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PostPosted: Sun Feb 14, 2010 2:25 pm 
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Htul wrote:
Quote:
The following cockerel is a similar genotype: Bl/Bl lav/lav (Splash Lavender), barred (B/b+ or B/B - note white legs although id+/id+), silver columbian restricted (e+/e+ Co/Co mo/mo), so can only go by eumelanin on tail, neck, etc:


Hi Kazjaps,

I was curious to know how to determine that the white legs in this cockerel occcurs in the presence of id+/id+ (I understand that B in and of itself is meant to have a suppressive effect on dermal melanin, but have always been curious as to how to confidently determine this, given the inhibitory effects of Id, and the relatively close linkage of Id and B - being separated by only 10 map units).

Cheers,
Htul


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PostPosted: Sun Feb 14, 2010 2:27 pm 
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KazJaps wrote:
Htul wrote:
Quote:
The following cockerel is a similar genotype: Bl/Bl lav/lav (Splash Lavender), barred (B/b+ or B/B - note white legs although id+/id+), silver columbian restricted (e+/e+ Co/Co mo/mo), so can only go by eumelanin on tail, neck, etc:


Hi Kazjaps,

I was curious to know how to determine that the white legs in this cockerel occcurs in the presence of id+/id+ (I understand that B in and of itself is meant to have a suppressive effect on dermal melanin, but have always been curious as to how to confidently determine this, given the inhibitory effects of Id, and the relatively close linkage of Id and B - being separated by only 10 map units).

Cheers,
Htul


Hi Htul,

Yes, I can't be 100% certain. All I can say is that no b+ Id segregated in the descendent e+/e+ offspring. The B gene for all my d'Uccles came from a single B allele, from a cuckoo d'Uccle hen (the same with the E or ER allele in these - all from a single E locus allele from this cuckoo hen). I only used one of her ER/e+ B-?/b+-id+ son's, this son coming from a pairing to an unrelated e+ based Db rooster with slate legs - no barring (e+/e+ id+-b+/id+-b+ Bl/bl+ lav/Lav+ Db/db+ Mo+/mo). The cuckoo hen had terrible d'Uccle type (also carrying mo - mottled), so no idea where the B gene originated from in this cuckoo line, & therefore no idea if there would have been a B-Id or B-id+ linkage originally (didn't appear to have Pekin in her, like other Aust. d'Uccle Cuckoo lines).

So, this cockerel:
Image
Here is his barring pedigree:
Image
*(sort of - used a closely related roo's pedigree, ie accurate on the paternal barring side from grandfather back to cuckoo hen, but not accurate on the father's maternal side (wrong maternal pedigree for father, but irrelevant - similar e+ id+-b+ hens used).

The following link - larger view (60KB size):
http://i631.photobucket.com/albums/uu37 ... arring.jpg

So the foundation cuckoo hen was his great-great grandmother (possibly great-great-great grandmother, not sure about father's generation). The foundation cuckoo hen's son, then a grandson were backcrossed to e+/e+ b+-id+ hens, and non-barred e+/e+ offspring were always slate/blue legged (p.s. - mo/mo mottled never affected id+ or E or ER leg colour, ie blue to slate shades). Not heaps of e+/e+ segregated over all the generations, so possible that it was B-Id but a crossover event never occurred in e+/e+ birds. The E or ER allele Barred birds were usually whitish/greyish-hint-legged, with typically some pigment remaining in-between scales. I tried to find an old thread at The Coop with B/B, B/b+ leg comparisons, but the search engine is not working for the archives at present.

p.s. Had Id in original Silver Porcelaine lines (eventually bred out), & e+ Id/id+ roosters were white-legged (or yellow - w segregating also). I.e. Id phenotype wasn't incompletely dominant in these lines (Id - dominant).

