Dscam2B, but not Dscam2A, is expressed in the PNS. (A and A’) Co-labeling of HRP (gray) and Dscam2A>CD8GFP (green) in filleted larvae shows broad expression of Dscam2A in the central nervous system (AB, axon bundle; SN, sensory neuron) and lack of expression in the periphery. Scale bar, 150 µm. (B and B’) Co-labeling of HRP (gray) and Dscam2B>CD8GFP (green) in filleted larvae shows broad expression in the central nervous system and PNS. Sensory neurons (SN) can be identified in the body wall as well as axon bundles (AB), which contain afferent motor neuron axons and efferent SN axons. Scale bar, 150 µm. (C–C’’) Co-labeling of HRP (gray) and Dscam2A>CD8GFP (green) at motor neuron axon terminals contacting muscles 6/7 confirm lack of Dscam2A expression in both Ib and Is. Scale bar, 30 µm. (D–D”) Co-labeling of HRP (gray) and Dscam2B>CD8GFP (green) at motor neuron axon terminals contacting muscles 6/7 confirms that motor neurons express Dscam2B. At this NMJ, Dscam2B is detectable in Ib and not in Is. Scale bar, 30 µm. (E) Schematic of electrophysiology setup used in this study. Spontaneous and evoked potentials are recorded from a sharp electrode in muscle 6. The axon bundle innervating muscle 6/7 is stimulated with a second electrode. Two motor neurons innervate these muscles: Ib expresses Dscam2B, Is does not.