CAMBIOS EN LA ACTIVIDAD DE ENZIMAS ANTIOXIDANTES DE Myriophyllum quitense EXPUESTA A ENDOSULFÁN A DIFERENTES TEMPERATURAS

Aquatic macrophytes have been widely used as environmental biomonitors because of their primary role in ecosystems and because water bodies are the final destination of many xenobiotics. Particularly, several biomarkers have been used in the genus Myriophyllum for toxicity tests. However, there is scarce evidence of the potential effect of the “confounding factors” on these biomarkers. The objective of the present work was to evaluate the possible effect of temperature on the activity of antioxidant enzymes in Myriophyllum quitense exposed to environmentally relevant concentrations of the insecticide endosulfan. The activity of the enzymes catalase (CAT) and guaiacol peroxidase (POD), as well as glutathione-s-transferase in the cytosolic (GSTc) and microsomal (GSTm) fractions, were evaluated in plants exposed to two temperatures: 11 and 19 oC, and two concentrations of endosulfan (ES): 5 and 10 μg/L. Interaction between temperature and ES concentration for CAT and POD activities was observed. Differences in the activities of all enzymes were detected when plants were exposed to 11 oC with respect to controls. However, no significant differences were observed in the enzymatic activities of the plants exposed to ES at 19 oC. These results emphasize the importance of considering the evaluation of factors such as temperature in bioassays, since its effect alters the toxicity of the contaminant.