FIG. 1.

S. flexneri kills C. elegans and accumulates in the nematode intestine. (A) Young adult hermaphrodite N2 nematodes were fed on lawns of either E. coli OP50, S. flexneri 2457T, S. flexneri 2457TΔinv, or S. enterica serovar Typhimurium SL1344 at 25°C, and nematodes were scored daily for survival. The survival curve represents data from 5 independent experiments, each using 20 nematodes. (B) The time required for nematodes to die (TD₅₀) was calculated using the survival data in panel A, representing data from five independent experiments. Asterisks indicate significant differences compared to data for OP50 (P < 0.05). (C) Young adult nematodes were fed on lawns of either E. coli DH5α or S. flexneri 2457T expressing GFP for 48 h and mechanically disrupted. Diluted lysates were plated on LB-ampicillin plates, and colonies were quantified in order to calculate S. flexneri cells associated with individual nematodes. These data represent 3 independent experiments, each using 20 nematodes. (D) Nematodes fed either E. coli DH5α or S. flexneri 2457T expressing GFP for 48 h were analyzed using a fluorescence stereomicroscope. (E) Confocal images show the anterior intestine of an animal fed S. flexneri 2457T expressing GFP for 48 h.