Complementation experiments of E. coli (ec) proton-type motor and switch mutants with V. parahaemolyticus (vp) sodium-type genes. Strains: 1, DFB232 (ΔfliMN)/pLM2047 (containing V. parahaemolyticus fliF locus); 2, DFB232/pLAFRII (parental vector control); 3, DFB228 (ΔfliM)/pLM2047; 4, DFB228/pLAFRII; 5, DFB225 (ΔfliG)/pLM2047; 6, DFB225/pLAFRII; 7, DFB210 (ΔmotAB)/pLM2058 (containing V. parahaemolyticus motAB); 8, DFB210/pLM1796 (containing the V. parahaemolyticus lafTU locus, which contains the lateral, proton-type motor genes); 9, DFB9 (wild type)/pLM1877; 10, DFB9/pLM2294; 11, DFB9/pLM2296; 12, DFB9/pLM2297. Plates A to C were incubated at 37°C for 60, 48, and 8 h, respectively. M agar in plates A and B contained 10 μg of tetracycline/ml for maintenance of the plasmids. M agar in plate C contained 40 μg of gentamicin/ml and 0.5 mM IPTG for induction of transcription of the fli genes contained on the expression vector pLM1877. fliMs, fliMshort.