para
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the article
any highlighting linking or underlining is ours
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our comments
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1
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INTRODUCTION
There had been much controversy concerning the genetics of unpatterned
tabbies in the American Shorthair (ASH) breed. In Figures
1a and 1b, are two female kittens about 4 months old. These
half-sisters were born 2 weeks apart. Neither is the outcross of
another breed. The sire of both kittens is a purebred shaded silver
male: GC, GP Melodygarden Stargazer. The dam of the kitten in Figure 1a
was a shaded cameo female (CH, PR Melodygarden Tidy Tips) and this is a
kitten picture of GC Melodygarden Northern Lights, CFA's first grand
champion shaded tortoiseshell ASH. The dam of the kitten in Figure 1b
is CH Solmer Ophelia of Stedam, a gold-eyed white masking brown-patched
tabby. This kitten was registered as a silver ticked tabby in
1996
before CFA declared that no ASH ticked tabbies were registerable in the
breed. Kittens of
this coloration naturally arise when a clear shaded cat, regardless of
lineage or color is crossed with a classic tabby or a solid masking
classic tabby.
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We have no
known date of posting. the reader will note from the references that
the most recent is 1999.
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2
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| 1a. Shaded tortie 4 mo
kitten |
1b. 'Ticked' tabby 4 mo
kitten |
Figure 1 - These kittens share the same
sire, a shaded American Shorthair.
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re highlighted in tile
1 based on our understanding
This is a dominance statement. If Wide band exists and the shaded
cats
is Wide band (Wb/Wb)then kitten b must be an example of wide band cat.
We go out on a limb here and assume here that "solid masked
tabby" is clearly more marked, coloured, and ticked that the kitten1b.
We then go the the internet and here is what we got.
 - -
bingo!!
1b is similar to Burmilla F1.
As the kitten
It is more marked that one parent (the tabby) and less than the
other (shaded parent), therefore there is at a second gene and we
suggest the following
shaded cat is Wb/-, swb/swb
and the tabby is wb/wb Swb/-.
delivering Wb/wb, Swb/swb
swb = super wide band and recessive
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3
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The purpose of
this article is to describe the genetics that make up the shaded ASH
pattern based on actual breedings. It not based on
theoretical of "how it is thought to be or ought to be" but rather "how
it is." The same
genetics have been consistent with 6 lines of shaded cats crossed with
classic tabbies from several different lines. Although written
from experience with shaded American Shorthairs, the genetics are
applicable to other breeds and many of the same genes work in nonshaded
patterns, such as the classic tabby pattern. This manuscript is meant
to provide the readership with information about to the genetic
inheritance of the shaded pattern and to show the relationship of
shaded and unpatterned tabbies with stripes. Because the genetics are
similar in other breeds and hopefully the readers will find the
information useful regardless of breed or color.
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This comment while
understandable and often repeated, caused us a great deal of
difficulty. It is "the Standard" vs "genetics". It is our view that if
the genetics are incorrectly described then errors compound themselves.
U this would
suggest the lines are largely homozygous and the "shaded males are
Wb/Wb swb/swb and the tabbies are wbwb, SwbSwb
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4
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HISTORY
OF THE SHADED AMERICAN SHORTHAIR
Before diving into the genetics, a short history of the shaded ASH
pattern is helpful. The history of the shaded ASH has been more
extensively reviewed elsewhere [1, 2]. The shaded silver is one of the
oldest ASH colors. In 1913, a shaded chinchilla female
was accepted for CFA registration as a "Domestic Shorthair", a breed
designation that later gave rise to both American and British
Shorthairs [3] The first silver shaded ASH competed for championship in
1951. Cameo and
shell cameo shaded ASH were accepted for championship in 1971
and in 1993, other colors including shaded blue, cream,
tortoiseshell, dilute tortoiseshell and their chinchilla/shell
counterparts were accepted. Non-silver shaded ASH (such as shaded golden)
are currently not recognized for championship. "Ticked" tabby ASH were
originally accepted as AOV, but later declared a disqualifier in
1993. They continued to be accepted for registration as AOV by CFA
until about 1996.
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1) That
would be in our view a Wb/-, swb/swb cat.
2) Ox
,OO, Oo cats The reds and torties. and d/d of that = Cream
3) B/-,
D/- Black,
B/- , d/d Blue
4) A/-
i/i, wbwb, Swb/- cats are disqualified
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5
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Currently, the
shaded silver ASH is the 3rd most popular color registered with CFA,
surpassed only by silver and brown tabbies. The color peaked in
popularity in the late 1970's then declined markedly in the 1980s. One
contributing factor was that shaded ASH breeders tended to
breed shaded-to-shaded to produce good color, but the cats
became inbred and the type did not keep up with the slow, but
constant refinements necessary
to be competitive in the show ring. As a result, the shaded ASH
became less competitive at the shows and sometimes got a reputation for
having poor dispositions,
genetic defects, and poor reproductive performance.
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recessive to
recessive same old story - -clearly one of the problems
that will arise with Burmilla to Burmilla breedings without the return
to the Burmese at regular intervals.
what constant
refinements are, or could be, needed or justified??
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6
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The shaded color
pattern is experiencing a comeback in the 1990s. Key to this comeback
is a need to breed shaded ASH to tabby ASH, because there are
insufficient shaded ASH lines to be genetically viable. Also an
understanding of the genetics behind the shaded color is essential to
being able to utilize tabbies in a shaded ASH program. Beginning with
some of the earliest shaded ASH breedings there has been an impression
that it is hard to nearly impossible to get the color back after
outcrossing with tabbies or other colors. Knowledge of the genetics
behind the shaded and classic tabby patterns helps explain why it takes between 2 and 4
generations to get the color back following a shaded to tabby breeding.
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yes,
- dealing with a triple factor, one of which is recessive, can be
very difficult with the possibility of loosing sight of it (the
necessary recessive) especially when there does not appear to be any
ability to recognize Swb in the golden ticked cat
I/I, Wb/Wb, swb/swb
X
i/i wb/wb, Swb Swb
delivers I/i Wb/wb Swb/swb as in figure 1b
probability is 1 in 2x2x2 or 1in 8 or about 12%. of getting back to the
desired
as is said it
will not happen in the first generation
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7
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THINK
OF COLOR PATTERNS IN SMALL UNITS
To follow the genetics, the reader must have an open mind and be
willing to drop some of the preexisting ideas or paradigms regarding
"color" inheritance. Cat "colors" are best described in terms of the
small independent attributes that are inherited. For example, a silver
tabby can be genetically defined as: agouti (tabby), classic
pattern, black (eumelanin), silver inhibitor gene, and a moderate undercoat width. A cameo tabby is
genetically similar to a silver tabby except the black (eumelanin)
pigment is replaced by a red (phaeomelanin) pigment. A black smoke differs from
a silver tabby only that it has the non-agouti gene, etc.
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agouti (tabby),
classic pattern, black (eumelanin), silver inhibitor gene,
=
A/-, ta/ta, mcmc, B/-, I/-.
the classic pattern we will discuss later
-here is a synopsis
U we are not sure what moderate undercoat width means
Cameo relates to a O cat that
is tipped. Given that Phaeomelanin
is much more subject to colour reduction by I (inhibitor) a
Cameo cat can well be not shaded and not agouti , the breeder/ judge
would not be able to differentiate and the cat would not breed true.
