Bioaccumulation and effects of the contraceptive hormone levonorgestrel were examined in the non-target organism Dreissena polymorpha. Molecular biomarkers of biotransformation, elimination, antioxidant defence and protein damage were analyzed after exposure to increasing concentrations of levonorgestrel in a flow-through system. The lowest concentration (0.312 μg L⁻¹) was 100-fold bioconcentrated within four days. A decrease of the bioconcentration factor was observed within one week for the highest test concentrations (3.12 and 6.24 μg L⁻¹) suggesting enhanced excretory processes. The immediate mRNA up-regulation of pi class glutathione S-transferase proved that phase II biotransformation processes were induced. Disturbance of fundamental cell functions was assumed since the aryl hydrocarbon receptor has been permanently down-regulated. mRNA up-regulation of P-glycoprotein, superoxide dismutase and metallothioneine suggested enhanced elimination processes and ongoing oxidative stress. mRNA up-regulation of heat shock protein 70 in mussels exposed to the two highest concentrations clearly indicated impacts on protein damage.

Here we report the effects of three Bt-rice varieties and their non-Bt conventional isolines on biological traits including survival, reproduction, and the activities of three antioxidant enzymes superoxide dismutase, catalase and peroxidase, in the Collembolan, Folsomia candida. The reproduction was significantly lower when fed Kemingdao and Huahui1 than those feeding on their non-GM near-isogenic varieties Xiushui and Minghui63 respectively, this can be explained by the differences of plant compositions depended on variety of rice. The catalase activity of F. candida was significantly lower when fed the Bt-rice variety Kemingdao compared to the near-isogenic non-Bt-rice variety Xiushui. This suggests that some Bt-rice varieties may impose environmental stress to collembolans. We emphasize that changes in activity of antioxidant enzymes of non-target organisms are important in understanding the ecological consequences for organisms inhabiting transgenic Bt-rice plantations.

The increasing production of nanomaterials will in turn increase the release of nanosized byproducts to the environment. The aim of this study was to evaluate the behaviour, uptake and ecotoxicity of TiO₂ byproducts in the earthworm Eisenia fetida. Worms were exposed to suspensions containing 0.1, 1 and 10 mg/L of byproducts for 24 h. Size of TiO₂ byproducts showed aggregation of particles up to 700 μm with laser diffraction. Only worms exposed at 10 mg/L showed bioaccumulation of titanium (ICP-AES), increasing expression of metallothionein and superoxide dismutase mRNA (Real-time PCR) and induction of apoptotic activity (Apostain and TUNEL). TiO₂ byproducts did not induce cytotoxicity on cœlomocytes, but a significant decrease of phagocytosis was observed starting from 0.1 mg/L. In conclusion, bioaccumulation of byproducts and their production of reactive oxygen species could be responsible for the alteration of the antioxidant system in worms.

Polycyclic aromatic hydrocarbons (PAHs) have been detected in some commercial teas around the world and pose a threat to tea consumers. However, green tea polyphenols (GTP) possess remarkable antioxidant and anticancer effects. In this study, the potential of GTP to block the toxicity of the model PAH phenanthrene was examined in human embryo lung fibroblast cell line HFL-I. Both GTP and phenanthrene treatment individually caused dose-dependent inhibition of cell growth. A full factorial design experiment demonstrated that the interaction of phenanthrene and GTP significantly reduced growth inhibition. Using the median effect method showed that phenanthrene and GTP were antagonistic when the inhibitory levels were less than about 50%. Apoptosis and cell cycle detection suggested that only phenanthrene affected cell cycle significantly and caused cell death; GTP lowered the mortality of HFL-I cells exposed to phenanthrene; However, GTP did not affect modulation of the cell cycle by phenanthrene.

To better understand chemical modes of action, emphasis has been given to stress responses at lower levels of biological organization. Cholinesterases and antioxidant defenses are among the most used biomarkers due to their crucial role in the neurocholinergic transmission and in cell homeostasis preventing DNA damage, enzymatic inactivation and lipid peroxidation. The main goal of this study was to investigate the effects of zinc and cadmium on survival and reproduction of E. albidus and to assess metals oxidative stress potential and neurotoxic effects at concentrations that affected reproduction. Both metals affected the enchytraeids’ survival and reproduction and induced significant changes in the antioxidant defenses as well as increased lipid peroxidation, indicating oxidative damage. This study demonstrates that determining effects at different levels of biological organization can give better information on the physiological responses of enchytraeids in metal contamination events and further unravel the mechanistic processes dealing with metal stress.

