Fig. 2. Targeted presynaptic dFMRP rescues all dfmr1-null NMJ structure defects. (A) Representative images of wandering third instar Drosophila larval NMJs; genotypes and treatments as shown. NMJs co-labeled for HRP (presynaptic marker) and DLG (postsynaptic marker), with three examples of each condition shown. (B-D) Quantification of NMJ synaptic branch number and area, defined for presynaptic area (HRP domain) and postsynaptic area (DLG domain). dfmr1-null terminals display overgrowth and over-elaboration. GS+E phenocopies dfmr1, and complete rescue occurs with RU486 constitutively driving presynaptic dFMRP expression. (E) Representative images of mini/satellite boutons; genotypes and treatments as shown. High-magnification images of boxed regions in A showing mini-boutons (arrowheads) in both dfmr1-null and GS+E genotypes and their absence following RU486 induction. (F,G) Quantification of normal (>2 µm diameter) and mini-bouton (2 µm diameter, attached to a normal bouton) number per NMJ in genotypes and treatments shown. n=12 animals for all conditions. Bars indicate mean±s.e.m. Dashed red lines highlight control level quantifications. ^**P<0.01, ^***P<0.001.