Plus this gold diluted Mille hen (eWh/eWh or eWh/e+) had white legs:
Image
But when crossed with unrelated e+/e+ id+/id+ rooster, produced all blue-slate legged offspring (including one son). She had a dominant gold diluter (& extreme eumelanin restriction), so maybe a candidate for Di - Dilute, as Di is incompletely dominant, with id+ leg colour a lighter intermediate blue when het. Di/di+ (source Brumbaugh & Hollander). I don't think eWh dilutes id+ leg colour in these d'Uccles, well not significantly. I've seen willow-legged Wheaten Modern Games, etc. Maybe the researchers that noticed id+ leg pigment dilution with eWh, had other modifying genes present (p.s. - some researchers (eg Smyth) believed that only eWh - Dominant Wheaten diluted id+ pigment, not ey - Recessive Wheaten)?

Sorry Raf - off thread topic, rambling on too. Can cut & paste elsewhere if you like?


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PostPosted: Sun Feb 14, 2010 3:09 pm 
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Thanks Kazjaps - I would agree that absence of b Id segregates from test crossing with b id+ hens is probably the best method to determine whether a presumed rooster is B id+, and not B Id (though to be reasonably confident of this conclusion, sufficient numbers of progeny need to be bred eg. statistically speaking, if the anticipated prevalence of such recombinant offspring is 10% of offspring, then you would need to breed 30 to be 95% confident of hatching at least 1 such chick, or breed 44 to be 99% confident of hatching at least 1 such chick).

I note that you also mentioned Id was completely dominant in your lines - is Id meant to be incompletely dominant in other lines? (I had always assumed that Id was completely dominant - or at least very nearly so, such that Id/id+ hets would be difficult to distinguish from any Id/Id sibs).

The observation re: your Millie hen is also most interesting, as is your observations re; lack of inhibitory effect on id+ of ewh. I had always assumed the latter to hold true (eg. in looking through various web-sites with wheaten varieties - those with willow or slate legs had, to me, always appeared somewhat lighter than the same breed with willow/slate legs on an e+ or eb base). However, it may well be true that some of this may be the effect of Di rather than ewh per se.

In which case, would you perhaps think that Di is a good candidate for the lighter shades of wheaten as opposed to darker wheaten shades (eg. 'clay-wheaten')?

Also, in your own expereriences, do you feel that there are specific genes that do have an effect in diluting id+?

Cheers,
Htul


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PostPosted: Mon Feb 15, 2010 1:49 am 
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The following from rokimoto (The coop) on genes modifying leg colour:
The Coop: Id/Id vs. Id/id+
Quote:
Id is sometimes not completely dominant. Hybrid males (Idid+) sometimes have noticable amounts of pigment in their dermis.

Genes like wheaten, mottling, dominant dilute, dominant white, and sex-linked barring are known to dilute shank pigment.


But there is alot of variation with these genes. E.g. I -dominant White: Pile, White Quail, Buff Mottled (Dom. White Millefleur), etc can have dark legs, and mottled/millefleur Belgians & Dutch bantams have blue or slate coloured legs, plus the dark-legged wheaten-based varieties, etc.
------------

Here are some of the willow-legged Wheaten Moderns (at a local show):

Wheaten Modern Hen 1:
Image
-------------

Wheaten Modern Hen 2:
Image
-------------

Wheaten Modern Hen 3:
Image

No real pattern there, ie none are dark wheatens - just average, & leg colour shade varies amongst them. Hen 3 is both light Wheaten & lighter willow legs, but others are a darker wheaten than Hen 1, but have lighter leg colour to her. Might be multiple modifying genes involved though.

---------------
I'll come back to this thread (need/want to read up more). I wanted to research effects of B - sex-linked barring on yellow skin shade (recall reading that B dilutes yellow skin some), but haven't looked everywhere yet. And there is something about Delawares - B & yellow skin, but haven't found the post (I was thinking D. Caveny made a comment, but haven't come across the post). eWh segregating in these also. I've misplaced my American Standards book - need for description of skin in Delawares.

Will be back :wink:

(p.s. I deleted old post - other thread).


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PostPosted: Mon Feb 15, 2010 10:41 am 
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That is very interesting (Hen 1 in particular) - I have not ever seen (either in the flesh, or as images) any ewh (or perhaps, even the elusive ey that rokimoto sought to sequence, but could not ever find) based birds that have such strong expression of id+.

