# Genes I don't believe really exist...



## SarahY

I've been thinking about the umbrous, extreme black and Dutch genes for some time now (in the case of extreme black, years) and I've come to the final conclusion that none of them actually exist as a gene; at most they must be modifiers.

Umbrous first. Umbrous is a problem with many ticked mice, whereby the self colour is concentrated at the spine. So an agouti would have more black pigment along the spine, an argente would have more dove pigment along the spine, and so on. It is a constant battle to selectively breed mice away from umbrous, so that they have totally evenly distributed ticking over the spine and down the sides, because mice are naturally umbrous. When one starts breeding with umbrous mice, you can selectively breed them to be even, seeing small improvements each generation. If umbrous was an actual 'gene', this little-by-little selective process couldn't happen. The mouse would be umbrous or it wouldn't. It is the same as breeding a tan to have a dark red belly. Umbrous definitely exists, you can see it, but I do not believe it is an actual gene in itself.

On to extreme black. I think this is again a case of modifiers. The theory is that extreme black (technically known as extreme nonagouti) is a dominant gene called 'ae', which is dominant in the same way as tan. Just as 'at' will always make tans (unless bred to reds), 'ae' will always make non-agouti. It can't be carried. This means that if you breed an extreme black mouse to a standard mouse, you would get extreme blacks in the litter. If you breed these siblings together, theoretically you'd get extreme and standard black in the litter. But what actually happens when you breed extreme black to standard black is that you get a litter of black mice all somewhere between the shades of the parents; blacker than the standard but not as black as the extreme. Breed these mice back to their parents and again, you'll end up with shades in between - but you will never see extreme blacks and standard blacks in the same litter. English blacks are all standard a/a, and I know this because when they get their hair through at one week old they have tan hairs in the ears. The extreme gene supposedly wouldn't allow this. Our English show blacks are as black, if not blacker, than many pictures of mice I've seen labelled extreme black. This is why I don't think extreme black is a gene - or if it is, it is a laboratory gene and not available in the fancy. I believe it's all about selective breeding. If you bred 'extreme' blacks to each other but paid no attention to selective breeding, you would end up with poor blacks eventually, riddled with tan hairs and pink toes.

Finally, the Dutch gene. After much test breeding I can say with complete confidence that Dutch is recessive spotted s/s and doesn't have its own gene. It is fortunate for trying to improve the variety that when you outcross to self or broken and back in again, the patches of colour naturally occur on the rump, cheeks and ears - which does make it appear as though Dutch has its own gene, or is a least a modified recessive spotting gene. This means that anyone with piebald mice can selectively breed them into Dutch mice!

Feel free to post your own thoughts on umbrous, extreme black and Dutch if you don't agree with me, or tell us what genes you don't believe exist


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## moustress

Sarah, you've hit the nail right on the head! :!:

I think it's a matter of definition and/or method as to whether any genetic factor is called a locus or a modifier. I have always thought that certain factors are a matter of luck and 'concentration' as to whether a 'modifier'. I think that ALL mousies' genetic material contain the potential to be extreme, or show 'sable-ing' or have their markings in a certain configuration, or what have 
you. I especially agree about the extreme black, as a matter of fact I was told years ago that it was a quality that needed to be 'conserved', indicating that it's concentration of the gene for darkness rather than a different gene.

Extending the principle, I also suspect that ALL quadruped mammals have the genetic material for the wide array of marking and coat types in a standard 'kit' of genes that have the potential, under the right combinations, to show a particular color or markings, or ticking, or fur type. If you think of cats, mousies, and rats, they all have varieties with Siamese markings. It just makes sense to me to think that there's a common grouping of factors for these things in different species.

It's a very juicy subject, that's for sure!


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## Malene

Umbrous and extreme non agouti do exist.
Umbrous: http://www.informatics.jax.org/javawi2/ ... l&key=1521
Extreme: http://www.informatics.jax.org/javawi2/ ... ail&key=12
I have never heard that a^e is dominant. It should be simple recessive. But it's true that they still need selective breeding. It won't automatically make a mouse all black, as you can see in the link.
Whether or not it truly exists outside labs, I don't know.


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## SarahY

'ae' cannot be recessive, unless it is an entirely seperate gene from the A locus. If you breed homozygous extreme black (ae/ae) to black (a/a) you'd get extreme blacks (ae/a), just the same as if you breed homozygous tan (at/at) to blacks (a/a) you'd get tans (at/a). It's a modification of 'a' just as tan is.

It could only be recessive if it was seperate, for example 'ex'. Extreme black (a/a ex/ex) x black (a/a Ex/Ex) would make blacks carrying extreme (a/a Ex/ex).

I'll believe in extreme black when someone breeds an extreme black (ae/a) to a black (a/a) and gets both in the litter


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## hyshqa

I definately agree with everything you said!

