#mouse genetics

[kedreeva]

Is splash like the merle genes in dogs?

I don't know enough about the merle gene in dogs, like which gene it is, but I don't believe it is, as Splash is actually a lab-created gene, as in they actually manipulated genes to make it, reportedly in the 80's. As far as anyone can tell, it was released to private breeders in the 90's (back when that sort of thing happened when mutations occurred in labs naturally, as well). Unlike in dogs, the spl gene is not associated with any ill health effects; in dogs, the merle gene can be associated with blindness or deafness. It also doesn't suffer the same issues as brindle, which is mainly found in AY mice, and AY mice are generally prone to obesity and fatty tumors.

Where Merle (in mice) develops over time from a solid coat, splash is visible from the time their skin starts to gain pigment as 5 day old pinks. It is ALSO not brindle, which exists in mice too- brindle starts with a deeply striped coat that gets muzzier as they age. And it's not roan, which also ticks out as it ages and has no solid color patches.

Merle:

Splash:

Brindle:

Roan:

A nice splash should be fairly evenly marked over the whole body, with no big clumps of color.

This is a poorly-marked splash:

compared to the first splash lady I posted, you can see the large clumps of color that give it an almost-merle appearance, except that the clumps still have dilution flecking.

[too-many-mice]

Fawn texels (long coat + rex)

Not the best pigmentation for viable yellows but still some lovey little mice

[amber-tortoiseshell]

I know a lot of animals have a Red gene, but are cats the only animal to have Sex Linked Red? I've heard of something similar in chickens but I don't know if it's the same thing. I just think the possibility of other Tortie animals is cool.

They are the only one with identified mutations on that specific gene. Chickens have some sex linked colors (most well known are barred, chocolate and silver), but since the bird Z sex chromosome dosage compensates* every gene individually, not with complete chromosome inactivation, there are no torties here. ("Tortie" used here as "an animal that carries two different alleles of a sex-linked gene which makes its phenotype a mix of two colors").

(*dosage compensation: When half of the population has two of the genes on the bigger sex chromosome and the other half has one (both the mammalian Y and the bird W chromosomes have hardly any genes on them), somehow it must be synchronised how much gene product is produced by those genes. Mammals solved this by calibrating the entire X chromosome together and turning off one in females. Birds do it by regulating every gene individually, so both Zs are on reduced activity in males.)

I know of three other mammals besides cats that have sex-linked colors: mice, horses and hamsters.

Mice have at least two genes (EDA and ATP7A) and a lots of alleles (respectively tabby, and brindled, mottled, pewter ect). In these alleles, heterozygotes are striped or patched, homozygotes and hemizygozes (XY animals whose X is mutated) are pale colored (if they don't die before birth).

Heterozygous tabby mouse (EDA variant); heterozygous tigrou mouse (ATP7A variant)

Horses has a gene called IKBKG or skin lesian brindle, its lethal in hemizygotes and probably homozygotes too.

Heterozygous brindle horse. This pattern is caused by X inactivation, the stripes are lesions on the skin.

Hamsters have an unidentified sex-linked yellow, very similar to the orange in cats. Heterozygotes are even called tortoiseshell.

Tortoiseshell hamster

Not sex-linked, but phenotypically very similar (black-orange dappled) are harlequin rabbits and bicolor guinea pigs for example (both are alleles of MC1R, the recessive red gene).

And although it doesn't share much similarity with the cat color, just the name, there's a quail color called calico too! (It's an unidentified agouti/ASIP mutation.)

homozygous calico quail

[zombeikid]

Can someone give me resources to mouse genetics? How the breeding, coloring, ect works? I’m fine with just links! I’ve tried looking myself but I’d like good, accurate sources but I’m not sure where to find them.

[kedreeva]

What mice projects are you currently working on? I only know you for peafowl breeding so it was surprising but cool to see you do mice as well! Any litters this year you're particularly excited about?

Currently I'm working on heavily downsizing my colony. At peak, I had a seal point siamese line, a chocolate point siamese line, a self black line, a self blue line, a few splash lines (black, chocolate, blue, siamese), a black pied line, and the tricolors (black, blue, lavender). I had a few random boxes of experimental breedings over the years (I've been breeding mice off and on for like....... 20 years, but most of these lines are within the last 10), for things like angora and satin and texel.

So RIGHT NOW, I have gone back down to a single maintenance self black cage, two cages of seal point siamese, a cage of lavender tricolor satins (which I may or may not keep, I've been hanging onto them because they popped up first here and did SO WELL breeding), two cages of black pied (that will go down to 1 soon), a cage of texel angora (new!), a cage of black splash (probably soon to go), and 7 cages of tricolor, with a few grow-out and sale bins. Most of these cages only have 2-4 mice in them at peak population, except for the grow out and sale bins, and one of the black pied bins, and they're almost never at peak, because the does get separated into maternity bins when they're ready to drop litters.

