Compatibility of ascorbate-glutathione cycle enzymes in cyanobacteria against low and high UV-B exposures, simultaneously exposed to low and high doses of chlorpyrifos.

This study deals with the comparative responses of the two cyanobacteria viz. Nostoc muscorum and Phormidium foveolarum against single and combined doses of low (UV-B(L,) 0.1 μmol m(-2) s(-1)) and high (UV-B(H), 1.0 μmol m(-2) s(-1)) fluence rates of ultraviolet-B radiation with low (CP(L), 1 μg ml(-1)) and high (CP(H), 2 μg ml(-1)) doses of the insecticide chlorpyrifos by measuring changes in growth, ascorbate-glutathione cycle enzymes and related metabolites. CP(L) and UV-B(L) both caused lesser increase in ROS but significantly stimulated AsA-GSH cycle enzymes. On the other hand, CP(H) and UV-B(H) posed inhibitory effects by enhancing ROS and inhibiting AsA-GSH cycle enzymes. Inhibitions in CP(H) or UV-B(H) treated samples were significantly prevented when they were supplemented with UV-B(L) and CP(L) (after 72 h), respectively by lowering down ROS and enhancing AsA-GSH enzymes and related metabolites which manifested in terms of improved biomass accumulation.