I'll also need to do a bit more reading up on this - but a thought that springs to mind is Smyth's postulation (in Crawford's Poultry breeding and genetics) on the existence of other alelles at the id locus eg. idM - which is believed to be responsbile for expression of dermal melanin at hatch - though I never ended up finding any published papers by Smyth subsequent to his para in PB&G. Perhaps an allele other than id+ or Id is at play in some of these dark-shanked wheaten birds?

Cheers,
Htul


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PostPosted: Mon Feb 15, 2010 2:58 pm 
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Location: N.E. NSW, Australia
Htul wrote:
That is very interesting (Hen 1 in particular) - I have not ever seen (either in the flesh, or as images) any ewh (or perhaps, even the elusive ey that rokimoto sought to sequence, but could not ever find) based birds that have such strong expression of id+.


Yes, those hens are probably eWh based, if anything like OEGB in inheritance mode.
The following from rokimoto:
The Coop: Id/Id vs. Id/id+
Quote:
Birchin and extended black as well as the eb allele often put pigment in the epidermis of the shank.

eb is an interesting allele, ie it is basically E - Extended Black, but has another mutation on the allele that attenuates the effects of the E mutations. So this makes sense that eb has a tendency to put some epidermis pigment on legs/feet (brownish to blackish shades).

Rokimoto did sequence a second wheaten allele (found in Buff Rocks -see link: - Genetics Website - E locus sequencing), but this one is coupled with the ER-fayoumi mutation (double mutant allele). Have to wait until they formally describe this allele (ie segregate, determine inheritance mode/phenotype). Going on expression of the other E locus alleles (& their allele mutations), it wouldn't be surprising to find some extra eumelanin pigment on this second wheaten allele, in comparision to the first wheaten allele (possibly feet/legs also).

---------------------
Htul wrote:
I'll also need to do a bit more reading up on this - but a thought that springs to mind is Smyth's postulation (in Crawford's Poultry breeding and genetics) on the existence of other alelles at the id locus eg. idM - which is believed to be responsbile for expression of dermal melanin at hatch - though I never ended up finding any published papers by Smyth subsequent to his para in PB&G. Perhaps an allele other than id+ or Id is at play in some of these dark-shanked wheaten birds?


I do have the Genetics Website - Leg colour section (bit of a summary on Id locus alleles):
http://www.edelras.nl/chickengenetics/m ... en_mut_leg

Id Locus Alleles (Id, ida, idc, idM, id+):
  • Id - Inhibitor of Dermal Melanin,
  • id^a - Ancona (mottled pigment),
  • id^c - Cornell Randombred White Leghorn line ( plumage & beak pigment present in dominant whites),
  • id^M - Massachusetts line (pigment expressed on day-old chicks (E, ER, e+ or c/c), but not expressed with I, except I E chicks - expressed later at approx 10 -12 weeks of age),
  • - plus id+ wild type (dermal melanin, not expressed on day-old chicks)

My e+ or eWh mottled d'Uccles (plus CJR's Millefleur Dutch Bantams) didn't express dermal pigment as day-olds, so probably not id^M in these. Most of my d'Uccles didn't have excessive white with the mottling (ie rarely gay mottling). I think that makes a big difference, especially noticeable on birds with foot feathers.

The following abstract on id^c, by McGibbon (1979):
Green shanks and adult mortality in chickens
J Hered. 1979 Jan-Feb;70(1):44-6.
Quote:
A mutation of recent origin in Cornell randombred Leghorn chickens causes the shanks to be colored green due to melanin-like deposition in the dermis, in contrast to normal yellow. Some pigment is often present in the mandibles and the mature feathers display an ashen cast. This mutant is determined by an allele, idc, on the sex chromosome. Excessive adult mortality with a high incidence of tumors, mainly hemangiomas, is associated with this gene--at least extending over a two-generation observation interval. Pullets receiving this mutant allele (idc) from their sire die at 2 to 3 times the rate of sisters, with yellow shanks, that carry the Id allele.