Smoke in this
context is a a/a cat ie.
a/a,
ta/ta, mcmc, B/-, I/-.
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8
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The vocabulary for
several color attributes have never before been defined so the terms
are lacking while other terms may mean different things to different
people. For example, the terms "ticked" or "ticking" means something
different to different people. For example, in Abyssinians, the term
"ticked" conjures up a cat that has multiply banded hairs and no
striping anywhere, while in Orientals the same term conjure up a cat
that is noted for having stripes on the head, neck, legs, and tail and
the banding on the hairs is not defined. American Shorthair breeders
may use "ticking" to refer to the intermixing of hairs in the dark and
light striped areas on a classic tabby. To provide a common ground, I
have either selected a single definition where several have previously
existed, or have invented vocabulary where it has previously not
existed.
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The never
ending problem of these kinds of discussion!!
A/- cats are agouti and have brick noses.(?)
a/a cats are non agouti
A/- Ta/- are abbytabby in our book
A/- , ta/ta, Mc/- are mackeral tabbys
A/-, ta/ta mcmc are classic tabbys
here is a synopsis
a Smoke is within common usage a aa, I/- cat.
BUT
there is vast amounts of comment in the literature here and elsewhere
that not all aa, I/- cats appear as smokes.
Therefore we will define a smoke as a non agouti wide band cat.
aa, Wb/- that can be either I/ or ii.
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9
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DEFINING SHADED
AND TICKED TABBY PATTERNS
A shaded cat
regardless of breed is defined by overall appearance, not by genetics.
"Shaded" is a pattern and not a color. Color refers to pigment and may
be black (eumelanin), red (phaeomelanin), blue (dilute eumelanin), etc.
Shaded ASH may be black-silver (silver shaded), red-silver (cameo
shaded), blue-silver (dilute shaded), black non-silver (shaded golden),
or other colors. Patterns define where color is present and typical
patterns may be classic or mackerel tabby, non-agouti, or unpatterned.
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We do not
agree. as commented above, standards must follow genetics. To do
otherwise invites chaos.
We suggest there are two major levels of
colour reduction
wide band Wb/- and the
superwide band swb operating as noted above.
other minor colour reduction genes must also be taken into account
'
they are
the sepia cb and cs genes vice C,
the dilutes/malteseing genes dd vice D,
bb vice B -genetic brown versus black,
and the O genes as mentioned above in comment tile 7
this is the
first time "Unpatterned " is used and refers to Ta/- cats see
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10
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The best
definition of a shaded pattern is one in which the hairs are tipped
with color and the overall appearance is of a cat without striping,
slightly darker along the top midline and shading to untipped (white on
a silver shaded) on the belly. A silver tabby shorthair has a white
undercoat, but is not a shaded cat because it has a striped pattern on
the torso. The
presence of a the silver inhibitor gene (described in
more later on) does not define a shaded cat, nor is it necessary for a
shaded, as in the example of shaded golden Persians. The perfect shaded
silver shorthair has black tipped hairs with a white (silver) undercoat
that extends at least 1/2 the way to the tip [4], unbarred legs, neck
and tail, a white underbelly and insides of the legs. Shaded and
chinchilla patterns are grouped together as shaded cats in this paper,
since the difference between the shaded and chinchilla cats varies only
in one pattern attribute, the width of the white undercoat. Evidence of
a pattern or barring on the legs, neck, and tail or, worse, on the body
is effectively penalized in every breed, even when not specifically
prohibited in the certain breed standards, such as the ASH standard.
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this appears to be an
argument for wideband
we
propose for the Burmilla a genetic based designation
ticked, wb/wb, Swb ?
shaded, Wb/-, Swb/-
tipped Wb/- swbswb
At this time we suggest swb is epistatic and unvisable without Wb
Levels of banding are variable in relationship to those above mentioned
colour reduction genes silver, brown, maltese/dilute, and sepiaand
should not be made by measurement.
Robinsens
Page 137 suggests leg banding as a function of
heterozygous - Ta/ta
We suggest the ideal Burmilla is as per the Burmese - -a Ta/Ta
cat.
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11
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Closely related to the shaded shorthairs are "ticked tabbies".
Both cats lack stripes
on the body, but a ticked tabby has stripes on at least 2 of the
following: head, neck, legs, or tail. As in shaded, the pattern
is defined by overall appearance of the cat, not by the tipping of the
hair. The hairs maybe tipped or multiply banded. Generally, a ticked
tabby appears darker than a shaded silver for one of three reasons: the
hair banding frequency is even, the hair banding frequency is short
giving the hairs multiple bands, or the color travels far down the hair
shaft. A moderately dark, distinctly-marked 4 month old silver "ticked"
tabby kitten is pictured in Figure 1b. I prefer to use the term
"unstriped or unpatterned tabby" to describe shaded and "ticked"
patterned cats combined.
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Confusing and unnecessary
unpatterned is herein used for a Ta/- cat and
abbytabby if you will. A shaded is a wide band tipped
Wb/- swbswb. two clearly different terms???
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12
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Shaded genetics may differ with coat length
The genetics governing mackerel and classic patterns are
relatively simple and largely involve a single gene, Tm_ (T- has also
been used for mackerel) or tbtb respectively.
Shaded genetics are considerably more complicated. Regardless of breed,
the genetics behind
the shaded pattern is composed of many genes working in concert. Although
the overall appearances of shaded patterned cats are quite similar from
breed to breed, the genetics
behind the longhair breeds and shorthaired shaded shorthairs can be
slightly different.
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My
understanding of this para is that it is considerably out of date.
Agreed
we see two as we have outlined above wb and swb
not agreed - we see the pattern genetics as
the same and as pointed out in this document (see tile 14) and others
the undercoat fur of a longhair will play some tricks on the eye
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13
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Shaded shorthair
cats do not have the luxury of having a long coat to obscure a pattern.
Although some "shaded" shorthairs may have a classic or mackerel tabby
pattern at birth, remnants of the pattern generally are apparent
throughout life and these cats are generally considered to have a
pattern fault that requires most to be shown as tabbies, if shown at
all. The clearest ASH and OSH are unstriped or unpatterned
tabbies. Unpatterned tabbies are not restricted to the ASH or
OSH breeds. They are a fundamental pattern also found in other breeds
including Abyssinians, Singapuras, Siamese, Burmese, and more rarely in
Persians and Russian Blues. The minimal requirements to produce a
shaded ASH are the following attributes: agouti gene, silver
inhibitor gene (ASH non-silver inhibitor cats are not recognized), the
undercoat width genes (widebanding genes), genes that affect the number
of bands of color on each hair, and genes that cause an unstriped body
type. Other minor
genes are important in producing the pale sparkling appearance and to
clear up the residual striping on both the torso and extremities.
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read A/-,
Ta/-. tabby or abbytabby
A/-, I/, Wb/-
and Ta/-
anothe case for wideband
???
see also comment re Robinsens page 137 in tile 10
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14
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The shaded pattern
in Persians appears to differ slightly from shaded shorthairs in only
two attributes: 1) They occasionally can be non-agouti (a very light
version of smoke), although this appears to be relatively rare; and 2)
they are more usually born striped (usually classic or
mackerel tabby) than unpatterned. Because of the long hair coat,
they can afford more variability than can shaded shorthairs.
