Figure 4.

The heterogeneity of hcn plasmid segregation. (A) A scheme showing the simplified impeded model of plasmid segregation, which includes two segregation steps and an intervening replication step. This model represents the processes of plasmid transfer between cell halves and the doubling of the plasmid copies after replication. (B) The proportion of inheritance (N_D/N_P) of plasmids (green spots) with respect to the copy number in parent cells (left panel) is shown. Each spot indicates a single division event. The upper boundaries of the yellow (gray dashed line) and orange (black dot-dashed line) regions are predicted from the deviations of the probability distributions following the simple random segregation model (analytical solution, 0.5 + N_p^−1/2) and the impeded segregation model (numerical solution), respectively. The right panel shows the probability distribution of the proportion of inheritance from the experimental results (green bars) as well as the prediction from the random segregation scenario (gray dashed line) and the impeded segregation model (black dot-dashed line). Because of symmetry and the fact that all plasmids should be eventually segregated into either one of the daughter cells, only the half region of the proportion of inheritance (N_D/N_P ≥ 0.5) is shown. To see this figure in color, go online.