I can't imagine the above id^c mutation occurring in exhibition lines (well not sustaining if a spontaneous mutation occurs).

-----------------
Back to the B - barred d'Uccles:
an old post at The Coop (2005):
The Coop: Lakenvelder day-old leg colour

Unfortunately I can't edit the post to update the photo links, so will post a few here.
The following a het. B/b+ Blue Mottled Cuckoo (day-old to grower age, plus feet):
ImageImage
Image

Unfortunately there was no photo of a B/B brother given for comparison, but I've given the following description:
Quote:
There is a little difference at this stage in leg colour between the two. The B/b+ bird has some remnant epidermal blue along the scales, yet the B/B is paler.


The homozygous B/B ER/e+ mo/mo Db? brother - thumbnails on plumage (but this B/B one has ER eumelanin restrictors):
ImageImage
Image
(more images at the following link at The Coop -What Causes this barring)

The Lakenvelder thread has further info on leg colour pigmentation, eg the following Lohmann article on effects of yellow pigmentation expression is good (mostly on egg yolk colour, but this related to yellow skin colour expression also):
FACTORS WHICH INFLUENCE PIGMENTATION
Eg, mentions dietary influences, nutrient balances (eg calcium -excess reduces yellow pigment colour), sunlight, health (eg internal parasites-lighten yellow skin/leg colour) etc.

----------------
Forgot to mention previously, but for some reason researchers found in some Co B genotypes, skin pigment colour was found to increase (going from memory - haven't re-read all these sources as yet).

The Melanin pigment paper by Smyth (1976) (in signature references) also has info on skin/leg colour.

Plus Smyth's second paper has more on leg/skin colour genetics: Smyth 1994: Melanin Pigmentation 0.5 MB

I haven't read this old one (1935) thoroughly as yet. Might not be worth it (old nomenclature, etc):
The inheritance of shank color in chickens (by Knox):
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1208630/

-------------

Will come back again, once I've read some myself. :wink:

-------------
Edit: typo.


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PostPosted: Tue Feb 16, 2010 12:36 am 
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The Knox paper was quite interesting and I don't think it was that out of date in terms of the genetic theories relating to id+/Id (though you have to amend the terminology used in the paper from d/D accordingly) - quite impressive, given that it is now a 75 year old paper! I must admit, though, that I haven't read it for some time (and only skimmed the link that you provided).


re: your reference to the observation that Co and B resulting in enhanced dermal melanin, even in the absence of id+ - I suspect the ref that you're thinking of is:

Jaap, R.G., 1955. Shank color and barred plumage in columbian-colored chickens. Poultry Sci. 34: 389-395 (I once had a copy of this, though I really have no idea as to where this is at the moment - its good that Poultry Sci has made recent volumes electronically available, but a shame that the archival volumes haven't been backscanned)

I have always thought this to be an unusual observation - especially in light of the fact that an established breed (the Delaware) is based on Co and B (and as far as I am aware, does not have particularly enhanced dermal shank pigment)

In terms of linkage between B and Id loci - I think the relevant ref is:

Bitgood JJ. 1988. Linear relationship of the loci for barring, dermal melanin
inhibitor, and recessive white skin on the chicken Z chromosome. Poult Sci.
67:530–533.

from dim recollection, this ref seemed to indicate that B id+ segregates actually did have some faint discernible dermal pigment? (again, one of those refs that I read some time ago, but not quite sure where I've put it).

I really wouldn't at all be surprised if there were various alleles in the id series (other than the aforementioned) that have not been formally characterised, particularly if they all phenotypically vaguely resemble id+ in the adult bird. Given that the conventional view is to consider shank colouration as dark vs light (and hence id+ vs Id), with the exceptions of the aforementionned idM, idc and ida which were noted as distinct phenotypes (and even then, Smyth is sceptical about ida), nobody really pays attention to the 'shades of grey'. Hardly surprising, really - the results are hardly as spectacular as playing around with plumage colour genetics (when was the last time a bird won a champion ribbon in a show based on the depth of colour of its shanks??).

