Fig. 6. Effect of cAMP on flagella inhibited by PRODAN-UV at the basal region (5–10 µm) in various concentrations of ATP and cAMP. MgATP concentrations were 10 µmol l^–1, 200 µmol l^–1 and 1 mmol l^–1. cAMP concentrations were 0 µmol l^–1, 5 µmol l^–1, 50 µmol l^–1 and 200 µmol l^–1. Key: move, intact distal portion shows sinusoidal, vigorous movement; tremble, intact portion does not show sinusoidal movement but does show slight vibration; stop, intact portion shows no movement. N=20 flagella examined for each condition.