Fig 2. TPEN effects on C. elegans metal content and lifespan are zinc-specific.

(A) TPEN effect on labile zinc levels is specific to the chelation of zinc. Wildtype worms were exposed to 200μM TPEN in the presence or absence of 500μM ZnSO₄ or 500μM MgSO₄ at L3 stage and collected at one-day old adult animals for analysis of relative labile zinc content. The representative micrograph shows that worms supplemented with zinc have elevated labile zinc content, while TPEN treatment decreased labile zinc. Equal molar levels of magnesium had no effect on basal or TPEN-induced fluorescence. Scale bar = 0.2mm. (B) Kaplan-Meier survival curve of worm populations exposed to zinc and/or TPEN. Wildtype worms were exposed to 200μM TPEN in the presence or absence of 500μM ZnSO₄ at the L3 stage and monitored for effects on lifespan. Mean and maximum population lifespan were reduced with zinc supplementation and increased with TPEN treatment (p < 0.0001, log rank test). Additional 500μM ZnSO₄ attenuated the effect of TPEN on mean and maximum lifespan. (C) Kaplan-Meier survival curve of worm populations exposed to magnesium and/or TPEN. Wildtype worms were exposed to 200μM TPEN in the presence or absence of 500μM MgSO₄ at the L3 stage and monitored for effects on lifespan. Mean and maximum population lifespan were increased with TPEN treatment (p < 0.0001, log rank test). Addition of MgSO₄ had no effect on mean and maximum lifespan.