Figure 5.
Mutation in asl affects the fidelity of polarity orientation in larval NBs. (A and B) Still images from time-lapse recordings of larval NBs expressing tubulin-GFP. Division axes and daughter cells are highlighted by color-coded lines and circles, respectively, for successive divisions (yellow, first; and green, second). The orientation of each division was judged by the position of the midbody (arrowheads). (A) In control NBs, the orientation of successive divisions varies little, and the interphase aster (t2, asterisk) coincides with the location of the apical spindle pole of the previous division (t0 and t1) and allows predicting the position of the apical spindle pole in the next division (t4). (B) asl mutant NB dividing twice (Video 9). Interphase asters are absent (t2), and variations in the orientation of the division axis were observed: in contrast to controls, daughter cells resulting from two consecutive divisions were born, in this case, separated by several daughter cell diameters (t1 and t4). (C) Plot of daughter cell bud site variations in asl mutant NBs (green) compared with control NBs (yellow). Time is shown in hours:minutes:seconds. Bar,10 µm.