Fig. 2: Neuronal expression of untagged and ALFA-tagged transgenes, but not Nrx-1-GFP, rescue the functional deficits at Nrx-1^null NMJs.

a–e Representative confocal images of NMJ 6/7 and NMJ4 from third instar larvae of the indicated genotypes stained for Horseradish peroxidase, HRP (green), which labels neuronal surface, and Cysteine-string protein, CSP (magenta), which labels presynaptic vesicles. These experiments were repeated three times with similar results. Scale bars, 20 µm. f–h Quantification of bouton number (f and h) and NMJ length (g) in the indicated genotypes; n = 10 for each genotype. i–m Representative traces of miniature junctional potentials (mEJPs) and evoked junctional potentials (EJPs) in control, Nrx-1^null mutant, and neuronally rescued larvae as indicated. EJPs are reduced at Nrx-1^null mutant NMJs and are restored upon neuronal expression of Nrx-1 or Nrx-1-AT but not GFP-tagged transgenes. n–q Quantification of mEJPs amplitude, mEJPs frequency, EJPs amplitude, and Quantal Content of the indicated genotypes; n = 9 for each genotype. Data are represented as mean ± SEM (one-way ANOVA with Tukey’s multiple comparisons); ****p < 0.0001, **p < 0.005, ns, p > 0.05. The boxes expand from the first to the third quartile, and the whiskers from minimum to maximum values; the center lines mark the mean values. Source data are provided as a Source Data file. Genotypes: control (w¹¹¹⁸), Nrx-1^null (Nrx²⁷³/Df), Nrx-1^null; MN> Nrx-1^{tag/no tag} (BG380-Gal4/+; UAS-Nrx-1^{tag/no tag}/+; Nrx²⁷³/Df).