KLP-7 is necessary and sufficient to maintain dynamic microtubules in the PLM neuron. (A) Illustration of the PLM neuron and kymographs of EBP-2::GFP reporter. Red and orange ROIs were used for the analysis of time-lapse movies (Video 1) of the Pmec-4::EBP-2::GFP (juIs338) reporter. Green and magenta arrows represent the microtubules of plus-end-out and minus-end-out polarity, respectively. (B) Representative kymographs (inverted grayscale) of EBP-2::GFP dynamics (Video 1) obtained from the ROIs in A in WT, klp-7(0), and Pmec-4::KLP-7B (shrEx95)[+]. The green and magenta traces represent microtubule growth events away from the cell body/plus-end-out and toward the cell body/minus-end-out, respectively. In all kymographs, the length (x axis) and time (y axis) scales are 10 µm and 10 s, respectively. (C) The histogram shows the fraction of microtubules with plus-end-out (P) or minus-end-out (M) polarity. The red arrowheads represent the segregation of fraction polarity values in the posterior process into 1 and 0 in the klp-7 mutant. N = 3–8 independent replicates, n (number of neurons) = 28–63. Ant, anterior; Pst, posterior. (D) The percentage of PLM processes with microtubules oriented in either unipolar or mixed manner. N = 3–8; n = 28–63. (E and F) Growth length and duration of the EBP-2::GFP tracks were measured from net pixel shift in the x and y axes, respectively, as indicated by the double-headed arrows in B. N = 3–4 independent replicates; n (number of EBP-2 tracks) = 92–628. (G) Kymographs of Pmec-4-GFP::PTRN-1 (juEx6455) reporter in WT and klp-7(0). (H) The number of growing minus ends in PLM processes as obtained from G. n = 3–5 independent replicates, n (number of neurons) = 16–25. (I) Kymographs obtained from the time-lapse movie (Video 2) of the Pmec-7-GFP::RAB-3 (jsIs821) reporter show the events of anterograde (green arrow trace) and retrograde (magenta arrow trace) movement. The white arrows show the stationary particles, whereas the red arrowheads represent RAB-3 particles frequently switching direction. (J and K) Quantification of the anterograde (Anter) and retrograde (Retr) movement events of GFP::RAB-3 particles obtained from I. N = 3–8 independent replicates; n (number of neurons) = 31–56. (L) Reversal frequency as measured by the number of reversal events divided by the total number of events. N = 3–5 independent replicates; n = 17–40 (number of neurons). For C, E, F, H, and J–L, *, P < 0.05; **, P < 0.01; ***, P < 0.001; ANOVA with Tukey’s multiple comparison test. For D, **, P < 0.01; Fisher’s exact test. Error bars represent SEM.