Down- and up-shift responses of strain BIB1300, which harbors a PrapA-mCherry promoter fusion that reports on sporulation timing and in which Ald expression can be controlled by an IPTG-inducible promoter. Cells were spotted onto an SM* gel pad. At the indicated time IPTG was added to the pad. This results in the expression of Ald in the progenitor cells of late spores. After sporulation was complete, spore revival was induced with L-alanine. The spores that will grow out are circled. Note that red-fluorescent late spores are able to grow out successfully.