A number of regulatory phenomena are being studied in the gram-negative bacterium, Escherichia coli: 1. The regulation of cell and medium cyclic AMP levels, and the relationship of these levels to the rate of synthesis of cyclic AMP dependent enzymes. 2. The function of the enzymes II of the phosphoenolpyruvate-dependent phosphotransferase system is being examined to determine whether transport and phosphorylating functions are separable or cannot be separated. 3. The nature of the lethal lesion in thymine-less death, and the mechanism leading to the production of this lesion.