Fluctuations in spo0A Transcription Control Rare Developmental Transitions in Bacillus subtilis
Figure 1
Growth and transcription from spoIIG, spo0A, and abrB promoter fusions to luc in DSM medium.
(A) The gray curve depicts growth measured by optical density at 600 nm. The gray line connects the OD points, which are not visible, but were taken every 1.5 minutes. The arrows point to inflection points in the growth curve. The open triangles show relative luminescence readings corrected for OD for the spo0A promoter and the heavy line shows the same for the spoIIG promoter. The ordinate scale to the left (×105) refers to the spoIIG promoter. The growth curves of these two strains are nearly identical (not shown). T0 is indicated by the downward pointing arrow. (B) Growth rate and transcription from the abrB promoter. Strains expressing luc from a promoter fusion to abrB were grown in DSM. The open circles indicate results for the spo0A+ background and the solid gray squares for a spo0A strain. The growth rate was numerically determined and is indicated by the gray line. Slightly negative values for growth rate indicate some lysis that occurred after T0. T0 is indicated by a downward pointing arrow for each strain, black for the wild type and grey for the spo0A mutant.