Mislocalization of <i>nanos (nos)</i> gene product causes egg chamber fusion in <i>lky</i>^<i>KO</i> ovaries.

A-B) Representative images of nanos (nos) mRNA FISH of control (A) and lkyKO (B). Surface views of Stage 3 egg chambers are shown. In (B), mEOS specifically expressed in the lkyKO germline is present in the FCs. Broken lines in B indicate the boundary of mEOS-positive (upper side) and negative (lower side) FCs. mEOS-positive FCs are also positive for nos mRNA. C) A representative image of ectopic expression of nos (with tubulin 3’UTR to enable translation in somatic cells) using c587-Gal4; Tub-Gal80ts driver shows egg chamber fusion after 4-days temperature shift in 29°C. D) A graph shows percentages of ovarioles with fused egg chambers. Introducing hypomorphic alleles of nos (nosL7 and nosBN) in the lkyKO background reduced the frequency of egg chamber fusion. For D, 30 ovaries were used from three individual experiments. E-F) IF staining for Vasa, Stat92E, and LaminC, showing stalk cells marked by LaminC and Stat92E expression in control (E) versus a fused egg chamber in lkyKO (F). G) A graph shows frequency of ovarioles of indicated genotypes with stalk cell mislocalization. H) A representative image of ectopic expression of nos using c587-Gal4; Tub-Gal80ts driver showing stalk cell mislocalization. I) A model for germline leakage causing egg chamber fusion in lkyKO ovaries. Contents from the germline leak into follicle cells and cause a defect in their specification and patterning, leading to egg chamber fusion. Adjusted P value from Dunnett’s multiple comparisons test is shown for C, and P value from Student’s t-test in G. For all data points, a minimum of 20 ovaries were used from two individual experiments. Scale Bars: 10μm.