Because of its toxicity and its ubiquity within aquatic compartments, uranium (U) represents a significant hazard to aquatic species such as fish. In a previous study, we investigated some biological responses in zebrafish either exposed to depleted or to enriched U (i.e., to different radiological activities). However, results required further experiments to better understand biological responses. Moreover, we failed to clearly demonstrate a significant relationship between biological effects and U radiological activity. We therefore chose to herein examine U bioaccumulation and induced effects in zebrafish according to a chemical dose–response approach. Results showed that U is highly bioconcentrated in fish, according to a time- and concentration-dependent model. Additionally, hepatic antioxidant defenses, red blood cells DNA integrity and brain acetylcholinesterase activity were found to be significantly altered. Generally, the higher the U concentration, the sooner and/or the greater the effect, suggesting a close relationship between accumulation and effect.

Poplar (Populus nigra) plants were grown hydroponically with 30 and 200 μM Ni (Ni₃₀ and Ni₂₀₀). Photosynthesis limitations and isoprenoid emissions were investigated in two leaf types (mature and developing). Ni stress significantly decreased photosynthesis, and this effect depended on the leaf Ni content, which was lower in mature than in developing leaves. The main limitations to photosynthesis were attributed to mesophyll conductance and metabolism impairment. In Ni-stressed developing leaves, isoprene emission was significantly stimulated. We attribute such stimulation to the lower chloroplastic [CO₂] than in control leaves. However chloroplastic [CO₂] did not control isoprene emission in mature leaves. Ni stress induced the emission of cis-β-ocimene in mature leaves, and of linalool in both leaf types. Induced biosynthesis and emission of isoprenoids reveal the onset of antioxidant processes that may also contribute to reduce Ni stress, especially in mature poplar leaves.

Biomarkers comprising activities of biotransformation enzymes (ethoxyresorufin-O-deethylase –EROD–, dibenzylfluorescein dealkylase –DBF–, glutathione S-transferase –GST), antioxidant enzymes (glutathione reductase –GR– and glutathione peroxidase –GPX), lipid peroxidation –LPO– and DNA strand breaks were analyzed in the clam Ruditapes philippinarum caged at Cádiz Bay, Santander Bay and Las Palmas de Gran Canaria (LPGC) Port (Spain). Sediments were characterized. Digestive gland was the most sensitive tissue to sediment contamination. In Cádiz Bay, changes in LPO regarding day 0 were related with metals. In LPGC Port, DBF, EROD, and GST activity responses suggested the presence of undetermined contaminants which might have led to DNA damage. In Santander Bay, PAHs were related with EROD activity, organic and metal contamination was found to be associated with GR and GST activities and DNA damage presented significant (p < 0.05) induction. R. philippinarum was sensitive to sediment contamination at biochemical level. Biomarkers allowed chemical exposure and sediment quality assessment.

The increasing use of nanotechnology highlights the need to understand and clarify the environmental impacts of nanomaterials. In this study, the acute toxicity and oxidative stress of titanium dioxide nanoparticles (nTiO₂) in mature marine abalone (Haliotis diversicolor supertexta) were assessed. No acute effect was found in any of the treatment groups with nTiO₂ concentration gradients ranging from 0.1 to 10mg/L. However, the activity of an antioxidant enzyme superoxide dismutase (SOD) significantly increased in the group that was exposed to 1.0mg/L nTiO₂. The content of a non-enzymatic antioxidant, glutathione (GSH), significantly decreased in the groups with an nTiO₂ concentration ⩾1.0mg/L. The level of lipid peroxidation (LPO) was found to increase as the nTiO₂ dose increased. Furthermore, NO was produced in excess in abalone. These results demonstrated that, although nTiO₂ is not acutely toxic to abalone, it does exert oxidative stress on abalone.

The biocide triclosan (TCS, 5-chloro-2-(2,4-dichlorophenoxy)phenol) is commonly used in several personal care products, textiles, and children’s toys. Because the removal of TCS by wastewater treatment plants is incomplete, its environmental fate is to be discharged into freshwater ecosystems, where its ecological impact is largely unknown. The aim of this study was to determine the effect of TCS on the antioxidant enzymatic chain of the freshwater mollusk zebra mussel (Dreissena polymorpha). We measured the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as the phase II detoxifying enzyme glutathione S-transferase (GST) in zebra mussel specimens exposed to 1 nM, 2 nM, and 3 nM TCS in vivo. The mussels were exposed for 96 h, and the enzyme activities were measured every 24 h. We measured clear activation of GST alone at all three dose levels, which shows a poor induction of the antioxidant enzymatic chain by TCS. CAT and SOD were activated only at 3 nM, while GPx values overlapped the baseline levels.