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#1 2012-04-14 16:34:28

ipf
Member
From: Salt Spring Island, BC, Canada
Registered: 2011-08-29
Posts: 168

sex linked traits

Some sex-linked loci are:
Brown eggshell color inhibitor    pr
Brown eye    br
chocolate plumage    choc
Dwarf    dw
Feathering Rate Genes    K, k+, kn, ks
Dermal melanin inhibitor (Foot/skin Color)    Id, id+, ida idc idM
ladykiller    lk
Sex-linked barring    B
Sex-linked white skin    y
Silver and Red-Gold    S, s+

On another thread, someone wondered if sex-linked genes (loci) are themselves linked - of course they are! All loci on the same chromosome are linked to each other, by definition.

Last edited by ipf (2012-04-14 16:42:19)

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2012-04-14 16:34:28

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#2 2012-04-15 12:56:13

poplar girl
Administrator
From: Athabasca, AB, Canada
Registered: 2011-06-30
Posts: 3159

Re: sex linked traits

These are the ones we had previous discussed in more detail in Topic 3 for the marraduna EO:

Barring. B/B or B/-. Sex linked trait. Z chromosome. 13.7 map units from the locus for dermal melanin. A modifier (masks the expression) of dermal melanin.

Inhibitor of melanin disposition in the leg. Id/Id or Id/-. Sex linked trait. Z chromosome. 13.7 map units from the locus for barring.

Rapid feathering. k+/k+ or k+/-. Sex linked trait. Z chromosome.

Gold for the s-series allele. s+/s+ or s+/-. Sex linked, located on the Z chromosome.


Raising red cuckoo (marraduna) Euskal Oiloak and self blue (lavender) & black Belgian Bearded d'Uccles.

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#3 2012-04-15 13:09:30

poplar girl
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From: Athabasca, AB, Canada
Registered: 2011-06-30
Posts: 3159

Re: sex linked traits

Ipf in reference to your comment "All loci on the same chromosome are linked to each other, by definition", this is reason I posed the question:

A distance of 50 LMU corresponds to independence. Note that, if two gene loci are far enough apart on a large chromosome, the crossover rate between them may be so high that they will map as if they are not linked.
http://www.cod.edu/people/faculty/fanch … emapping2.

I am not sure how large the Z chromosome is but I wondered if perhaps some of the traits were located far enough apart that they do not appear linked.


Raising red cuckoo (marraduna) Euskal Oiloak and self blue (lavender) & black Belgian Bearded d'Uccles.

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#4 2012-04-15 13:49:43

ChestnutRidge
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From: Western Virginia
Registered: 2011-07-05
Posts: 251
Website

Re: sex linked traits

Lady killer? :shock:

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#5 2012-04-15 14:14:03

poplar girl
Administrator
From: Athabasca, AB, Canada
Registered: 2011-06-30
Posts: 3159

Re: sex linked traits

Further studies with a sex‚Äźlinked lethal gene in the fowl

A. K. Sheridana
[...]

British Poultry Science
Volume 20, Issue 6, 1979, pages 571- 573
Available online: 08 Nov 2007

ABSTRACT
1. The ladykiller (lk) gene has been located on the sex chromosome of the fowl. It is 4.2 map units distant from the feathering rate locus (k) and 11.2 map units distant from the dwarf (dw) locus.

2. Most of the embryonic mortalities associated with this gene occurred between 3 and 4 d of incubation.


Raising red cuckoo (marraduna) Euskal Oiloak and self blue (lavender) & black Belgian Bearded d'Uccles.

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#6 2012-04-15 14:18:48

poplar girl
Administrator
From: Athabasca, AB, Canada
Registered: 2011-06-30
Posts: 3159

Re: sex linked traits

There is a table of the Z chromosome traits and some linkages here:
http://www.edelras.nl/chickengenetics/linkages.html

What do the q and p mean in the locus column ipf?


Raising red cuckoo (marraduna) Euskal Oiloak and self blue (lavender) & black Belgian Bearded d'Uccles.

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#7 2012-04-15 14:31:17

ipf
Member
From: Salt Spring Island, BC, Canada
Registered: 2011-08-29
Posts: 168

Re: sex linked traits

PG - yes of course, you are correct, if they are far enough apart they don't appear to be linked. I guess it depends on how you define linked - is it "tend to be inherited together" or "located on the same chromosome"? Functionally the first of course makes more sense, but as an admitted theorist, I tend to think in terms of the second.

The Z chromosome is pretty big - the 5th largest. For comparison, chromosome 1 has 195,000 bases(195 Mb), and chromosome 3 has 110 Mb. The Z contains about 82 Mb and about 1000 genes. It is less gene-dense than any chicken autosome, with 11 genes per megabase, which is less than half of the chicken autosomal average of 25 genes per megabase.

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#8 2012-04-15 14:38:06

ipf
Member
From: Salt Spring Island, BC, Canada
Registered: 2011-08-29
Posts: 168

Re: sex linked traits

Lady killer - a sex-linked recessive allele. When carried by a female (lk/-) it is lethal, and female embryos die in the first few days of incubation. Heterozygous males (lk/Lk+) are ok.

Sorry, hadn't seen your response of a few minutes ago, PG.

Last edited by ipf (2012-04-15 14:41:37)

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#9 2012-04-15 14:40:26

ipf
Member
From: Salt Spring Island, BC, Canada
Registered: 2011-08-29
Posts: 168

Re: sex linked traits

Re p and q - I have no idea! Usually p and q refer to probabilities, where p+q=1. That is clearly not the case there. . .

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#10 2012-04-15 14:51:15

poplar girl
Administrator
From: Athabasca, AB, Canada
Registered: 2011-06-30
Posts: 3159

Re: sex linked traits

"Arms" of the chromosomes maybe ipf??


Raising red cuckoo (marraduna) Euskal Oiloak and self blue (lavender) & black Belgian Bearded d'Uccles.

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#11 2012-04-15 14:57:18

ipf
Member
From: Salt Spring Island, BC, Canada
Registered: 2011-08-29
Posts: 168

Re: sex linked traits

I wondered about that too, but some chromosomes have neither p not q, while others have both, so are divided into three sections. And chromosomes only have two arms.

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