Fig. 2. Dynamics of dying da neuron dendrites. (A) Frames from Movie 1 (see supplementary material) of wild-type neurons (C161-GAL4>CD8::GFP) in the dorsal region of the prepupa (boxed region in Fig. 1B). The drawing shows distal arbors of ddaF (yellow), ddaB (green) and ddaD (blue) at 0 h APF. At 0 h arbors have a uniform caliber indistinguishable from those of the larva. By 2 h APF the dorsal branch of ddaF develops constrictions and swellings (yellow arrows). By 3 h APF the swellings become bead-like (yellow arrows). Between 3 and 4 h APF the branch severs, leaving blebs of GFP. The branches of ddaB generate swellings (green arrows). Between 4 and 6 h they sever, and the GFP blebs rapidly disappear, leaving only ddaD intact (blue arrow). Scale bar: 20 µm. (B) Projected z-stacks of ddaF in a wild-type animal (C161-GAL4>CD8::GFP). Cell bodies and proximal arbor (p) are shown on the left with the distal (d) dorsally projecting arbors on the right. At 1 h 30 min a distinct bead forms at a proximal branch point (arrow), whereas the most distal part (to the right) is intact. By 3 h the distal region is completely beaded. At 4 h the beads have moved position. Scale bar: 25 µm. (C) Projected z-stack of dorsal abdomen of wild-type (C161-GAL4> tub::GFP) at 3 h APF. The distal and proximal regions (boxed) are shown in the panels on the right. The distal arbor of ddaF has distinct beads (yellow arrows) whereas ddaD has a uniform distribution of tub::GFP (blue arrow). The nucleus and the proximal branches of ddaD and ddaE are intact, next to remains of ddaF (yellow arrowhead) and ddaB (green arrowhead). Dorsal is up and anterior to the left. Scale bar: 40 µm. (D) p35 inhibits cell death in all neurons expressing GFP and p35 at 5 h APF (C161-GAL4>CD8::GFP, p35). Left panel shows intact cell bodies; arrowheads indicate ddaF and ddaA (yellow), ddaB, (green), and ddaD and ddaE (blue). The arbor of ddaD (blue arrow) would normally be the only one left by this time in development. Right panel shows distal arbors of the same cells. Scale bar: 30 µm. (E) At 18 h APF all neurons are still alive in C161-GAL4 animals expressing p35. Arrow indicates intact primary branches of ddaB and ddaF. Scale bar: 30 µm.