They act within the hair follicle to switch pigment synthesis between weak and dark. It is crucial to think that alleles at this locus interact with Locus E alleles. (As) - DOMINANT BLACK: This allele produces uniform coverage of colored pigment over the total body. Its activity is explicit in all dogs with negro or brown coats. The (As) allele is nearly completely dominant over others in the A series. The dark color ranges from pure negro to a black with a brownish cast (seal). Geneticists are unsure if the allele is incompetent to produce pure black without additional aid from another locus, or if the brown cast indicates a heterozygous allele. (Ay) - DOMINANT YELLOW: The (Ay) allele restricts dark pigment, producing yellow colors. When homozygous, the surface can be clear gold, but much has black tipped hairs, especially on the lead and kill the back. (at) - BLACK AND TAN PATTERN (BICOLORED): The typical tan points are above each eye, on each cheek, on the lips and lower jaw, extending below the throat, two spots on the chest, below the tail, and on the feet to the pasterns and hocks, extending up the internal sides of the legs.These tan points can occur onblack or seal, blue, chocolate or red solid colored dogs. A big trade of mutation can come with these tan points, even inside the profundity of the pigment. In some dogs the tan points are not always marked and the color contrast is not always distinct. Locus B Series - Black/Brown Pigment (B)black pigment (b)brown pigment This locus contains just two alleles, the dominant (B) producing black skin and nose pigment and the (b) recessive allele, producing brown pigment. In dogs that are red or buckskin, the Locus (B) alleles are explicit in skin color, most visible around the eyes and nose. The black nose indicates the genotype is (BB) or (Bb), both which would be uttered as black nose because of the authority of the (B) allele. A lighter brown or red nose is (bb), or homozygous recessive. Being homozygous recessive, both parents must add one recessive (b) gene to the issue to make the red nose. When breeding two dogs with the (bb) genotype, the only resulting combination in the pups would be ( bb) or red nose. Locus C: Pigment depth The Locus C series controls the product of pigment throughout the coat. In dogs, the expression of the Locus C alleles is based on reflection rather than experimental studies. The American Staffordshire Terrier breed is felt to give but the dominant (C) allele at this locus. The C allele allows the entire manifestation of color, of black and light pigments. The allele (cch) or Chinchilla Dilution,found in other breeds at this locus, causes the light pigments to be diluted out in several degrees. This would account for the varying shades found in many littermates depending on their homozygous or heterozygous pairing. The chinchilla dilution allele (cch) does not affect the black pigment, thus allowing for the white dog with dark skin pigment and black nose. Other researchers (Robinson) feel that other modifier polygenes are responsible for this phenotype. CCfull color Ccchmedium shade cchcchpale shade Locus D pair: Pigment density (D)intense pigment density (d)dilute pigment concentration The locus D pair modifies the density of the pigment. The dominant (D) gives full density in both the heterozygous (Dd) or the homozygous (DD) combination. The homozygous recessive (dd) alleles dilute the color. When the dogs basic color is produced by dark pigment, genotype (Bbdd) or (BBdd)yields the colour known as blue. The dark coating is limited as good as the skin pigment to a grey or blue pigment around the eyes, pads and nose. When the dogs basic color is produced by a light pigment the genotype bbdd (dilute brown pigment) produces a fawn with a silvery cast known in our breed as a fawn/bluies. The skin pigment around the eyes is flesh colored as good as a red or brown colored nose. Locus E Series: Extension (Em)black mask (Ebr)brindle (E)extension of colored pigment (f)restriction of black pigment The Locus E alleles affect the propagation of colored pigment, and all of the alleles at this locus interact with those of locus A. (Em) - BLACK MASK: This allele is prevalent to all others in the serial and is expressed as a dark cloak on dogs that are not solid black. One researcher, Robinson, considers the grounds that the black mask belongs in the E series as improbable and assigns it to a different series. (Ebr) - BRINDLE PATTERN: The tabby allele produces the brindle pattern with chevron or bars of black pigment on a setting of light pigment. In dogs with the dominant (As) allele, which produces a hearty surface of black pigment (brown or black), the (Ebr) allele is masked because there is no light pigment on which it can act. It is predominant over the extension (E) allele. In our breed, interactions with alleles at the B and D loci produce a fertile mixture of brindle colors: Ay-B-D-Ebr-black brindle Ay-B-ddEbr-blue brindle Ay-bbD-Ebr-brown or chocolate brindle Ay-bbddEbr-fawn brindle (The (-) as the s allele at the locus pair denotes an allele that is uncertain because of the predominant nature of the first allele. It could be homozygous or heterozygous with any of the other alleles. (E) - EXTENSION: The E allele produces normal extension or manifestation of colored pigment. It interacts with Locus A alleles to make a variety of effects: As-E-black/brown Ay-E-red or buckskin with or without black ticked hairs (on lead and back) referred to as sable in other breeds (ee) - RESTRICTION: The homozygous (ee) alleles restricts the face of black pigment, producing the yellow shades by light pigment. It does provide the formula of colored pigment on the nose, lips and eye rims. It is recessive to all other alleles in the E series. Homozygous (ee) alleles interferes with the look of most Locus A alleles. As-eebuckskin Ay-eelight tan Locus G pair: Progressive Graying (g)uniform color throughout life Research concludes that the AST