FIG 1 .

C. elegans enters diapause in the F2 generation as a defense against moderate pathogens. (a) Population growth on different pathogenic (P. aeruginosa PAO1, S. Typhimurium MST1, and P. aeruginosa PA14) and nonpathogenic (E. coli OP50 and S. Typhi Ty2) bacteria in the second generation. Population growth on all bacterial strains was normalized against population growth on E. coli OP50. (b) Dauer formation in the second generation of animals grown on different pathogenic and nonpathogenic bacteria. (c) Photographs of dauers on pathogenic and nonpathogenic bacterial lawns taken with a Sony XCD-SX910 camera on a trinocular SMZ745 stereomicroscope. (d) Photographs of animals treated with 1% SDS after growth on the three different bacteria. Pictures show a representative fraction of the 1% SDS drop. (e) Intestinal CFU of nondauer and dauer worms in the second generation growing on pathogenic and nonpathogenic bacteria. (f and g) Photographs of an F2 nondauer (f) animal fed with GFP-expressing E. coli or P. aeruginosa PAO1 and a dauer (g) animal fed with GFP-expressing P. aeruginosa PAO1. Scale bars represent 100 μm. Arrows show cuticular thickenings of dauers, ridges, or alae (red), and large striated zones along the body (yellow). ****, P < 0.0001; *, P < 0.05; ns, not significant. Error bars indicate standard errors of the means (SEM) of at least three biological replicas done in triplicates.