VEGETATIVE LAMBDA DNA .4. FRACTIONATION OF REPLICATING LAMBDA DNA ON BENZOYLATED-NAPHTHOYLATED DEAE CELLULOSE

Fractionation on a column of benzoylated-naphthoylated DEAE cellulose has been used successfully to separate pulse-labeled, replicating bacteriophage lambda DNA from completed phage DNA or completed ring DNA molecules. Sedimentation analysis of the heterogeneous replicating DNA in neutral and alkaline gradients indicates the presence of closed single-strand rings and of linear DNA strands ranging in length from smaller than to not quite twice that of the viral DNA strands. A model of DNA replication is presented which can, by the timely interaction of specific nuclease or polynucleotide ligase enzymes, account for the various DNA forms encountered. © 1969.