Effects of Rtnl1 mutant alleles on presynaptic tdTom::Sec61β levels. (A) Representative examples of confocal projections and quantifications of WT and Rtnl1¹ larvae showing the distribution of the ER marker tdTom::Sec61β in Type I NMJs (muscles 1/9 NMJ). Samples were immunostained for tdTom, GFP, and Dlg to distinguish between Type Ib (arrows) and Type Is (arrowheads) NMJs. Genotypes: D42-GAL4, UAS-tdTom::Sec61β, UAS-CD4::tdGFP/+, in either WT or Rtnl1¹ background. (B) Representative examples of confocal projections and quantification of WT, Mut, OE, and Mut + OE larvae showing the distribution of the ER marker tdTom::Sec61β in Type I NMJs (muscles 1/9 NMJ). Genotypes: WT - Rtnl1⁺; D42-GAL4, UAS-tdTom::Sec61β/+, Mut - Rtnl1¹⁸/Rtnl1¹; D42-GAL4, UAS-tdTom::Sec61β/+ OE - Rtnl1⁺; D42-GAL4, UAS-Rtnl1::GFP/UAS-tdTom::Sec61β Mut + OE-Rtnl1¹⁸/Rtnl1¹ ; D42-GAL4, UAS-Rtnl1::GFP/UAS-tdTom::Sec61β. For A and B, plots show individual larval datapoints and mean ± SEM; y-axis indicates arbitrary units (au) after normalization to control (WT); sample size (number of larvae) is indicated within the plots for each genotype. For each larva, several NMJs between A2-A6 segments were analyzed, and the mean value is shown as a larval datapoint. Student’s t tests were performed for pairwise comparisons, except for tdTom::Sec61β intensity in Type Ib NMJ comparison (A), where a Mann-Whitney U test was performed. Scale bars, 10 μm.