Is there anything fun I can do with ...

[Sparklee]

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Thanks for your input, SS. I hadn't really paid much attention before to the fact that white (dom and rec) turn off pattern genes. Do you mean it specifically turns off Pg?

 

[nicalandia]

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No.. Dominant white can turn any eumelanin(black feather pigment) in to white. pheomelanin(gold/silver feather pigments) are almost left untouched(Fading/diluting effect can be seen, example Red Pyle OEG), just look how Buff laced Wyandotte look, they are just gold laced wyandottes, basicaly their black lacing was turn into white lacing and their gold color was faded into buff by Dominant white.. that's how poweful is Dominant white, but not as powerful as the recessive white(c) gene, because any bird with two copies of recessive white is entirely white..

here in this pic you can see the effect of Dominant white on the same pattern.

 

[Sparklee]

Perfect illustration. Thank you. (Typing it will help set it in my brain. Dominant white doesn't turn off Pg. It just covers the black and sometimes the red is covered also and/or diluted -- it just depends. Hetero dom white vs homo dom white is also something to remember because hetero dom white can leak black.)

 

[tadkerson]

Dominant white effects how the black pigments are packaged and allowed to reach the cells that form the feather. If the pigments are not packaged properly the pigments can not be incorporated into the feather- so you get a white feather. Sometimes the packaging works when a bird carries one dominant white gene- so you get some feathers with black pigment. Dominant white does not effect the packaging of red pigments- so you can get red/buff color in a dominant white bird.

Recessive white works differently- the enzyme called tyrosinase is not produced or produced at very low levels in a recessive white bird. The recessive white gene is a mutant- so it does not allow for the normal production of tyrosinase. No tyrosinase- no red or black pigment can be produced. You get a white bird. Recessive white is a form of albinism. This albinism does not effect the nerve tissues- so the birds can have color in their eyes. Hypothetically- the eye does not need as much product (tyrosinase) to produce color as the feathers. The cells that form the eye arise from different embryonic cells than the skin- this undoubtedly has an effect upon the action of the gene mutation. There are other alleles that are found at the same locus as the recessive white gene- red-eyed white and autosomal albinism- both are forms of albinism.

The pattern gene is like a choreographer- it makes all the black pigments go to certain places on the feather. In both birds their are no black pigments to choreograph, therefore no lace or spangle will be found on the bird.

I have not seen any research but have personally experienced the secondary color pattern of ghost barring. I have no answer for the cause. I have also produced light gray birds that were dominant white. I worked with dominant white for over 6 years and had some interesting patterns produced on the males- females usually were white or white with some black. I did not do anything with the birds at the time because I did not have the facilities to do more work.


For those that want to know- the recessive white gene has an avian retroviral sequence insertion (Avian Leukosis Virus (ALV) family) that effects intron 4 and not the exons that are in the coding region of the gene. This insertion effects the transcription of the coded area of the tyrosinase gene. The transcripts are mutated which effect the translation of the messenger RNA into a tyrosinase precursor.



Tim

 

[Sonoran Silkies]

Love the analogy of pattern genes being choreographers

I'll have to read and re-read all the cellular level stuff. This is where my lack of a biology background becomes a nuisance.

Here's a question for you: are recessive white birds more likely to become infected with leukosis? And does vaccination against leukosis have any affect on plumage pigmentation of a recessive white bird?

 

[nicalandia]

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.. me too.

 

[tadkerson]

The avian leukosis has sub groups A,B,C,D and J. Each subgroup virus is different than the other subgroup viruses. Certain chicken strains have resistance to the virus which is due to inheritance. The most common type (in USA) of leukosis virus is the group A. There is a dominant gene and a recessive gene that is found in chickens that will impart resistance to a chicken for the subgroup A virus. All the other subgroups can be suppressed by a recessive gene that is specific to the subgroup virus.

I would imagine if a bird is vaccinated for leukosis the vaccine would be made to help with the A and B subgroup because they are the most common in the USA- A being the most prevalent.

The leukosis virus can be passed on to the offspring through eggs. Chicks that hatch will contain the virus. It can also be passed from one bird to another bird through feces.

A vaccination should not effect the color of a bird. The vaccine contains only the virus coats (a glycoprotein shell) of the A and B viruses. The chickens immune system will destroy and digest the protein coats while building immunity. The antibodies will mark the coats as foreign and special kinds of white blood cells will engulf the coats and digest them.

There are other kinds of vaccines but the inactivated whole virus ( mentioned above) is the easiest to make and is effective.


Tim