Nickel and arsenite‐induced differential oxidative stress and antioxidant responses in two Anabaena species

Abstract

In recent years, release of chemical pollutants has increased due to anthropogenic activities. Heterocystous filamentous cyanobacteria constitute dominant paddy microflora and are excellent biofertilizers augmenting rice productivity. Cyanobacteria are frequently exposed to toxic metals, nickel and arsenic are one of the major toxicants present. We exposed two species of diazotrophic cyanobacteria Anabaena sp. PCC 7120 and Anabaena doliolum, to sub-lethal concentrations (15.0 and 9.0 μM) of Ni and (17.0 and 11 mM) of arsenite (AsIII) and analyzed at different days of treatments (0, 1, 7, and 15 days) for oxidative damage and antioxidative biomarkers. Lipid peroxidation was enhanced (1.5- to 2.5-fold increase in MDA content), indicating damaging effects of Ni and As(III) on membrane. Although Ni and As(III), both induced oxidative stress in both species, Anabaena PCC 7120 experienced less stress than A. doliolum. This could be explained by a higher activity of antioxidant enzymes catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR) in Anabaena PCC 7120 (4.6-, 2.0- and 1.4-fold [Ni ] 3.2-, 2.5-, and 2.08-fold [As]) compared to A. doliolum (4.2-, 2.5-, and 1.3-fold [Ni ] and 3.2-, 3.33-, and 1.8-fold [As]). Moreover, superoxide dismutase registered less inhibition in Anabaena sp. PCC 7120 (1.5 and 1.8) compared to A. doliolum (1.8 and 2.3) under Ni and As(III) stress. In addition to, IBR revealed that As(III) imposes severe impact on both strain, however, A. doliolum suffers most. Therefore, the study demonstrates interspecies variation in survival strategy of two Anabaena species and difference in potential of two different toxicants to produce oxidative stress.

Nickel and Arsenite Responsive Proteomic Alterations in Cyanobacterium Anabaena PCC7120

“…Cyanobacteria respond to heavy metals by altering several antioxidant enzyme activities such as superoxide dismutase, catalase, glutathione peroxidase, ascorbate peroxidase, and the synthesis of low molecular weight compounds such as carotenoids and glutathione (Rosen, 1999). In our previous study (Prajapati et al, 2018), oxidative stress and antioxidant response in two Anabaena species (Anabaena PCC7120 and Anabaena doliolum) exposed to nickel and arsenite stress was investigated which suggested the enhance activities of antioxidant enzymes and the decrease in MDA contents in the cells as an adaptive response to metal stress. Cyanobacterial adaptation to stress is coupled with profound changes in proteome.…”

The Glutathione System: A Journey from Cyanobacteria to Higher Eukaryotes

“…However, its equilibrium at neutral pH was altered by neither NADPH nor by disulfide reducing reagents [ 197 ]. Cyanobacterial GR activities were increased in response to unusual growth conditions (increasing the concentration of phosphate [ 197 ] or replacing nitrate by ammonium [ 194 ]) or stresses triggered by pesticides [ 198 ] and metals [ 199 , 200 ]. In addition to other players [ 201 ], GR was shown to protect the O 2 -sensitive nitrogen-fixing nitrogenase enzyme from oxidative stress in the cyanobacterium Gloeocapsa LB795 [ 202 ].…”