Motility analysis. (A) Swimming velocities of wild-type, oda2-t, and oda2 live cells (n = 50). The average velocity (standard deviation) for each strain (μm/s) was as follows: the wild type, 161.6 (9.2); oda2-t, 87.8 (9.4); and oda2, 50.6 (6.6). (B) Comparison of the average swimming velocities for the wild type and mutants deficient in outer-arm DHCs (n = 50). (C) Flagellar beat frequencies for the wild type and mutants deficient in outer-arm DHCs measured using the FFT method (22). (D) Images of isolated axonemes beating in a medium containing 1 mM ATP and 10−8 M or 10−4 M Ca2+. Six images are shown for a single axoneme with variable time intervals so as to illustrate the sequence of beat pattern. The beat frequency (standard deviation) measured for 20 axonemes under these conditions was as follows: at 10−8 M Ca2+, 69.5 (11.4) Hz for the wt, 48.4 (3.4) Hz for oda2-t, and 28.8 (2.8) Hz for oda2, and at 10−4 M Ca2+, 78.7 (13.2) Hz for the wt, 14.5 (2.7) Hz for oda2-t, and 15.1 (4.8) Hz for oda2. Temperature, 25°C. Bar, 10 μm.