Whereas wild-type larval neuroblasts during asymmetric cell division expand the apical cortex during anaphase, the Pkn06736/Df(2R)w73-1 mutant neuroblasts first expand the basal cortex which subsequently retracts and then the apical cortex is enlarged, causing a temporarily inverted asymmetric anaphase figure followed by a symmetric one and finally normal asymmetric figure. The cell curvature along the apical-basal neuroblast cortex from early anaphase to telophase is also abnormal in Pkn06736/Df(2R)w73-1 neuroblasts: While wild-type cells show a cortical ingression (negative curvature) in a basally shifted position at early anaphase stage, this ingression develops into a pronounced cleavage furrow but remain at approximately the location. In contrast, the mutant neuroblasts initiate furrowing close to the apical cortex and this ingression then shifts basally during anaphase.
Even prior to anaphase, during metaphase, the Pkn06736/Df(2R)w73-1 neuroblasts display significant cell shape deformation of the apical cortex - both positive and negative changes in curvature while in wild-type neuroblasts the curvature change very little during metaphase.
This abnormal shape dynamics is underpinned by spatiotemporal aberrations in myosin localization pattern and activity.
Egg length is significantly reduced in Pkn06736/Pkn06736 female germline clones.
During nurse cell dumping, egg chambers mutant for Pkn06736/Pkn06736 show increased nurse cell-to-oocyte membrane collapse, leading to abnormal presence of ring canals, border cells and/or nurse cell nuclei in the oocyte cytoplasm.
Females with Pkn06736/Pkn06736 germline clones show intermediate abnormal accumulation of F-actin in nurse cells of stage 10 egg chambers.
No adult homozygotes emerge. 10% of homozygous embryos show a dorsal closure phenotype. Germline clones produced mutant embryos, about 55% of which showed defects in dorsal closure. No defects in patterning or in the central and peripheral nervous systems or somatic muscles were found. When embryos from germline clone mothers are examined for cell shape, despite apparently normal leading edge cell stretching, all epidermal cells adopt an unstretched polygonal shape.