PGC nuclear position predicts the site of lobe formation. (a, c, and e) PGC nuclei before (a), just before (c), and just after (e) lobe formation; dashed lines indicate PGCs. (b and d) Quantification of PGC nuclear positions before the period of lobe formation (b) and just before lobe formation (d). The center of the nucleus is shown relative to the center of the PGC, with scaling indicating distance in microns. Approximate position of the PGC plasma membrane is shown. (f) Position of lobe formation relative to the medial-lateral axis. (g–i) Centrosome position (arrowhead in h) in PGCs determined using the SPD-2-GFP marker. (j) Temperature-shift regime IV, used for experiment in l–o’. (k) Quantification of lobe formation in binucleate zen-4 mutant embryos pooled from six experiments. (l–o’) Mononucleate control and binucleate zen-4 PGCs. DIC images reveal nuclear localization (dashed lines outline PGCs, nuclei are in clear regions). Green checkmark represents successful P4 division, red X indicates failed P4 division. * indicates nuclear position, and L indicates the lobe. ns, not significant. Fisher’s exact test. Scale bar, 5 µm.
