Author Topic: E-locus (aka MC1R)  (Read 7636 times)

John W Blehm

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E-locus (aka MC1R)
« on: March 08, 2015, 01:54:45 PM »
http://www.edelras.nl/chickengenetics/mutations1.html#gen_mut_elocus
The E locus Chicken/Down Color Pattern
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The E locus alleles produce the base primary colour/patterns to which varieties are build upon.

Each Ameraucana variety is based on an e-locus gene.  Since birds get a gene from each parent it is important that the pair of genes at the e-locus (location of the "e" genes) are the same.  There are at least 9 e-locus genes, but the main ones that are associated with Ameraucanas, in order of dominance are...
E = Extended black, sometimes just referred to as Extended
ER = birchen aka crowwing
eWh = dominant wheaten
e+ = wildtype, normal or sometimes duckwing
eb = brown, was also called partridge (ep)
ey = recessive wheaten, "y" stands for Yellowish-white chick down

Here are some of the varieties that can be built from these foundational genes...
E = black, white, lavender, blue, splash
ER = brown red, blue, splash, birchen, lavender, white, black
eWh = buff, wheaten, blue wheaten
e+ = silver
eb = partridge, buff
ey = wheaten, blue wheaten, buff

I've underlined the varieties that I think are best based on these e-locus genes.  Note I don't think blacks and blues should be based on the same e genes, so they shouldn't be bred together as most of us have done in the past.  To get the best blacks they should be based on E, but the best laced blues may be based on ER.     
 
Mike Gilbert replied...
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I would just add that I don't think you can get a buff based on eb with proper undercolor.   Buff Columbians are based on eb, Buff Orpingtons and others are based on eWh.  And there is another good reason for not crossing blacks with blues besides the e locus gene.   Good blacks will most often be based on sex linked gold (s) while the best blues will be based on silver (S).   Having said that, the two can be crossed as long as you use a male of the color you are shooting for and only keep his female offspring, disposing of the males.  That's because the females will have their father's (S) or (s) as the case may be.  Sex linked characteristics are not passed down from mother to daughter, only father to daughter.
E-locus

my reply...
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"I don't think you can get a buff based on eb with proper undercolor.

That's a good point.  I bred buffs for many years before I knew enough to check the undercolor of my birds before using them as breeders.  Now I only breed from those with buff feather and shaft undercolor.

"Undercolour: (by Dr Okimoto)

Wheaten has a cream feather undercolor. e+ and eb have a gray feather undercolor even in the presence of Co. eWhe+ Coco+ heterozygotes have the gray feather undercolor and birds that I have that are eWheb CoCo (I crossed a New Hamp to a Columbian Wyandotte) also have the gray feather undercolor, but it is lighter and looks more silvery than gray. If you find that your birds are eWheb and they have a white or cream feather undercolor they may have melanotic. Birds with melanotic often have a white feather undercolor, but this may be an interaction with some other genes because I don't think that they all have a white undercolor."

From - http://www.edelras.nl/chickengenetics/mutations1.html#gen_mut_elocus

Mike added...
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It takes more extra melanizing genes to make a black male that is all black, without leakage, if he is based on ER instead of E.   Even on E, it takes some extra melanizers, but not as many.   If you start crossing blues with blacks, and I will say that it CAN be done successfully (save only the females from the cross that are the same color as their sire), you do run the risk of losing the dark undercolor and possibly the good green sheen to the top color.  It depends on unknown modifying genes.   More important, I believe, is that black should be based on sex linked gold, while blue should be based on sex linked silver.   Blues need to be "silver" so they don't get rusty when the feathers become worn, and blacks can achieve the best green sheen when based on "gold."  Also, if you have GOOD blues, when you cross them with blacks there is a high probability the blacks may not be carrying the pattern gene (Pg) and columbian (Co) that are necessary for good lacing on blues.  Those are my thoughts, but some may disagree.
« Last Edit: January 10, 2018, 08:44:59 PM by John W Blehm »

Stan Alder

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Re: E-locus
« Reply #1 on: March 25, 2015, 10:40:41 AM »
In the link you provided for chick down color, it shows that ER chicks are not as black as the E chicks....looks like the ones with the yellow faces are the ER????
Is that correct??

