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#101933 - 02/04/12 06:47 PM Re: Journal papers online - reference list [Re: Redcap]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2805
Loc: Australia
Thank you Spicifer for posting the new research smile

Henk, I've got Chromosome 6 (Group VII) listed on the chromosome linkages web page. But none of the genes listed are pigment or other mutations commonly related to exhibition /chicken breeds that we are usually interested in here (eg genes: Ade-A, Pgm-2, Gc, Alb).

Going by the manuscript provided, it seems it is a first to find a pigment altering mutation on the COMTD1 gene (not even previously noted in mice before).

--------------------
Yes, the NCBI map has COMTD1 on chicken Chromosome 6. But you have to zoom in to the specific region on the chromosome to see the gene (not all genes are shown with initial view).

From the manuscript:
Quote:
The Inhibitor of Gold locus was mapped—by linkage analysis in a pedigree
segregating for IG—to a 3.58 megabase (Mb) region located between
the nucleotide positions 12,388,399–15,970,174 on chicken chromosome 6.


NBCI chicken master map:

Chromosome 6, region 14,389,800-14,397,800 bp (zoomed in)

Then if you click the "zoom out" blue graphic in left navigation column, it gives a good map of the whole chromosome, with position of COMTD1 on it.
Unfortunately I can't provide a direct link here on the forum as the NCBI url generated has square brackets within (messes up the code for posting).

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#101935 - 02/04/12 08:07 PM Re: Journal papers online - reference list [Re: Henk69]
Poultch Offline
Coop Keeper

Registered: 01/25/10
Posts: 660
Loc: New Zealand
Originally Posted By: Henk69
What else is on 6?



Originally Posted By: Wieslaw
I do not want to derail the discussion, but I have an extra question on barring. According to some papers, what we call 'barring gene' is actually (in the world of genetisists) synonymous with tumor suppressor gene. I have asked about it before(without getting an answer): Is B better to suppress tumors than b? If not, why bother with barring at all?



above quote taken from the B and Id thread

Suppression or necrosis?
http://www.ncbi.nlm.nih.gov/protein/NP_001186416.1
I see tumor necrosis factor is on 6 along with what seems to be a cell suicide protein
barring is now thought to cause prem death of melanocytes, rather than suppression of melanin production, is this what you mean?

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#101947 - 02/05/12 04:45 AM Re: Journal papers online - reference list [Re: KazJaps]
Henk69 Offline
Moderator
Classroom Professor

Registered: 02/13/06
Posts: 3208
Loc: Netherlands
Originally Posted By: KazJaps


NBCI chicken master map:

Chromosome 6, region 14,389,800-14,397,800 bp (zoomed in)

Then if you click the "zoom out" blue graphic in left navigation column, it gives a good map of the whole chromosome, with position of COMTD1 on it.
Unfortunately I can't provide a direct link here on the forum as the NCBI url generated has square brackets within (messes up the code for posting).



Direct link?

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#101951 - 02/05/12 05:05 AM Re: Journal papers online - reference list [Re: Henk69]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2805
Loc: Australia
Yes, thank you Henk wink

Must be good to have super-mod powers smile

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#101952 - 02/05/12 05:10 AM Re: Journal papers online - reference list [Re: KazJaps]
Henk69 Offline
Moderator
Classroom Professor

Registered: 02/13/06
Posts: 3208
Loc: Netherlands
Yes, the power of html. Kal (htm)el wink

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#101992 - 02/07/12 02:03 AM Re: Journal papers online - reference list [Re: Henk69]
Redcap Offline
Ruler of the Roost

Registered: 08/14/06
Posts: 954
Loc: Germany
This book could be interesting for You
Database: Cornell University Library
Author/Creator: Regnier, Victor.
Title: Hormone ovarienne et caracteres raciaux du plumage chez le coq et la poule domestiques. Etude de genetique experimentale ...
Published: Paris, Editions du Bulletin biologique de la France et de la Belgique, 1937.
Description: 1 p. l., 214 p., 7 l. illus., V pl. (3 col., 2 fold.) diagrs. 25 cm.


In Crossings of Malines <-> brown Leghorn , brown Leghorn <-> Andalusian and in a third combination cocks were injected with female hormones or ovarian were removed, to see what happens with plumage.
Similar to these studies
http://jhered.oxfordjournals.org/content/26/8/299.full.pdf
http://www.springerlink.com/content/y774275g5426p338/fulltext.pdf
_________________________

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#102306 - 02/19/12 10:46 PM Re: Journal papers online - reference list [Re: KazJaps]
Terry Offline
Bantam

Registered: 02/19/12
Posts: 47
Loc: Qld Australia
re: The "silver" Japanese quail and the MITF gene: causal mutation, associated traits and homology with the "blue" chicken plumage.
Do you believe that the Blue mutation is a MITF gene as this suggests or are they really equivalent to the Dun mentioned as an allele of PMEL17?
MITF interfers with melanoblast migration, therefore should alter both eumelanin and phaeomelanin, however homozygous Blue still produce normal phaeomelanin levels. This is consistent with the PMEL17 function.
What are your thoughts?

