Thimerosal-Derived Ethylmercury Is a Mitochondrial Toxin in Human Astrocytes: Possible Role of Fenton Chemistry in the Oxidation and Breakage of mtDNA

Figure 3

Colocalization of Mitotracker and carbonyls in normal human astrocytes. Thimerosal induces oxidative damage at the mitochondrial level. Control and 14.4 𝜇M Thimerosal-treated cells prepared using MT (red) and Hoechst (blue), with FITC-Avidin/Biotin-Hydrazide carbonyl labeling (green). (a) A large ethylmercury-treated cell showing an increase in green ROS damaged cell contents as a function of distance from the nucleus. (b) Two boxes from (a) highlighting the correlation between MT (red) and carbonyl (green) signals. (c) The two vertical lines in (a) indicate the position of fluorophore intensity profile interrogation. Red: MT, green: carbonyls, blue: Hoechst, black: a simulation of the levels of ROS damage generated by combining fractions of the MT and Hoechst signals. In both samples the simulation is a poor match for the actual ROS-induced signal, with cross-correlations of ROS versus simulation giving 𝑅₂ values of only 0.68 and of 0.86, respectively.