dormant until triggered? Either in the womb during development or once born in the outside world?

 

[moustress]

Yes; either or both. The Time article is dynamite; of course I want to know more, more, more!! The epigenes (epi = means outside of) are perched on the outside portion of the DNA at the point where linkages (the step part of the ladder)are attached. Apparently every cell type has it's own different bunch of epigenes.

Research has already yielded two new drugs for human based on controlling and changing specific kinds of epigene activity.

 

[Lime Green Mouse]

Genetics (and its subfields of course) are probably the fastest growing field in biology right now, second only to biotech. I could never do the math for it...lol! But Moustress, if you really want to know more about epigenetics specifically, you could go sniff out the scientific journals at your library. I bet there's tons of recent stuff published on it that Time could barely scratch the surface of.

 

[Jack Garcia]

There have been a few epigenetics articles about Avy/* (American brindle) mice published in various science journals in the last few years. They deal with maternal diet during pregnancy. I don't have any offhand but I'm sure you can find some on a Google search (that's where I originally ran across them).

 

[Lime Green Mouse]

I'm also searching through A&M's articles, as their library has about a million journal subscriptions. Most of them are open access, too. I'll let you know what I find

 

[moustress]

I'd like references to sources that aren't too technical for me to understand. Science News tweaks the edge of my envelope of understanding. The article in Time is very comprehensible; not saying I wouldn't look for more, but like with the article I've been slogging through on Cattanach's Translocation, there's only much of the specialized jargon I can absorb at one sitting. It's easy to think you understand something without knowing that how word usage varies from discipline to discipline. I rely on Wikipedia for definitions of words I don't grok, but then I lose my track going back and forth. It's fun, up to a point....

 

[Lime Green Mouse]

Some of the ones I've found are Open, some are only sharable through person to person email, and some don't say anything on their copyright. I can't post any of the ones I've found so far on the forum anyways, since I downloaded them in PDF and I think the journals I pulled them from are password protected (another reason not to share them broadly). I've sent you a PM with a few of the titles if you're interested in them and I can email them to you, otherwise you should totally check out the google articles like Jack recommended, or search at your library. If nothing else, the abstracts are usually readable

 

[moustress]

That's very sweet of you; thanks!

 

[Jack Garcia]

Almost all of them are available freely within the US as long as you go through a library (either public or private). If the library itself doesn't have direct access to said journal, they can get an Interlibrary Loan of the materials, sometimes on the same day.