A sex-linked, recessive eye-color mutation in Drosophila melanogaster. This was the first Drosophila mutation to be understood biochemically. The vermilion gene encodes tryptophan oxygenase, an enzyme that converts tryptophan to formylkynurenine (q.v.). This is the first step in the reaction chain that leads to xanthomatin, the brown pigment in the Drosophila eye. If formylkynurenine is supplied in the diet of larvae containing mutant alleles of v, the adults that develop show normal eye color. The first vermilion mutation to be isolated resulted from a transposon (q.v.) insertion. See Chronology, 1935, Beadle and Ephrussi; Drosophila eye pigments.
Subjects: Genetics and Genomics.