Fig. 3. Pharyngeal pumping rate in WT and skn-1 (ok2315) untreated and GEE-pretreated worms at 0 hours (A and B) and 24 hours (C and D) post 6-hour MeHg exposure. The number of pharyngeal contractions per minute was observed in worms in E. coli OP50-seeded NGM plates with a microscope. MeHg induced a dose-dependent decrease in pharyngeal pumping rates immediately post 6-hour exposure and GEE exerted protective effects only in skn-1 (ok2315) worms at 25 μM MeHg. Post 24 hours, the worms showed a recovery in the pharyngeal pumping rate to control levels, with the exception of the 50 μM MeHg group. (#) Represents a significant difference between control and metal exposed worms by two-way ANOVA followed by Bonferroni's multiple comparison test (p < 0.05) and (*) represents a significant difference between untreated and GEE-pretreated worms by two-way ANOVA followed by Bonferroni's multiple comparison test (p < 0.05). Data are expressed as means ± SEM, n = 4, 10 worms analyzed per group in each assay.