Figure 5. Postsynaptic Ca²⁺ signals are selectively eliminated by input-specific botulinum neurotoxin (BoNT-C) expression.

(A) Schematic depicting silencing of MN-Is transmission by selective expression of BoNT-C in MN-Is. The postsynaptic Ca²⁺ indicator SynapGCaMP8f is indicated in the postsynaptic compartment, which should receive transmission only at MN-Ib neuromuscular junctions (NMJs). (B) Representative images and traces of spontaneous postsynaptic Ca²⁺ transients at MN-Ib and -Is NMJs using the new postsynaptic GCaMP8f indicator in Is>BoNT-C (w;MHC>GCaMP8 f /+;R29E07-GAL4/UAS-BoNT-C). Right: quantification of averaged transients, confirming that synaptic Ca²⁺ events are selectively eliminated at MN-Is NMJs but intact at MN-Ib. (C) Averaged traces and images of evoked postsynaptic Ca²⁺ transients at MN-Ib and -Is NMJs. Right: quantification of averaged evoked transients, confirming that evoked synaptic Ca²⁺ events are selectively eliminated at MN-Is NMJs but intact at MN-Ib. (D) Schematic depicting silencing of MN-Ib transmission by selective expression of BoNT-C in MN-Ib. (E, F) Similar analysis as shown in (B, C) at MN-Ib-silenced NMJs (Ib>BoNT-C; w;MHC>GCaMP8 f /+;dHB9-GAL4/UAS-BoNT-C). Synaptic Ca²⁺ events are selectively eliminated at MN-Ib NMJs but intact at MN-Is. Error bars indicate ± SEM. ****p<0.0001. Additional statistical details are summarized in Supplementary file 2.