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#102352 - 02/21/12 05:44 PM Re: Journal papers online - reference list [Re: Wieslaw]
Terry Offline
Bantam

Registered: 02/19/12
Posts: 47
Loc: Qld Australia
Maybe it is that simple with the domestic fowl, but in virtually all other domestic animals mutations of the brown locus (TRP1) (Chocolate)has been deemed highly desirable both as a single expression and in combination with other genes. Perhaps it is the extensive distribution of phaeomelanin in the fowl that helps produce colours which appear similar to brown eumelanin, thereby making the TRP1 mutations less distinct.
Terry

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#102367 - 02/22/12 01:16 AM Re: Journal papers online - reference list [Re: Terry]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2807
Loc: Australia
These mutations are taking off now. I think choc is highly desirable (choc probably a TYRP1 mutation, similar to sex-linked roux in Quails, but not aware of choc been DNA sequenced). It was mainly a matter of multiplying a rare mutation, & getting the mutation into main stream European & American exhibition breeds.

Here are a couple of articles by Sigi on Dun (Id) and Chocolate (choc) - explains a bit of the history in chickens:

*On I^D Dun & choc

* Chocolate Chabos

It seems there have been at least two main waves of sex-linked chocolate in chickens, and both times occurring within the past 30 years or so. Once was Clive Carefoot (UK) obtaining Black Orpington eggs, & by chance these were carrying the choc gene. A second main wave in Asia (possibly multiple times?). One known Asian one was from a cross between a Red Jungle Fowl & Chabo (Japanese Bantam) hen (see the above article).

Dun Id has been around for much longer. It probably has been in fighting Game stock for many decades / over a century maybe. But I imagine having Bl -blue in the gene pool as well didn't help its distinction. Plus possibly hidden in varieties such as Ginger Reds, and may have been the base gene for old Game brown-breasted varieties, Birchen Duckwings, Coffee-laced, etc.

The trouble with Id is that it can look similar to a bad Bl/bl+ - dark greyish tones, only a hint of brown, and rustiness in blues is an exhibition flaw. But with certain modifiers, Id can look as beautiful as Clive Carefoot's Chocolate Orpingtons.

Eg, variation in Id shades:

Dun Polish (from Feathersite):

Dun Sumatra (from Backyard Chickens Forum: )


Chocolate Orpington (Clive Carefoot's line):


P.s. - looks like both choc and Id need those enhanced green sheen modifiers (found in Sumatras and Orpingtons) to give that rich glossy chocolate brown tone.

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#102402 - 02/23/12 01:14 AM Re: Journal papers online - reference list [Re: KazJaps]
Terry Offline
Bantam

Registered: 02/19/12
Posts: 47
Loc: Qld Australia
KazJaps said
"I think choc is highly desirable (choc probably a TYRP1 mutation, similar to sex-linked roux in Quails, but not aware of choc been DNA sequenced"

I have not seen any papers on it, but as someone with experience in other avian species, the TRP1 Brown mutation is so distinctive it cannot be missed. I would confidantly say it is almost the easiest mutation to identify to locus in birds, even if we have to wait for the scientists to confirm.

As you say Roux has been sequenced in Jap Quail, it exists as Chocolate in Muscovy and Turkeys, is present in over 20species of Parrots (Cinnamon), also Canaries, many finches (Cinnamon or Fawn) and King Quail.

Thanks for the articles on Dun and Choc

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#102403 - 02/23/12 01:31 AM Re: Journal papers online - reference list [Re: Terry]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2807
Loc: Australia
Terry, have you heard of any DNA testing on pigment mutations in domesticated avian birds other than poultry? I recall reading of the zebra finch genome project, but not aware of any specific pigment mutations identified through DNA sequencing.

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#102404 - 02/23/12 01:55 AM Re: Journal papers online - reference list [Re: KazJaps]
Terry Offline
Bantam

Registered: 02/19/12
Posts: 47
Loc: Qld Australia
KazJaps
They are quite advanced in reproducing the genome sequence, you can check it online and search for known loci. TRP1 is on the Z as expected ;-). But there has been no papers correlating mutations and specific phenoptypes to specific loci.
All the papers I have found on DNA sequences are for Chickens or Jap Quail - commercial species prevail at this point as they have a strong basis in old fashion genetics to work from.
But aviculturists are busy watching it closely and extrapolating from poultry into aviculture species.

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#102406 - 02/23/12 04:21 AM Re: Journal papers online - reference list [Re: Terry]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2807
Loc: Australia
Thanks for the info Terry (explains why I haven't found the research at Pubmed).

I forgot to mention earlier. Bl - probably dilutes phaeomelanin a little. Usually Wyandottes are Blue Laced Red - added phaeomelanin intensifier(s) in the genotype. Need to compare bl+/bl+ siblings.

