Recordings in Mctp^OG9 mutant third instar larval neuromuscular junction under standard conditions show significantly decreased ESPS amplitudes and quantal content, but no changes in mEPSP amplitudes, as compared to controls. These neuromuscular junctions also show significantly decreased EPSC amplitudes across 0.3-1.5mM Ca[2+] concentrations, enhanced facilitation in short-term release (i.e. significantly increased PPR (EPSC[[4]]/EPSC[[1]]) at 0.7-1.5 mM Ca[2+] concentrations), significantly decreased EPSC average amplitudes and significantly decreased P[[train]], but no significant changes in cumulative EPSC or EPSC average rise time, as compared to controls. There are no measurable changes in action potential calcium influx (average peak amplitude of calcium transients and average decay for a either single action potential or trains of five action potentials), as compared to controls.

These neuromuscular junctions show a qualitatively normal microtubule cytoskeleton and show no change in active zone ultrastructure or vesicle distribution: no change in vesicle diameter; no change in the average number of vesicles per active zone; no change in the average vesicle distance from the center of the presynaptic T-bar; no change in the absolute length of the active zone.