FIG. 4.
Quantitative measure of complementation from β-galactosidase assays with strains MR1904 (carD3), MR1905 (carD′), MR1906 (carDSa), and MR1907 [carDSa(S198A)] bearing the reporter lacZ gene fused to the CarD-dependent promoter PQRS. Cell cultures were grown in the dark to exponential phase, divided in two, and grown for a further 6 h with one half in the dark and the other in light. Samples were then collected, and β-galactosidase activities (in nanomoles of o-nitrophenol produced per minute per milligram of protein) were measured. Values for cells grown in the dark (filled bars) and those exposed to light (empty bars) and the corresponding standard deviations are shown.