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#102439 - 02/24/12 01:26 AM Re: ey revisited [Re: Htul]
Terry Offline
Bantam

Registered: 02/19/12
Posts: 47
Loc: Qld Australia
Htul said
>re: the modern game cross between wheaten and 'partridge' ('partridge' is one of those unfortunate terms that means completely different things to different people - and could be either be e+ or eb accordingly): the hen looks like she has a >salmon breast - is this in fact the case?


I certainly dont view them as salmon in the same context as our Silver Grey and Red Dorkings.

>Also, eb chicks can vary widely in their appearance: from practically "e+-like" to being quite distinct from e+: however, I believe e+ chicks (in the absence of other modifiers) should not have a broken eyestripe or headstripe, which otherwise can sometimes be found in e+-like eb chicks.

Obviously I need to look far more closely at the chicks in future as well as the adults birds and reassess my view of them

re: alleles of MC1R
The geneticists look at any change in DNA sequence as an allele, but from the applied prespective, the important thing is if the phenotype changes and DNA sequences that correlate with those. Which of course you know.
How many alleles is it for Tyr in humans now? about 80? And how many actually produce distinct phenotypes?
But then your point that slight differences which do not at first seem important in creating change in the base phenotype, might interract different with other mutations - particularly any that have direct functional involvment with MC1R - like Agouti (when they find it - could it be Mh or Co?). That has great merit. and Pg must have some interraction with MC1R as well.

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#102441 - 02/24/12 02:11 AM Re: ey revisited [Re: Henk69]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2864
Loc: Australia
You will notice in Morejohn's paper that he extracted/segregated E locus alleles back to E locus allele alone - the rest wild-type (including with the ey Cornish, ie got rid of other modifiers). The same seems the case with the cited Light Sussex - Pease & Cock (1951) research (ie no Co when describing E locus allele - Black Red male, salmon hens). It was Carefoot that didn't seem to extract E locus alleles back to rest wild-type.

Smyth and others had eWh tester lines too (without Co, etc, ie the rest wild-type). From memory, I think they extracted eWh from recessive white commercial stock (with eb, Co, Ml & various others). eWh was found to be incomplete dominant to e+. They also had eb tester line (rest wild-type), and had ebc (rest wild-type - removed Db from Sicilian Buttercups), ER-Fayoumi, etc. Although I don't recall them making specific E tester lines, eg usually use W.C.Black Polish, Black Minorca, etc for E. Sometimes (in the early days), they may mention occasionally some minor modifier segregating in a tester line. And there was one Red Jungle Fowl line with a red enhancer segregating (R. Okimoto mentioned this). So they do take into consideration any variations in tester lines.

The ey recessive wheaten Red Jungle Fowl line (used by Morejohn, Brumbaugh & Hollander) didn't have Co etc modifiers. It appears to be a mutation that occurred in wild-type Red Jungle Fowl.

Co is incomplete dominant. The following is the phenotype when CJR crossed Millefleur (Co/Co) with wild-type (Light Brown Dutch Bantam e+/e+ co+/co+):


Het. Co/co+ males looked very similar to Buff Columbian (Co/Co), but not quite a clean buff ground colour (ie, tend to be a bit patchy). I couldn't work out the pure Millefleur E locus alleles from chick down, but closest to eb Co s+, not buff eWh Co s+. There never seemed to be e+ Db or eb Db chick down segregating in the Millefleurs, nor the crosses. So CJR's Millefleurs seem to be eb Co/Co mo/mo, as suggested by the Dutch breeder she obtained stock from (& European geneticists).

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#102443 - 02/24/12 02:43 AM Re: ey revisited [Re: KazJaps]
KazJaps Offline
Classroom Professor

Registered: 08/30/02
Posts: 2864
Loc: Australia
The main problem at the moment with chicken MC1R DNA sequences is that there is no consistency with E locus allele references. I.e. one paper will cite a specific sequence as being E allele, yet it is clear from other research that the sequence is the ER -Leghorn allele. The same is occurring with ebc & eb (same sequence referring to either). So datum reference points need to be cleaned up, i.e corrections need to be made to some papers, get them all singing the same song.

Hate to keep being repetitive, but there is a second wheaten allele sequenced by R. Okimoto. It's just that it is wheaten mutation coupled with the ER-Fayoumi mutation. I can't see two known mutations, known to modify wild-type individually (one add phaeomelanin in hens, one add eumelanin in both), not producing a distinctive phenotype when combined. It probably wouldn't be the same allele sequence as in the recessive wheaten Red Jungle Fowl line (unless two mutations occurred at the same time).

