FIG. 4.

Growth curves of cells by optical density. Panel A, BR825 cells carrying pALA2529 (mvp⁺) (squares; shown also in Fig. 2 and repeated here for comparison), pALA1557 (par⁺) (circles), or pALA1286 (mvp⁺ par⁺) (crosses); panel B, growth of strain CC4118 carrying pALA136 (triangles), pALA2529 (squares), pALA1557 (circles), or pALA1286 (crosses). Cells were grown as described in the legend to Fig. 2, except that 25 μg of spectinomycin/ml was added to the CC4118 cultures to ensure the retention of the element that blocks P1par activity (see footnote to Table 1). A duplicate experiment gave virtually identical results.