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#102325 - 02/20/12 08:17 PM Re: Journal papers online - reference list [Re: Terry]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2805
Loc: Australia
Hi Terry,

That's interesting.

We know Bl - Blue gene is not on the PMEL17 locus through test breeding, as a single bird can have both Dominant White I/I (on the PMEL17 locus) plus Bl/Bl too.

Although in chickens (& many other species) the PMEL17 mutations (eg I - dominant white, Id -dun, Is-smoky) affect eumelanin only (mostly), there has been research that indicates that the dilution gene found in Charolais cattle (Dc) (dilutes both eumelanin and phaeomelanin) is a mutation of PMEL17 (SILV) too. Another PMEL17 dilution mutation in Highland cattle also dilutes both eumelanin and phaeomelanin:

Quote:
The pigment-specificity of mutations in the SILV gene observed in other species [22-25] is in agreement with the critical role reported for this protein in eumelanosomes but not in phaeomelanosomes [28] and the suppression of PMEL17 expression seen in murine phaeomelanosomes [29,30]. However, recent work in Highland cattle reported a 3-bp deletion in exon 1 of the bovine SILV gene associated with the dilution of both red and black pigments [16]. This finding, and the likely association of the SILV gene and the Dc locus, which affects both pigments, are intriguing and may suggest that the role of PMEL17 differs between species. This is plausible as the genuine function of the SILV gene product in pigmentation is not completely understood [14] and the biological basis of pigmentation may vary with species. Mutations in the SILV gene that have only been shown to affect eumelanin background are located in the c-terminal sequence of the SILV gene and affect the transmembrane or cytoplasmatic domains of the protein [22-25]. It is possible that mutations closer to the N-terminal end (such as exon 1, where both cattle mutations are found) could lead to more general interference with pigment production.


Ref:
Genetic effects on coat colour in cattle: dilution of eumelanin and phaeomelanin pigments in an F2-Backcross Charolais x Holstein population.
Gutiérrez-Gil B, Wiener P, Williams JL.
BMC Genet. 2007 Aug 16;8:56.
full paper

-------------------
Plus SLC45A2 (or MATP) mutation - S silver in chickens dilutes phaeomelanin only, but in other species mutations on this gene are generally albino like, dilute both eumelanin & phaeomelanin (including one in chickens - s^al sex-linked imperfect albinism).

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#102328 - 02/21/12 12:47 AM Re: Journal papers online - reference list [Re: KazJaps]
Terry Offline
Bantam

Registered: 02/19/12
Posts: 47
Loc: Qld Australia
Hello KazJaps
In many species MITF mutations produce piedbald/spotting phenotypes because of their impact on cell migration. I was surprised and disbelieving to read that it could cause the Blue phenotype.
But with further consideration I realised that this transcription factor is responsible to initiating transcription of most of the important melanogenic enzymes (tyr, TRP1, TRP2, etc). So a missense mutation would reduce eumelanin production and at the same time maintain phaeomelanin production, or even enhance it. (You would know that Phaeomelanin is enhaced when tyrosinase is down regulated)
If you consider the homozygous Blue laced Gold Wyandotte, the phaeomelanin is richer than that produced in heterozygous Blue Laced Gold or Gold Laced.
I am still interested in the phenotypic difference between Dun and Blue. 'Blues' in different breeds seem to vary in the degree of depth of melanin colour. In some breeds Bl/+ are almost black and others quite blue, whilst Bl/Bl can be silver in some breeds and classical splashed in others.

With regards SLC45A2 (or MATP), as this protein transports enzymes into the melanosome, it is likely that the Silver allele interfers with cysteine transport into the melanosome for phaeomelanin production, as there are no enzymes specific to phaeomelanin.
In aviculture we like to call this locus the sex-linked ino locus, apart from the null mutations which produce virtual complete melanin loss, there are lots of examples of missense mutations producing different levels of melanisation. But none that effect phaeomelanin only - all reduce eumelanin equally.

Although this Silver allele is so far unique in the fowl, there are other genes well known in other species have only recently started to appear in fowl - TRP1 (the Chocolate Orpington) and Agouti. TRP1 mutations would be the most common mutation across all avian species (always sexlinked in these) and also common as the autosomal brown locus in mammals. So why has it not been established as a colour in different breeds of chickens during the hundreds of year people have bred them???
regards
Terry

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#102334 - 02/21/12 06:23 AM Re: Journal papers online - reference list [Re: Terry]
Wieslaw Offline
Moderator
Classroom Professor

Registered: 09/18/09
Posts: 3768
Loc: Denmark
Originally Posted By: Terry
So why has it not been established as a colour in different breeds of chickens during the hundreds of year people have bred them???


Up to this day the vast majority of breeders are people who breed to a standard, so mutations are usually mercilessly removed from the gene pool as oddities, you can actually get such birds for free if you're lucky and you know what you're looking for. Secondly, chocolate on many birds may not look particularly attractive (washed out black). It may also play a role.

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