Plus another eb variation (one less mutation) was sequenced. But unfortunately the alleles weren't extracted on to wild-type.

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#102444 - 02/24/12 03:48 AM Re: ey revisited [Re: KazJaps]
Wieslaw Offline
Moderator
Classroom Professor

Registered: 09/18/09
Posts: 3825
Loc: Denmark
Originally Posted By: Kazjaps
The main problem at the moment with chicken MC1R DNA sequences is that there is no consistency with E locus allele references


In my opinion one of the main problems is, that some of the researchers are not real poultry breeders , and they simply do not know what exactly they are dealing with. They should start with reading this forum, and THEN research.

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#102445 - 02/24/12 04:03 AM Re: ey revisited [Re: Wieslaw]
Henk69 Offline
Moderator
Classroom Professor

Registered: 02/13/06
Posts: 3228
Loc: Netherlands
The entire forum? Would be nice to see the-coop references in scientific literature... wink

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#102446 - 02/24/12 04:24 AM Re: ey revisited [Re: Henk69]
Wieslaw Offline
Moderator
Classroom Professor

Registered: 09/18/09
Posts: 3825
Loc: Denmark
Yes, the entire forum. I did it, there are no excuses why they couldn't.

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#102447 - 02/24/12 04:46 AM Re: ey revisited [Re: Wieslaw]
SilverSilkie Offline
Ruler of the Roost

Registered: 12/05/11
Posts: 1125
Loc: Belgium
Why the real poultry breeders from this forum not become researchers, this would be much more easier , no !

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#102448 - 02/24/12 04:55 AM Re: ey revisited [Re: Wieslaw]
Htul Offline
Coop Keeper

Registered: 03/02/07
Posts: 495
Loc: Australia
Originally Posted By: Terry
.....I certainly dont view them as salmon in the same context as our Silver Grey and Red Dorkings.


That may well be true - but nor is it of the colour of breast you would expect in an eb pullet (and perhaps, as you've alluded to previously: the issue of codominance is at play)

Originally Posted By: Terry

re: alleles of MC1R
The geneticists look at any change in DNA sequence as an allele, but from the applied prespective, the important thing is if the phenotype changes and DNA sequences that correlate with those.


That's the thing - Kazjaps has beaten me to it: but there have been no studies focused on "extracting" the MC1R variant in question, and putting it on an otherwise wildtype background and few enough, even with the classical alleles. No doubt, this is due to the great expense and time investment that would be required - but I, for one, would find it extremely interesting to go into a poultry show filled with 'brown leghorns' (or even better, red junglefowl) that varied only in their posession of one of the 32 MC1R variants (that have been found thus far - no doubt there are more 'out there'). Unfortunately, my interest alone is not going to fund that kind of research.

Wieslaw: many of these researchers probably would not even be poultry breeders per se (indeed, their workplaces may even forbid them from keeping poultry as a biosecurity measure). But Kazjaps has the essence of the problem: the attribution of certain stocks to a specific E locus variant seems relatively aribitrary, and not based on 'extracted' phenotype: only based on what breed X is "meant" to be according to previous researchers or maybe limited phenotypic data, that doesn't factor in other modifiers (I recall that Kerje et al allocated the individual(s) sequenced for ebc as being ebc due to
The ebc allele
is associated with the buttercup phenotype which is very
similar to the wild type but the light parallel back stripes are
irregular and wider and the dorsal head stripe is broken and
irregular compared with the pattern observed in wild type
chicks (Smyth et al. 1980)
.

This may be true - but there are probably modified eb that also fulfil these phenotypic criteria (especially since the ebc was not derived from Sicilian buttercups, but from a synthetic broiler line). Further, there is also no mention in these papers - other than Guo et al (2010) - of how many individuals of each breed were sequenced to account for any within-breed variation.

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#102449 - 02/24/12 05:13 AM Re: ey revisited [Re: Htul]
Htul Offline
Coop Keeper

Registered: 03/02/07
Posts: 495
Loc: Australia
I agree with SilverSilkie - that would be much easier! (afterall, that's how Carefoot started publishing his papers)

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#102450 - 02/24/12 05:14 AM Re: ey revisited [Re: Htul]
Wieslaw Offline
Moderator
Classroom Professor

Registered: 09/18/09
Posts: 3825
Loc: Denmark
Htul, it is exactly the example that comes to my mind each time the subject comes up. I think the guys in Sweden have made such a number once or twice, where they were not fully aware what the in-sent sample was from or something like that.

If they are not allowed to keep birds, then it would be EVEN MORE advisable for them to read this forum.

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