Probing the mechanism that controls the fidelity of polarity orientation in larval NBs. (A–D) Still images from time-lapse recordings of larval NBs. Fluorescent reporters are indicated to the left of each row. Division axes, daughter cells, and apical crescents are highlighted by color-coded lines, circles, and asterisks, respectively, for successive divisions (yellow, first; green, second; and red, third). (A) An NB mutant for pins. This cell, which lacks interphase asters, divides three times, producing daughters that are scattered over an arc of ∼180° (t0 and t2; Video 10). (B) An NB mutant for polo. Two inactive centrosomes (arrowheads) are visible in interphase (t1). (C) An NB expressing Khc-73 RNAi. The arrow in t1 points to the stable microtubule-nucleating apical centrosome. (D) An NB expressing Par-1–GFP. The arrow in t1 points to the apical aster during interphase. (E–H) plots of apical crescents or daughter cell budding site variations in NBs mutant for pins (E) or polo (F) or expressing Khc-73 (G) or Par-1–GFP (H). Green indicates mutant NBs and yellow indicates control (worniu-Gal4 UASCherryTubulin) NBs. Time is shown in hours:minutes:seconds. Bars,10 µm.
