Cobalt and manganese stress in the microalga Pavlova viridis (Prymnesiophyceae): effects on lipid peroxidation and antioxidant enzymes.

Pollution of marine environment has become an issue of major concern in recent years. Serious environmental pollution by heavy metals results from their increasing utilization in industrial processes and because most heavy metals are transported into the marine environment and accumulated without decomposition. The aim of the present study is to investigate the effects on growth, pigments, lipid peroxidation, and some antioxidant enzyme activities of marine microalga Pavlova viridis, in response to elevated concentrations of cobalt (Co) and manganese (Mn), especially with regard to the involvement of antioxidative defences against heavy metal-induced oxidative stress. In response to Co2+, lipid peroxidation was enhanced compared to the control, as an indication of the oxidative damage caused by metal concentration assayed in the microalgal cells but not Mn2+. Exposure of Pavlova viridis to the two metals caused changes in enzyme activities in a different manner, depending on the metal assayed: after Co2+ treatments, total superoxide dismutase (SOD) activity was irregular, although it was not significantly affected by Mn2+ exposure. Co2+ and Mn2+ stimulated the activities of catalase (CAT) and glutathione (GSH), whereas, glutathione peroxidase (GPX) showed a remarkable increase in activity in response to Co2+ treatments and decreased gradually with Mn2+ concentration, up to 50 micromol/L, and then rose very rapidly, reaching to about 38.98% at 200 micromol/L Mn2+. These results suggest that an activation of some antioxidant enzymes was enhanced, to counteract the oxidative stress induced by the two metals at higher concentration.

Genotoxicity evaluation and a primary risk assessment of organic pollutants in the drinking water sources of Nanjing, China.

An increasing number of industrial, agricultural, and commercial chemicals in the aquatic environment leads to various deleterious effects on organisms, which is becoming an increasingly serious problem in China. In this study, the comet assay was conducted to investigate the genotoxicity to human body caused by organic concentrates in the drinking water sources of Nanjing City from Yangtze River of China, and health and ecology risk due to expose to these organic pollutants were evaluated with the multimedia environmental assessment system (MEAS). For all the water samples, they were collected from four different locations in the drinking water sourcr samples, es of Nanjing City. The results of the comet assay showed that all the organic concentrates from the water samples could induce different levels DNA damages on human peripheral blood lymphocytes, and a statistically significant difference (p<0.01) was observed compared with the solvent control, which demonstrated the genotoxicity was in existence. According to the ambient severity (AS) of individual compound, we had sorted out the main organic pollutants in the drinking water source of the four waterworks, and the results showed that there was some potential hazard to human body for all the source water, namely the total ambient severity (TAS) of health for each water source was more than 1. However, the TAS of ecology for each water source was less than 1, which indicated that it was safe to ecology. The results of this investigation demonstrate the application of the comet assay and the MEAS in aquatic environmental monitoring studies, and the comet assay found to be fast, sensitive, and suitable for genotoxicity monitoring programs of drinking water source.

Growth and phosphate uptake kinetics of Microcystis aeruginosa under various environmental conditions.

Growth and uptake of exogenous phosphate by Microcystis aeruginosa in batch culture under different temperature, photoperiod, and turbulence were studied by the method of phosphate isotope tracer. Relatively high temperature, long photoperiod and strong turbulence increased the cell density of M. aeruginosa in these batch cultures. The initial rapid uptake of phosphate by M. aeruginosa was independent of the temperature, photoperiod, and turbulence. Similarly, maximum exogenous phosphate uptake was not related to these environmental factors. However, elevated temperature and turbulence shortened the time, required to obtain maximum P accumulation. The growth of M. aeruginosa could alleviate the phosphorous leakage. Total amounts of exogenous phosphate uptake to M. aeruginosa and the phosphorus leakage of M. aeruginosa were significantly influenced by the growth state of M. aeruginosa closely correlated with the environmental factors. The maximum volume of exogenous phosphate uptake to M. aeruginosa was 46% of added exogenous phosphate in water with 16 hours of photoperiod. Thus, total amounts of exogenous phosphate uptake to M. aeruginosa were more strongly affected by the photoperiod length than temperature and turbulence.

[Genotoxicity effect of organic pollutants in Meiliang Bay of Taihu Lake on microalga Euglena gracilis].

Organic pollutant ingredients and content of water samples from Taihu Lake were analyzed by GC-MS. Results showed that Taihu Lake was already contaminated by the organic pollutant, and 15 kinds of targeted organic pollutants were detected. At lower concentrations (1 time), organic pollutants could not have notable effect on the growth of Euglena gracilis, but could increase the content of photosynthetic pigment. At higher concentrations (5, 10 times), organic pollutants restrained the growth of E. gracilis remarkably, and decreased the content of photosynthetic pigment. Activities of SOD and POD increased with the content of organic pollutants. It is indicated that organic pollution could induce activities of antioxidation enzymes in E. gracilis. TOM and TM for the genotoxicity assay increased and DNA damage was found. In higher concentration groups, DNA damage was serious and had an obvious dose-effect relationship. It is indicated that Meiliang bay water may have potential mutagenicity. Comet assay combined with SOD analysis was of value to genotoxic monitoring of polluted water and was a suitable biomarker for organic pollutants in water.