Fig. 1.

H₂S increases thermotolerance in wild-type C. elegans. (A) Animals exposed to H₂S survive longer than untreated controls at high temperature. Nematodes were moved to 35°C in the same gaseous atmosphere in which they had been cultured (SI Fig. 5). The mean survival time of animals grown in H₂S was 65.5 h (solid line; n = 136), compared with 9.1 h (n = 96) for untreated controls (dashed line). (B) Prior exposure to H₂S is required to survive high temperature in H₂S. All animals were grown in room air without H₂S and then moved to 35°C in the presence or absence of 50-ppm H₂S. Animals first exposed to H₂S at high temperature had a mean survival time of 2.1 h (solid line; n = 20), whereas the control group exposed in room air survived for 7.3 h (dashed line; n = 20). (C) The continuous presence of H₂S in the atmosphere is required for increased survival at high temperature. Animals were exposed to 35°C in room air. Animals grown in H₂S before heat shock survived 7.3 h (solid line; n = 20), which is not significantly longer than untreated controls (dashed line; 7.0 h; n = 20). Indicated P values were determined by log-rank analysis.