Minling Gao

Toxic effect of different ZnO particles on mouse alveolar macrophages.

To study the toxicity mechanism of ZnO nanoparticles on mouse macrophages, the toxic effect of different ZnO nanoparticles on mouse alveolar macrophages (MH-S) was investigated in this study. The results showed that the 24h IC(50) of four ZnO particles were 48.53, 47.37, 45.43 and 26.74 μg/ml for bulk ZnO, 100 nm, 30 nm and 10-30 nm ZnO particles, respectively. At the concentration of 10 μg/ml and below, dissolved zinc ions induced metallothionein synthesis, enhanced cellular resistance to oxidative stress. ZnO particles mainly induced cell apoptosis. When the concentration of ZnO particles was 20 μg/ml and above, excessive zinc destroyed mitochondrial function and cell membrane, caused cell necrosis. Dissolved zinc ions first cause toxicity in MH-S cells. However, the toxic effect of dissolved zinc ions may exist a threshold on mouse macrophages, inducing about 50% cell death. The toxic difference of different ZnO particles mainly depended on the effect of nondissolved ZnO particles.

Cytotoxicity of different sized TiO2 nanoparticles in mouse macrophages

With large-scale production and wide application of nano-titanium oxide (TiO2), its health hazard has attracted extensive attention worldwide. In this study, mouse macrophages (Ana-1 and MH-S cells) were used to evaluate the cytotoxicity of different sized TiO2 nanoparticles. The results showed that TiO2 nanoparticles caused low toxicity, especially in MH-S cells. There was a difference in the cytotoxicity induced by different sized TiO2 particles. The 25 nm anatase particles induced the strongest cytotoxicity and oxidative stress, followed by 5 and 100 nm anatase particles; in contrast, 100 nm rutile particles induced the lowest toxicity. Although TiO2 nanoparticles induced high levels of intracellular reactive oxygen species (ROS), the determination of ROS demonstrated that the inherent oxidative capacity of TiO2 nanoparticles was lower in the absence of photoactivation. Therefore, the generation of intracellular ROS could not completely depend on inherent oxidative capacity of TiO2 nanoparticles. Toxicity of TiO2 nanoparticles could mainly depend on the structural characteristics.

Interactive effect of oxytetracycline and lead on soil enzymatic activity and microbial biomass

Interactive effect of oxytetracyline (OTC) and lead on soil enzymatic activity and population of microbes was studied in the paper. The results showed effect of pollutants on bacteria, actinomycetes and enzymatic activity increased in the order: (OTC+Pb)>Pb>OTC, (OTC+Pb)>Pb>OTC and (OTC+Pb)>OTC>Pb, respectively. However, impact of pollutants on fungi decreased in the order: (OTC+Pb)<Pb<OTC. The analysis of X-ray photoelectron spectroscopy (XPS) showed that binding energy and atomic percentage of Al, Fe, C, O, N, Si, Mg and Ca altered after the amended with OTC or Pb. The decrease of oxygen atom density and increase of binding energy can be associated to the charge transfer, resulting from oxygen and carbon atoms coordinated with metal ions, other chemicals or partial decomposition. Thus, the findings of this study can provide a better insight into the interaction of both pollutants and their impacts on soil quality.

Effect on enzymes and histopathology in earthworm (Eisenia foetida) induced by triazole fungicides

Earthworms are an ideal biological model in toxicity assays and environment monitoring studies, especially for the toxicity of pesticides on soil ecosystem. However, There are very little data on the toxicity of triazoles on earthworms despite the fact that such data are critical in assessing their fate and potential toxic effects in soil organisms. To address this issue, earthworms were exposed to triazoles (triadimefon, triadimenol, difenoconazole and propiconazole) to study biochemical and histopathological examination. The results showed protein content significantly increased in treatment of difenoconazole compared to control. There were no significant differences between controls and triadimefon treated groups, while the glutathione peroxidase (GSH-Px) activity is significantly lower than control. Other triazoles also had an inhibitory effect on GSH-Px activity at higher concentration. The histopathological examination showed the epidermis and the epidermis cell of earthworm was ruined at lower triazoles concentration. The arrangement of smooth muscle layer disordered, and some cell disintegrated with concentration increasing of pesticides. Cell pyknosis, cytoplasm deep stained, nucleus concentrations were observed in the treated group with propiconazole.

