Mutant flies show a significant decrease in ommochrome pigment levels and some reduction in drosopterin pigment levels compared to wild type.
Mutant flies have reduced red pigment in the eye compared to controls.
The primary pigment cells in ltd1 flies lack the large electron-lucent xanthommatin granules seen in wild type, while the granules in the secondary and tertiary pigment cells are fewer in number than normal and abnormal in shape and density of their content. The photoreceptor cells lack the small xanthommatin pigment granules seen in wild type.
Uptake of kynurenine, which is produced in the fat body, by the Malpighian tubes, where it is converted to 3-hydrokynurenine, is defective; similar defect seen in eye discs. Sullivan and Sullivan postulate that ltd is a transport mutant that prevents the substrate kynurenine from reaching the sites of its conversion to ommochrome.
Exhibits reduced levels of phenoazinone synthetase, an enzyme involved in the condensation of 3OH kynurenine molecules to xanthommatin, as do other mutants deficient in ommochrome synthesis.
Administration of 3 hydroxykynurenine without effect on eye colour.
Studied phenotypic interaction with other eye-color mutants.
Deficient in ommochrome synthesis. Lack detectable levels of 3OH kynurenine despite normal levels of kynurenine hydroxylase activity.
Eye colour: clear, light, translucent yellowish pink; resembles lt1 but is lighter, darkens with age. Ocellus colour: colourless. Malpighian tubule colour: colourless.