Otherwise,
the genetics behind the color patterns of the Persians and shorthaired
breeds are very similar. |
again
A/- tata,
Mc/- or mcmc
agouti, abbytabby not, mackeral or classic
this does not
agree with the green comments in tile 12
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15
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GETTING THE STRIPES OFF THE BODY
Shaded ASH are agouti (tabby) patterned - the agouti gene, A_
All silver shaded ASH cats are genetically agouti or
"tabby-patterned cats". Normally shaded shorthair cats are not a
variant of the non-agouti (black smoke) pattern as had been suggested
by early publications [3]. Although some shaded Persians are probably
non-agouti, in shorthaired cats, even non-agouti (black smoke) cats
with a very wide silver undercoat tend to have a black mask that
betrays the true color. The tabby nature of the shaded can be seen in
the following attributes: shaded ASH cats have pigmentation around the
eye (eg black "eyeliner" in a shaded silver) surrounded by a white
(silver) zone, pigmented lips, a brick red or pink nose,
colored paw pads, and frequently colored hair the back of the feet. Genetically, however, the
unpatterned cats carry either classic or mackerel or both traits
"masked" by the unpatterned tabby pattern.
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As above
all Agouti cats are "tabby"
there are "abbytabbys", mackeral tabbies and classic tabbies and there
are spotted tabbies that are subs of the mackeral and classic but
they do not appear to be in play here althought they have appeared in
the Burmilla coming from Burmese breedings.
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16
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The agouti gene
(A_) is a dominant gene that allows the hairs to be banded so the cat
appears as a tabby (Figure
2). The converse gene, the non-agouti recessive mutation (aa), causes the banding to disappear as
melanin is over produced. An example of an agouti cat is a brown tabby and
its non-agouti converse is a solid black. |
We could not find
a figure 2
this would be
a "standards" term not a genetic term. A brown tabby might be in
genetic terms
agouti, Brown, full colour, not dilute, abby[tabby]. (A/-, bb, C/-
D/-, Ta/-)
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17
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The term
non-agouti is a misnomer - the cats still carry the genes for hair
banding and because of this, often a faint tabby pattern can be seen on
solid black cats. The agouti gene is still somewhat operative, but
melanin synthesis remains hyperactive despite the activity of the gene.
The terms "melanistic"
or "hypermelanistic" are probably better terms than non-agouti.
Agouti and non-agouti hairs are depicted in Figure 2. Most of
the molecular knowledge of the agouti gene has been extrapolated from
mice. In wild type brown agouti mice, the agouti gene encodes an
inhibitory protein, the agouti protein and is responsible for the light
banded areas of the hair. When a new hair is growing, the melanocytes
start laying down eumelanin (black pigment) producing a black band. |
interesting
We
could not find a figure 2
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18
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Microscopically,
the hairs look coated with dense black pigment. The agouti protein is
produced at the same time and when concentrations reach a certain high
level, the agouti protein causes eumelanin to be down-regulated (turned
down or off) and replaced with phaeomelanin, producing a brown pigment band
in the case of a brown tabby. Microscopically, the phaeomelanin is less
dense and has a reddish cast. After a while the agouti protein itself
becomes down-regulated and eumelanin synthesis resumes. The result is a
new black band. The turning off an on is more or less efficient and
although the bands look fairly sharp to the eye, microscopically switch
from eumelanin to phaeomelanin sputters a bit so the boundaries are
somewhat indistinct. The hair in Figure 2 is
divided into two areas, the colored tip and an area, I will refer to as
the "undercoat width" because in cats,
these two areas act as if they
are regulated by different genes that are inherited separately. The undercoat width genes
are described in more detail later in this paper. |
phaeomelanin, is
generally referred to as orange - as in a O
type Burmese tht are called "red "cats or Cream as in
the dd Dilute/maltesed form.
see G Stephens edit 2 page15 and Robinsons edit 4 p 143
This is, I
think, a poor use of terms See Robinsons page 127 --
undercoat is a term used for down or wool hair.
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19
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Figure 3 - Hairbanding in Classic Tabby
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this is
good presentation.
See Robinsons edit 4 Page 136
.. cats "have a second system of pigmentation that other species
lack - - interspersed throughout this agouti coat. This striping is
caused by a marked reduction in the amount of agouti protein receptors
or agouti protein itself in certain areas of the skin, eliminating the
eumelanin to phaeomaelanin shift"
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20
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The agouti gene
probably works similarly in cats and brown tabbies appear to produce
both eumelanin and phaeomelanin similar to the wild type agouti mouse.
However, agouti mice are stripeless and mouse genetics are unable to
explain how stripes occur in cats. Stripes are remarkable because they
represent variable expression of the agouti gene. Both the light and
the dark striped areas have multiply banded hair, but the banding
frequency (discussed later) varies in these sites. In a classic tabby,
in the black stripes areas the hair follicles are coordinated to
produce hairs with a black (eumelanin) tip followed by a brown
(phaeomelanin) band in the undercoat in
the case of a brown tabby or no
melanin in the case of a silver tabby (Figure 3).
In the light areas,
the hair follicles collaborate to form a different banding pattern
with
shorter pigmented tips and higher banding frequency. Here, the
hairs
are multiply banded, usually black, light, black followed by a light
undercoat. As one
moves from the back to the belly, the frequency and
length of the colored bands decreases. |
see
comments above
re undercoat
see comments linked
one
would wonder if wideband is disruption of this secondary
pattern so
that the whole body has reduced receptors. a
modification of the modification or whatnot??
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21
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Figure 4 - Hairbanding in Silver Shaded
The drawing in Figure 4 shows a similar change in a shaded silver cat,
though as will be discussed in a later section, the hairs often are not
evenly banded. Exactly how
stripes are molecularly regulated so the dark and light stripe areas
are distinct is not clear. In shaded shorthairs, stripes are
suppressed so a shaded shorthair appears similar to an agouti mouse.
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22
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Silvery appearance - the Silver
Inhibitor Gene, I_
In the ASH breed, all shaded cats are required to have a silver
inhibitor genes (I_) and currently shaded cats lacking the silver
inhibitor gene (such as shaded goldens) are not recognized for
championship in the breed. The silver inhibitor gene is dominant and
the genetics have been recently reviewed by Heather Lorimer [5]. The
term "silver" refers to the white
banded areas of the hair, not to the pigmented areas, such as
the black tip on a silver shaded or classic tabby. Silver classic
tabbies are more accurately described as black-silver tabbies, as they
are in some non-CFA registries. A
cameo tabby is more accurately described as a red-silver tabby, a pewter tabby a
blue-silver tabby, etc.
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Cats can be
shaded (read wideband) in both silver (I/-) and golden (ii)
What is Pewter
CFA Breed Standard: American Shorthair
Warm fawn overtones or patina over the whole. Eye color: brilliant
gold. BLUE SILVER PATCHED TABBY (Pewter Patched Tabby): ... BLUE SILVER
TABBY (Pewter Tabby): undercoat white
http://www.cfa.org/breeds/standards/american-sh.html
22 Apr 2007 20:39:55
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23
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In the purest
form, silver differs from white predominantly by mechanism. In white
cats, either the melanocytes (the cells that make the pigment), are
lacking because they failed to migrate to the white areas of the coat
(for example, in the case of the dominant white gene or the white
spotting gene) or the melanin biochemistry is abnormal and can't be
made (as in the case of some of rarer recessive whites). The lack of
melanin is called amelanotic and a cartoon of a white hair is seen in Figure 5.
