A, immunological analysis of WT and petC-deficient Synechocystis PCC 6803 strains using antibodies against the major subunits of the cytochrome b6f complex (cytochrome f, cytochrome b6, and SU IV) and CydA. B, effects of HL on growth rates of WT and ΔpetC mutants. Cultures with identical initial optical densities have been exposed to LL for 28 h, followed by HL illumination for 30 h, and then by LL again. Error bars indicate the S.D. of three to five independent experiments.