Reactive oxygen species and Ca2+ are involved in cadmium-induced cell killing in yeast cells

Cadmium (Cd) is one of the most toxic heavy metals. It is of great environmental concern and its toxicity has been investigated in a variety of cells. In this study, we elucidated the toxic effects of Cd in cells of yeast (Saccharomyces cerevisiae). Our results showed that Cd2+ (0.05-5.0 mmol.L-1) significantly inhibited yeast cell growth, and the inhibitory effect was positively correlated with Cd2+ concentrations. Cd2+ caused loss of yeast cell viability in a concentration-and duration-dependent manner. Intracellular reactive oxygen species (ROS) and Ca2+ levels increased in yeast cells after exposure to 5.0 mmol.L-1 Cd for 6 h. Cd2+-caused cell viability loss was blocked by antioxidants (0.5 mmol.L-1 ascorbic acid or 500 U.mL(-1) catalase) or Ca2+ antagonists (0.5 mmol.L-1 ethylene glycol tetraacetic acid or 0.5 mmol.L-1 LaCl3). Moreover, a collapse of mitochondrial membrane potential (Delta psi(m)) was observed in Cd2+-treated yeast cells. These results indicate that Cd-induced yeast cell killing was associated with the elevation of intracellular ROS and Ca2+ levels and also the loss of Delta psi(m).