Siamese Cat Oriental Genes

In the later decades of last century, some breeders, attracted by the lithe elegant type of the
Siamese cats, removed the gene for Siamese colour distribution by selective breeding,
producing a whole new breed of animal we now know as the Orientals. These retain the
lovely length and elegance of the Siamese type but have no contrasting body pallor. And
whereas the Siamese eyes are a striking deep blue, that of the Orientals is green, which at its
best is quite stunning. They come in all the colours that Siamese exhibit in their points though
the analogue of the Siamese seal appears as deep true black in the Oriental. There is also a
white variety with blue eyes (due to a gene that is quite different from the partial albino that
codes for Siamese pattern), the Foreign White. There are Tortie and Tabby varieties of
Oriental, but the presence of pattern on the body allows us to distinguish between spotted,
classic and ticked forms of tabby, not the case with the Siamese in which pattern is confined
to the points where these distinctions are not easily made.

Siamese Cat

Oriental Genes

Into the Orientals another genes have been introduced, that are not permitted in the Siamese breed. These restrict the pigment in each hair shaft to varying degrees. One such type produces the ‘smokes’ that have pigment in a fair proportion of the terminal hair shaft, while another is responsible for the ‘shaded’ pattern, where the terminal pigmentation is restricted to closer to the tip. Again all the colours and patterns available in the Siamese points may appear in the pigmented areas of these cats’ coats.

Two further genes expressed in the Orientals but not the Siamese are the Silver gene which turns the background colour of the tabbies and the undercoats of the smokes and shadeds to a bright silvery white that produces striking contrasts, and the gene for patching, quite recently seen in this country, which has produced a stunning new breed in the Oriental section that is starting its progress toward Championship status in GCCF Shows. This patching gene has produced the new Bi-colour Orientals, some of which are very beautiful and whose progress will be interesting to watch.

As in the Siamese, the long hair genes have been introduced to the Oriental breed, producing the Oriental Longhair (originally named the Angora), the Oriental equivalent of the Balinese, currently seen in all the colours and patterns of the Oriental Shorthairs with the exception of the Bi-colour one. No doubt this will soon be introduced. It is interesting to consider how the enormous number of Siamese Cat and Oriental breeds have evolved or been developed from a relatively small number of seal pointed Siamese imported from the East in the nineteenth century. When you consider the number of pattern variations and then factor in those for colour and hair length, the number of possible variations is impressive indeed. Perhaps you would like to calculate how many are possible.

Siamese

A female Siamese cat is a female as she possesses a matched pair of the X chromosomes, while, when an X is paired with a Y chromosome, this results in the cat’s being a male. Now the X and the Y chromosomes carry not only genes that are concerned with the determination of the gender of the individual, but also other genes that have nothing at all to do with this. The colour gene for red is one of these and it is carried on a unique part of the X chromosome that is not paired by a comparable part of the Y which is significantly shorter than the X. Let’s call the X chromosome that carries the gene for redness Xr while one that doesn’t carry one we’ll call Xo. If a male cat’s sex chromosomes are XrY he will be a red because these is no partner gene on the Y chromosome to modify the r on his one X chromosome. If a female cat is XrXr she has a pair of red coding genes and will be a red. If, however, she is XrXo she will be a tortie. Why does this happen do you think?

Well it all depends on a curious thing that happens to eac h pair of X chromosomes in all females. The fertilized ovum starts to divide on its way to becoming a formed foetus, but at some stage of this process, and it may vary a bit from cell to cell, each decides that it can do without one of its X chromosome pair and one is kicked out. Once this happens, all the descendents of the cell retain the same controlling X chromosome. Now this happens at random, so roughly half the cells retain and are dominated by one of the X chromosomes and its genes and half are dominated by the other; and this goes for all their descendents of course till adulthood.. Now the product of the red gene is one of the only ones that are easily identifiable by our eyes, without complex laboratory testing, (other than characteristics specifically associated with gender), and we can identify its presence at once.

Thus the tortoiseshell appears in the XrXo female where each patch of red on the coat represents cells that have all descended from one cell which has decided long ago to retain the Xr in charge, while the non red areas are descended from cells that have decided to demote the Xr and
leave the Xo in charge. Now if the decision about the X chromosome were made at the stage at which there were only 2 cells in the embryo, then the adult cat would be exactly half red and half non red the ‘blaze’ line would extend from the tip of the nose to the end of the tail which would look a bit peculiar. However, the time in development at which the decision about the X chromosomes is made is rather later when there are many more cells in the embryo and varies from embryo to embryo. As a result each tortie (or of course, tortie point) cat has a different pattern of red and not red patching.

You ad here Siamese Cat Oriental Genes Search article Siamese Cat Oriental Genes with url https://carecatdogs.blogspot.com/2012/05/siamese-cat-oriental-genes.html,Dont Copy Paste this article Siamese Cat Oriental Genes This article protected google DMCA Siamese Cat Oriental Genes Thanks You.