calico cat genetics
fwaddle at CHI1.UNCFSU.EDU
Tue Jan 21 18:17:03 EST 1997
Steven Pirie-Shepherd (srps at galactose.mc.duke.edu) wrote:
> Aeykay Ess (ditts at hotmail.com) wrote:
> : HI Netters
> : I have a couple of questions regarding calico cat genetics. I know
> this is not
> : the appropriate newsgroup for these queries, so I would appreciate
> if somebody
> : could direct me to such a newsgroup (or provide the answers).
> : 1) What is the genotype of calico cats and their parents.
> : 2) What is the origin of the white patches on these calico cats.
> As I recall (but this may be wrong), the colour gene is on the x
> chromosome, and since females have have two of these per cell, one
> close down or 'condense' into a barr body. This gives rise to a mosaic
> colour on the animal as the condensing is random from cell to cell.
> dont have two X chromosome in genreal, so they dont have a barr body,
> they dont have the mosacitiy..BUT it is possible to be XXY
> syndrome?). The superfluous X chromosome shuts down, resulting in a
> male..so basically all calico cats are female, unless they are male,
> which case they must be kleinfelter cats..make sense? --
>The gene for orange is O. Its allele for non-orange (black) is o.
The gene locus is on the X chromosome. A tortoiseshell cat inherits O
from one parent and o from the other. In any mammal with two X
chromosomes, one X becomes a Barr body (named after Murray Barr who
discovered it). Most genes on that X are nonfunctional. In the skin
of a tortoiseshell cat, those hair cells containing a functional
allele O produce orange hair. Those containing functional allele o
produce black hair. These cells tend to be mixed together, often
producing alternating bands of color down the back. White patches is
due to an autosomal gene. I don't know if it is dominant to nonwhite,
or recessive. However, the gene tends to cause the functional O
bearing cells and the functional o bearing cells to separate out into
discrete patches. Some cats are gray and cream instead of black and
orange. This is due to a dilution gene which is autosomal and
recessive to full color.
A year or two ago, I had opportunity to buy a calico male - for $1000!
Calico males must have two X's to be calico, and they must have a Y
chromosome to be male. Which makes them equivalent to Kleinfelter
humans, and probably sterile.
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