Analysis of synaptic growth in mutants of genes differentially regulated in ewgl1mutants. (a,b) Quantification of synaptic growth in mutants of genes differentially regulated in ewgl1mutants. Type 1b boutons at muscle 13 were quantified and are shown as means with standard error (n = 18-22) in transheterozygotes for either a chromosomal deficiency or a second allele from mutants of genes down-regulated (a) or up-regulated (b) in ewgl1mutants that were significantly different (ap ≤ 0.0001, bp ≤ 0.001, cp ≤ 0.05) compared to controls (y w and y w transheterozygous for the corresponding chromosomal deficiency) except for genes involved in basal metabolism. Detailed genotypes with corresponding bouton numbers are listed in Table S2 in Additional data file 1. Genes are clustered according to their function with the color codes used in Figure 4. Note that genes down-regulated in ewgl1mutants are highly enriched for expression in the nervous system (90%) while only a minor portion of genes up-regulated in ewgl1mutants is expressed in the nervous system (36%). (c) Summary of mutants in genes differentially regulated in ewgl1mutants with synaptic growth defects and model of EWG regulation of these genes and their roles in synaptic growth regulation. CNS, central nervous system; PNS, peripheral nervous system.