leg color in black copper marans

[tadkerson]

I read some of the information on the Marans thread and would like to post this to answer some questions.

Genetics 101

This post deals with white to black shank color in chickens. Marans should carry the gene for white skin and therefore have white skin.

This post only deals with black copper marans. Please do not ask questions about other breeds or varieties.


1. The shank has two layers of skin that deals with shank color.

2. The top layer of skin is called the epidermis and is made up of the scales and the area between the scales.

3. Just under the scales (epidermis) is a layer of skin called the dermis.

4. Certain genes add black pigment to the epidermis and other genes add black pigment to the dermis.

5. The extended black gene (E) is an allele to birchen (E^R) and wheaten e^WH. The extended black gene will add eumelanin (black pigment) to the epidermis or scales. Research indicates that birchen will add some black pigment to the epidemis- usually it does not add black pigment to the epidermis. The birchen birds I have been working with express more than a small amount of black in the epidermis. This could be the case for your black coppers.

If your bird carries an extend black allele, this allele (E) will add black pigment to the scales and very little to none in the tissue under the epidermis. You will be able to see pigment in the scales and not the dermis under the scales.

Normally the birchen allele ( the allele in black copper marans) does not add black pigment to the scales but it can add small amounts.

A bird could have the black copper phenotype ( what the bird looks like) and carry one extended black allele and a birchen allele. This is what I call a pseudo-birchen or false birchen. In this case the bird will have black pigment in the scales because the bird carries an extended black allele.

If a marans breeder is having problems with solid black females being produced from crossings, this is an indicator that the extended black allele is found in the breeders.

The wheaten allele inhibits the addition of black pigment to the epidemis ( scales ) of the chicken. Wheaten birds may show some brown pigment in the scales.


6. Another gene called dermal melanin will add black pigment to the dermis. Dermal melanin is a recessive sex-linked gene. The allele to dermal melanin is dermal melanin inhibitor. Males can have two dermal melanin alleles or a dermal melanin inhibitor allele and a dermal melanin allele or two dermal melanin inhibitor alleles.


The color in the male shank dermis depends on the dermal melanin gene.

two dermal melanin = dark blue shanks

dermal melanin inhibitor + dermal melanin = white or very light gray/ light blue shanks

dermal melanin inhibitor + dermal melanin inhibitor= white shanks



Females can only have one allele; they carry either dermal melanin or dermal melanin inhibitor.

dermal melanin = blue shanks

dermal melanin inhibitor= white shanks



7. Epidermal scales pigmented with black are black or dark slate ; dermal tissues pigmented with black are blue or dark blue.

Tim

 

[VillageChicken]

Here's a related question. Is the Id sex-linked gene incompletely dominant or stronger in two doses like B/b & S/s? It's theorized that BC marans hens have darker shanks because they are only Id/- and not Id/Id like the roosters. I wonder if instead it is simply that the ER allele is more easily melanized in hens, shanks included.

 

[tadkerson]

Quote:
The dermal melanin inhibitor gene does not effect the black pigment that is added to the epidermis (scales) of a chicken. I would discount any expression of Id in the darker shanks of females. The darker leg color would be due to the presence of female hormones in the epidermis.

From the PM- I have not worked on hackle color and I have not read any research that deals with hackle color. Could be any number of things- my best guess is that it is a modifier of the gold allele or it may have to do with a promoter of the gold allele.

Tim

 

[kathyinmo]

I find this information fascinating and interesting. Thanks for this thread!

Tim, Could you do another thread about yellow legs? Specifically, I am wondering why some of my Delawares have a greenish tint, some pale ivory, and others bright yellow.

 

[nicalandia]

Quote:
The dermal melanin inhibitor gene does not effect the black pigment that is added to the epidermis (scales) of a chicken. I would discount any expression of Id in the darker shanks of females. The darker leg color would be due to the presence of female hormones in the epidermis.

From the PM- I have not worked on hackle color and I have not read any research that deals with hackle color. Could be any number of things- my best guess is that it is a modifier of the gold allele or it may have to do with a promoter of the gold allele.

