Expression profiles of sigma factors with unknown function and the effects of down-regulation. (a) Expression profiles of CAC3267 (open triangles), CAP0167 (filled squares), and CAP0157 (open circles) as ratios compared to the first expressed timepoint. Gray bar indicates the onset of transitional phase. (b) Expression profiles of CAC0550 (filled circles), CAC2052 (open squares), and CAC1766 (filled triangles) as ratios compared to the first expressed timepoint. Gray bar indicates the onset of transitional phase. (c) Ranked expression intensities of the sigma factors. White denotes a rank of 1, while dark blue denotes a rank of 100 (see scale). Gray squares indicate timepoints at which the intensity did not exceed the threshold value. (d) Microscopy time-course of asRNA strains compared to WT and plasmid control strains. Microscopy samples from WT (I) and pSOS95del (II) cultures (as controls) and three asRNA strains taken for two timepoints over a course of 72 hours. At 72 hours, WT (I) and pSOS95del (II) exhibit the typical clostridial forms (white arrows), while asCAP0166 (III) shows advanced differentiation with forespores and endospores (orange arrows) already visible. Strains asCAP0166 (III), asCAP0167 (IV), and asCAC1766 (V) show a novel, extra-swollen clostridial form (yellow arrows).