The research described in this application is designed to elucidate basic genetic control mechanisms operating during infection with the E. coli bacteriophage T4 and T7. The extent of genome transcription during T4 infection will be studied by S1 nuclease digestion and by in vitro translation. The studies on T7 will be carried out to determine the size of specific T7 late messengers as determined by RNA gel electrophoresis and in vitro translation. In addition the control of T7 messenger RNA expression will be studied in vivo and in vitro.