[Induction of intracellular endonuclease synthesis in Serratia marcescens by agents suppressing DNA replication]

Endonuclease synthesis in Serratia marcescens was studied in the presence of agents selectively suppressing DNA biosynthesis: nalidixic acid, mitomycin, hydroxyurea and thymine limitation. All the agents suppressing DNA replication induced exocellular endonuclease biosynthesis irrespective of their action mechanism. The greatest inducing effect was exerted when the agents were added to cells in the late exponential phase. Endonuclease biosynthesis was induced 1-2 hours after adding the agent and was inhibited with chloramphenicol. The induction of exocellular endonuclease synthesis in Serratia marcescens by the classical inducing agents of a SOS response seems to be indicative of a Lex A regulated process.