Tim

Tim do you know if Dominant Dilute effects Dermal or Epidermal? I have read that it behaves like Id.., Id should have No effect on Extended black birds, but some genes may help it like Mo, Barring like the ones found on production type white leghorns..

 

[Arielle]

Great level of detail, Tim. Another thread to "favorite" into my marans file.

How is this melanizing of the shanks related to the over melanization seen in many BCM. Would you consider providing the details on this (or directing me to a previous thread? My males have a great deal of color over their backs, yet my females from the same flock have less color than I expected, IMO. (red/copper is usually high on the neck, and doesn't extend as far down the neck as the males).


Please understand, I'm totally new at marans. THey are rather complicated.

(Sexlinks are MUCH easier.

 

[tadkerson]

Quote:
The dermal melanin inhibitor gene does not effect the black pigment that is added to the epidermis (scales) of a chicken. I would discount any expression of Id in the darker shanks of females. The darker leg color would be due to the presence of female hormones in the epidermis.

From the PM- I have not worked on hackle color and I have not read any research that deals with hackle color. Could be any number of things- my best guess is that it is a modifier of the gold allele or it may have to do with a promoter of the gold allele.

Tim

Tim do you know if Dominant Dilute effects Dermal or Epidermal? I have read that it behaves like Id.., Id should have No effect on Extended black birds, but some genes may help it like Mo, Barring like the ones found on production type white leghorns..

Genetics 101

I have not worked with dilute- to the best of my knowledge it only effects dermal melanin. No one has determined if it does or does not effect epidermal melanin (black in scales). The dermal melanin inhibitor (Id) only effects dermal melanin and not the epidermal melanin that would be found in the scales of an extended black bird or in some cases a birchen bird. The extended black gene adds black pigment to the scales and little or none to the dermis. There is no research on how dominant dilute may or may not effect the expression of the extended black allele in the shanks or in plumage.

Black copper marans should carry sex linked dermal melanin inhibitor. Females or males that have heavily pigmented scales carry extended black. The dermal melanin inhibitor will not effect the black in the scales. Birds that have very dark legs would be extended black and carry dermal melanin. On legs that are very dark, one can determine if a bird carries dermal melanin by checking the center of the birds foot sole. This area does not have epidermal coloring- if the center is white the bird carries dermal melanin inhibitor- if the skin is blue the bird carries dermal melanin.

Tim

 

[pinkchick]

Tim~


THANK YOU for posting this and making it very easy to understand! You ROCK!!!!!

 

[tadkerson]

Quote:
Genetics 101

If I say birchen in this post, I am referring to the birchen allele and not the birchen primary color pattern. Black copper are birchen.

In birchen and extended black females, the estradiol and estrogen found in the skin inhibits the production of red pigment. This is why birchen females have more black in their plumage. The hormones are effecting the production of pheomelanin (red) pigment. Birchen females will tend to have darker shanks than males for the same reason- they produce more black pigment than males. The level of female hormones in the skin will effect the amount of black in the plumage. More hormones- more black.


I have not found any research that deals with the control of non-black in the hackles of birchen males and females. I am currently working with the birchen allele but I am not to the point where I can say anything about the none-black controlling mechanism dealing with the brown-red (BCM) hackles. My birchen birds carry all kinds of gene combinations so anything that would apply to them would not help with your problem. There are genes like columbian, dark brown, melanotic and charcoal that can control the hackle color but they should not be carried in the BC marans.

That's the best I can do. If someone has been working with brown-reds or black coppers for years- they would be able to tell you what to look for. I can make suggestions but they would only be guesses on my part.

Tim

 

[nicalandia]

Quote:
Tim do you know if Dominant Dilute effects Dermal or Epidermal? I have read that it behaves like Id.., Id should have No effect on Extended black birds, but some genes may help it like Mo, Barring like the ones found on production type white leghorns..

Genetics 101

Tim

I love your Genetic 101 Tim...