KLP-7 and PTRN-1 together maintain the mixed polarity state of microtubules in the posterior process. (A and B) The analysis of EBP-2::GFP dynamics in ptrn-1-(0) and ptrn-1 (juEx5550)[+]. The green and magenta traces represent microtubules of plus-end-out and minus-end-out polarity, respectively. (C) The histogram shows the fraction of plus-end-out (P) and minus-end-out (M) microtubules as obtained from the kymographs shown in B. Ant, anterior; Pst, posterior. (D) The percentage of PLM processes with microtubules oriented in either a unipolar or mixed manner as derived from C. For C and D, N = 3–5 independent replicates; n (number of neurons) = 23–63. (E) The punctae (magenta arrowheads) of centrosomal reporter Pmec-4::GIP-2::mCherry (shrEx413) in the cell body and posterior process of the PLM neuron. (F) Kymographs of EBP-2::GFP movies in the posterior process from early developmental stage L1 to L3. (G) The distribution of plus-end-out and minus-end-out microtubule populations in the posterior process as obtained from F. The red arrowheads represent the segregation of fraction polarity values into 1 and 0. (H) The fraction of unipolar versus mixed-orientation posterior processes as obtained from F and G. N = 3–4 independent replicates; n (number of neurons) = 28–60. For C and G, ***, P < 0.001; ANOVA with Tukey’s multiple comparison test. For D and H, ***, P < 0.001; Fisher’s exact test. Error bars represent SEM.