The purpose of this project is to locate the genes controlling cyclic nucleotide phosphodiesterase activities in Drosophila melanogaster by genetic and cytological means. Three paths to this goal are being followed. Segmental aneuploidy is being used to localize the structural genes for cAMP and cGMP phosphodiesterases to regions and the genome defined by translocation breakgpoints in the salivary gland chromosomes. Mutants resistant or sensitive to drugs which inhibit these enzymes are being sought. Electrophoretic variants are also being sought by gel electrophoresis. BIBLIOGRAPHIC REFERENCES: Tsuzuki, J. and Kiger, J. A., Jr., A. Simple Method for Density Gradient Zonal Electrophoresis with Imidazole-Glycine Buffer and its Application to a Study of Cyclic AMP-Binding Protein. Preparative Biochemistry 4(3), 283-294 (1974). Tsuzuki, J. and Kiger, J. A., Jr., Cyclic AMP Binding Proteins in Early Embryos of Drosophila melanogaster. Biochimica et Biophysica Acta 393, 225-235 (1975).