When I got my first mice last year they were piebald and very randomly marked other than one buck which had a slight resemblance to dutch in the sense that he looked like he had two splattered-on eye patches that were very joined and spread far down to his nose and behind down his back, and he had a poorly defined coloured rump. I bred him to the piebald does and then back into the line again and quickly started seeing mice more closely resembling dutch! (Left is the original buck, right is one of his offspring: http://i51.tinypic.com/1ep7uq.jpg)


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## Anne

according to what i have read extreme black should be lover than a on the locus, so an extreme should be a^e/a^e and a a/a^e should be a black that carries extreme.

http://hiiret.fi/eng/breeding/genetics/a-e.html


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## SarahY

Gotta say, I don't agree with anything they've written there, and I usually find Finmouse so good! :lol: English blacks are a/a.

It's interesting that in the link (kindly posted by Malene) Jax says extreme nonagouti is ae/ae _and_ ae/a, while Finmouse says that ae/a is black _carrying_ it, which just doesn't make any sense! :lol:

Saying ae/a is black carrying extreme is like saying that at/a is self carrying tan - which we know it isn't, or that BE Cream/bone (c/ce) is an albino carrying stone/beige - which we know it isn't. It just doesn't work like that because it's a modification of self gene, not a recessive gene all of its own.


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## Anne

however, it being the lowest on the allele, will explain why you dont get extreme blacks in a pairing with a normal black (a/a).

I have never heard before that it should be anything but recissive, and from the mating I have seen with mice that should be or carry extreme, it doenst make sence if its not recissive til normal black.

also it says in malenes link "The a^e mutation was found among descendants of an irradiated mouse. ae is recessive to all other alleles except a^l." (I put in the ^'s)


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## Malene

You can't really compare it to tan, as it is higher in dominance, than a.

Where on jax does it say that a^e/a is an extreme black?
The picture is just to show the difference between a^e/a^e and a^e/a, I guess. If you click on it, it says: "Pictured left to right: a^e/a^e and a^e/a. *Homozygotes* for a^e are very dark all over with no yellow hairs in the ears or around the nipples and perineum. a^e is recessive to *all other* alleles except a^l."


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## SarahY

Oh I see, I read the page wrong. I read "extreme nonagouti ae/ae and ae/a". Sorry about that  Still there's not much difference between the two mice in the picture, is there? Not like a pet shop black and a show standard black.

If the gene is written ae/ae, how can it be different in the way it works to tan? How can ae/a only carry it and not display it?

If anyone does breed 'extreme' blacks, I would be very interested to see pictures of 10-14 day old kittens, when most varieties (including a/a black) have tan hairs in their ears. Otherwise I don't think we can say we have it in the fancy as we have no proof at all, especially as the show black babies we have here do have the tan hairs in their ears. Better selective breeding is what makes good blacks, not some mystery extreme gene 

EDITED: Just to clarify about English show blacks being a/a due to the tan hairs in their ears, here is a show-line black kitten with his dove foster-siblings, all of whom have the tan hairs inside their ears (really sorry about the rubbish pictures, they're the only ones I have of black kittens this age):



















These are the parents, neither bred by me and both from excellent, winning show stock:


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## moustress

It's odd :?: that the photos in that site show mousies that don't look at all like the extreme blacks found in the mouse fancy. They have pink feet and ears, which don't occur in show extreme blacks...


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## SarahY

Yes, that's what I thought... and yet show blacks are waaaaay darker without the need for the extreme gene!


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## SiamMeece

SarahY said:


> Saying ae/a is black carrying extreme is like saying that at/a is self carrying tan - which we know it isn't, or that BE Cream/bone (c/ce) is an albino carrying stone/beige - which we know it isn't. It just doesn't work like that because it's a modification of self gene, not a recessive gene all of its own.


As I always understood, a is dominant over ae so an a/ae mouse is supposed to be a normal black mouse phenotypically. That's why they are referred to as extreme carriers. at is co-dominant with a, so both alleles come to expression like c/ce or ch/ce so neither of these alleles are carried.

I have been breeding "extreme" blacks for a couple of years, but the mice that were supposed to be a/ae were always some sort of intermediate, never normal black. I have never seen yellow hairs in the ears but did so on their vents, which made me a bit sus. As far as I know all the extreme black mice in Holland find their origins in the UK and the breeders that brought them to Holland claimed they were extreme black as in ae/ae as were the siamese they brought with them. Sarah, your remark that all British black mice are a/a just confirms what I have been suspecting for some time and that is that I have been breeding a/a mice all the time (like many other breeders all over Europe)


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## SarahY

> As I always understood, a is dominant over ae so an a/ae mouse is supposed to be a normal black mouse phenotypically. That's why they are referred to as extreme carriers. at is co-dominant with a, so both alleles come to expression like c/ce or ch/ce so neither of these alleles are carried.


I think I see, thank you. Maybe ae/a wouldn't have enough concentration of pigment to show any difference but ae/ae would.



> As far as I know all the extreme black mice in Holland find their origins in the UK and the breeders that brought them to Holland claimed they were extreme black as in ae/ae as were the siamese they brought with them. Sarah, your remark that all British black mice are a/a just confirms what I have been suspecting for some time and that is that I have been breeding a/a mice all the time (like many other breeders all over Europe)


This is what I had thought! Extreme non-agouti may well exist in laboratories (and I'm sure they would know!) but I've seen no evidence of it within the fancy. Our good show blacks look just like your good show blacks. I think that the breeders of decent blacks in the worldwide mouse fancy should stand up and proudly say that they are able to breed bog-standard a/a to such a high quality


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## Rhasputin

Umbrous behaves like it should. I have mice here which LOOK umbrous and are simply bred to be dark on top, and mice which ARE umbrous, and breeding them is completely different.

