Developmental and genetic studies on kynurenine hydroxylase from Drosophila melanogaster

Abstract

The level of kynurenine hydroxylase was measured throughout the development of wild type and the eye color mutants v, cn, st, ltd, cd, kar, w, ca, bri and p(P) of Drosophila melanogaster. In all cases except cn a bimodal distribution of enzyme activity during development was observed. Activity is initially detectable in 2nd instar. A maximum is reached in early 3rd instar. Activity declines prior to puparium formation. Shortly after pupation, activity rises dramatically to reach a maximum about 5 times the peak larval level. Maximum activity persists for a short time, and then falls sharply prior to emergence. No activity is detectable in cn, cn3, or cn35(K). In pupae which have 0, 1, 2 or 3 doses of the cn+ allele, activity is proportional to the number of + alleles. This provides further evidence that the cn locus contains the structural gene for kynurenine hydroxylase. Kynurenine hydroxylase is a useful gene product for studying the events of imaginal disc differentiation.