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How can you tell if a longhair cat is silver tabby or silver shaded? Also, at what age does a silver shaded/chinchilla manifest its final color?
The Tabby pattern is actually masked in most solid coats, in the same fashion that epistatic white masks coat colours. The non-agouti (hypermelanistic) allele is the recessive "a" - as opposed to the dominant, wild-type "A" which codes for the agouti shift phenomenon causing hairs to be B pigmented at the tips and O pigmented at the roots. In Shaded coats and Ticked coats, however, there are two secondary patterning alleles (T), one of which produces a Ticked or non-patterned agouti tabby (i.e. Abyssinian), having no stripes or bars, and the other (I) is an inter-reactive modifier to "A/a" which gives Smoke patterns to the homozygous recessive (I-aa), leaves a portion of the Tabby pattern in place when "iiA" (Shaded), and yields Cameo when "I-O."Thank you. I did some quick research online and I concluded that genetically speaking, both have the agouti and inhibitor genes, but I didn't find comprehensive information that explains the presence of barring in the silver tabby and its absence in the shaded. I suppose the key has to do with the wide-band (poly)gene(s)?
Thanks for the reply. So a silver tabby should not carry the (T) allele but has to be heterozygous/homozygous for both the (A) and (I) alleles?The Tabby pattern is actually masked in most solid coats, in the same fashion that epistatic white masks coat colours. The non-agouti (hypermelanistic) allele is the recessive "a" - as opposed to the dominant, wild-type "A" which codes for the agouti shift phenomenon causing hairs to be B pigmented at the tips and O pigmented at the roots. In Shaded coats and Ticked coats, however, there are two secondary patterning alleles (T), one of which produces a Ticked or non-patterned agouti tabby (i.e. Abyssinian), having no stripes or bars, and the other (I) is an inter-reactive modifier to "A/a" which gives Smoke patterns to the homozygous recessive (I-aa), leaves a portion of the Tabby pattern in place when "iiA" (Shaded), and yields Cameo when "I-O."
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Thank you for including the link pertaining to the research; as a biology student interested in genetics I very appreciate that. I wasn't expecting my question would lead me to such interesting aspects!.
All Tabbies are either AA or Aa, and the Inhibitor allele - I/i - produces hairs which are either white at the base (the dominant: I), or (with the recessive: i) self-coloured at the base.
The expressive value of the modifier or modifiers (predicted) gives various Smoke and Cameo coats (e.g. a badly expressed or weak "a" or an overexpressive "I" will perform almost as the Dilution allele does, yielding a washed-out Smoke or Cameo).
Simple Truth: we don't yet know enough about the interaction of Wide Band and Polys to even comprehend how the complex values render themselves, though we know the extremes of Wide Banding, since breeders have been "accidentally" using this as a focus in certain cats (e.g. Chinchilla Persians, which show the effects of WB and silver). Les Lyons is in the midst of a long term study of Silvers (and Goldens) which will ultimately answer the whole question (doubtless - she's absolutely tenacious), and the research call may be found here:
Silver and Golden
The particular interaction between the modifier alleles and the Melanin Inhibitor, Agouti and Banding mutations falls at the extreme outside edge of our understanding at present (my own knowledge stops roughly at the spelling of the word "cat"). Your question is of sufficient depth that a decent explanation would need come from a geneticist who's been involved specifically with the study of these particular loci, and their interaction, which narrows the field considerably.
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Your contribution is much appreciated though. Honestly, I should have phrased my question differently.Duh- I feel stupid with the way I answered. I just thought it was asked by someone who couldn't tell the difference between a silver tabby and a shaded! Thanks for a good answer, not lame like mine!
posiepurrs - Lynda - your answer was absolutely on-target, and offered insight from a breeder's perspective that most of us couldn't have mustered, and your having taken the time to reiterate the Breed Standards for Persians no doubt gave many of us a quick education as well. It wasn't until Post #3 that the OP mentioned the agouti and inhibitor genes, wide banding and cetera, and then - after your reply - it became clear that the question was centered more upon genetics than it was upon simple physical observation.Duh- I feel stupid with the way I answered. I just thought it was asked by someone who couldn't tell the difference between a silver tabby and a shaded! Thanks for a good answer, not lame like mine!
We may not have evidence to judge that what you say is true, but we can tell it makes so much sense..
GeoDjay - This solely opinion, based upon crude observation, and wholly anecdotal, with no preponderance of scientific evidence: I don't believe that the hypothetical modifiers all qualify as alleles. I expect we'll find that the interaction between Wide Banding and the Inhibitor allele are more pathway switches, and that eumelanin and phaeomelanin are acted upon in different fashions - and secondarily, that the breadth of the agouti banding (that is, the height of the colouration from skin to hair tip) is controlled by a Transport Protein. Tertiarily, I also suspect (given this possibility) that we'll find that these integral transmembrane proteins act upon colour and pattern in cats in the same fashion as the vacuolar iron transporter in tulips works to aid the anthocyanins in producing "blue" colouration, or in the same manner as the carotenoid-binding protein acts upon the Y gene in silkworms - but this is little but wild surmise on my part.
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Now and then I'm actually semi-coherent.We may not have evidence to judge that what you say is true, but we can tell it makes so much sense.
I will definitely check out the links.Now and then I'm actually semi-coherent.
GeoDjay - Incidentally, posiepurrs is a long-time breeder (from the late nineteen eighties or early nineteen nineties, as memory serves) of great Silvers and Goldens, who selects for eye colour, and who shares her breeding points in public, as opposed to so many breeders who try to hide their own research and selection process:
eye color in Shaded silver and golden persians
If you love Shaded Silvers, her "Camie" (Grand Champion Posiepurrs Camelia):
posiepurrs camelia - Google Search
will knock your socks off.
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GeoDjay - You're certainly welcome, of course, for my rather sophomoric replies. So you're a modern-day biology student with great manners and an abiding interest in learning? Good grief, from which part of the nineteen fifties did you transport here, and could you please go back if time and convenience allow, and retrieve my Mickey Mouse wristwatch that was left behind when we moved in 1956?I would like to say that this thread has inspired me to research more about feline genetics and ethical breeding and made me want to contribute more to the feline field in the future, and so I thank posiepurrs and 1CatOverTheLine for taking their time to answer my questions. <3
Unfortunately, the time machine I use isn't very sophisticated so I can't choose which part the 1950s I want to travel to. (There is only a 1950s button!) but I think it's only a matter of time until (let's hope it's too long) I can randomly travel back to 1956 and retrieve your Mickey Miuse wristwatch (I think missing it has been a great burden to you), but don't ask me where I'm hiding my time machine unless you're willing to keep the answer a secret and take it to your grave! ;PGeoDjay - You're certainly welcome, of course, for my rather sophomoric replies. So you're a modern-day biology student with great manners and an abiding interest in learning? Good grief, from which part of the nineteen fifties did you transport here, and could you please go back if time and convenience allow, and retrieve my Mickey Mouse wristwatch that was left behind when we moved in 1956?
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Hah! Too late - you already told me tomorrow.but don't ask me where I'm hiding my time machine unless you're willing to keep the answer a secret and take it to your grave! ;P
Thank you for sharing this hereI happened to remember this article by Dr Tracy Smith, who has a PhD in the field of genetics and is also a silver Persian breeder. There are other articles on this website too that may be of interest.
Wyndcreste Silver Persians: Available Chinchilla and Shaded Silver Persian kittens Cats for Sale