Overexpression of activated WAVE results in border cell cohesion defects. (A) Quantification of border cell numbers in wild type and trans-heterozygous cyri mutant egg chambers. Statistical significance was tested using the Mann–Whitney test, P value = 0.343. WT: n = 27, cyriΔ11/Df: n = 30. Three independent experiments for each genotype were performed. (B–D) Maximum intensity projections of five confocal slices of stage 9 egg chambers overexpressing a membrane-tethered WAVE construct (WAVE^Myr) under the control of the C306 driver, stained for DNA (DAPI, blue), F-actin (phalloidin, grey), and anti-EYA (green); anterior is to the left. (B) Maximum intensity projection of a stage 10 egg chamber overexpressing WAVE^Myr. Scale bars represent 50 μm. White arrowheads mark border cells (bc). (C and D) Detailed views of boxed areas in B show an abnormally elongated border cell cluster and border cohesion defects. White arrowheads mark border cells (bc) whereas polar cells (pc) are marked by yellow arrowheads. Scale bar represents 10 µm. (E) Removal of one copy of wave in cyri mutant background reduced the lagging border phenotype, although the difference was not significant. N numbers are indicated, P value: ns = 0.1607, ***<0.001. (F) Gel filtration profiles of endogenous WAVE complexes from S2R+ cells overexpressing wild type CYRI (CYRI^WT) and Rac-binding deficient variant (CYRI^R163/164D) constructs. Complexes co-fractionated with high molecular weight complexes at 500–700 kDa sizes. The elution profile of proteins of known molecular mass is indicated at the bottom. Source data are available for this figure: SourceData FS4.