Figure 5.

Boule expression inhibits axon pruning of γ neurons. A, 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′, B′, Single confocal section through OK107-GAL4 labeled cell bodies from wt (A′) or EP3659 (B′) larval MB neurons immunostained against Boule protein. C, 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 before axon pruning in third-instar larvae (C₁, D₁), at the peak of axon pruning in 12 h APF pupae (C₂, D₂), and in the adult (C₃, D₃). The solid arrows denote intact axons; the dashed arrows denote degenerating axons; and the 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 bars, 50 μm.