The Chromosome of Escherichia coli

Abstract

Autoradiography of Escherichia coli, labeled with tritiated thymidine and lysed with duponol, has shown that the bacterial chromosome comprises a single piece of DNA which is probably duplicated at a single growing point (Cairns, 1963). Further, it seemed likely from the variety of structures seen that this DNA is in the form of a circle while it is being replicated, even though no intact replicating circles had, at that time, been found.