Figure 1

NMJ overelaboration in Fak56 mutants. (A, B) Muscular and axonal patterns in A3 segments shown by horseradish peroxidase (HRP)-labeled axonal branches of motor neurons (green), and Pha-labeled muscular pattern (magenta). NMJs 6/7, 12/13 and 4 are shown for wild-type (A) and Fak56^{N 30/K 24}(B). In these and all other figures, scale bars represent 20 μm unless specifically indicated. (C, D) NMJ 6/7 phenotypes in A3 segments shown by HRP-labeled axons (green), Syt-labeled synaptic boutons (red) and Pha-labeled muscles (not shown). Arrows and arrowheads indicate type Ib and Is boutons, respectively. (E) Quantification of bouton numbers and total branch length that are normalized to total muscle 6/7 areas for wild-type, Fak56^{N 30/K 24}, Fak56^{N 30/K 24};elav>Fak56, and Fak56^{N 30/K 24};MHC>Fak56. In this and all following quantifications, values are mean ± SEM, asterisks indicate p < 0.05 by Student's t test and sample numbers are within each bar. (F-H) NMJ 4 in A3 segments of wild-type (F) and Fak56^{N 30/K 24}(G) are labeled as in (C, D), and quantifications of bouton number and total branch length are shown in (H). (I) Quantification for the number of branches at NMJ 6/7s of wild-type and Fak56^{N 30/K 24}. Branches originating from the nerve entry point are primary (1°), and subsequent branches with at least three boutons are defined progressively with one higher order (2°, 3° or >3°). (J, K) Electrophysiological recording of postsynaptic currents in wild-type and Fak56^{N 30/K 24}in 0.2 mM [Ca²⁺]. (J) Cumulative frequency plot to compare amplitudes of mEJPs in wild-type and Fak56^{N 30/K 24}. (K) Representative traces (left panel) and mean peak amplitude (right panel) of EJPs in wild-type and Fak56^{N 30/K 24}. Calibration: 30 ms, 5 mV for evoked release.