2BrownDogs (7/13/2008)
They are incredible, no? They are very very rare though...like one in a million +, so chances are the Labbies in your paper are most likely mixes.
The tan point marking in Labs is fairly more common, as apparently Gordon setters were bred to Labs in the arly history of the breed. The gene is recessive and can be passed down many generations before a tan point pup is produces.
The mosaic and brindling have something to do with gene abnormalities which is way to technical for me to understand. LOL here's the explanation:
"Brindling describes alternating expression of black and red color in the hair throughout the coat. There are several possible causes for this fault that occasionally appears in Labs. One cause may be attributed to the "ebr" allele that controls brindling in many other breeds of dogs. For expression of this trait, both sire and dam would have to carry the mutant "ebr" allele, which is recessive to the "E" allele, but more dominant than the mutant "e" allele for yellow.
Alternatively, brindling in Labs may be the result of what geneticists call a mosaic. A mosaic indicates differences in the somatic tissue of heterozygotes that come about during mitotic division of somatic cells (recall from above that somatic cells are those that make-up the body). There are two possible ways by which an individual may become a mosaic. The first is called chromosome nondisjunction by which during division into daughter cells, one of the chromosomes fails to separate from its duplicated chromosome. As a result, one daughter cell receives an extra chromosome and the other receives an unpartnered-chromosome.
The second way that a mosaic may be produced is called chromosome loss by which the chromosome containing the dominant allele gets left behind when the daughter cell's nucleus reconstitutes.
In either situation described above, the daughter cells of these altered somatic cells will contain the same alterations. As a result, one will observe a mosaic or brindled pattern of normal color mixed with color produced by the altered somatic cells. This condition has been reported in a Lab showing mosaic black and yellow coat color. When this Lab was bred to other Labs of normal coat colors of black, chocolate, or yellow, it was determined that the variation in color was not due to a mutated E locus allele (like the "ebr" allele) because none of the offspring demonstrated this phenotype. Rather, this coat characteristic was attributed to a chromosomal alteration as described above.
Therefore, the brindling phenotype rarely observed in Labs might be the result of a stable allele mutation (such as the "ebr" allele), or a random somatic chromosome mutation involving the E or B loci. "
Got all that? Anyway, I would not buy a brindled Lab...especially out of the local paper!
Cool 2brown, I actually got that..... (but are we surprised?)
I'll draw some diagrams of some of this stuff when I get the chance and scan them. A lot of the concepts are much easier when you see a picture.