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no fig. 5
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24
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In silver tabbies, the
melanocytes can produce melanin normal for that color, but expression
is down-regulated to severely decrease or stop melanin production in
the areas of the hair that would normally be colored phaeomelanin in a
brown tabby. In a silver tabby, these areas appear white as seen in Figure 5.
Microscopically, the melanin does not just turn off, but may sputter a
bit and low levels of melanin may be present even in areas that appear
white to the eye. Because of the residual melanin, the undercoat should
be technically described as silvered, not white. However, because of
common use in breed standards, a silvered undercoat
will be referred to as "white". If an inhibitor gene is
unable to completely block phaeomelanin, the resulting cat appears
bronzed or "tarnished".
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no fig. 5
Please note
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26
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The silver inhibitor
gene has a slightly different effect in a non-agouti cat.
As seen in the last drawing in Figure 5, the
silver inhibitor gene does not affect the tip of the hair, but rather
only lightens the undercoatarea.
If the inhibitor gene is unable to completely block residual eumelanin
production, the undercoat
appears gray, a common problem in some
black smoke cats.
Heather Lorimer has suggested that the silver inhibitor gene may and
may be a mutation of the gene responsible for turning the phaeomelanin
(brown pigment) off and on. As
she has noted, the silver inhibitor gene can have a more profound
effect on red (sex-linked orange gene) than it does on black pigment in
all breeds. Because of this complexity, this paper deals
predominantly with black pigmented (shaded silver) cats. The
effect of the silver gene in combination with the red can be
exaggerated.
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read "smoke"
(aa, I/-) in their terms
no fig. 5
Is this the golden
smoke (aa, ii, Wb/-) in our terms - -we think so
as we have
noted in tile above
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27
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To Stripe or Not to Stripe - the
major unpatterned tabby gene, U_
Although much has been made about distinguishing between shaded cats
that are born without a tabby pattern from those born with a tabby
pattern, the two types are genetically similar and differ only in gene
or gene cluster that defines stripes or no-stripes on the body.
Traditionally, tabby cats are thought of as cats with stripes. There
are two genetically distinct patterned tabbies: classic and mackerel
tabbies. Spotted tabbies are variants of mackerel or classic tabbies
and have other genes (spotting genes) that influence the mackerel or
classic patterns to break into spots. Unpatterned shorthair tabbies
without stripes on the body have traditionally been divided into shaded
cats and "ticked" tabbies.
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What follows in tiles 27
-35 is Dr. Johnson's version of "tabby" genetics. That is the
inheritance of agouti cats ( A/-) that are abbytabby
(our word) mackeral tabby and classic tabby.
We see this as out of date based on Robinsons edit 4 pages 136 and 137.
and our review of same
We clearly view Robinson's as the more recent document based on
references to Lorimer (private conversations).
We therefor take an
abbytabby as (Ta/-, Mc??) masking the other two versions
a Mackerel tabby as (tata, Mc/-) and
a Classic as (tata, mcmc)
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28
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Older textbooks [4,
6] report there are 3 tabby patterns: the unstriped Abyssinian-type
(Ta_), mackerel (Tm_), and classic (tbtb) that are present at the same
genetic site (allele). Because a cat has paired chromosomes, a cat can
carry only 2 genes at that site. The classic pattern is recessive to
other patterns. The Abyssinian type pattern is reported to be dominant
to both mackerel and classic patterns while the mackerel pattern is
dominant to the classic pattern. Most texts indicate all three patterns
are alleles of the same gene [4, 6]. Contrary to popular belief, Ta
probably does not determine the banding frequency of hairs on the hairs
on the body (eg, determine whether the hairs are "ticked" versus
"tipped"), but rather determines whether there is striping on the main
part of the body, the torso.
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29
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The unstriped tabby
pattern of ASH (U_ denoting unpatterned or unstriped tabby) appears to
be genetically similar to or the same as the Abyssinian-type tabby
(Ta), although whether they are identical has been a matter of debate.
U_ of the ASH appears dominant (or at least partially dominant) over
both the mackerel and classic patterns for the first generation of
crossing shaded to the recessive classic pattern. Crossing clear shaded
ASH to classic tabbies produces first generation (F1) kittens that have
tabby markings on the neck, legs, and tail, and generally no or weak
tabby markings on the body. This is illustrated in Figure 6 and an
actual First generation breeding is found in Table
1.
|
We do not show a figure 6
this a the
duplication of the breeding in Fig 1
Thsi is how we see it assuming
homozygous cats, and clear =Ta
Wb is wide band and swb is suprwideband =tipped
the cross is
AA, II, TaTa, (mcmc?probable) WbWb, swbswb
X
AA, i/i, tata, mcmc, wbwb SwbSwb.
gives
AA, Ii, Ta/ta, mcmc Wbwb Swbswb
that is an agouti, silver, abbytabby, wide band, and not tipped
(swbswb)
Given that the tipped cat (as in chinchilla) can clearly mask the
Ta characteristics of the cat (Chinchillas are not considered to be
abbytabbys) there is no clear reason to assume the shaded cats
are TaTa cats and they most likely are tata mcmc cats as
are all in that line.
We are clearly seeing the effect of wideband.
|
30
|
The U_ gene is not a
true complete dominant, since the heterozygote allows the striping on
the head and extremities to be expressed. Partial, incomplete, or
co-dominance is probably closer to the truth.
Second generation breedings indicate the three patterns (mackerel,
classic and unpatterned) can not be at the same allele. In the second
generation (Table 1) three tabby patterns
emerged: unstriped, classic, and mackerel (Figure 7).
This example clearly illustrates that all three tabby patterns can not
be on the same gene group. Because the male was a recessive classic, he
could not carry either mackerel or unstriped tabby. The female had to
carry all 3 patterns.
|
I disagree.
I do not see partial dominance. Based on the above.
I believe the conclusions to incorrect here and will explain below.
|
31
|
Table 1
FIRST GENERATION (F1)
Classic red tabby male x silver unpatterned agouti (shaded silver)
female
|
Unpatterned agouti
1M black smoke
(non agouti masking unpatterned tabby)
2F "shaded" tortoiseshell
1M "shaded" silver
|
Classic tabby
|
Mackerel tabby
|
SECOND
GENERATION (F2)
Classic red tabby male x shaded tortoiseshell female F1 [3 breedings]
|
Unpatterned agouti
1F shaded cameo
2F shaded tortoiseshell
1M shaded silver
|
Classic tabby
1F brown patch
1F cameo
1M brown
1F silver patch
1M red
|
Mackerel tabby
1M cameo
1M silver
1F brown patched
2F, 1M red
|
M=male
F=female
|
|
This is
apparently a different set of breedings to that described above. The
reader must remember O is more
susceptible to I/- therefore this is in our view a less that
perfect example.
to start we assume homozygous characteristics and then modify it from
the outcomes as discussed below.
sire- AA, ii, ta/ta, mcmc Ox, wbwb SwbSwb
becomes Aa, ii, ta/ta, mcmc Ox, wbwb Swbswb
dame - AA, II, TaTa, (mc?) oo, WbWb, swbswb
becomes Aa, II, TaTa, Mcmc
oo, WbWb, swbswb
1 Black smoke therefore parents are both heterozygous
A and we make it so
2 shaded torties Oo all females had to be torties
all kittens are silver Ii - probable dame homozygous all
are wide band Wb/wb
one is tipped (shaded silver) means sire is Swb swb- and we make it so.
second breeding
sire- Aa, ii, ta/ta, mcmc
Ox, wbwb Swbswb
2dame- A/- Ii, Tata, mc? Oo,Wbwb, swbswb
becomes AA Ii, Tata, Mcmc Oo,Wbwb, swbswb
-there are no smokes = 2dame is AA probable and we make it so
- the % of non Ta cats -is reasonable
- given we have Mc cats Dame must have been Mcmc making 2dame same we
make it so.
