The purpose of this project is to reveal the amount and kind of genic variation at structual gene loci and regulatory gene loci, that occurs in natural populations of Drosophila. Several structural gene loci for enzymes and haemolymph proteins will be intensely examined by a variety of techniques of gel electrophoresis and heat and urea denaturation to detect alleles not usually found by standard methods of electrophoresis surveys. Three proteins will be sequenced and their amino acid substitutions will be searched for isogenic lines derived from natural populations, where the lines cannot be distinguished by electrophoresis. It will then be possible to assess how much variation is present at the most elementary level of analysis and the past results on electrophoresis can be evaluated. Finally, genetic variation at regulatory loci will be studied by searching for induction and repression of enzymes and also by surveying various developmental stages using electrophoretic gels as a screening device for visualizing single gene products. We will search for timing variants and tissue distribution variants.