Additional analysis of Cytochalasin B treatments.

(A) Apical and basal planes for cells in tissues treated as in main Fig 2C–2G, with the addition of the fluorescent phalloidin channel, which stains total filamentous actin (white). Green = anti-GFP, bristle precursor cell; red = anti-Scabrous; blue = DAPI, staining DNA. Tissues have been treated for 5 minutes with either DMSO (upper panels) or Cytochalasin B (lower panels). Apical panels demonstrate that junctional actin is still observable even after 5 minutes of Cytochalasin B treatment. Basal panels demonstrate that basal signaling filopodia are sensitive to 5 minutes of cytochalasin B treatment. Genotype: neur-GAL4, UAS-GMCA/+. (B) Intracellular Scabrous puncta of bristle precursor cells analyzed in main Fig 2F–2G. Anti-Scabrous positive puncta that colocalized with anti-GFP were considered intracellular for bristle precursor cells. Apical puncta were counted in a single apical z-plane. (n) = number of cells analyzed. A minimum of 5 nota were analyzed per condition. NS values: 5 min DMSO v CytB, p>0.99; 30 min DMSO v CytB, p = 0.57; 60 min DMSO v CytB, p>0.46, by Kruskal-Wallis multiple comparisons test. Mean ± SD shown. (C) Basal puncta were counted in a single basal z-plane. Treatment times and conditions are listed. NS values: 5 min DMSO v CytB, p>0.99; 30 min DMSO v CytB, p = 0.39; and *, p = 0.05 by Kruskal-Wallis multiple comparisons test. Mean ± SD shown. (TIF)