PYRIDINE-NUCLEOTIDE METABOLISM IN IMAGINAL DISKS OF DROSOPHILA-MELANOGASTER

Pyridine nucleotide metabolism of imaginal disks of D. melanogaster was studied in vitro by incubating disks with labeled nicotinic acid in the presence and absence of ecdysterone. The major labeled compounds found within the disks were NAD, NADP and nicotinic acid. There was preferential uptake of nicotinamide over nicotinic acid, although the Priess-Handler pathway was used exclusively. The presence of ecdysterone produced a small increase in the NADP/NAD ratio, and an increase in NAD synthesis, probably to compensate for increased NAD turnover.