breed are homozygous (gg) with dogs retaining their coloring throughout their lifetime. The G dominant allele present in other breeds produces a silvering or graying of the cake over time and the recessive (g) allele, giving a consistent color throughout the dogs lifetime. Locus M Pair: Merle Pattern (m)uniform pigment Research has shown that our breed has just the recessive (m) allele at this locus. The homozygous recessive (mm) produces a uniform pigment in the breed. The (M) dominant allele produces the blackbird or dapple pattern. The dominant (M) allele has been identified in Collies, Shetland sheepdogs, Australian Shepherds, Cardigan Welsh Corgis, Great Danes, Louisiana Catalhoula, Spotted Leopard Dogs and Dachshunds. Locus T Pair: Ticking (t)no ticking Research has shown that our breed has just the recessive allele (t) at this locus which in the homozygous recessive (tt) allows no ticking. The dark ticking that we see in our stock is set on the Venue A serial by the dominant (As) allele, not on the Locus T Pair. In some breeds this is known as a sable. In the APBT, traditionally this colour is called black or brown ticked. There are modifier polygenes that manipulate the position and extent of the black ticking in the breed. The dominant (T) allele at this locus causes the tiny flecks of pigmented hair in otherwise non pigmented (or white) areas. The T allele is distinctive in breeds such as the English setter and many of the dog breeds. Locus S Series: White Pattern The alleles of the Locus S series create the white markings that are frequently seen in our breed. Researchers identify four alleles at this locus: Ssolid color siIrish spotting sppiebald spotting swextreme piebald spotting The above sequence reflects the decreasing areas of pigmented hairs. There is some inquiry about the relative authority of and interaction between the alleles in their heterozygous forms because the formula is complicated by modifier polygenes which affect all of the alleles. Our breed, which research shows carries all 4 of the alleles, show all ranges of white markings from solid colors to all white. (S) SOLID COLOR: The homozygous (S) alleles produce a strong colored coat. The modifiers will, on occasion, produce a little number of white markings on the throat, chest, toes, abdomen and belly. (***KATE, INSERT DIAGRAM 1 HERE***) (si) - IRISH SPOTTING PATTERN: This allele produces a form of white on the muzzle, forehead, chest, belly, feet and bottom tip. The varying size of the white field is moved by the positive and minus modifiers. Breeds thought to be homozygous for this are the Boston Terrier, Basenjis and Collies. (***KATE, INSERT DIAGRAM 2 HERE***) (sp) - PIEBALD SPOTTING PATTERN: This allele produces a widely varying areas of white.In the homozygous (spsp) genotype you would see a white dog with black patches. (***KATE, INSERT DIAGRAM 3 HERE***) (sw) - EXTREME PIEBALD SPOTTING PATTERN: This allele further decreases the pigmented area and, depending on the positive or minus modifiers, the design can range from solid clean to white with spots on the ears, around the eyes, and in the rear area. (***KATE, INSERT DIAGRAM 4 HERE***) GENOTYPE SUMMARY in the American Staffordshire Terrier: BlackAs-D-E- BlueAs-ddE- Black & TanatatD-E- RedAyD-E- FawnAyddE- Brindle Ay-D-Ebr- Blue BrindleAy-B-ddEbr- CONCLUSION: Question # 1: In times past, the dingy color was considered as rare in the breed.How are kennels now producing blue dogs in such large numbers? The D Locus pair is the loci that modifies the black Pigment pattern to dark with the homozygous recessive (dd) alleles. Because kennels are selecting blue individuals which are homozygous recessive (dd) the only allele that a blue parent can afford to their progeny is the recessive (b) allele. Breeding two blues together doubles up the recessive trait to (dd) which modifies the dominant (As) allele to blue. If a resulting offspring happens to get the (Ay) allele from one of its parents, then the (dd) will modify this color to a fawn/bluies.If breeders are breeding dogs for the dark color, since the factor is homozygous recessive, 100% of their offspring will be (dd) and depending on the (As) or (Ay) allele on the Venue A series will have low or fawn/bluies pups. Question # 2: It is potential to get a puppy with a black nose from two parents, both with red noses? The red nose in our breed is produced from the Locus B pair with the homozygous recessive (bb) genotype in compounding with the (Ay-) genotype. Mating two dogs with the genotype (bb) the issue would be 100% of the pups having red noses (bb). If a pup with a black nose was produced in one of my litters where both parents had red noses, then DNA testing with parentage verification would be requisite to determine the actual sire to the black nose pup.New alleles can be produced through mutation, but proof of blood would hold to be determined using DNA to find out a duel sired litter. Question # 3: Where does the coffee color come from? The coffee color comes from the Locus B pair with the homozyous recessive (bb) in compounding with the (As) allele. The dilution gene (dd) will also modify this dark chocolate to a weak or almost milk chocolate. In most cases, the nose color is too light brown or as we say chocolate/red nose. Question # 4: How did I get a brindle from a line that has never had brindle dogs? The Locus E Series (Ebr) allele causes the brindle color pattern when this dominant allele is presentin combination with the (Ay) allele. The (Ebr) allele is dominant except in dogs with the (As) allele. In the character of the (As), the (Ebr) allele does not give a light pigment to run on, the brindle will remain hidden. In tracing a brindle dogs bloodline, somewhere in the generations you should see a brindle dog since the (Ebr) allele is dominant. Again, if this was my litter, I would ask forparentage verification using DNA to rule out a dual sired litter.
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