(A, B) Representative traces and quantification for baseline synaptic transmission at the third instar larval NMJ following muscle-specific perturbation in SMN. Both over-expression and knockdown of SMN result in smaller EJP and mEJP amplitudes. As a result quantal content is not significantly altered in experimental animals. 9–10 animals are tested for each genotype. Vertical scale bar = 10 mV for EJP and 5 mV for mEJP; Horizontal scale bar = 100 ms for EJP and 200 ms for mEJP. Mean resting membrane potentials are: Control = 74mV, UAS-SMN = 66mV, SMN-RNAi-C24 = 63mV, SMN-RNAi-N4 = 62mV. Mean muscle input resistances are: Control = 13.2MΩ, UAS-SMN = 12.4MΩ, SMN-RNAi-C24 = 12.5MΩ, SMN-RNAi-N4 = 11.8MΩ. (C) Staining of third instar synapses with anti-HRP and anti-GluRIII shows indistinguishable staining intensities and pattern of glutamate receptor distribution following SMN knockdown in muscles. Scale bar = 5 μm.