Cycle-specific replication of chromosomal and F-plasmid origins.

There have been various proposals for the pattern of F-plasmid replication during the division cycle. Here we show that the recent studies of Gordon et al. (Cell 90, 1113-1121, 1997) on the duplication and segregation of green fluorescent protein (GFP) labeled replication origins of the Escherichia coli chromosome and the F plasmid during the division cycle support the proposal that the F plasmid replicates with a cell-cycle-specific (artiocyclic) pattern.