DNA Replication in Escherichia coli: Location of Recently Incorporated Thymidine Withi Molecules of High Molecular Weight DNA

Abstract More than 50% of the [3H]thymidine incorporated during short pulses into the DNA of Escherichia coli 15T- can be extracted by alkali as high molecular weight DNA. Density gradient centrifugation and digestion with exonuclease I suggest that these large pieces of DNA are composed of newly synthesized DNA attached to pre-existing material at the 3′ end of the molecule.