Depending on lines, but Dominant White when homozygous tends to partly wash out phaeomelanin too (quite significantly in a Pile Modern line I have, even though they have a red enhancer).

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#102416 - 02/23/12 05:22 PM Re: Journal papers online - reference list [Re: KazJaps]
Terry Offline
Bantam

Registered: 02/19/12
Posts: 47
Loc: Qld Australia
KazJaps said
"Bl - probably dilutes phaeomelanin a little. Usually Wyandottes are Blue Laced Red - added phaeomelanin intensifier(s) in the genotype. Need to compare bl+/bl+ siblings. "

Actually I mentioned that I disagree with this. I have bred alot of Blue Laced Gold Wyandottes this year in both hetero and homozygous form plus lots of Gold Laced, all from the same line but four different matings. Without exeption, the Bl/Bl birds have stronger phaeo than the Bl/+ and wildtype. And I then realised that since MTIF regulates tyr transcription to some degree, a mutation that down regulates MITF would reduce tyr and this is a prerequisite for phaeomelanin production.
Without exception, these Bl/Bl birds also have narrower lacing than their siblings, it appears without the normal tyrosinase levels, the phaeo can spread wider on the feather.

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#102427 - 02/23/12 07:34 PM Re: Journal papers online - reference list [Re: Terry]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2807
Loc: Australia
In the following thread The Coop: White tailed Reds - see Jereon's comments, eg:

Quote:
About the diluted pheomelanine which is several times visible by blue :

One of our friends have Mille Fleurs and Blue Mille Fleurs Belgian d'Uccle. When they have blue they mostly show a very light ground colour. He has sometimes some Buff Columbian and Blue Buff Columbian birds in his offspring. When they have the Bl-gene they are mostly very pale.
When I look at Blue Quail d'Anvers at shows, I mostly see the colour of the breast is much lighter than the colour by normal Quail birds.

But the strange thing is : it isn't always so.

Later he posted examples.
Blue Buff Columbian and Buff Columbian:


There is also gold diluted varieties in Belgian bantams. They have ig (or similar) phaeomelanin diluter in the Belgian gene pool - this explaining some varieties as Lemon Millefleur, White Lemon Quail, etc. But a conversion I had with a European d'Anver breeder some years back, indicated that in his line he was getting the White Lemon Quail phenotype from Bl/Bl alone (& no I - Dom. White in the gene pool). The bl+/bl+ segregates were a normal Quail phaeomelanin shade, ie not Lemon Quail (no ig in there).

I've noticed similar slight phaeomelanin dilution happening in my Bl Belgians too, but it was hard to work out specifics as I had very mixed lines, both phaeomelanin intensifiers and phaeomelanin diluters segregating, plus there are differences with Db and Co base phaeomelanin shades too (both these segregating also). But I had wondered, & thought it an interesting project to see if any correlations with shade of blue to the shade of phaeomelanin. Eg, do dark blues correlate with any phaeomelanin dilution, is it only light blues that correlate with some phaeomelanin dilution, & so on....
I.e. try to pin-point the following by Jeroen: "But the strange thing is : it isn't always so".

----------------
*Another observation. It was harder to get clean mottled eumelanin banding in Bl/bl+ Blue Millefleur than with their bl+/bl+ siblings. Bl/bl+ tends to wash out the edges of the eumelanin with the mo/mo white tip:

*But once again - not always.

A bl+/bl+ version for comparison:


(sorry - blurry. Lol I wonder if I had reading glasses when I edited the last photo).

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#102606 - 03/03/12 06:01 AM Re: Journal papers online - reference list [Re: KazJaps]
Terry Offline
Bantam

Registered: 02/19/12
Posts: 47
Loc: Qld Australia
KazJaps
The photo below illustrates very well my opinion that when homozygous Blue, then MITF is downregulated, reducing tyr and causing an increase in phaeomelanin. The heterozygous phenotype does not vary consistently from GLW but may be slightly paler in phaeomelanin on average

The birds in the photo are siblings from the same mating pen

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#102615 - 03/03/12 07:01 PM Re: Journal papers online - reference list [Re: Terry]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2807
Loc: Australia
Thank you for the photo.

Interesting that the Bl/bl+ appears slightly lighter gold ground colour than the average bl+/bl+ Aust. Gold Laced black line, yet the left Bl/Bl splash bird is darker than the average Aust. G.L. bl+/bl+ line. The left Bl/Bl bird is a darker eumelanin (eg blue head/upper neck) than the right. The Bl/bl+ a mid blue, maybe slightly lighter than average.

Any chance the line descended from breeders in the process of introducing/setting phaeomelanin intensifiers, ie possible het. red enhancers segregating in the line?

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