W3 PM Biomarkers
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in Ballroom 3

(GUR-1117-819171) Analysis of antioxidant enzymes and ROS production in Daphnia magna in response to widespread environmental pollutants.

Gurska, J¹, Lampi, M¹, Xie, F¹, Greenberg, B, ¹ University of Waterloo, Waterloo, Ontario, Canada

ABSTRACT- Due to ubiquitous presence of oxygen and its radical derivatives or reactive oxygen species (ROS) organisms have evolved protective systems consisting of antioxidant mechanisms to prevent damage. ROS include hydroxyl radical, superoxide anion and hydrogen peroxide. Ubiquitous, environmental contaminants are often present together in complex mixtures, such as metals and polycyclic aromatic hydrocarbons (PAH). These have been shown to increase production of ROS leading to cellular damage including lipid peroxidation, protein degradation and DNA damage. Previously in our lab, organisms such as Daphnia magna, Vibrio fisheri and Lemna gibba have shown greater than additive toxicity to mixtures of oxidized PAHs and metals. Toxicity via catalytic ROS production has been investigated as a source of synergism, and it is further being investigated in Daphnia magna. To evaluate whether this organism is responding to such stress, protective mechanisms in the form of catalase and glutathione S-transferase, superoxide dismutase were examined. These enzymes are part of the antioxidant system and induction of enzymatic activity would indicate oxidative stress. To complete this evaluation the increase in production of ROS was evaluated with the use of an ROS sensitive fluorescent dye assay. Analysis of common contaminants was performed; in particular possible production of ROS in the presence of Hg was evaluated showing elevated ROS production. Hg also caused decreases in catalase activity. Anthracene with concurrent ultraviolet radiation exposure produced increase in both catalase and glutathione S-transferase activity. These assays are principal to the analysis of PAH and metal induced oxidative stress, and provide evidence of its occurrence.

Key words: Daphnia magna, ROS, antioxidant enzymes