PCMs are regulated by meiotic progression but not by pairing. (A) Projections of selected time points showing GFP::HIM-8 and mCherry::histone from single nuclei in the TZ or the premeiotic zone. The left images show complete X PC trajectories overlaid on a projection of the initial time point. Times are given in minutes and seconds. Bars, 1 µm. (B) Step-size distributions of X PCs in premeiotic zone nuclei and TZ nuclei with unpaired X PCs (premeiotic: 2,248 steps, 38 trajectories, and 3 datasets; TZ unpaired: 1,443 steps, 26 trajectories, and 3 datasets). Mann–Whitney U test, P = 10⁻²¹². (C) Step-size distributions of unpaired and paired X PCs in TZ nuclei (TZ paired: 3,779 steps, 65 trajectories, and 6 datasets). Mann–Whitney U test, P = 0.85. (D) Fraction of steps >0.6 µm in different meiotic stages and in syp-1(me17), chk-2(me64) and sun-1(jf18) mutant animals (syp-1(me17): 2,698 steps, 45 trajectories, and 3 datasets; chk-2(me64): 1,620 steps, 30 trajectories, and 2 datasets; sun-1(jf18): 2,650 steps, 45 trajectories, and 3 datasets). (E) RMSD plots for all trajectories. The plateau at ∼2.5 µm reflects the distance limit for travel on the surface of a sphere ∼3.5 µm in diameter. (F) The change in distance between unpaired GFP::HIM-8 foci in TZ nuclei (vertical axis) is plotted as a function of the size of individual steps (horizontal axis). Longer steps, corresponding to PCMs, do not tend to bring X PCs closer together.