Figure 1. The chromosome of Salmonella divided into quarter segments calibrated in minutes and megabasepairs (Mbp).

The locations of the origin of chromosome replication (oriC) and the site at the mid-point of the chromosome terminus at which chromosome dimers are resolved by site-specific recombination (dif) are indicated. The locations and directions of transcription of the stpA and hns genes are shown. The numbers in parentheses are the coordinates (in Mbp) of the first nucleotides of their open reading frames; the zero reference point is at 100 minutes (4.8 Mbp). The chromosome is bi-directionally replicated from the origin to the terminus and in Salmonella the stpA and hns genes are both located in the left replichore.