Combined effects of oxytetracycline and Pb on earthworm Eisenia fetida

Combined effects of oxytetracycline (OTC) and Pb on lysosomal membrane stability and coelomocyte apoptosis of earthworm were studied in the paper. Compared with control, the lysosomal membrane stability decreased and coelomocyte apoptosis increased in the treatments of single OTC and Pb contamination. As for compound pollution, combined effect of (5 mg/kg OTC+50 mg/kg Pb) treatment on earthworm lysosomal was synergistic (except 28 d). However, it was antagonistic at higher concentration of (10 mg/kg OTC+50 mg/kg Pb) and (20 mg/kg OTC+50 mg/kg Pb) treatment. In addition, coelomocyte apoptosis of earthworm decreased significantly compared with single OTC, indicating an antagonistic reaction. And joint toxicity of OTC and Pb decreased significantly with the increasing OTC concentration.

Biomarker analysis of combined oxytetracycline and zinc pollution in earthworms (Eisenia fetida).

To determine the interactive action of antibiotics and heavy metals, this study assessed pollutant-induced responses of cellular biomarkers in earthworms (Eisenia fetida) exposed to zinc (Zn(2+)) and oxytetracycline (OTC) in soil. Lysosomal membranes were damaged and coelomocyte apoptosis occurred with exposure to the individual and combined pollutants. Compared with Zn(2+) alone, lysosomal membrane stability and coelomocyte apoptosis decreased in the Zn(2+)-OTC combined treatment, possibly as a result of complexation of Zn(2+) and OTC at alkaline pH. Such complexation could reduce the toxicity of the pollutants. Lysosomal membrane stability and coelomocyte apoptosis are sensitive biomarkers and could be economical and rapid tools for the monitoring and assessment of a variety of pollutants.

Toxic effects of nanomaterial-adsorbed cadmium on Daphnia magna

Chemical immobilization technologies involving the use of chemical absorbents such as nanomaterials have been recommended for the remediation of Cd-contaminated water and soil. The impact of nanomaterials or nanomaterials coexisting with other contaminants on aquatic organisms has been reported, but information on the toxic effects of nanomaterial-adsorbed cadmium (Nano-Cd) on aquatic organisms is lacking. This study aimed to investigate the acute and sub-acute toxicity of Nano-Cd on Daphnia magna by using a method developed based on the standard Organisation for Economic Co-operation and Development (OECD) 202 guidelines. The toxicity of cadmium chloride (Cd2+), nano-manganese dioxide-cadmium (nMnO2-Cd), 20nm nano-hydroxyapatite-cadmium (nHAP20-Cd), and 40nm nano-hydroxyapatite-cadmium (nHAP40-Cd) to D. magna was in the following order: Cd2+> nMnO2-Cd > nHAP20-Cd > nHAP40-Cd. Further, nMnO2-Cd, nHAP20-Cd, and nHAP40-Cd showed acute toxicity to D. magna of level II grade according to the Commission of the European Communities and OECD standards. Exposure to low and medium, but not high, Nano-Cd concentrations increased the activities of peroxidase, superoxide dismutase, catalase, and anti-superoxide anion. Thus, Nano-Cd, particularly at high concentrations, could exert oxidative damage in D. magna. An increase in Cd2+ and Nano-Cd concentrations gradually increased the malondialdehyde content, indicating cell membrane damage caused by the production of excessive O2-. Thus, the use of nanomaterials after adsorption of Cd is associated with a potential risk to aquatic organisms.

