Figure 5.

Loss of coordination of sporulation program with DNA replication in non-pulsing strains could lead to sporulation defects. A. Fraction of cells that have formed spores by 25hrs into starvation in different strains. Bars and error-bars respectively show the means and standard deviation of spore fraction calculated using 3 independent measurements for each condition.. B. Phase-contrast and fluorescence microscopy (PspoIIR-cfp) images from a time-lapse experiment showing the difference in timing of SpoIIR activation/Asymmetric septation in sporulation and sporulation defects. T0 represents the time of birth for each indicated cell (yellow outline). T2, T3 etc. indicate time after birth in hours. Time-point of SpoIIR activation/Asymmetric septation in each case is marked by blue box. Asymmetric septation and σ^F activation happen late in the cell-cycle (T5) during normal sporulation as compared to the sporulation defect cases. Early activation of σ^F in the whole cell at T2 results in cell death. Early asymmetric septation at T2 produce a small daughter cell (red outline) which dies without activating σ^F in the forespore. Scale Bars: 2μm. C. Quantification of number of defects per spore produced over 30hrs in starvation conditions by the pulsing WT strain (green bars) and the non-pulsing strains i0F^gltA (yellow bars) and Trans-kinA^amyE (purple bars). Error-bars indicate the standard deviation of 3 independent measurements. The defects/spore ratio is significantly higher for non-pulsing strains. D. Time difference between birth and SpoIIR (a σ^F reporter) activation/Asymmetric septation in cell-cycles that produce spores and those that end in lysis due to sporulation defects. SpoIIR activation/Asymmetric septation happens significantly earlier in cell-cycles that end sporulation defects.