I'm honestly just excited to get the tricolors back on their feet and be producing well, and producing healthy litters that aren't mean. I'm still going to have to do more work with them, since the black pied line was squirrelly, but at least at the moment there are plenty to choose from AND they're dropping full tri litters, no splashed or plain pied babies mixed in.

I'm also a leeeeeeetle bit excited to have gotten some texel angora. I don't know how well they'll do, or if they'll mix well with my lines, but I really, really, really, rEALLY want to see if I can get a blue siamese splash texel angora line.

THIS MF was sterile and never gave me a single goddamn kid and still to this day is the prettiest mouse I ever made (outside his type, he had pretty bad type)

But that COLOR, the POINTS, the luxurious coat!!

First thing first is just establishing the angora texel line, weeding any genetic health problems they may have, and then I can figure out how to get from here to there. LUCKILY for me, they appear to be siamese tricolor already, so I should be able to cross with a blue and get close quickly. "Quickly" will likely be a year or more from where I'm at, but that gives me something to work on.

[kedreeva]

What does “self black” mean when you talk about your mice? I can only think of the genetics term “selfing” which is mostly used in selective breeding of plants, where a plant is fertilized with its own pollen.

It means the animal is one solid color all over, with no markings of any kind. So, no white spots, no different color markings (like tan or splash), no fading/shading (like Siamese or Burmese). Just one color, just one shade of that color.

Some stuff doesn't make them not self, it just makes them poor quality, like for self black, pale tail/ears/legs is pretty common and would be either a fault or disqualification in a show. Especially white markings on the tail. Blacks often have tan fault hairs on their sides, vents, nipples, and ears, and can have what's called "milk mouth" where they get tan or white hairs around their mouth. They also can have white toes/nails because those are the hardest faults to breed out. I'm 4 years in and still working on these faults, but they look significantly better than the average self black you would find in a pet store, and the line HAD been cleaned of other mutations. I don't know if it is still clean, but a good self black line is great for cleaning out other lines or using for outcrosses to help another line, which was the point of this line originally.

[kedreeva]

Have you posted anything about C dilutes in mice? Like PEW, albino, colorpoint, chinchilla etc etc? I’m looking for more information about it.

SOME, since I work with siamese (c^ch), but not a lot about any other c dilutes. I work with a, b, and d (black, chocolate, and blue). You would be most likely to find discussion on the /mouse tag of my blog, /mouse+genetics, /genetics+experiments+with+mice, /siamese mice, or /siamese+line. Be aware some of the older posts have incorrect info, as I was still learning genes for the mice back then.

However! There's a great genetics website for mouse genes (actually there's a TON of sites with good mouse genetics info because mice have been studied to hell and back due to being... well. the most-used vertebrate in science), found here. They use the UK/European names for mutations, which sometimes vary slightly from the US names. Any breeders or other sites may talk about some of the same mutations (like dove/lilac) with some variation. This linked site will (usually) give you the gene name and locus, and you can use that to look up scientific papers that involve the genes, if you want to read more about them.

[kedreeva]

Question! From my understanding, genetic linkage is the tendency for genes to be inherited together because they’re physically close on the same chromosome. Is that something that shows up with the species you work with?

Depends! As far as colors and patterns are concerned, there's no known "linkage" in the mutations for peafowl (I don't believe there is "linkage" in colors or patterns for mice or quail, either, but I am less sure). Even though "peach" in peafowl is an inseparable purple + cameo combination, having cameo doesn't make a bird more likely to have purple also, and vice versa.

There ARE some linked health issues with some colors, but for peafowl it hasn't been proven to be "linked" or "because of" the gene. Which means, if a bird has gene A they are likely to also have gene B then that's two separate genes experiencing being on the same chromosome vs a bird that has gene A and gene A changes the color but that change in color is a side effect from Gene A's actual function. A good example of this is "progressive pied" in peafowl (NOT actually progressive pied but that's what it got called) is actually vitiligo in the USA. The spread of white is the result of dying pigment cells from the condition's autoimmune effects, the two aren't separate things. When you see progressive pied, you see autoimmune issues and other health issues. With charcoal, you see sterile hens and shorter lifespans, but no one knows for sure why. AY is a lethal homozygous gene and het AY mice tend to be overweight and prone to cancer, but I can't remember if that's a link or because of effect. Silver/Andalusian quail tend to be smaller/not grow as big (but I don't know why because I just avoid the color). Albino quail do poorly but I can't remember why. Manx mice have physical problems resulting from the bone loss in their hips from missing tails. I'm sure there's other stuff I'm forgetting but that's off the top of my head.