Figure 5.

Dia is required for segmental groove morphogenesis. (A–A′) Wild-type, stage 13. Dia, and Arm colocalize at cell vertices (arrowhead). (B–B′) Wild-type, stage 12. Dia and F-actin accumulate apicolaterally in constricting cells (arrowhead). (C and C′) Wild-type, stage 12. Dia (green in C′) and F-actin (red in C′) accumulate at the posterior boundary of groove founder cells (marked by en-GFP in green). Dia and F-actin colocalize at cell vertices. (D and D′) Stage 12: levels of dia protein are strongly reduced in maternal and zygotic dia⁵ mutants. (E and E″) Stage 12: maternal and zygotic dia⁵ mutant. E-Cad is lost from the cell cortex in some areas, and F-actin is irregularly distributed in aggregates (arrowheads in E and E′). (F) Stage 12: wild-type embryo stained for E-Cad in green. (G) Stage 12: maternal and zygotic dia⁵ mutant. Because of failure of cytokinesis epidermal cells are frequently multinucleated (arrowheads). (H and H′) Stage 13: dia⁵ maternal and zygotic mutant. En (green) is distributed in segmentally repeated bands of cells. Segmental grooves do not form. (I and I′) Stage 12: maternally mutant, dia⁵ heterozygous embryo. Segmental grooves form at the posterior margin of en domains. Bars, 5 μm (A–G) and 20 μm (H and I).