Expression of the translational sspG-lacZ fusion in various spo mutants. Strains with a PY79 background (A) and a CU267 background (B) were sporulated by the resuspension method, and β-galactosidase was assayed as described in Materials and Methods. Time 0 is when sporulation was initiated. The symbols used for the various strains are as follows. (A) •, IB470 (spo+); ○, IB469 (spoIVCB), (B) •, IB492 (spo+); ■, IB494 (gerE36); ▵, IB498 (this strain does not contain an sspG-lacZ fusion but rather has a cotA-lacZ fusion in a spo+ background).