Ectopic BrZ3 expression generated a stereotypic ectopic arbor in the adult dbd neuron during metamorphosis. (A, B) Morphology of the dendritic arbor of the dbd neuron in the last larval stage of controls (A: C161-GAL4 > UAS mCD8::GFP) and individuals expressing BrZ3 (B: C161-GAL4 > UAS mCD8:GFP, UAS-BrZ3 dbd [dbd[+BrZ3]]). (C-E) The effects of expressing different Broad isoforms in dbd on its dendritic morphology at the end of metamorphosis. (C) Pharate adult morphology of dbd[+BrZ3]; arrowhead, anti-Broad-Core immunostaining. (D) Morphology of dbd[+BrZ1] is similar to control. (E) Morphology of dbd[+BrZ4] was variable but typically maintained contact with muscles. Bracket: dbd arbor in adjacent muscle grooves. (F) Control pharate adult dbd. (F') Y-projection. (G, H) Examples of dbd[+BrZ3] ectopic combs (brackets) posterior to dorsal abdominal muscles. Loss of anterior dendrites (asterisk) occurred in 25% of dbd[+BrZ3] neurons. (G', H') Y-projections showing the ectopic comb (arrows) was superficial to the muscle layers, veering toward the cuticle. (I, I') MAP1B-like antibody labeled microtubules in the ectopic arbor 'backbone' and some branches (arrowhead): green, anti-CD8; magenta, Futsch; 50 h APF. (J) Control neurons (black) had thicker dendritic bundles than dbd[+BrZ3] neurons (green). The trend line shows a significant negative correlation between dorsal-ventral ectopic arbor height and main bundle thickness among dbd[+BrZ3] (r = -0.49, P < 0.01). Scale bar = 50 μm. Immunostaining except for (I): green, anti-CD8; magenta, phalloidin.