Differential response of antioxidative defense system of Anabaena doliolum under arsenite and arsenate stress.

This study offers first hand information on the arsenite (As(III)) and arsenate (As(V))-induced oxidative stress and changes in antioxidative defense system of Anabaena doliolum. A requirement of 58 mM As(V) as compared to only 11 mM As(III) to cause 50% reduction in growth rate suggests that As(III) is more toxic than As(V) in the test cyanobacterium. In contrast to above, oxidative damage measured in terms of lipid peroxidation, electrolyte leakage and peroxide content were significantly higher after As(V) than As(III) treatment as compared to control. Similarly all the studied enzymatic parameters of antioxidative defense system except glutathione reductase (GR) and non-enzymatic parameters except glutathione reduced (GSH) showed greater induction against As(V) than As(III). Interestingly, higher increase in non-enzymatic counterpart than enzymatic in both the stresses suggests that detoxification is mainly managed by former than the later. This confirms the belief of pronounced stimulation of the antioxidative defense system by As(V) than As(III). In conclusion, the cyanobacterium may survive better in As(V) than As(III) contaminated fields because of its low toxicity and pronounced induction of antioxidative defense system. Copyright 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.