Figure 6: dlg mutants display defects in pair pulse facilitation and in the calcium dependency.

(A) Representative traces of synaptic current recordings at 0.2 mM or 2 mM extracellular calcium concentration for WT, dlg mutants and CAC1 expressing dlg mutants in response to two stimulus separated by 20 ms. (B) Top: quantification of the pair pulse facilitation. The responses are normalized to the first pulse⁴³. All mutants display increased facilitation that is rescued by the presynaptic expression of Cacophony, Bottom: quantification of the pair pulse depression. The responses at this calcium concentration are normalized to the first pulse⁴⁴. All mutants display decreased depression that is rescued by the presynaptic expression of Cacophony. Panels (C–E) left represent the average quantal content of the evoked synaptic current responses at different extracellular calcium concentrations for WT and the different dlg genotypes. The panels on the right present the data normalized to the maximal value for each genotype calculated by the curve fitting shown in the left. (C) Average quantal content of the evoked synaptic current responses at different extracellular calcium concentrations for WT and dlg mutants. (D) Average quantal content of the evoked synaptic current responses at different extracellular calcium concentrations for the motoneuron driver (GAL4-OK6) or the muscle driver (GAL4-C57) in the dlgS97⁵ mutant background with or without (genetic mutant control) expression of UAS DLGS97. (E) Average quantal content of the evoked synaptic current responses at different extracellular calcium concentrations for the motoneuron driver (GAL4-OK6) or the muscle driver (GAL4-C57) in the dlgA^40.2 mutant background with or without (genetic mutant control) expression of UAS DLGA. Each data in (B–D) corresponds to the average ± SEM of six larvae with at least 20 synaptic responses recorded. *p < 0.05, **p < 0.01 respect to the WT.