Fig. 6

Fold difference in mRNA level of arcA gene in the presence of Cu²⁺, NAC or both Cu²⁺ and NAC. The mRNA level of arcA gene was normalized to that of 16S rRNA, and the mRNA level of arcA gene in cells treated with Cu²⁺, NAC or both Cu²⁺ and NAC was compared to that in the control cells at each time point. Data are the means for three independent experiments and are presented as the means ± SD. *, P < 0.05 and **, P < 0.01