Conservation of the B. subtilis sporulation regulatory cascade in Epulopiscium sp. type B. Sporulation-specific sigma factors (circles), associated transcription factors (diamonds) and other signal transduction or regulatory proteins involved in sigma activation (rectangles) are shown. Colors of the proteins indicate the gene presence in Epulopiscium (green), on the core list but not in Epulopiscium (red), and absence from the core list (blue). Control of gene expression is indicated by dotted lines and arrows. Signaling pathways and other protein interactions are denoted with solid lines and arrows. Temporal transcriptional progression through the cascade is shown by the position on the diagram with earlier stages near the top. A detailed explanation of the regulatory cascade as it occurs in B. subtilis is provided in the text. Figure is adapted from de Hoon et al. (2010).