Oxidative stress and lipid peroxidation in response to a heavy metal in Euglena gracilis.

ROCCHETTA I., RUIZ L., CONFORTI V. AND RÍOS DE MOLINA, M.C.

Villa Carlos Paz, Cordoba

Congreso; XXXVIII Reunión Anual Nacional SAIB; 2002

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Euglena gracilis shows metabolic and morphological changes when is exposed to different stress conditions. In this work, the response to oxidative stress was studied in two strains of Euglena gracilis exposed to Cr+6 during 96 hs. Both strains, one isolated from a highly polluted river (MAT) and the other from a culture collection (UTEX 364), were grown in a mineral culture media (Buetow). All treated cells exhibited a higher activity of antioxidant enzymes, SOD and catalase, than the control. In addition, high levels of conjugated dienes, protein carbonyls and malondialdehyde content were observed, indicating events of lipid peroxidation and protein oxidation at the lowest chromium concentrations assayed. A reduction of total glutathione content found in treated cells suggested that high levels of ROS exceeded the overall antioxidant capacity. On the other hand, an increase in the ß carotene content suggested a photoprotection increased, specially in the commercial strain. For testing the antioxidant activity, an Euglena homogenate was added to an homogenate of rat suffering oxidative stress. The oxidative damage to lipids was determined by the TBARS reaction. The highest protection was obtained with the UTEX strain. These results would show that an antioxidant defenses increase is not enough to avoid oxidative damages induced by the acute chromium treatment.