Western blots using specific antiserum against purified polar flagellins. Molecular weights are indicated. a, cytoplasmic fractions of strains: 1, A. hydrophila AH-3 (wild type); 2, AH-3ΔPseB mutant; 3, AH-3ΔPseF mutant; 4, AH-3ΔPseB mutant complemented with pBAD-PseB; and 5, AH-3ΔPseB mutant complemented with pBAD-PseBCj. b, A. hydrophila AH-3 (wild type). C, cytoplasmic fraction; M, whole membrane fraction. The fractions were separated as described under “Experimental Procedures.”