Growth and antioxidant defense responses of wheat seedlings to di-n-butyl phthalate and di (2-ethylhexyl) phthalate stress

Phthalate acid esters (PAEs) are vital environmental hormone-like chemicals that are noxious to plants, animals, and human beings. In this study, the influences of di-n-butyl phthalate (DBP) and di (2-ethylhexyl) phthalate (DEHP) on the seed germination, root morphology, and various physiological changes of wheat seedlings were investigated by analyzing superoxide anion (O2-) accumulation, antioxidant enzyme activity, and lipid peroxidation. DBP and DEHP were found to obviously inhibit germination only at high concentrations, but significantly affected root morphology even at lower concentrations. Their toxic effects were the most severe on root elongation, followed by shoot elongation, and were the least severe on germination rate, indicating that root elongation was the best index for evaluating DBP and DEHP eco-toxicity. DBP and DEHP also enhanced O2- and malondialdehyde levels and membrane permeability, as well as produced changes in the antioxidant status and PAE content in the stem and leaf (combined tissues, hereafter shoot) and root tissues. The activities of superoxide dismutase, catalase, and peroxidase increased at low and medium DBP and DEHP concentrations, but declined at high PAE concentrations. These results indicated that PAEs could exert oxidative damage in the early development stage of wheat, particularly at higher concentrations. DBP and DEHP accumulation was higher in the roots than in the shoot tissues, and their levels in these tissues increased with increasing PAE concentrations, supporting their more-serious toxic effects on roots than those on shoots. Further, the physicochemical properties of DBP rendered it more harmful than DEHP.

Avoidance behavior of Eisenia fetida in oxytetracycline- and heavy metal-contaminated soils.

To determine the behavior of oxytetracycline (OTC) and heavy metals in soil, this study assessed the pollutant-induced avoidance behavior of earthworms (E. fetida) exposed to zinc (Zn2+), lead (Pb2+), and OTC in soil. The results showed a clear avoidance response within 48h of exposure to the highest concentrations of pollutants. Moreover, E. fetida was shown to be more sensitive to Zn2+ than to Pb2+ and OTC. Compared with OTC alone, the net response of earthworms increased in the OTC-Zn2+ and OTC-Pb2+ combined treatments, indicating a synergistic effect. Moreover, the net response (NR) of the earthworms was higher for OTC-Zn2+ than it was for OTC-Pb2+, possibly reflecting the differences in essential characteristics of Zn and Pb.

Oxidative stress and DNA damage in zebrafish liver due to hydroxyapatite nanoparticles-loaded cadmium

This study investigated the acute and sub-acute toxicity responses in zebrafish following their exposure to hydroxyapatite-loaded cadmium nanoparticles (nHAP-Cd). The results indicate that cadmium chloride (Cd2+), 20 nm nHAP-Cd (nHAP20-Cd), and 40 nm nHAP-Cd (nHAP40-Cd) caused toxicity in zebrafish; the toxicity levels were in the following order: Cd2+ > nHAP20-Cd > nHAP40-Cd. Furthermore, nHAP-Cd showed level II grade of acute toxicity in zebrafish; the gradation was done on the guidelines of the Organization for Economic Co-operation and Development 203. We also found that Cd2+ ions and nHAP-Cd affected the malondialdehyde (MDA) levels and membrane permeability of zebrafish livers; these effects were compliant with the changes in antioxidant levels. The results of enzyme assays indicate the following notion: following the exposure of zebrafish to 0.12-0.93 mg/L nHAP-Cd, the activities of peroxidase, superoxide dismutase, and catalase enzymes increased significantly. Moreover, the content of anti-superoxide anion also increased substantially. This increasing trend of enzymatic activity was observed until the concentration of nHAP-Cd reached 1.86 mg/L nHAP-Cd. By increasing the concentration of both Cd2+ and nHAP-Cd, we found that levels of DNA damage had increased substantially in zebrafish liver; this effect was visualized by performing comet assay.