It will really only be when the gene for the id locus is mapped that sequencing may reveal variation that otherwise was not apparent (and to that end, I note from my attempts to find the Bitgood ref that Rokimoto is actually second author in a recent paper : Dorshorst et al (2010) Genomic Regions Associated with Dermal Hyperpigmentation, Polydactyly and Other Morphological Traits in the Silkie Chicken in Journal of Heredity (so new that it doesn't yet have page refs, but has been released as an epub ahead of print; fulltext not available, but the abstract is avaiable http://jhered.oxfordjournals.org/cgi/content/abstract/esp120v1) which appears to be try to map the Id locus.


On the issue of day-old dermal shank pigmentation - on one of the same hatchery sites that you referred to in your Coop Lakenvelder post - I also noted that the gold pencilled hamburgh. However, in your post there, you mention the GPH as being ER based - I was under the impression that they were eb based? (which, to my untrained eye seems to be borne out in the chick down colours - eg.compare and contrast the chick down around the head of gold campines vs GPH - the GPH having lighter heads with some dark markings which I would have thought fell within the spectrum ofeb). If so, then, like the Lakenvelder (and as you raised in that post) - is this idM, or modifiers of id+ at play to allow expression on day old chicks?

On the point re: SSH and dark shanks though: I really think this is purely dermal rather than epidermal in origin, despite the ER base (else, shouldn't the adult shank colour be black, rather than slate?), and I think that the day old dark shanks is a similar phenomena to that in Lakenvelder.

Cheers,
Htul


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PostPosted: Thu Feb 18, 2010 12:18 pm 
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Hi Karen and Jeff,

this topic is really interesting to me as i breed Light Barred Plymouth rocks, i havent got much knowledge from peer reviewed articles that you two reference, and i really need to improve notes and records.

I do find different expression of yellow leg colour in my line, from light straw to deep orange yellow, these are most preferable. From what i have read Id restricts dermal melanin and allows the expression of yellow legs, this seems to be such a simple extrapalation to me because why is there such an array of yellow leg expression? Sometimes legs even appear white in pullets until they reach their bloom towards laying occurs. i cannot cull for legs as they do always improve to yellow. Is there another gene or inhibitor affecting the leg colour? maybe an accumalitve type effect?

Cheers

Christian

_________________
Interested in Plymouth Rocks, Breeder of Light Barred Standard


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PostPosted: Sun Feb 21, 2010 1:37 am 
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intoChooks wrote:

I do find different expression of yellow leg colour in my line, from light straw to deep orange yellow, these are most preferable. From what i have read Id restricts dermal melanin and allows the expression of yellow legs, this seems to be such a simple extrapalation to me because why is there such an array of yellow leg expression? Sometimes legs even appear white in pullets until they reach their bloom towards laying occurs. i cannot cull for legs as they do always improve to yellow. Is there another gene or inhibitor affecting the leg colour? maybe an accumalitve type effect?

Cheers

Christian



Id restricts dermal melanin, so allows either white (W+w or W+W+) or yellow (ww) shanks to express. However, your observation does agree with what appears to be understood about the phenotypic expression of ww and Smyth (in Crawford) mentions, that, in addition to environmenntal factors (eg. carotenoids in the diet) that yellow pigmentation of the shanks is also affected by sex and genetic factors and that:"Genetic effects were due to unidentified modifying genes that included a sex-linked component (Moyer and Collins, 1960; Zervas et al., 1962)"

MOYER, S. E., and COLLINS, W. M.
1960. HERITABILITY OF INTENSITY OF
YELLOW SHANK PIGMENTATION IN
CROSS-BRED BROILER PROGENY.
Poultry Sci. 39: 662-663.

Zervas et al.
1962 Genetic variation and covariation in yellow shank pigmentation intensity and 8 week body weight of chickens. Poultry Sci 41: 1247-1254

Cheers,
Htul


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