Mike Gilbert

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Re: E-locus
« Reply #2 on: March 25, 2015, 10:53:48 AM »
Stan, black and brown red chick down color is all over the board - depending on modifying genes.   Unless you are familiar with a particular line you can't really tell one from another most of the time.   Blacks do tend to have more white/yellow in their down than brown reds though.   Look at the chick pictures I posted yesterday.   Those are brown reds. 
Mike Gilbert
1st John 5:11-13

John W Blehm

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Re: E-locus
« Reply #3 on: March 25, 2015, 12:24:13 PM »
In the link you provided for chick down color, it shows that ER chicks are not as black as the E chicks....looks like the ones with the yellow faces are the ER????
Is that correct??
When I look at the photos of chicks from the link the ER chicks appear to have more black down.  As Mike said they do vary though depending on perhaps unknown modifiers.  Go to the Photos page of our site and compare the bantam & large fowl blacks (E) and brown reds (ER).  Many if not most of those photos are ones I took of my birds.  I think it is interesting that with the LF the brown red chicks are almost completely black, while the bantam brown red chicks look about the same as the black chicks.  Even though I would think bantam and LF brown red Ameraucanas would be based on all the same color influencing genes, the phenotype of the chicks indicate they are not.
The same is true of silver Ameraucanas.  The bantam chicks and LF chicks have a little different phenotype and even as they mature their adolescent feathers are different.   
« Last Edit: June 25, 2016, 12:08:01 PM by John W Blehm »

John W Blehm

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Re: E-locus
« Reply #4 on: June 21, 2015, 09:11:07 PM »
On The Coop forum I found a link to a paper called Association between polymorphism in the melanocortin 1 receptor gene and E locus plumage color phenotype.

Most of the subject is over my head and really not important to me as a breeder.  I did find a few things of interest though.  One was the inclusion of both "E*BC, buttercup; and E*Y, recessive wheaten" in their list of E Locus genes, because there has been speculation these don't exist and were other genes with modifiers that made them appear to be something else. 
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One of the main genes is the E locus with several different alleles, including (in order of dominance):
E*E, extended black;
E*R, birchen;
E*WH, dominant wheaten;
E*N, wild type;
E*B, brown;
E*BC, buttercup; and
E*Y, recessive wheaten (yellowish-white; Smyth, 1990; Crittenden et al., 1996).
These alleles affect the distribution of the 2 melanin pigments (eumelanin and phaeomelanin) in feathers, and are important for accurate down color sexing.

I noted the way they wrote the gene is different from what I'm used to and "N" for wildtype was new to me.  I found out the "N" stands for "normal" and the newer way of designating the symbols or names in Nomenclature for naming loci, alleles, linkage groups and chromosomes to be used in poultry genome publications and databases.

In discussing E*R the E locus paper also says Our results suggesting that the birchen phenotype has at least 2 different SNP associated with it. These 2 alleles may give 2 different phenotypes (black breasted or black breasted with lacing in white or gold), traditionally assigned to the effect of the Columbian restriction gene (Smyth, 1990).
I'm not sure how much lacing they are referring to, but this may help us understand the lacing and sometimes lack of it in the upper breast area of brown red Ameraucana males.
« Last Edit: June 26, 2015, 11:42:47 AM by John W Blehm »

Mike Gilbert

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Re: E-locus
« Reply #5 on: June 21, 2015, 10:48:42 PM »
That is interesting and would explain a lot.   What does SNP stand for?
Mike Gilbert
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Suki

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Re: E-locus
« Reply #7 on: June 22, 2016, 10:41:18 PM »
I noted the way they wrote the gene is different from what I'm used to and "N" for wildtype was new to me.  I found out the "N" stands for "normal" and the newer way of designating the symbols or names in Nomenclature for naming loci, alleles, linkage groups and chromosomes to be used in poultry genome publications and databases.

Makes reading the Jeffrey's book on Bantam Genetics confusing...speaking of which, that's one that the ABA really should reprint.  It goes for $100.00 these days ...used.


Sue Paolini

Mike Gilbert

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Re: E-locus
« Reply #8 on: June 23, 2016, 08:36:22 AM »
I noted the way they wrote the gene is different from what I'm used to and "N" for wildtype was new to me.  I found out the "N" stands for "normal" and the newer way of designating the symbols or names in Nomenclature for naming loci, alleles, linkage groups and chromosomes to be used in poultry genome publications and databases.

Makes reading the Jeffrey's book on Bantam Genetics confusing...speaking of which, that's one that the ABA really should reprint.  It goes for $100.00 these days ...used.Sue Paolini

I checked the ABA Store and found Jeffrey's book is still available for $30, probably in soft cover.  Here is the link:   http://www.bantamclub.com/aba/index.php/store/books/bantam-chickens
Mike Gilbert
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Suki

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Re: E-locus
« Reply #9 on: June 23, 2016, 11:01:28 PM »
Ichecked the ABA Store and found Jeffrey's book is still available for $30, probably in soft cover.  Here is the link:   http://www.bantamclub.com/aba/index.php/store/books/bantam-chickens

thank you Mike.  Believe it or not I have checked there, not once but several times, and always seemed to have missed it so I 'm glad it showed up for you.  FWIW, several have told me that they used that in tandem with the http://chickencolours.com/ book.

thanks again Sue Paolini
NePA