Double mutant analysis using pharyngeal pumping suggests SV recycling defects. (A) C. elegans neuromuscular function is assessed as pharyngeal grinder (arrow) movement during feeding. (B–D) Complete loss of endophilin-A, synaptojanin, or syndapin (unc-57(ok310), unc-26(s1710), or sdpn-1(ok1667)) did not alter smn-1(ok355) pharyngeal pumping defects. (E and F) Complete loss of Munc-18 or synaptobrevin [unc-18(e234) or snb-1(md247)] exacerbated smn-1(ok355) pharyngeal pumping defects. Additive defects with SV exocytosis loss-of-function mutants suggested that SMN-1 depletion impairs the SV recycling pathway. Total number of animals tested listed for each genotype ± SEM; Mann–Whitney U test, two-tailed: *P < 0.05; **P < 0.01; ***P < 0.001; n.s., not significant.