-given only 4 of 15 are shaded (unpatterned) - - from breeding
only 50 % would be wideband and of those only 50% would be tipped
(swbswb)=25% thus that number is reasonable.
given one is a cameo that is therefor ?? we find this outcome a
verification of wide band and our supposition of swb. 2 genes one
dominant and one recessive.
|
32
|
Figure 7 - F1 shaded bred to Classic Tabby
If the gene behind shaded ASH's is a single dominant gene U_, it is on
a separate allele that "masks" the underlying tabby pattern. Table 2
illustrates the expected inheritance if a single dominant gene, U_
produced unstriped tabbies. For the sake of illustration, a shaded
"homozygous" shaded female is bred to a classic male without a shaded
background.
|
This tile 32 and the one
below 33 apparently discuss a third breeding..??
We do not see the genetics this way and believe this to be out of date.
- based on Robinsons 4th edition in regard to Ta and Mc. We also
believe Wb is operational as is also our speculated swb.
we do not agree with Dr. Johnson'sconclusions - - we work
out the possibilities below
|
33
|
Table
2
Expected inheritance with a single unpatterned gene U_
Homozygous classic tabby (uutbtb) x
homozygous shaded carrying mackerel tabby (UUTmTm)
First generation (F1) Table 2a
|
Parent 2
U Tm
|
Parent
1
u tb
|
UuTmtb =
Unpatterned tabby carrying mackerel and classic patterns
|
Homozygous classic tabby (uutbtb) x
heterozygous shaded
female (UuTmtb)
Second Generation (F2) Table 2b
Parent 1
|
Parent 2
|
Offspring
|
u tb
|
U Tm
|
UuTmtb
Unpatterned tabby carrying mackerel and classic patterns
|
U tb
|
Uutbtb
Unpatterned tabby carrying classic pattern
|
U Tm
|
uuTmtb
Mackerel tabby
|
u tb
|
uutbtb
Classic tabby
|
U_= Unpatterned tabby
uu = Patterned tabby
uuTm_ = Mackerel tabby
uutbtb = Classic tabby
|
(Note:
what is seen opposite may not be what you see if you print.)
Homozygous classic tabby Sire
AA, BB, CC, DD, ii, oo, tata, mcmc wbwb SwbSwb
Homozygous shaded carrying mackerel tabby dame
AA, BB, CC, DD, II, oo, TaTa, McMc,WbWb, swbswb
at play
ii, tata, mcmc wbwb
SwbSwb (male 1)
X
II, TaTa, McMc,WbWb, swbswb
all kittens first gen
I/i, Ta ta Mc mc Wb wb Swb swb
that is
silver, abby tabby, Wide band but not tipped with
mackerel and classic patterns carried
second generation breeds original male and kitten who could not be "shaded"
as pointed out is 1b
ii, tata, mcmc wbwb SwbSwb
X
I/i,
Ta ta Mc mc Wb wb Swb swb
50% are silver
50% are abbytabby (unmarked is her term)
25%
are mackerel tabby 25% are classic
50 % will be wide band see 1D kitten
none will be tipped.
as above this exercise is inconclusive and out of date.
I could do a distribution diagran as opposite but it would blow the
readers mind and prove nothing with it's 2x2x2x2x2=32 possibilities
|
34
|
The shaded masks
homozygous mackerel tabby as is true with most homozygous shaded ASH,
in my experience. The recessive inversion of U_ will be called u and uu
allows the cats to express a stripped mackerel (Tm_) or classic tabby
pattern . Because both parents are homozygous (shaded - UUTmTm, classic
uutbtb) all F1 kittens are unstriped tabbies carrying both mackerel and
classic tabby patterns (UuTtb). This fits the data of the example.
Table 2 shows what happens when the F1 kittens are bred to a classic
tabby. Again, this fits the example seen in Table 1
|
again we do not agree.
The table 1 kittens have a different parents that do table 2
|
35
|
While this is a simplest view of
unpatterned inheritance, the genetics of shaded cats is more complex. A
shaded shorthair is more than a homozygous unpatterned cat. A shaded
ASH must have a silver inhibitor gene, a wide undercoat width,
and
proper banding of the hair so it appears tipped with color. While the
homozygous unpatterned gene (UU) may be the most important attribute
for removing striping, other minor unpatterned genes are important in
removing the residual striping and giving the final appearance of
shaded. The minor genes also probably are important in shaded Persians.
|
ditto comments abve
Wide band
without the conclusions. swb is the tipping.
|
35
|
GETTING RID OF THE
RESIDUAL STRIPING - Chaos, Confusion, and Erase polygenes
Although the unpatterned gene in the homozygous state, UU, removes most
of the pattern on the torso and extremities, other genes are necessary
to complete stripelessness and remove the remnants of bars and enhance
the appearance of being shaded. These minor genes are inherited
separately from U_ and appear to be inheritable from each other. The
concept of minor genes has been long accepted and one text refers to
these minor genes as polygenes [6]. Most, if not all, probably are
coded by multiple genes.
|
An
unfortunate use of terms, - -Pollygenes = I do not know.
|
36
|
Because these genes are
inherited separately from the unpatterned gene U_, patterned (striped)
tabby cats can inherit them and show attributes normally associated
with unstriped cats and vice-versa. As illustrated in Figure 7, tabbies
that inherit some of the minor polygenes tend to have ticked or faded
patterns. There are at least 2 attributes that are associated with the
shading on the torso and main body of shaded ASH. These genes have not
been previously described, so for lack of better terms. I will name
them Chaos and Confusion. A third gene was proposed by Cathy Galfo from
her work with shaded OSH. It has been called 'Erase' and appears to
remove some of the residual barring on the extremities.
|
|
37
|
Confusion
A good shaded silver ASH the tipping on the ends of the hair may appear
even on quick inspection, but close inspection reveals that, like
snowflakes, nearly every hair is different from each other (Figure 8).
One has a short black banded tip, the next may have 2 dark bands, the
next may have a medium black tip, etc. Thorough inspection reveals some
hairs are even solid black or all white. And some hairs are utterly
preposterous - my all-time favorites are the hairs that are multiply
banded from the tip to the base of the hair with the record being 7
dark bands in one hair. This loss of coordination from hair to hair, I
term "Confusion". This is in sharp contrast to Abyssinian-type banding
that tends to be very even.
|
I see nothing of a
genetic understanding or value here.
|
38
|
The major differences in the
darkness of the two kittens in Figure 1 is not
the width of the white undercoat or the tipping (both discussed in the
next section), but rather the evenness of the hair banding. The shaded
kitten in Figure 1a, has a very high level of Confusion and has hairs
characterized by very uneven band width as seen in the photograph (Figure 8a) and cartooned in Figure 9. Confusion
serves to give the shaded cat the "sparkling" appearance and appears to
influence the gradual blending and fading of the color from top to
bottom. In Figure 8b, the ticked tabby kitten
has an even tipping with all hairs having bands about the same width
inherited from its tabby parent. For this kitten, 10 hairs removed from
the upper torso and are similar to the Abyssinian type banding
cartooned in Figure
8. Confusion present in the shaded kitten has the effect of
making the torso darker on the top and gradually shading to white
below. The ticked tabby kitten has even color which stops abruptly at
the pale abdomen.
|
read fig 9
Again , as Dr Johnson does not appear to have an
understandng of the inheritance of Ta and Mc cats and uses terms
indiscriminately there is much confusion here of a non genetic kind.
|
39
|
|
|
8a.
