The ommatidia of the dull red compound eyes of Drosophila contain two classes of pigments, one brown (the ommochromes) and one bright red (the drosopterins). Studies of the precursor compounds isolated from eye color mutants played an important role in the development of the one gene–one enzyme concept (See Chronology, 1935, Beadle and Ephrussi). An example of an ommochrome is xanthommatin. Hydroxykynurenine, a compound biosynthesized from tryptophan, serves as a precursor of xanthommatin. Flies lacking the plus allele of the cinnabar gene are unable to synthesize hydroxykynurenine, and therefore this is sometimes called the cn + substance. Drosopterins are pteridine derivatives. Sepiapterin is a precursor of drosopterin that accumulates in sepia mutants. It also gives the Drosophilia testis its yellow color. Structural formulas are given above. See formylkynurenine.
Drosophila eye pigments
Subjects: Genetics and Genomics.