Induction of oxidative stress in the red macroalga Gracilaria tenuistipitata by pollutant metals.
Heavy metals are environmental pollutants that have the potential to induce severe stress-reactions in organisms on land as well as in the sea. We have studied effects of short term sublethal concentrations of copper (Cu2+) and cadmium (Cd2+) on the reactive oxygen metabolism of the marine red macroalga Gracilaria tenuistipitata. Additions of either 0.2 ppm Cu2+ or 1 ppm Cd2+ caused decreased growth (approximately 60%), increased oxidation of lipids and increased oxidative damage to proteins as shown by increased content of protein carbonyl groups. Together this strongly suggests an induction of oxidative stress. Cu2+ caused more oxidative damage than Cd2+. As a response to the increased oxidative stress, addition of Cu2+ induced the activities of catalase, ascorbate peroxidase, and superoxide dismutase. In contrast, Cd2+ only caused increased catalase activity. Ten-fold lower concentrations of the metals did not cause an increase in enzyme activity. Both heavy metals also increased the content of the antioxidants beta-carotene and lutein. The results show that Cd2+ and, to a larger extent, Cu2+ induce oxidative stress in short-term experiments and the seaweed responds by increasing the activity of the reactive oxygen metabolism.
Collén
J
J
Departamento de Bioquímica, Universidade de São Paulo, CP 26077, CEP 05599-970, São Paulo, SP, Brazil. collen@sb-roscoff.fr
Pinto
E
E
Pedersén
M
M
Colepicolo
P
P
D000975:Antioxidants / Q000494:pharmacology; D060387:Ascorbate Peroxidases; D002104:Cadmium / Q000633:toxicity*; D002374:Catalase / Q000494:pharmacology; D003300:Copper / Q000633:toxicity*; D018384:Oxidative Stress; D010544:Peroxidases / Q000494:pharmacology; D000461:Rhodophyta / Q000502:physiology*; D013482:Superoxide Dismutase / Q000494:pharmacology; D014873:Water Pollutants / Q000633:toxicity*
D000975:Antioxidants; D014873:Water Pollutants; D002104:Cadmium; D003300:Copper; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase