Fig. 3.

Scrib and Dlg are required for SAJ apical positioning and organization. (A-C″,I-K) Cross-sections. (A‴,B‴,C‴) MIPs. (D-F‴) En face sections through apical membrane (0 µm), SAJs (−3.6 µm), basolateral membrane and basal junctions (BJs), where red arrowheads indicate altered Arm localization or organization compared with wild type. (G,L) Heat maps. Arm puncta displacement along apical-basal axis, from MIPs, with pixel intensity plotted against distance from apical surface. Vertical bars indicate individual embryos. scrib-RNAi (B,E,J) or dlg-RNAi (C,F,K) disrupt Arm polarization during cellularization and gastrulation. Arm does not effectively enrich at apical SAJs (B-C‴, red arrowheads) or BJs (yellow arrowheads) and accumulates in puncta along the basolateral membrane (cyan arrowheads). (G) Heat maps showing Arm distribution from mid- to late-cellularization. (H) scrib-RNAi significantly reduces Arm enrichment in SAJs versus basolateral domain. Box and whisker plot (median, upper and lower quartile limits, and range). (I-K) Arm mislocalization after scrib-RNAi and dlg-RNAi persists during gastrulation (stage 7). (L) Arm distribution at stage 6-7. Scale bars: 10 µm.