Figure 2.

Loss of centrosomes and the SAC dramatically alters brain architecture. (A) Diagram of the third instar brain. Each hemisphere has an optic lobe and CB region containing many NBs (green and red circles). NBs expressed Dpn (green) and Mira (red). (B–M) WT, single, and double mutant brains stained for Dpn and Mira. (B–G) The horseshoe-shaped stripe of medulla NBs in WT (B and E) was also present in single mutants (C, D, F, and G), as was a normal lamina (H vs. I and J). Both were absent in mad2 sas-4 (K–M), though residual medullar NBs may have remained. WT and single mutant CB NB populations were similar (B–G, yellow arrows). In double mutants, some seemingly normal CB NBs remained (K–M, yellow arrows), though others were very enlarged (K–M, blue arrows). (N–T) WT and double mutants labeled with F-actin (phalloidin). F-actin labeling also revealed substantial medulla reduction and retention of CB NBs in double mutants (N vs. O) as well as reduction/disorganization of medullar axons and the medullar neuropil (P and S vs. Q, R, and T), though some neuroepithelial cells remained in double mutants (Q and T). (U and V) WT and double mutant brains labeled with FasII. Double mutants retained a mushroom body and commissural axons but lacked incoming axons from eye disc photoreceptors. IPC, inner proliferative center.