Fig. 5. Boule expression inhibits axon pruning of γ neurons.

(A and B) Axons of wt (A) and EP3659-expressing (B) adult MB neurons. OK107-GAL4 drives expression of mCD8::GFP and EP3659 in all classes of MB neurons. Immunostaining against FasII (magenta) weakly stains γ neuron axons and strongly stains α/β neuron axons. FasII positive axons outside of the α lobe are unpruned γ neurons (γ*). (A’ and B’) Single confocal section through OK107-GAL4 labeled cell bodies from wt (A’) or EP3659 (B’) larval MB neurons immunostained against Boule protein.

(C and D) Developmental axon pruning of wt γ neurons (C) and γ neurons expressing EP3659 (D). The γ-neuron specific driver 201Y-GAL4 marks γ neuron axons prior to axon pruning in third instar larvae (C₁ and D₁), at the peak of axon pruning in 12 hours APF pupae (C₂ and D₂) and in the adult (C₃ and E₃). Solid arrows denote intact axons; dashed arrows denote degenerating axons; dashed yellow line denotes the midline. All images are confocal Z projections visualized using anti-mCD8 (green) for mCD8::GFP and anti-FasII (magenta) labeling. n ≥ 12 brains for each time point. Scale, 50 µm.