Shaded tortie 4 mo kitten
|
 |
|
8b.
'Ticked' tabby 4 mo kitten
|
|
|
40
|
Confusion appears to be a loss
coordination of the hair follicles to make hairs with the same banding
frequency as its neighbors. A good classic tabby has a very even color
and a low level
of 'confusion'. Within a stripe, the hairs in any location have nearly
the identical banding frequency as their neighbors (Figure 10).
Figure 9 - Shaded tortie and ticked tabby
|
interesting observations
|
41
|
Uneven shaded type banding -- Even tabby banding
light
stripes
dark stripes
 --
Figure 10 - Shaded and classic tabby banding.
The hair follicles are coordinated to produce the same amount of
melanin for the same distance on the hair. The width of the dark band
may be longer on the top of the cat compared to the bottom, but the
progression is smooth and the dark tipping appears very even.
Similarly, in the light striped areas, the hairs are multiply banded
but the banding is very even. The hair follicles in the stripe areas
are well coordinated with each other and relate to what the other is
doing.
|
interesting observations
|
42
|
Patterned classic ASH tabbies
are selected for even hair tipping (little Confusion), otherwise the
pattern looks very uneven and mottled. In many cases, when a shaded cat
is crossed with a classic tabby, the evenness of tipping appears to be
dominant and the F1 generation are ticked tabbies similar to the one
shown. Confusion is common in silver Persians - most silver and
Chinchilla Persians have some banded hairs, if observed closely. Some
Chinchilla Persian breeders have reported that some judges will put a
Chinchilla Persian in a Silver category if they see solid black hairs.
Based on the ubiquitous nature of this gene, it probably is not
appropriate to classify a Persian based solely on this single attribute
and the color probably should be assigned based on the overall
appearance of the cat regardless of a few solid black hairs.
|
It is worth reminding the
reader that a shaded cat as is addressed here can also be a tipped cat
and that these genes that cause this shading and tipping(Wb and swb)
mask the cats true pattern. (Ta or Mc variant)
|
43
|
Abyssinians are selected for
evenness of banding and they tend to less Confusion expression, as a
general rule than do shaded ASH. It is a subtle difference, but
Abyssinians tend to have a sharper demarcation between where the body
ticking ends and the unticked underbelly or insides of the legs begins.
In shaded ASH, this contrast is softened so the tipping of the body
subtly blends into white on the belly. Patterned tabby ASH, on the
other hand, are selected very even coat patterns and either lack
Confusion genes or perhaps have a different set of genes that resist
Confusion expression (hypothesized Unconfused genes).
|
I rest my case.
What is also important is that since the cat is selected for an even
coat in the ASH shaded version, there would be a selection process that
would take it away from it's original type which I understand from this
article was a classic tabby, and move it towards a Abbytabby ( a
tata.mcmc to a Ta/-, ? )
|
44
|
A special category of Confusion
attribute is called Roaning. Roaning is a rare trait in which solid
white hairs are intermixed with normal hairs. A black roan has white
hairs intermixed with black, giving it a flea-bitten look. Roaning can
be inherited separately from the more common uneven Confusion banding
width and is relatively rare. In
shaded ASH, Roaning is one genetic strategy by which a shaded may
become a chinchilla.
|
???
|
45
|
Chaos
Chaos also disrupts the striped pattern, but appears to be inherited
independently of Confusion. In a classic tabby, Chaos causes an
intermixing of the light striped areas into the black and vice-versa
and is probably responsible for many cases of what ASH breeders call
"ticking" of a classic tabby pattern. In these cats, the coat banding
is even for the type of hair expressed, it is just that the hairs occur
at an abnormal site.
In shaded ASH, Chaos serves to eradicate residual striping that "breaks
through" on the torso. Unstriped cats that lose these Chaos attributes
tend to show "ghost" striping as can be seen on the back of the ticked
tabby in Figure 8b. "Ghost stripes" on an
unpatterned tabby are different than those of a true mackerel tabby. In
a true mackerel tabby, the dark striped areas have different banding
than the light striped area as for classic tabbies cartooned in Figure 10. "Ghost dark stripes" generally have the
same number of bands as the "light stripe" areas, its just that the
tipping has changed a little to line up evenly suggesting some
coordination of banding. "Ghost striped" unpatterned tabbies are also
genetically different from true mackerel tabbies. Breeding two "ghost
striped" unpatterned tabbies together can produce a clear unpatterned
shaded, while breeding two true mackerel tabbies together never produce
a clear unpatterned shaded.
|
I disagree.
As in Fig 1 A tipped cat when bred to a tabby
cat (wbwb,Swb/-) will produce an in between cat as a result of a
dominant ( Wb) and a resessive (swb)acting together.
The math proof of that, Dr. Johnson provides in her results in Table 1
|
46
|
Erase and other genes that
affect the stripes on the extremities
Residual striping on the extremities (neck, legs and tail) may persist
even in the presence of homozygous UU, Chaos, and Confusion. Other
clean-up genes are necessary to remove the residual stripes. Cathy
Galfro has proposed an "Erase" gene as it appears to be inherited
discretely to "erase" the residual markings on shaded OSH.
The defined leg markings on Singapuras indicate that minor tabby
patterns on the extremities can be genetically fixed with appropriate
selection while all other tabby striping are suppressed. Stripes in
these same places can be present on homozygous shaded cats as residual
markings. In shaded ASH, Erase or several Erase-like genes appear to be
needed to remove striping on the legs, neck, and tail.
|
is this the swb swb??
It is also worth note that "Erase", "Chaos" and "Confusion" are given
no genetic symbols nor are they provided with a dominant recessive
discussion or treatment.
As such, it is specualtion.
|
47
|
TIPPING IS AN ILLUSION -
Undercoat width and banding frequency polygenes
The natural banding of an unpatterned cat hair is similar to the light
striped areas on classic tabbies and usually starts with a dark band,
followed by a light band, followed by a dark band. Getting this
multiple banding down to just a colored tip has been accomplished in
shaded ASH by using several genetic strategies.
All shaded cats have a wide undercoat width, so this section will start
with a description of the "Widebanding genes".
|
What strateges ??
|
47
|
Undercoat Width Genes
(Widebanding genes)
The first description of genes that determine the width of the
undercoat has been credited to Joan Wasselhuber who coined
the term
"Widebanding" genes. Undercoat width genes determine the width of the
undercoat whether or not the
cat has a silver inhibitor gene. The term "undercoat" used in this
paper refers to part of the hair shaft closest to the body and includes
both guard hairs and the shorter hairs often referred to as "undercoat"
hairs. As previously illustrated in Figure 2, both
silver and non-silver cats can have hairs characterized by a pigmented
banded tip and an unpigmented (eg. Silver tabby) or phaeomelanin
pigmented (brown tabby) "undercoat".
|
Sure wish they
had not used that term.
