A GENETIC-ANALYSIS OF AROMATIC AMINO-ACID HYDROXYLASES INVOLVEMENT INDOPA SYNTHESIS DURING DROSOPHILA ADULT DEVELOPMENT

Around 50 min after adult ecdysis, a significant increase in DOPA cont ent is observed in Drosophila melanogaster. This increase, which is fo llowed by increases of other catecholamine sclerotizing precursors, pa rallels the visually observable pigmentation and hardening of the adul t cuticle. Since this DOPA concentration developmental profile is corr elated with cuticle formation, we have analyzed the involvement of aro matic amino acid hydroxylases in this process by determining the same profile in mutant strains affecting these hydroxylations, either direc tly (defects in the genes coding for these hydroxylases), or indirectl y (defects in genes involved in the biosynthesis of the essential pter in cofactor, tetrahydrobiopterin). The altered profiles of the pterin biosynthesis defective strains Pu-2/SM1 and cn pr(c4)/cn pr(m2b) showe d that some pterin is required for these metabolic changes. Meanwhile the altered profiles of the Hn(r3) and ple/TM3 strains directly implic ate the phenylalanine and tyrosine hydroxylase enzymes. An analysis of the phenylalanine hydroxylase protein presence during the period of t he first 3 h post adult ecdysis in thorax plus abdomen extracts has sh own that although the protein is present during the complete developme ntal period, no changes in the cross reacting material amounts are obs erved.