Brindle -- question for the genetics wizards - Page 2

Had a rethink of your Q Jamille.  There is a colour known as 'seal' or 'bad black' that occurs in other breeds eg the Whippet, and also cross breeds, where the overlying colour is black but some light pigment shows through in places. 

This is thought to be caused by heterozygous genotype on the K locus.  Eg  a Whippet  - A^y  K k^y - the K locus having semi dominant expression in this case, allows the sable to show through very slightly as a light under shading.

This also occurs in tanpoint expression ( a^t   K k^y ) and is quite common in crossbreeds where the underlying light pigment (tan) shows though slightly in the usual tanpoint areas - lower legs, face, chest spots etc.  If dominant black were present in the GSD, there's no reason why this shouldn't occur in this breed too and it could be that the expression of the tan points, albeit a very ghostly expression, occurs at a later stage of development than usual.


This is a seal Whippet

[sorry, can't get the hot link to work]

Nope sorry.  The photo will show in the edit box but not on the thread.

Here's some pics of seal whippets:





And just for interesting point of anomaly, a dog that apparently has the same temperature sensitive color mutation that siamese cats and rodents have. It was found in Russia, but got loose before it could be studied. I can't help but hope it's intact, so the genetics for this trait might be passed on.




 

I'm afraid if I stare at it too hard at the whippet I'll break it!  I want to ask about the dominant black in GSD.  Is it presumed completely eliminated from the breed, or?  I think I recall something about possible presence of it in some Russian lines?  It's said that the black found in some lines of wolves was inherited from a domestic canine crossover thousands of years back, and that it's of the dominant form of black.

Just a quick comment

"The Belgian Terv is supposed to carry both forms of black."

This is incorrect.  The Belgian Tervuren can carry the recessive black, but if it carried dominant black, it would be a black dog, ie a Belgian Groenendael.  The Groen can be either the dominant or recessive black.  And the dominant black Groens can carry the genes to produce fawn/black mask dogs (AKA Tervuren). 

I did see an "oops" litter of Kuvaz x Malinois pups once, from registered parents whose pedigrees I know (ie no DS anywhere in that Mali pedigree) and the pups were all brindles. 

Daryl,

Here's a whippet for you. It's a condition known as "double muscling," the result of a mutation that hinders the myostatin protein (which limits muscle growth while present), and the results are massive muscles.


One copy of the gene takes a normal whippet and produces a particularly fast and athletic looking dog:



 
Two copies results in this:




 
It's also found in lother species like livestock, rodents, and apparently in people as well (albeit it rarely). The human aspect is of particular fascination because researchers are looking at a way to block myostatin and promote muscle growth to treat disease where patients waste away. Other positive correlations with the double muscling, most notably increased speed and decreased bodyfat. Negative results can be increased cardiovascular strain, and in the case of many bully whippets, the tendancy for an overbite.

The best known human case is toddler Liam Hoekstra, who has demonstrated uncanny strength and agility since infancy.

 
 
 

(and I've just hyjacked my own thread)

I'm quite familiar with the myostatin gene, I was only commenting on the delicate appearance of the dog.  But the bully whippet looks like he'd be pretty fun to tip over :-D

Fascinating information on genetics presented by Pod and others on this thread.  It has been some very interesting reading.  Particularly the portion discussing the dominant black versus the recessive black and its expression.

The subject requires concentration so you understand what you are reading, but then I saw the pic of the overly muscled Whippet and I about fell over!  I have never seen anything like that before.  I had, of course, heard of the toddler with this condition, the young bodybuilder, but I had no idea that dogs could be affected with this condition.  It sure could make breed identification a challenge.

With the cardiac strain caused by the musculature, I wonder what sort of a lifespan such a dog would have. 

Sorry, I know that's not what this thread was about, didn't mean to hijack it.  Again, fascinating information and I'm glad to see a thread like this one on this board.

Crys

""This also occurs in tanpoint expression ( at K ky ) and is quite common in crossbreeds where the underlying light pigment (tan) shows though slightly in the usual tanpoint areas - lower legs, face, chest spots etc. If dominant black were present in the GSD, there's no reason why this shouldn't occur in this breed too and it could be that the expression of the tan points, albeit a very ghostly expression, occurs at a later stage of development than usual"""

Pod, 

Thanks for the replies,     I am excited that this Dominant Black may be an answer, to alot of questions that I have had over the years.    In the years that I have been breeding, I have had colors and patterns that didn't quite fit into the normal concept that black is always recessive. 

So, another question  is:

So Would it make sense if a B/T is carrying The Dominant black  and is bred to a Sable that is out of 2 sables ( Shouldn't be carrying Dominant Black)

Produce:

- Solid Black
- B/T
- average Sable
- Dark Sable


So if it Is Possible for the Sable to be Hidding the Dominant Black as well.?  If the coat shows Black points in E Locus areas that Bi-colors might express , like Tarheels and Toes?  But, because the Sable has the phaeomelanin pigment to offer for hidden Brindle or possibly hidden Dominant Black ?   Could the Sable dog be more likely to offer the Dominant Black over the B/T. 

The B/T, comes from a Solid Black Dam and a B/T Sire( out of 2 Sables).  I suspected at first that the Dominant Black comes from the Dam, because she has produced Delayed expressed Bi-colors. 

But now, I am wondering about the Sables also being a factor ?
If this sable comes from a long line of Sable until about 3 generations back there were 2 bi-colors bred together that produced a Sable 2 generations back.

Would Dominant black explain 2 sables producing B/T ?    Or is this more the normal Dominant/Rececive odds at play ?

My mind is going crazy !! LOL !!

so, if the sable is not hidding Dom. Black.  then can I assume that the B/T is carring it and it overides the Sable on Sable genetics?

I am starting to babble.  Way to tired for this awesome topic. 

Hope to continue tomorrow with a Fresh mind ! 



Also, here is a picture of a Dog that I suspect has Dominant Black being expressed by the delayed Bi-color affect up the legs. 



Thanks again for an AWESOME TOPIC !!!!!

Jamille,

In your example, I don't understand why the recessive black wouldn't produce all of the colors you are discussion. The b/t dam with a black parent would have the black recessive, the sable sire out of two sables could be sable/sable, sable/bt, or sable/black depending on the genes his parents carried.

Two sables can produce black and tan, depending on the recessive genes they are carrying, for example,

Sable/Bt bred to Sable/b would give you the options of: Sable/Sable (looks sable), Sable/bt (looks sable, sometimes with saddle patterning), Sable/b (dark sable), and bt/black (dark black and tan).

But, also, a sable couldn't carry the dominant black gene, because the dog would then be black with the possibility of producing sable puppies if the puppy didn't inherent the dominant black gene (50% chance, assuming the dominant black gene only came from one parent).

As far as the black-seeming dog with brown that comes in as the dog ages, the dog could indeed be a normal black GSD--with 2 genes for the recessive black coloration with something at the K locus to cause the tan "bleed through" points. (Pod, please correct me if I'm wrong in my understanding here!) You don't need the dominant black gene for that to be the case.

Christine