Fig. 2. Mis-expression of pspD reporter is rescued by the presence of wild-type cells in chimeric structures. Patterns of pspD reporter expression in wild-type, ampA^– and chimeric structures formed by 2 day bacteria-fed cells are shown. Samples were prepared as described in Materials and Methods. All samples shown were stained for ß-galactosidase activity for 2 to 3 hours. (A) 100% wild-type cells, reporter in all cells; 18 hours of development. (B) 100% ampA^– cells, reporter in all cells; 18 hours of development (C) 50% wild-type cells/50% ampA^– cells, reporter in all cells; 14 hours of development to show mound stage. Arrows in B,C indicate the position of prestalk cells at the mound periphery at this stage. These cells are stained in B, but unstained in C. (D) 50% wild-type cells/50% ampA^– cells, reporter in all cells; 18 hours of development. (E) 50% wild-type cells/50% ampA^– cells, reporter in ampA^– cells only; 18 hours of development. (F), 10% wild-type cells/90% ampA^– cells, reporter in all cells; 18 hours of development. Black arrows in A,D,E,F indicate the tips that are composed of prestalk cells and devoid of prespore cells. Gray arrows in E indicate clustering of ampA null cells carrying the pspD reporter clustering at the base of the prespore zone.