Changes in Nitrate Reductase Activity, Lipid Peroxidation and Antioxidant System in the Moss Polytrichum sp. Subjected to Hexavalent Chromium Toxicity

摘要

Changes in nitrate reductase (NR) activity and subsequent induction of oxidative stress in Polytrichum under chromium toxicity were investigated. Exposure of Cr at different concentrations for 24 h and 48 h reduced the NR activity in moss cells with significant inhibition after 48 h at 100 mM of Cr. Reduction of total chlorophyll occurred in moss cells after Cr treatment. High accumulation of Cr was seen in after 24 h and 48 h. Cr prompted malondialdehyde (MDA) production. Increase in MDA content suggested oxidative stress in moss cells. The increase in MDA content was followed by activation of antioxidant enzymes like catalase (CAT), guaiacol peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase (SOD). Increasing trend for all the enzymes was seen after 24 h and 48 h of Cr treatment. Increase in CAT, GR or SOD was highly significant with increase in concentration and duration of treatment of metal. In case of GPx, the enzyme activity decreased after 48 h of Cr exposure.