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#101908 - 02/03/12 06:09 AM Re: Correct % of genetic recombination of B and Id [Re: Redcap]
Wieslaw Offline
Moderator
Classroom Professor

Registered: 09/18/09
Posts: 3770
Loc: Denmark
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?

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#101924 - 02/04/12 01:07 PM Re: Correct % of genetic recombination of B and Id [Re: Wieslaw]
Marvin Offline
Lord of the Fowl

Registered: 11/23/06
Posts: 1991
Loc: Nicaragua
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?

I was not aware of the wies..

Originally Posted By: KazJaps
Some more paper reviews..

The inheritance of shank-color in Nagoyas and White Silkies.
Y. SAEKI), N. ONISHI and M. TAKETOMI
Nihon Chikusan Gakkaiho Vol.25 , No.2-4(1954)pp.127-132
abstract
* The following on sex-linked Barring & Id effects to Fm on shank and comb/beak pigment:
Quote:
2. The expression of shank-color in White Silkies is mainly due to id gene, but the black shanks showing various degrees in the shade were observed unexpectedly in F1 males from the crosses of W. Leghorns ŚW. Silkies or B. P. Rocks ŚW. Silkies.
This may perhaps be caused by the partial suppression of barring induced by the stripe genes hidden under the white plumage in Silkies..
the Link is not working no more..


Edited by Marvin (02/04/12 01:09 PM)

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#101945 - 02/05/12 04:09 AM Re: Correct % of genetic recombination of B and Id [Re: Wieslaw]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2807
Loc: Australia
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?



Sex-linked barring in chickens is controlled by the CDKN2A /B tumour suppressor locus.
(Pigment Cell Melanoma Res. 2010 Aug;23(4):521-30. Epub 2010 Mar 29.)
full paper
Quote:
Loss-of-function mutation in CDKN2A is a major risk factor for familial forms of melanoma in humans (Goldstein et al., 2008;
Randerson-Moor et al., 2001). Furthermore, Sviderskaya et al. (2002) reported that the expression of Ink4a-Arf in mice causes melanocyte senescence and stimulates pigment synthesis. A plausible mechanism for Sex-linked barring in chickens is that the CDKN2A mutation(s) we identified results in premature cell death, which in turn leads to the formation of white bars lacking melanocytes. This may then be followed by a new wave of melanocytes recruited from a pool of stem cells, which migrate, colonize the feather follicle, produce melanin and form the next black bar.

Thus, the mutations causing Sex-linked barring in chickens may have an opposite effect than mutations associated with familiar forms of melanoma in humans (i.e., premature cell death versus reduced cell death).


So their theory is that the B mutation(s) is different to mutations on CDKN2A /B in other species that make them susceptible to melanomas.

Note the B "mutation(s)" - possibly plural. There are two variations of mutations that were found on CDKN2A /B, but because white plumage birds were used, they couldn't determine if there is a difference in phenotype with each. But they are confident that B - barring is caused by mutation(s) on the CDKN2A /B gene.

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#102256 - 02/17/12 06:49 PM Re: Correct % of genetic recombination of B and Id [Re: KazJaps]
Poultch Offline
Coop Keeper

Registered: 01/25/10
Posts: 660
Loc: New Zealand
Marvin, you might want to have a look of this dark legged pullet and what seems to be her sister on a of auctions on NZ's equivalent to ebay

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