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Smoke Pearl (Male - dgdg To, Female - dgdg ToTo)

Smoke Pearl is a colour formed by combining the Dark Grey gene, dg, with the sex linked Yellow gene, To. For this reason, it is compatible with both, although Yellow is probably the slightly less "potentially confusing" match of the two, should a Smoke Pearl mate be unavailable. This is because, since the gene for Yellow, To, (and its opposite, non yellow, given the symbol to), is found on the "X" chromosome. Since this is one of the sex chromosomes), its effects are shown slightly differently in males and females.

Females have a pair of X chromosomes, males have one X chromosome and a chromosome called the Y chromosome. Since female hamsters only have X chromosomes all their eggs will contain one X chromosome. Males have an X and a Y chromosome, so half of their sperm will contain an X chromosome, half a Y. An X bearing sperm unites with an X egg to form an XX embryo, (which will be female), while a Y bearing sperm unites with an X egg to produce an XY, (male), embryo. In other words, a male hamster passes his X chromosome only to his daughters and his Y chromosome only to his sons, while a female passes an X chromosome on to both her sons and her daughters.

The Yellow gene, To, is not completely dominant; if an animal has a Yellow, (To), gene and a non Yellow, (to), gene it will show patches of Yellow and non Yellow fur. This pattern is called Tortoiseshell and, obviously, all Tortoiseshell hamsters must be female, (because only females have two X chromosomes and so only they can have two different genes at the Yellow site). Male hamsters, having only one X chromosome, must show whichever gene is on that chromosome.

A female Smoke Pearl produces eggs which all carry the Dark Grey gene, dg, and all carry the Yellow gene, To. Both her sons and her daughters will always inherit the Yellow and Dark Grey genes. If she is mated to a Smoke Pearl male, (who will produce sperm carrying the dg gene and whose X bearing sperm ONLY will contain the To gene), the result will be male and female Smoke Pearls - Smoke Pearl is true breeding. Mating to a Yellow male would produce the same interaction with the Yellow gene, but, since the young would inherit only one dg gene, (the other would be a Dg gene from their Yellow father), they would be Yellow, not Smoke Pearl.

Mating the same female to a Dark Grey male will give a different effect. All the babies will inherit a dg gene from each parent, but the males, having only one X chromosome, (from their Smoke Pearl mother), will be Smoke Pearl. The females, (inheriting a To bearing X chromosome from their mother and a to bearing one from their father), will all be Dark Grey Tortoiseshells. Mating a Smoke Pearl female to a Golden male would produce Yellow males and Golden Tortoiseshell females.

If the above mating is done "the other way around", (i.e., a Dark Grey FEMALE to a Smoke Pearl MALE), the results are slightly different. The female will produce eggs all containing an X chromosome with the gene to, for non-Yellow, on it. The male's sperm will contain either a Y chromosome or a To bearing X one. Since all the males inherit their X chromosome from their Dark Grey mother they are all Dark Grey. The females, inheriting an X chromosome from each parent will still be Dark Grey Tortoiseshells, because they have inherited a To bearing X, (from their father this time), and a to bearing one, (from their mother). Mating to a Yellow male would produce Golden males and Golden Tortoiseshell females.

Mating Tortoiseshell females produces yet more combinations. Since they have a To bearing X chromosome AND a to bearing one, half of their eggs contain the To gene and the other half the to one. Mating to a Smoke Pearl male will give Dark Grey and Smoke Pearl males and Smoke Pearl and Dark Grey Tortoiseshell females, (in both cases the colour is dependent on which X chromosome the youngster inherits from its mother). Mating to a Dark Grey male would give Dark Grey and Smoke Pearl males and Dark Grey and Dark Grey Tortoiseshell females. If Yellow or Golden males were used, instead of Dark Greys or Smoke Pearls, the results would be Yellows instead of Smoke Pearls, Goldens instead of Dark Greys and Golden, (instead of Dark Grey), Tortoiseshells.

As with all colours derived from Dark Grey, Smoke Pearls can carry the "kinky tail" genetic fault. Animals with bent or curled tails should not be bred from, as this is believed to lead to spinal problems, as it does in Manx cats.

When Smoke Pearls are bred only to other Smoke Pearls for several generations, the young are not infrequently smaller than average, as a result of the influence of the dg gene. This progressive reduction of size can be minimised by mating "out" to Yellows every few generations.

NHC Standard
SMOKE PEARL (dgdgTo = male; dgdgToTo = female)
TOP COAT Pale greyish cream to the roots
BASE COLOUR Pale greyish cream
BELLY FUR Ivory, almost white
CRESCENTS Ivory, almost white
TICKING Heavy and even black ticking
CHEST BAND Pale greyish cream
CHEEK FLASHES Black - not solid but concentrated ticking
EAR COLOUR Dark grey, almost black
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