Fig. 5: Characterization of YARS1^CMT-induced defects at the Drosophila larval NMJ by genetic modulation of the actin-bundling protein Fim.

a Neuronal expression of YARS1 rearranges presynaptic F-actin (Lifeact::Ruby) from the bouton border proximity (arrows) inwards. Scale bar – 5 µm. b Quantification of the Lifeact::Ruby signal redistribution, as detailed in the Methods and Supplementary Fig. 8a; n = 12 NMJs from six larvae per genotype; ***p = 0.0006 and p < 0.0001 for YARS1^WT and YARS1^E196K respectively after a two-sided unpaired t test. c FRAP image sequences of the SV marker Syt::eGFP co-expressed with dYARS1^WT or dYARS1^CMT. Scale bar – 2 µm. d The mobile fraction of synaptic vesicles, determined by FRAP of the Syt::eGFP signal, declines in dYARS1^CMT compared to YARS1^WT- expressing larval NMJs, and is restored in mutants with decreased Fim levels (Fim^e03892); n = 15, 29, 12, 23, 17 and 17 individual boutons (from left to right). Data in bar graphs are mean values ± SEM.. **p = 0.0064 and p = 0.0046 for dYARS1^E196K and dYARS1^G41R, respectively after a two-sided unpaired t test. Source data are provided as a Source data file.