[Jacob-list] Re: Freckles and Ticking outside the showring

[Linda]

What great timing, Fred.

I was recently discussing freckling versus ticking with someone.  I've been looking all over for the JSC Journal with your article on the subject.  

Linda
 
www.patchworkfibers.com
Registered Jacob Sheep, Angora Rabbits, Handspun Yarn

On Thu, 27 Apr 2006 01:50:40 EDT, Jacobflock at aol.com wrote:
> These two genes seem to be in Jacobs and the evidence seems to
> support a "piebald gene" hiccup.  Spinners probably know more about
> freckles and ticking than many show judges. 
>
> The Jacob dominant black and recessive piebald begin to work in
> embryo, immediately .  The results of these color genes show up and
> are visiible at about one month.  The Jacob's dominant black comes
> from the melanocytes formed in the embryonic skin cells.  The cause
> is the protein tyrosine which produces the black ... eventually
> hair, wool, hooves, horns, nose, knees, etc.; a copper based
> protein.  The recessive white pieblad spotting (ss) (as opposed to
> dominant Spotting (SS)) is operating in conjunction with the
> tyrosine protein and "shuts off" the eumelanin producing
> melanocytes.  The piebald gene messenger "says" to the dominant
> black, "you can't go there".  If the "piebald" gene is loud enough
> and "super" strong, the result is a 80% white offspring; strong a
> perfect 60-40 or 40-60 etc.,  weak piebald produces a 20% white. 
> An so it goes as the cells grow from embryo to fetus. 
>
> Two genetic "mistakes" have been observed.  First, a piebald gene
> that skips spots and produces "Freckles" (a piebald painting error
> ... like skipping a spot of black) and these freckles are often
> observable at birth.  Freckling (production of black fiber from
> black skin) seems to be dominant to non-freckling.  Some freckling
> is the production of a black skin spot (often with white fiber)
> which is the result of the sun's rays exciting melanin in the skin
> (we 'melanin' tan from the sun).  Second, "Ticking" which is not
> visible at birth but appears as a growing number of black spots
> with black fiber that increase in number and size as the Jacob ages
> ... it may even appear to turn almost completely black with aging. 
> Ticking also seems to be dominant to non-ticking. 
>
> Thus, to conserve a consistent piebald gene, one might watch both
> parent and offspring and note the expression of freckles and
> ticking so that the gene pool will not get overloaded by these
> genes just as we avoid the extremes of the very "oversctive" or
> "underactive" piebald gene or even avoid the misplaced Jacob
> piebald pattern gene in breeding efforts. 
>
> There are a number of articles available on these genes and a
> starting point might be COGNOSAG (Committee on Genetic Nomenclature
> on sheep and goats).
>
> Fred Horak

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