Cell cycle parameters of MG1655 cells grown in the absence or presence of 5 mM.

HU.
aτ is the generation time in minutes from one representative cell culture used in the flow cytometry and immunostaining experiments.
bAverage DNA content, cell mass and DNA per mass were derived from flow cytometry measurements from the cell culture in a. as described in Materials and Methods. All values are relative to MG1655 grown without HU.
cThe oriC/terC ratio was determined by Southern blot analysis and quantitative PCR as described in Materials and Methods and is the average from 2–5 independent experiments. The standard deviation is included.
dThe C+D period (in minutes) was determined from the DNA histogram of cells treated with rifampicin and cephalexin and the generation time as described in Materials and Methods.
eThe C period (in minutes) was found from the formula oriC/terC = 2C/τ. The average τ- value from 2–5 independent experiments was used in the calculation.
fThe D period (in minutes) was found by subtraction of C from C+D.
gFor calculation of average number of forks per cell, see Materials and Methods and legend to Figure S1.