Fig. 5. Blocking ecdysone signaling in da neurons with EcR^DN. (A) Projected z-stack of wild-type neurons (C161-GAL4>CD8::GFP) in the dorsal abdomen at 16 h APF. (B) Projected z-stack of neurons expressing EcR^DN (C161-GAL4>EcR^DN; CD8::GFP) in the dorsal abdomen at 16 h APF. No severed branches are present and only a few blebs of GFP are evident. Arrows indicate distal dendrites of ddaD and ddaE, arrowheads the distal dendrites of ddaF. Scale bar: 20 µm. (C) The proximal branches of dorsal da neurons in a wild-type animal at 16 h APF are thinned. Scale bar: 7 µm. (D) Equivalent proximal branches of dorsal da neurons expressing EcR^DN at 16 h APF show no thinning. Asterisk indicates cell bodies of ddaF and ddaB still present. (E) Distal region of branch in a wild-type animal at 16 h APF. Arrows indicate fragments. (F) Distal region of ddaD expressing EcR^DN at 16 h APF. Arrow indicates retraction bulb. (G) Dynamics of the pruning of dorsal da neurons expressing EcR^DN during early metamorphosis. Arrows indicate branch retraction. At 24 h APF the dendrite branches are shorter and the retraction bulbs have increased in size. Branches continue to retract (arrows). Arrowhead in 25 h 30 min and 26 h 40 min identifies a distal severing event. Scale bar: 20 µm (16 h APF); 25 µm (other times).