I
wonder if she means fig 3
|
48
|
The width of the undercoat is
varies depending on where it is on the cat. An example of distribution
of the undercoat width was seen in a silver tabby in Figure
3. The
undercoat width is narrowest closest to the spine line and longest
close to the belly. In the ASH breed, all colors with a silver
inhibitor gene are required to have a "white" undercoat present on all
parts of the cats, including along the spine line. When
the pigment goes to the roots, it
is considered a pattern-fault in silver tabbies.
|
read - -wide band
width
OK
that would
be narrow band??
|
49
|
The undercoat width for
nonsilver colors is not defined in the ASH breed. Some brown tabbies have
a wide undercoat as evidenced by a warm brown color underlying the
black stripe area, while in others the black striped areas are black to
the roots. Even in these dark cats, microscopically the eumelanin is
less dense at the base of the hair. In the ASH brown tabby, either of these patterns is
considered correct.
|
Thus it would appear
that some (golden) tabbies are both
"wideband"(Wb/-) and may well be superwide (swbswb) band given
that the golden is much less of a colour reducer than silver
(I/-) and is phenotypically harder to pinpoint, in
our view.
|
50
|
In mice, the silver inhibitor
gene may strongly influence the width of the undercoat. This is
different than in cats, where the silver inhibitor gene probably has
little influence on the width
of the undercoat when the melanin type is eumelanin (black pigment) but
may have an effect with sex-linked orange phaeomelanin. If the
width of the undercoat was linked to the expression of the silver
inhibitor gene, logically all the silver kittens arising from a silver
shaded to brown tabby breeding should all have the broad white
undercoat of the shaded parent responsible for donating the silver
inhibitor gene.
Instead as noted by others [5], the kittens express a variety of
undercoat widths ranging from very narrow (dark) to very broad (light).
Shaded cats
crossed with very dark tabbies often have very dark silver offspring.
|
yes agreed
I/-, Wb/wb,
swbswb
x
ii, wbwb Swb/-
delivers
I/i, wbwb.
Swb swb
a silver narrowband cat
see sales discussion Opra kittens
|
51
|
The widebanding genes (Wb) are
probably polygenetic which would allow for the great variability seen
in the undercoat widths in cats. Precisely how the agouti, silver
inhibitor, and widebanding genes interact on a molecular level is not
clear. One possibility is the widebanding genes influence the agouti
protein production to remain high so that eumelanin pigment remains
inhibited or down-regulated. Another possibility is
that the widebanding gene encodes for
a second inhibitory protein that also down-regulates
eumelanin.
|
precisely as we have
explained - -there are 2 , one dominant , the second
recessive.
The only thing we are unclear of is if the two act separately - - - or
is swb is dependent on Wb
|
52
|
In the case of the black smoke,
a cat that has both non-agouti and silver inhibitor, the two genes
appear at odds with each other. As mentioned previously, the non-agouti
gene is able to suppress the influence of the silver inhibitor gene at
the tip of the hair, but not at the base (in the widebanding zone) so a
silver undercoat is present (Figure 5).
However, in many cases the effect is not perfect. Black smokes may have
color faults, especially if one of these genes are expressed at a
higher level than the other. In some cases, a poorly expressed
non-agouti gene or an over-expression of the silver inhibitor gene will
lead to a pale "washed out" black smoke. Over-expression of the
non-agouti gene or under-expression of the silver inhibitor gene will
cause the undercoat to appear gray instead of white.
All shaded cats (both long- and shorthaired breeds) need a
broad undercoat width to give the shaded its pale silvery appearance.
If a short undercoat width is present, the cat appears as a tabby
(mackerel, classic or unstriped "ticked" tabby depending on the
underlying genetics).
|
where is fig 5
We do
not agree with the current definition of smoke being non
agouti, silver (aa, I/-). There is far to much evidence we have at
Horizons (sales discussion Opra
kittens) and in all texts on the subject,
including Robinsons' and Gloria Stephens Legacy to disprove that
theory. A cat can clearly be non agouti and silver and not be a smoke.
We therefor take the position that a smoke is a Wideband cat (aa ,
Wb). A solid, as is a Burmese, is a narrowband cat (aa,wbwb).
The variation that is seen in smokes is due to the cat being golden (
ii ) at the lower end and silver, wideband (I/-,swbswb) at the upper
end. Other colour inhibition genetics also influence what is seen as
variation in the band width i.e. sepia , and dilute.
The reader should also understand as we believe the case to be proven
that a solid cat can be silver , therefore it can also be golden,
and thus the genetics of DM as proposed and discussed by Pat Turner in
Robinsons p 141 edit 4 does not exist. dmdm is really the
manifestation of golden and in fact Apricot, the pale cream is a
genetic silver ( I ) cat. the Taupe is a silvered lilac and Caramel ,
the silvered blue.
It is only in the dilutes (dd cats) that the eye can see the difference.
ii=dmdm
|
|
I/-= Dm/
|
|
cream
|
dd,Ox,ii
|
apricot (pale
cream)
|
dd.Ox, I/
|
lilac
|
aa,bb.dd.ii
|
Taupe
"paler lilac"
|
aa,bb.dd.I/ |
blue
|
aa, BB, dd, ii |
caramel
"lighter than blue but not lilac"
|
aa,
BB, dd, I/- |
It is our intention to test this theory with DNA testing.
|
53
|
Banding Frequency genes
Banding frequency can be defined at the number and width of the
pigmented bands present on the hair of an agouti cat. The agouti gene
permits the hairs to have banded colors, but other genes (banding
frequency genes) influence the number of bands that actually occur on
the hairs. An ideal shaded silver hair is characterized by a single
broad eumelanin band at the tip while Abyssinian-type banding is
characterized by multiple (at least 2) small eumelanin bands
interspersed with light bands (phaeomelanin). At a molecular level,
banding frequency probably translates to the time interval in which an
agouti protein that turns on and off. Even though the banding looks
precise to the eye, under the microscope, black pigment (eumelanin) may
appear in the light band (phaeomelanin) areas.
|
Do not agree - -just read
wide band and super wideband. another try at wide band - the
penny did not drop???
|
54
|
Several genetic strategies
appear to play a part in producing the illusion of tipping in the
shaded phenotype. In the ideal shaded cats, the tip of the hairs are
pigmented, but the shaft is non-pigmented or otherwise silver. In Figure 11, three
possible genetic strategies are depicted. In the first genetic
strategy, shown in drawings Ia-c, the banding frequency decreases, but
the undercoat width (square brackets) remains the same. In the first
drawing (Ia) a hair has 3 rather small black bands suggesting the
agouti protein turns on and off fairly rapidly. In drawing Ib, the
banding frequency changes so agouti protein is influenced to produce 2
medium black bands before it turns off. Finally, with more selection,
the banding frequency is selected to produce only one band (Ic). In
this model, the hair is truly tipped with color; changing the width of
the undercoat does not influence the tipping.
|
no fig 11
suggest the reader look at fig 10 and the
drawings in reverse order
|
55
|
In the second genetic strategy,
drawings IIa-c, the banding frequency remains the same but the
undercoat width is selected to be progressively wider, until it cuts
off the second dark band. This give the illusion that only a single
band is present, while genetically the cat is coded for multiple bands,
but the bands closest to the base are "masked" by the undercoat width.
