Metal-induced oxidative stress

Metal toxicity is commonly assumed to result through non-specific and inadequate binding of metals to physiologically important molecules. In addition to this, toxic metals may compete with or replace similar essential metals with the resultant modification of conformation and loss of biochemical activity. Moreover, metal toxicity is related, at least in part to the enhancement of oxidative stress induced in exposed organisms. Heavy metals can induce oxidative damage both by increasing the cellular concentration of reactive species (ROS) and by reducing the cellular antioxidant capacity.

In a previous study we have examined the potential of various metals to induce ROS formation in the alga Chlamydomonas reinhardtii (Szivak et al. 2009). ROS were quantified using an oxidation sensitive fluorescent dye and flow cytometry. Our study showed that both redox and non-redox active metals enhanced intracellular ROS levels in response to environmentally relevant low concentration of metals. Elevated ROS level occurred at metal concentrations that are not inhibitory to the photosynthetic activity of algae. Using various fluorescent dyes characteristic of different cellular functions and structures we are currently analyzing the sensitivity of other cellular targets in order to better evaluate the consequences of elevated ROS formation in algae.

References

Szivak I, Behra R, Sigg L. 2009. Metal induced reactive oxygen species production in Chlamydomonas reinhardtii (Chlorophyceae). J. Phycol. 45, 427-435 (2009)