Fig 2. SMK-1 confers resistance to bacterial infection and ultraviolet radiation in adult C. elegans.
(A) Animals expressing the Plys7::gfp in vivo reporter for DAF-16 transcriptional activity were examined by fluorescence microscopy at D6 of adulthood. Age-synchronized isogenic animals could be assigned to one of three categories based on the relative expression of GFP observed in the intestine. “Low”: little to no GFP expression “Medium”: GFP expression most apparent in the anterior portion of the intestine but also at lower levels toward the midbody. “High”: robust GFP expression along the entire length of the intestine. DIC, differential interference contrast image corresponding to the fluorescence image (GFP) shown above. (B) Quantification of worms in the Low (blue), Medium (orange), and High (grey) categories of Plys7::gfp expression at the L4 stage and D6 of adulthood following RNAi treatment targeting either daf-16 or smk-1. n>200 animals for each RNAi treatment in three biological replicates. The average number of worms in each category is shown with error bars representing standard deviation from the mean. (C and D) Results of Pseudomonas aeruginosa infection assays. The survival of C. elegans subjected to RNAi against indicated genes beginning at L1 and exposed to P. aeruginosa continuously beginning at L4 (C) or D6 of adulthood (D) is plotted as the fraction of animals alive as a function of time. (E and F) Results of UV irradiation assays. Survival curves for C. elegans subjected to RNAi against the indicated genes from L1 until death and exposed to 1000 J/m2 UV radiation at L4 (E) or D6 of adulthood (F). Hours represent time elapsed since the end of the irradiation treatment. (G and H) Results of heat stress assays. Survival curves for RNAi-treated C. elegans incubated at 35°C beginning at L4 (G) or D6 of adulthood (H) until they died. Hours represent the total time worms were incubated at 35˚ C. Beginning at the L1 stage, worms were maintained on RNAi plates without interruption for the duration of their lives. n>90 animals for each RNAi treatment in three biological replicates. Purple, L4440; yellow, daf-16 RNAi; blue, yellow, smk-1 RNAi.