Sooty

Hmmmmmm. In my little non-molecular-understanding brain, makes sense to me.

Like melanism? I think I mused about that somewhere around here. In wild cats and mice its a mutation on the MC1r that causes it, making an agouti animal much darker, sometimes almost black. Other species get it too (foxes defintely, I've seen one). Its not the same as self black, which is a mutation on the agouti locus.
I've also seen extreme black mice- they are like a normal black self mouse but with a super abundance of black melanocytes, the ears and tail and feet are totally black not pinkish like normal. Not sure what mechanism causes that.

Well, there is no reason why it could not be linked to Agouti...that would actually make a lot of sense...now all we have to do is get people to test all their sooty red based animals for Agouti!!! :rofl

The only species I know of that has melanism and extension is mice. I'll have to do some searching on google scholar.

I've always wondered about it being tied to or effected by agouti. Lace gets occasional sooty and she is 'AA'. Not sure if that tells us anything. *shrugs* I will look for some sooty reds who have been tested for agouti tonight.

i have battle all the time with someone who believes that aa is liver chestnut.

Yeah I know someone like that too. Unfortunately all of the 'AA's I know back it by being some of the palest chestnuts I've ever seen.

lol I also used to know someone like that too.
(for newcomers)- It's been proven that it is absolutely false!

a question about agouti, I have now seen 2 chestnut mares that are both AA & min sabino and both have lighter coloured boddies and dark red legs (like a red dun would have)

Now I know agouti dose not affect red, but what would case these mares to have that type of shade to them?

What about this new Red "gene" they have just unearthed....does that affect the way they look??

I've had a look at some small animal colour genetics stuff. Rabbits have E locus mutations-
'Steel' [i]'Es-[/i]' or dominant or agouti black, extends the black colour in an agouti to make it very dark, dark bellied with very little yellow banding/ticking. I'm guessing this is melanism though I've not seen it called that in rabbits. It is dominant to normal agouti.
'[i]ee[/i]' makes a yellow rabbit that may or may not have darker colour shading on the points and/or hair tips - if this is extensive they are called sooty fawn but they can also just be plain yellow with no shading at all and still be [i]ee[/i]. I can't find any info yet on the possible mechanism of it but it seems to work the same as sooty in [i]ee[/i] horse. It is recessive to normal agouti.
[i]Ese[/i] is steel colour so the darkening effect of the steel mutation can't affect the sootiness of the [i]ee[/i] mutation, as if the rabbit has at least one Es it will be steel (or black if [i]aa[/i]) not yellow.
If the same thing is happening in horses as rabbits you would be getting dark bay (poss black bay or brown?) as a mutation on the [i]E[/i] locus darkening normal agouti [i]E-[/i] and being dominant to it like the Es gene mutation in rabbits, and [i]ee[/i] (yellow/red) being recessive to Es- and E- and sometimes showing sooty shading, sometimes not, but the sooty shading not having any relationship to the dark shading of Es.

ETA the only explanation I could find of sootiness in [i]ee[/i] rabbits was that the [i]ee[/i] mutation simply wasn't 'strong enough' to override the black supression that the mutation was trying to do. The sootiness in rabbits does seem to be temperature related too, the darkest areas being on the coolest parts of the rabbit. The sootiness can be bred out by selective breeding and I've also read that the agouti staus of an ee rabbits can affect the sootiness.

Dakota: I don't know. Supposedly not, but I've encountered the same thing.

[quote="rabbitsfizz"]What about this new Red "gene" they have just unearthed....does that affect the way they look??[/quote]

Nope. They're identical.

Uh okay so reds that have been tested for Agouti, eh? Here are the test results for my VERY 'sooty' palomino Morgan Metigoshe Mariah...

Red Factor: a/a
Agouti: A/a
Cream Dilution: N/Cr

Her legs are darker than her body is as well as her mane and tail being nearly 'black'. Pictures here:
http://s225.photobucket.com/albums/dd77…" onclick="window.open(this.href);return false;

Does this help?

~"It is said that only those who believe in unicorns can see their horn. Belief is a powerful experience, for without it, most dreams would not be realized…" - Kim McElroy~

It does to me. I'd like to see a bunch of these... I'm hammering on a new theory. LOL

Ohhh... Do tell!
..…............................................
Drcharltonjr- love the different signatures each time.

Well... agouti doesn't effect pheomelanin. No one will argue that point (unless they've lost it ;) ). However, who's really to say all chestnuts are all pheomelanin. I have personally believed for a long time that there are at least two genes capable of selectively turning eumelanin on, sooty and gray (and the agouti bases having fewer melanomas seems to support that theory). If these genes (and maybe others) can turn eumelanin on, there's nothing to say agouti couldn't then act on THAT. I've just grown tired of hearing "it's not black, it's just [i]really[/i] dark red" when we don't know that and it LOOKS VERY black.

Just want to add something about rabbits- the sooty on yellow is not low grade agouti type colouring, it doesn't look like agouti at all.

Unfortunately there are just [i]bound[/i] to be a couple of Agouti neg. Reds out there, lurking, waiting to bust the theory.
But it sounds reasonable to me, and until those A neg Reds turn up I am willing to give it a trail run!

Has anyone actually analyzed the hair samples to see if they are eumelanin or pheomelanin?

That's exactly what I wanted to know Monster. I actually debated gathering some samples for HoofPick.

RF: Even if we do find some 'A' reds that "blow the theory", it could be possible those have even something else going on. So far we've seen one uber dark with 'A', but she maintains the idea some by having much darker legs than body.

If anyone is interested sooty supposedly occurs in self yellow ([i]aaee[/i]) rabbits and not in agouti based yellow ([i]A-ee[/i]).

HAH! More evidence! Certainly not proof... but interesting nonetheless.

Interesting theroy...I like it!

I have a chestnut mare with not a trace of sootiness who is AA

[img]http://img.photobucket.com/albums/v295/…]

She's not particularly pale (though her legs are, but it looks like she has mild pangare' and possibly flaxen), but she's as clear-coated as it gets. She doesn't even have counter-shading. Wow.

Okay, 'nother thought/question...does sooty cause on chestnut the "patterning" that can be seen on bays? (once that's answered, there's another thought that either goes away or comes into play...but I don't want to put it down yet...here's hoping I can remember it!)

Diane

Patterning?

can't think of a better term, but what I mean is how sooty "lay over" the withers, 'drips' down the neck, can darken the head, etc...kinda like someone dumped some charcoal dust over the horse, and it stuck in damp places. LOL

Diane

Here are two examples from the bay album:

"clear" bay--no darkening on the topline anywhere...

http://www.equine-color.info/v/bay/MSU+…" onclick="window.open(this.href);return false;

"sooty" bay...darker patches/patterning (I'd say this guy was heavily sooty!)

http://www.equine-color.info/v/bay/Dier…" onclick="window.open(this.href);return false;

Diane

Now you're going to confuse the issue because you're bringing brown into it. :rofl That second horse is brown IMO.

DunCentralStation posted this collage of tested browns once and you will see that horse definitely fits the profile:
http://images.yuku.com/image/jpeg/17136…" onclick="window.open(this.href);return false;
According to her last post it seems a tremendous number of bay bases we thought were sooty are actually testing out brown instead.
Do you have another example that might not be brown?

But I do know what you mean. I don't think so. IME sooty on red bases works from the bottom up. However Lace has VERY obvious face masking, wither bars, dorsal barbs and even neck shadowing like a dun would have. Since we think sooty mimics dun factor that could imply she's got some sooty from the top down. However she gets sooty creeping up from her feet to her body.

So I dunno, but most of the time, on reds, I don't think so.