Tissue specific effects of ommochrome pathway mutations inDrosophila melanogaster

Abstract

SummaryThe tissue-specific effects of 17 mutations affecting the synthesis of brown eye pigment (xanthommatin) have been investigated by combining them withchocolateandred cells, two mutations causing ectopic pigmentation of the Malpighian tubules and larval fat body (which normally only synthesize pigment precursors). The majority of mutations block the pigmentation of four organs: the normally pigmented eyes and ocelli, and ectopically pigmented tubules and fat body. They represent genes that would appear to be required for the normal operation of the pathwayper seand are likely to encode structural proteins. Mutations at 5 loci affect pigmentation of a subset of organs:cdandpoaffect only the eyes and ocelli;karaffects the eyes, ocelli and fat body;carcauses excretion of pigment from tubules; and z affects pigmentation of the eyes alone. Of these loci, only z has been shown to encode a regulatory protein and the role of the remaining four gene products is not clear. Two mutations affecting the red eye pigments (drosopterins),bwandmal, do not substantially perturb brown pigment synthesis in any of the four organs.