Effects on ciliogenesis of phosphodead OSM-3 mutants. (A) Amphid and phasmid cilia of osm-3^S96C mutant animals. Cilia are visualized with GFP-tagged endogenous mutant OSM-3. Arrows indicate the ciliary base. Arrowheads indicate the junctions between the middle and distal segments. Scale bar, 5 μm. (B) Quantification of cilium length (mean ± SD) in WT and phosphodead osm-3 mutant animals. N = 39–46 animals. Statistical significance, compared with the control with a matching color code, is based on Student’s t test. **P < 0.01; ***P < 0.001. (C) Histogram of anterograde IFT velocities of OSM-3^S96C kinesins at the middle (top) and distal (bottom) ciliary segments. Velocities and numbers of IFT particles (N) are indicated. The plots were fit by a Gaussian distribution. Statistical significance, compared with OSM-3^S96A with a matching color code, is based on Student’s t test. n.s., not significant. Data are mean ± SD. (D) IFT velocity summaries of OSM-3::GFP in animals of indicated genotypes. Comparisons were performed to osm-3^S96D and osm-3^S96A, respectively. n.s., not significant; *P < 0.05 by Student’s t tests. m.s.: middle segment; d.s.: distal segment. (E) Ciliary defects in the let-92 mutant animals were rescued with WT LET-92 expressed under the control of ciliated neuron-specific promoter Pdyf-1. Scale bar, 5 μm. (F) Histogram of OSM-3::GFP velocities in animals of indicated genotypes. (Top) anterograde IFT along the middle segments (Antero. m.s.). (Middle) anterograde IFT along the distal segments (Antero. d.s.). (Bottom) retrograde IFT (Retro.). Each plot was fitted by a Gaussian distribution. Comparisons were performed between WT and other strains. n.s., not significant; ***P < 0.001 by unpaired Student’s t tests. m.s.: middle segment; d.s.: distal segment.