Figure 6.

Pb²⁺-induced depletion of heme is O₂-dependent. Cells expressing HS1-M7A were conditioned with the indicated concentration of Pb²⁺ and allowed to recover in an anoxic, nitrogen-rich (N₂) atmosphere or in air (O₂), and total heme (A), labile heme (B), and viability (C) were measured. All data represent the mean ± S.D. (error bars) of triplicate cultures, and statistical significance was assessed using a two-sample t test. Black asterisks, statistical significance between the indicated pairwise comparisons of conditions; red asterisks, statistical significance relative to 0 μm Pb. *, p < 0.05; **, p < 0.01; ***, p < 0.001; n.s., not significant.