C. elegans strains and culture conditions

Worms were grown and maintained on nematode growth medium (NGM) agar plates seeded with Escherichia coli OP50 as previously described [17]. The wildtype strain N2 (Bristol) and the mutant strains RB1660 clec-4(ok2050) II. and HT1593 unc-119(ed3) III. were obtained from the Caenorhabditis Genetics Center (CGC, Minnesota, USA). The clec-41(tm6722) V. and clec-42(tm6526) V. mutant animals were obtained from the National BioResource Project (NBRP, Tokyo, Japan) [18]. Strain MY1116 clec-4(ya1) II. was generated using the dpy-10 co-CRISPR strategy according to [19, 20] and subsequently outcrossed three times with the N2 strain, yielding MY1117. The double mutant MY1127 clec-41(tm6722);clec-42(tm6526) was obtained by crossing the respective strains. Generally, all mutant strains were outcrossed at least three time with the same wildtype N2 prior to use, clec-4(ok2050) mutants were outcrossed 10x, their mutations were confirmed by PCR, and the resulting lack of expression validated by RT-PCR (S2 Fig and S1A Table).