Ivory: a recessive white-eyed tryptophan metabolism mutant with intermediate F2 - and R 1 - progenies in the flesh fly Sarcophaga barbata.

The recessive autosomal gene ivory (i) causes white eyes in the flesh fly Sarcophaga barbata. The mutation completely blocks the synthesis of formylkynurenine. Ivory larvae and ivory imagoes are able to synthesize xanthommatin if formylkynurenine and kynurenine respectively are provided with the food. The eye colour of the F2- and the R1-mutants respectively is intermediate because these animals have taken up xanthommatin precursors that were excreted by the wild-type larvae. The white eye colour is not influenced by temperature. The viability of the ivory stock is somewhat lower than that of the wild-type stock. The mutation ivory is homologous to the mutation vermilion of Drosophila melanogaster and to the mutation green of Musca domestica respectively.