Disruption of NPHP-4 is sufficient to increase the velocity of WDR-60–deficient dynein-2 through the TZ region. (A) GFP::CHE-3 kymographs of phasmid cilia from the indicated strains. Single and merge channels for particles moving anterogradely and retrogradely are shown. Arrowhead labels the base, and white dashed line marks the limit of the TZ region (1 µm). Scale bars: vertical 5 s, horizontal 2 µm. (B) Frequency of IFT particles detected at the distal segment of cilia for each represented strain (n ≥ 23 cilia). (C) GFP::CHE-3 velocity moving in the anterograde and retrograde direction along the cilia of the indicated genotypes (n ≥ 345 particle traces were analyzed in ≥23 cilia for each strain). Gray rectangles highlight the TZ, as previously defined. (D) Average velocity of GFP::CHE-3 crossing the TZ region of the same cilia analyzed in C, for each indicated genotype. XY velocity graphs are shown as mean ± SEM, and graphs in columns are shown as mean ± SD. One-way ANOVA followed by Sidak and the Holm–Sidak multiple comparisons were used to analyze the datasets in B and D, respectively. *, P ≤ 0.05; **, P ≤ 0.01; ****, P ≤ 0.0001.