Decrease the undercoat width and the multiple bands become apparent
again.
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The most common genetic
strategies in shaded ASHs appear to be a combination of II and III. The
dark bands become broader and a wide undercoat is necessary to produce
the illusion of tipping. The evidence for this is present
microscopically. On many hairs a band of increased melanin is often
microscopically apparent in the region where the second dark band would
normally be present. In other words, tipped hairs are genetically
banded hairs, but the melanin synthesis in the inner band is
down-regulated, probably by the influence of the widebanding genes, so
visually it appears only one band is present. The single band frequency
(strategy 1) either is very rare or does not occur in shaded ASH. In
contrast, Abyssinians are selected for a banding frequency that turns
off and on rapidly so multiple bands are apparent before the undercoat
cuts of the remaining bands or selection of a relatively narrow
undercoat.
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Classic tabbies have multiply
banded hairs present in the light striped areas. As previously
illustrated (Figure 3), the banding varies
according to location on the body. Tabbies also show variation in
banding frequency with most tabbies having 2 colored bands along the
spine, some having 3 colored bands, and a few having only 1 colored
band. This multiple banding in the classic tabby parent influences the
banding frequency of the F1 generation of a shaded x tabby outcross and
multiple bands usually dominate.
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Taking apart the shaded color
So what actually happens when shaded ASH are bred to classic tabbies?
First generation outcrosses of a clear shaded silver (no leg bars) with
a classic tabby result in all the kittens having no striping on the
torso but bars on the extremities and head. Similar genetics occur
regardless of the tabby or shaded lines. I and other ASH breeders have
found this to be the pattern in a variety of other shaded lines
including Allstar, Banchory, Darksun, Erosgata, Fanthai, Gatico, Marya,
Norpark, and Sanabel. Barring on the first generation kittens occurred
even though a variety of classic tabby lines were used: Amex, Solmer,
Murjani, Obiwan, or Stedam lines.
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Whether these kittens are light
or dark depended on the classic partner. Some classic tabbies appear to
be permissive to the shaded traits and the kittens are light enough to
be registerable as shadeds. Other classic tabby lines are clearly not
shaded-permissive and all the kittens are dark (and registered as
ticked tabbies in my cattery until this was prohibited by CFA).
Generally the darkness of the F1 has been linked to a narrow
widebanding gene and excessively even color, both attributes
that contribute to a clear classic tabby pattern. As mentioned above,
multiple banding is more frequent than single banding tipping. Rather
than being evidence of hybridization, these are predictable
recombinations of traits inherited from both parents.
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The shaded ASH phenotype is a
collection of attributes, not a single gene or gene product. The shaded
ASH genotype is probably nearly identical to that in Oriental
Shorthairs and differs from most Persians, probably only in the
presence of the unpatterned gene. Recently a Chinchilla breeder sent me
pictures of her kittens which do not have patterns at birth, laying to
rest the myth that Persians
do not have unpatterned cats.
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some Persians are
Ta/. OK not all are tata Mc/-
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Putting it back together
It will come as no surprise to a shaded breeder of any breed that
outcrossing to tabbies or any other non-shaded cats can make it hard to
regain the shaded pattern. It is hoped that this article will lend
better understanding as to why it is so difficult to regain a shaded
pattern following outcrossing to a tabby pattern. The complexity of the
shaded pattern is unequalled by any other pattern/color combination. At
least 6
independently inherited traits need to be recovered to form the
shaded pattern following breeding of a shaded to a classic.
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A/-, B/- C/- D/-
I/-, O/-, Ta/ ,(Mc), Wb/- swb
we count 10
a b ,c, d, mc - are probably not in play.
O should not be
equals 4
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Breeding back to a homozygous
shaded stock often results in loss of type, while breeding two superior
type outcross heterozygotes together results in better type, but
regaining the shaded pattern is hit-and-miss (and with the law of
averages, mostly miss). Rarely are the progeny of two outcrosses
homozygous at all genes. With patience, close observation, and a sound
understanding of the genetics behind the pattern, progress is possible
in 2 to 4 generations, even in the shaded ASH pattern.
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yup
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SUMMARY
The shaded shorthair genotype is one of the oldest American Shorthair
color patterns and genetically most complex color patterns ever
reported. Many attributes that make up the shaded shorthair phenotype:
agouti, unpatterned tabby (U_), at least 3 sets of polygenes that clean
up the residual striping, and at least 2 sets of polygenes that
influence the number of bands on the hairs. The outcrossing of shaded
ASH with classic tabbies show these attributes are independently
inherited. First generation
kittens show distinct stripes on the head, neck, legs, and tail and may
be appear very light (shaded) or very dark (ticked tabby) depending on
the recombination of genes inherited from each parent. A sound
understanding of the genetics behind the shaded color is essential to
being able to utilize tabbies in a shaded ASH program. Knowledge of the
genetics behind the shaded and classic tabby patterns helps explain why
it takes between 2 and 4 generations to get the color back following a
shaded to tabby breeding.
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This understanding needs
to be updated to Robinsons 4 edition
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ACKNOWLEDGEMENTS
Special thanks to Dawn Skupin for her review and encouragement. The
writer would like to thank the following persons for their input: Margo
Melles for scientific review; Heather Lorimer and Lorraine Sheldon for
scientific discussion; Dawn Skupin, Leo Halblieb, Gail Johnson, Kathy
Needham, Janee Waterman, Wayne Park, David DeOre, and Dee White for
sharing their breeding stock and for Nobuko Kuruso, Mary Robinson,
Gayle Johnson, Charlene Rankin, Howard Webster, and Jeanette McCormick
for sharing their experiences with shaded American Shorthairs.
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Given Loraine is the
editor of Robinsons 4th edition of 1999 I am surprised Dr.
Johnson did not use Ta and Mc , "see" the "wideband" genetics and
understand a second recessive - in our view, the math clearly
demonstrates it.
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REFERENCES
Johnson CW. The shaded American Shorthair. In 1999 Cat Fanciers'
Association Yearbook, Cat Fancier's Association Inc, New Jersey, in
press
Johnson CW The shaded American Shorthair. Cat Fanciers' Almanac
15(7):14, 1998
Edwards VA A rainbow of colors. American Connection, Fall 1994
Stephen G.
Legacy of the Cat. Yama-Kei Publishers Co. Ltd 1989 Japan
Lorimer. The silver inhibitor gene. Cat Fancier's Journal
Wright M, Walters S. eds. The Book of the Cat. Summit Books, 1980, New
York
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Current Gloria Stephens
Legacy of the cat is dated 2001 and yes we have spelled it correctly.
We did correspond with Gloria a few years ago and understand that since
then she has died.
Gloria Stephens
TICA's "Great Communicator," Gloria Stephens, is gone. She passed away
in her sleep on July 28, 2005 at her home, but she left an indelible
mark in the ...
www.showcatsonline.com/x/gloria-stephens.htm - 11k - Cached - Similar
pages
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.
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Lavina as an
adult
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photo at 3
days
at 6 weeeks
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the sire
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photo Jan 2010
this is a lilac tortie burmese paw photo on the same day as above under similar conditions
