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#92588 - 11/12/10 03:01 AM Re: whence came lavender [Re: Henk69]
Black Feather Offline
Bantam

Registered: 09/18/07
Posts: 57
Loc: France
Hello,

It has been said in previous posts, but I can summarize :

Lavender is a mutation in the gene called Melanophilin (MLPH), on the chicken chromosome 7.

The MLPH protein plays a role in the transport of melanosome (containing melanins) from melanocyte to keratinocyte. A mutations in the gene coding for MLPH can lead to impaired transfer of melanin (as patches of pigment instead of regular distribution).

Many mutations in MLPH gene have been characterized in other species : dog, mink, cat, mouse, rat, human, quail. They are all dilutions of melanins (from black to blue-grey, from red to buff or cream), sometimes called blue in these species.

But the Blue locus in chicken is different. It is not a mutation of MLPH (Lav), nor PMEL17 (I). There is an indication that the phenotype called 'Silver' in Quail (gene MITF) is homologous to chicken Blue phenotype :

Silver Quail

About similarities between species, it's worth to note that the mutation corresponding to type III Griscelli syndrom in human is identical to the mutation observed in chicken lavender (same change in DNA and in the MLPH protein).

I don't think we know precisely the geographic or breed origin of lavender phenotype (as we don't know when appeared most of the variations in chicken).

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#92591 - 11/12/10 05:16 AM Re: whence came lavender [Re: Black Feather]
Sigi Offline
Ruler of the Roost

Registered: 11/23/06
Posts: 1150
Loc: Holland
Okay now my contribution, in ordinairy people language, for what I understood of this:
lav is different from other dilutions because it prevents the pigment to enter into the keratine because it got stuck in the filaments, a spaghetti kind of structures which push the pigment to the dendrites where the bridge is between pigment production cell and the keratine (feather stuff) cell.
Because of this traffic que, the pigment enters the feather in a weird way, not evenly, therefore the little transverse bars you can see in lavender feathers. Best seen in hackle.

The other diluters.
Black diluters: dun colour,choc, blue, are not correctly melanized pigment granules due something which prevents the pigment granules to colour totally into black. This has to do with a proteine and a so called 'oxidation' (tyrosynase is obtructed or something like that, in the absence of cysteine).
The amount of pigment (number of granules) is in these dilutions the same as when there was no oxidation. Its the colour of the granule which changed, not the amount of pigment.
In lavender its the amount of pigment granules which is unaltered in colour (black, red) itself, which makes the lighter colour to our eyes.
For red dilutions the same oxidation thing happens except for silver which prevents pheomelanine to enter the feather in the S/s+ version, and therefore the yellow colour, which should be similar to the way lavender prevents red/gold to enter the feather.

The difference with other animals compared to chickens, is that in other animals a dilution of the coat is caused by a 'lavender-like' action (in some species called agouti), and not because of the change of colour of the pigment granule itself.
This is comparitive genetics and for what I understood there are different names for the same things. There is no agreement in how to call things in different animals, so there might be different names for the same actions.

How about this 'simple wisdom'? Please correct me.
I prefer normal stupid-people explanations above complicated language.


PS. sex linked imperfect albinism seems to be the same as the 'lavender-like' action.


Edited by Sigi (11/12/10 05:19 AM)
Edit Reason: ps added

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#92613 - 11/12/10 01:14 PM Re: whence came lavender [Re: Sigi]
Henk69 Offline
Moderator
Classroom Professor

Registered: 02/13/06
Posts: 3208
Loc: Netherlands
I have doubts about the amount being unaltered in these diluters.
Splash and khaki are too light imo.

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#92617 - 11/12/10 03:33 PM Re: whence came lavender [Re: Henk69]
Sigi Offline
Ruler of the Roost

Registered: 11/23/06
Posts: 1150
Loc: Holland
Those are not fluids, lavender is a fluid...

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#92623 - 11/12/10 06:15 PM Re: whence came lavender [Re: Sigi]
Sonoran Silkies Offline
Flock Leader

Registered: 10/09/08
Posts: 345
Loc: Arizona
I am interested, but barely following the discussion; way too technical. Which of course means I want to learn the technical aspects and have a better understanding. Any recommended resources?

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#92634 - 11/13/10 03:57 AM Re: whence came lavender [Re: Sigi]
Henk69 Offline
Moderator
Classroom Professor

Registered: 02/13/06
Posts: 3208
Loc: Netherlands
Originally Posted By: Sigi
Those are not fluids, lavender is a fluid...


You lost me there.

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#92687 - 11/15/10 09:16 AM Re: whence came lavender [Re: Henk69]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2806
Loc: Australia
Thank you Black_Feather smile

Very interesting research. Handy are those Quail x chicken hybrid experiments (now Silver x Blue).

As the Silver Quail journal paper mentioned that the MITF gene has been sequenced in Gallus, I imagine it won't be long before the chicken Bl allele is DNA sequenced - tested for a MITF mutation?

Thanks again.

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#92701 - 11/16/10 11:10 AM Re: whence came lavender [Re: Black Feather]
Redcap Offline
Ruler of the Roost

Registered: 08/14/06
Posts: 954
Loc: Germany
Originally Posted By: Black Feather
Hello,

It has been said in previous posts, but I can summarize :

Lavender is a mutation in the gene called Melanophilin (MLPH), on the chicken chromosome 7.

The MLPH protein plays a role in the transport of melanosome (containing melanins) from melanocyte to keratinocyte. A mutations in the gene coding for MLPH can lead to impaired transfer of melanin (as patches of pigment instead of regular distribution).

Many mutations in MLPH gene have been characterized in other species : dog, mink, cat, mouse, rat, human, quail. They are all dilutions of melanins (from black to blue-grey, from red to buff or cream), sometimes called blue in these species.

But the Blue locus in chicken is different. It is not a mutation of MLPH (Lav), nor PMEL17 (I). There is an indication that the phenotype called 'Silver' in Quail (gene MITF) is homologous to chicken Blue phenotype :

Silver Quail

About similarities between species, it's worth to note that the mutation corresponding to type III Griscelli syndrom in human is identical to the mutation observed in chicken lavender (same change in DNA and in the MLPH protein).

I don't think we know precisely the geographic or breed origin of lavender phenotype (as we don't know when appeared most of the variations in chicken).


Here You can get the whole paper
http://www.biomedcentral.com/content/pdf/1471-2156-11-15.pdf
Very interesting to see the "silver" quail-chicken hybrids!
_________________________

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#92728 - 11/17/10 06:36 AM Re: whence came lavender [Re: Redcap]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2806
Loc: Australia
The following paper has the bleu (lavender) quail x lavender chicken hybrid photos:

Testing Homology of Loci for Two Plumage Colors, 'lavender' and 'recessive white', With Chicken and Japanese Quail Hybrids:
http://jhered.oxfordjournals.org/content/93/1/73.full.pdf

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#92786 - 11/19/10 04:10 PM Re: whence came lavender [Re: KazJaps]
Wieslaw Offline
Moderator
Classroom Professor

Registered: 09/18/09
Posts: 3769
Loc: Denmark
According to this article:

http://www.leghorn.nl/artikelen/Isabel%20patrijs-UK.pdf

lavender leghorns(isabel) popped up spontaneously in Germany in seventies in a flock of gold flitter browns.The same mutation again or a different one(rhetorical)?

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