The ones that are selectively bred to be dark on top, always produce more with dark tops, and the ones that are umbrous, produce the exact percent of umbrous babies that a punnet square would predict.


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## Wight Isle Stud

every animal and bird, fish etc has evolved to be darker on top than under. its a matter of natural selection wherby if something stands out against a back ground it will get eaten. It doesnt matter if a mouse is light under as it doesnt have any predators from below, but it certainly has from above, so therfore the mouse has a tendancy to develop a darker back. we select away from this as we want the same colour all over. 
Our Self blacks in the fancy are better than the extreme blacks I have seen photographs of. However, if an extreme black is incapable of developing tan hairs anywhere, but our self blacks certainly are, then I submitt this is a case of genetical extreme blacks have not been developed by the power of selective breeding like our english blacks have. I therfore will say that, from a standing start, if the extreme black were to be developed by selective breeding over decades like the english self blak has then it would be a far superior mouse than the English.For discussion !!


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## Wight Isle Stud

moustress said:


> It's odd :?: that the photos in that site show mousies that don't look at all like the extreme blacks found in the mouse fancy. They have pick feet and ears, which don't occur in show extreme blacks...


I bet they have just used a photo of a black, any black, wihout realising the photos will be looked at in extreme detail.


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## SiamMeece

Some interesting umbrous info:

http://www.ias.ac.in/jarch/jgenet/40/229.pdf


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## WillowDragon

If we are going to talk about umbrous and 'extreme'... Lets add cordovan into that too! b^c is supposed to be the good shade of show type chocolate... Or so i recall reading!

K xx


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## m137b

I don't know if I personally beleive Extreme blacks exist in the fancy, I know some breeders make claims to have them. But I don't see a difference in the mice they call extreme and the show quality blacks others post pics of. And outside of sending samples to a lab, and paying an arm and a leg to have them tested I can't see how you could prove they are or aren't.

As far as yellow hairs in the ears on pups, I'm confused, are you saying normal show quality blacks have yellow in their ears as pups and by the time they're weaned it's black? Or is that just that one pup?


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## moustress

About ten years ago I got a pair of extreme blacks from a West Coast breeder. When they say extreme black, that's what it is.There is no hint of pink or any other color ANYWHERE! Inky black inside the ears, inky black toenails...really something to see. But the bodies were weird, out of scale to the huge ears and humongous long tail.


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## m137b

Moustress: What you've described is a Show Quality black. The animal's color intensity isn't due to the extreme non-agouti gene itself, it's due to selective breeding.


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## Rhasputin

A show quality black, and a show quality extreme black will look the same, and be able to compete against each other.

A poor quality black and a poor quality extreme black, will similarly have pink extremities, white toenails, pink ears, etc, HOWEVER. . . The extreme black, to my understanding, will have no yellow hairs on the genitals or face.


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## WillowDragon

From what i have read in the past... The extreme factor does not eliminate tan hairs, it just eliminates the tan in them, it makes them colourless.


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## Laigaie

Selective breeding is the slow and careful accumulation of modifiers. Either these things are caused by a single gene, be they simple or partial recessives, or they're caused by a combination of modifiers. The problem in trying to figure out which one you have, really, is that you have both. Especially if you're working with show quality animals. A show-quality black might be extreme, umbrous, or neither, but with modifiers that make them effectively the same.

The differing experiences that many people seem to have with these alleged genes could very well reflect differences in whether people have modifiers, genes, or a combination. If the children of an extreme and a standard black are either one or the other, you're looking at a simple recessive. If they're either one, the other, or of a single shade between, it's a partial recessive. If they're all of varying shades, you're dealing with a set of modifiers that are passed on separately (much harder to breed with). It seems perfectly reasonable to think that such a gene might exist, but not be present in the majority of lines, or be a variety of different genes in different lines, plus sets of modifiers in other lines, so that each person breeding with umbrous or extreme has a different experience with them.

It would take a massive number of breedings with very controlled circumstances to determine scientifically which is most likely, and I doubt anyone focuses enough on those particular genes only to be able to handle such a massive undertaking. You'd be talking about thousands of mice, just to handle basic statistics on all the combinations of various lines of alleged extreme mice, and that's after acquiring said mice from all over the world. And all that just to raise the bar on how black is black.


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## sugarmice

I totally agree with you Sarah. I have had mice pop up with berkshire markings as well as other marked varieties... just from otherwise standard broken markeds. I could definately selective breed to get a line of Berkshires or Dutch going, despite not starting out with one. This confirms to me that marked mice are just ss mice, with a sprinkle of luck that makes them pleasingly marked.
I would like to bring up about cordovan, as another user mentioned within this thread. Is it a seperate gene do you think? Do you experienced breeders have cordovan mice? Would you say cordovans are noticeably better than standard "b"s?


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