Toxicity and physiological alterations were determined in Pseudococcus viburni nymphs treated with Artemisia annua methanolic extract. The leaf dipping bioassay showed LC50 values of 0.287% and 0.194% 24 and 48 hours post-exposure. Activities of general esterases were significantly higher in the control nymphs than in those which had been treated except for the 48 h time interval using α-naphtyl acetate. The activity of glutathione S-transferase using CDNB (1-chloro-2,4-dinitrobenzene) in the control nymphs, was significantly higher than in the control at both time intervals while no significant difference was observed after 24 h in addition to the higher enzymatic activity in the treated nymphs after 48 h. All three aminotransferases were significantly more active in the control nymphs except for time intervals of 24 h for γ-glutamyl transferase and 48 h for alanine aminotransferase. Higher activities of lactate dehydrogenase, acid- and alkaline phosphatase were found in the control nymphs than in treated nymphs for all time intervals. Activities of the enzymes involved in the antioxidant system including catalase, peroxidase, superoxide dismutase, ascorbate peroxidase and glucose-6-phosphate dehydrogenase was increased in the treated nymphs compared to the control. Results of the current study demonstrated toxic effects of A. annua methanolic extract on P. viburni nymphs causing mortality and physiological turbulences.
Two fungal strains, isolated from Livingston Island, Antarctica (Penicillium commune 161, psychrotolerant and Aspergillus glaucus 363, mesophilic) were investigated for a relationship between growth temperature and oxidative stress response. Cultivation at temperatures below - (10 and 15°C and 10 and 20°C for P. commune and A. glaucus, respectively) and above (25°C and 30°C for P. commune and A. glaucus, respectively) the optimum caused significant difference in growth and glucose uptake in comparison with the control cultures. Enhanced level of reserve carbohydrates (glycogen and trehalose) was determined under cultivation at different temperatures from the optimal one. While the highest content of trehalose was found in the exponential phase, glycogen accumulation was observed in the stationary phase when growth conditions deteriorate. The growth at temperature below- and above-optimum caused strain-dependent changes in two antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT). While SOD activity in the psychrotolerant strain increases with decreasing of growth temperature, the mesophilic A. glaucus demonstrated marked reduction of it at below- and above-optimal temperature. Decreasing trend of CAT activity was observed in both strains below the optimal temperature indicating a lack of antioxidant protection from this enzyme under the cold stress conditions.