(A) Representative traces from control (PBacf01736/PBacf02482 = parental line in which cmpyΔ8 deletion was generated), cmpyΔ8 homozygotes, and motoneuron rescue flies (D42Gal4, cmpyΔ8/UASCmpy, cmpyΔ8). Recordings were obtained from muscle 6 of abdominal segments A2-A4 at 1.0 mM extracellular Ca2+. Top traces are representative evoked EJPs and bottom traces are spontaneous EJPs. (B-D) Mean mEJP amplitude, mean EJP amplitude, and quantal content for the indicated genotypes (n = 18 for control, n = 17 for cmpyΔ8 homozygotes, n = 8 for D42Gal4, cmpyΔ8 and UASCmpy, cmpyΔ8 controls, and also for D42Gal4, cmpyΔ8/UASCmpy, cmpyΔ8 rescue). Mean mEJP amplitude is not significantly different for any of the genotypes compared to wild type. Mean EJP amplitude is decreased 28% in cmpy nulls and is fully rescued by neuronal expression of Cmpy. (E) Representative traces of evoked (top) and spontaneous (bottom) excitatory potentials from control (Canton-S), gbb1/gbb2 transheterozygotes, gbb1/gbb2; D42Gal4/UASGbb9.1, and gbb1/gbb2; D42Gal4 cmpyΔ8/UASGbb9.1 cmpyΔ8 larvae. Recordings were obtained from muscle 6 of abdominal segments A2-A4 at 1.0 mM extracellular Ca2+. (F-I) Mean mEJP amplitude, mean mEJP frequency, mean EJP amplitude, and quantal content for the indicated genotypes (n = 8 for control, n = 10 for gbb1/gbb2, n = 11 for gbb1/gbb2; D42Gal4/UASGbb9.1, and n = 11 for gbb1/gbb2; D42Gal4 cmpy∆8/UASGbb9.1 cmpyΔ8. (F) Mean mEJP amplitude is not significantly different for any of the indicated genotypes compared to wild type. (G) Mean mEJP frequency is reduced 74% in gbb null mutants and is fully rescued by motoneuronal gbb in the presence and absence of cmpy. (H) Mean EJP amplitude is decreased 70% in gbb mutants and is rescued to 88% of control levels in gbb1/gbb2; D42Gal4/UASGbb9.1 animals. Loss of Cmpy impairs the ability of motoneuronal Gbb to rescue evoked EJPs in gbb nulls by 30%. (I) Quantal content is decreased 67% in gbb mutants and is rescued by motoneuronal Gbb. Loss of Cmpy impairs the ability of motoneuronal Gbb to rescue quantal content in a gbb nulls by 26%. * p<0.05, ** p<0.01, ***, p<0.001, n.s. not significant. Error bars are SEM.