Labrador Retriever coat colour genetics fur colour but those with black skin can potentially produce a Dudley. Dudleys breed true for both fur and skin. The ability of the E locus to override the coat colour directed by the B locus is a classical example of epistasis, where multiple genetic loci affect the same observed trait. The E locus also determines whether the phenotype due to the third genetic locus affecting coat colour will be evident. This locus is recognised as affecting coat colour through the expression of pheomelanin, the pigment responsible for red and yellow pigmentation. The effects on pheomelanin pigmentation are only seen
Terry Pratchett's The Colour of Magic programming at Sky One, also appears as the Alchemist. A teaser trailer, released in late February 2008, featured principal cast members, including Rincewind, Twoflower, Trymon and the Arch-Astronomer of Krull, attempting to describe octarine, the 'colour of magic'. The teaser concludes with the film's tagline: "a pigment of your imagination". Two more trailers were released in March 2008, containing a more complete synopsis, with narration by Brian Cox. The trailers formed part of a multimillion-dollar advertising campaign in partnership with Amazon.com and Borders Books. In addition to conventional adverts in national newspapers and banner ads on sites including MSN.com and