Replication and transcription in a convergent orientation cause higher levels of plasmid instability after HU induction than when in a codirectional orientation. Box plot of the percentages of change in plasmid stability in MEC1 cells carrying YHK8, AHP1, TSA1, and RNR3, in either convergent (−F) or codirectional (−R) juxtaposition relative to the ARS1 origin, after exposure to HU compared to the control (before exposure to HU) in a synchronous culture. Note that negative values denote increased plasmid loss. Each box encloses 50% of the data with the median value of the variable displayed as a line. The top and bottom of the box mark the upper and lower quartile (limits of ±25% of the variable population), respectively. The lines extending from the top and bottom of each box mark the minimum and maximum values within the data set.