Fig. 3

ogre mutants have both maternal and zygotic cytokinesis defects. (A-D) DIC bright field recordings of the zygotic cytokinesis defect. Panels are selected frames from two simultaneously recorded video time-lapses. (A) Wild type and (B) mutant sibling at the onset of gastrulation (6 h), initially mononucleate cells (blue) round up, divide and separate before fusing back together in the mutant. (C) Mid gastrulation (8 h), mutant cells attempting to divide round up and exhibit tiny projections over their cell surface, some cells (violet) fail to complete furrow ingression whereas other cells (blue) do. (D) Late gastrulation (9 h), binucleate mutant cells (green) also exhibit projections as they round up only no cleavage furrow forms. (E) Schematic of cytokinesis defects. Early gastrulation, daughter cells separate, but fuse back together. Late gastrulation, the furrow regresses and cells fuse back together. (F) Fluorescent recording of the transient maternal cytokinesis defect. At onset of epiboly (4.3 h), an enveloping layer cell (labeled with lineage tracer) in a phenotypic wild-type embryo completes furrow ingression before fusing back together. An hour later the binucleate cell rounds up and exhibits violent protrusive activity before it successfully divides into two characteristic enveloping layer cells.