In vivo and in vitro DNA replication and recombination have been studied both genetically and biochemically in Bacillus subtilis in which genetic transformation is possible. Current peojects are: 1) Role of ATP in ATP-dependent DNase. 2) In vitro transformation by using permeable cell system. 3) In vitro DNA replication by using permeable cell system. ATP's role as an energy-supplier for unwinding double helical DNA has been indicated in the reaction of ATP-dependent DNase and a similar role of ATP in DNA replication is under investigation. BIBLIOGRAPHIC REFERENCES: O'Sullivan, A., Howard, K. and Sueoka, N. (1975) Location of a Unique Replication Terminus and Genetic Evidence for Partial Bidirectional Replication in the Bacillus subtilis Chromosome. J. Mol. Biol. 91, 15-38. Bastia, D., Sueoka, N. and Cox, E.T. (1975) Studies on the Late Replication of Phage Lambda: Rolling Circle Replication of the Wild Type and a Partially Suppressed Strain, Oam29 Pam80. J. Mol. Biol, in press.