Globally carbon nanoparticles are increasingly utilized, yet it is not known if these nanoparticles pose a threat to the environment or human health. This investigation examined 'as-prepared', and acid cleaned carbon nanoparticle physicochemical characteristics (by FTIR, TEM, FESEM, UV-VIS and X-ray microanalysis), and whether these characteristics changed following 2.5-7 yr exposure to pH neutral saline or fresh water. To determine if these aqueous aged nanotubes were cytotoxic, these nanotubes were incubated with human epithelial monolayers and analyzed for cell viability (vital staining) and ultrastructural nanoparticle binding/localization (TEM, FESEM). The presence of Ni and Y catalyst, was less damaging to cells than CNT lattice surface oxidation. Extended fresh water storage of oxidized CNTs did not reduce surface reactive groups, nor lessen cell membrane destruction or cell death. However storing oxidized CNTs in saline or NOM significantly reduced CNT-induced cell membrane damage and increased cell survival to control levels. Oxidized SWCNTs in pH neutral fresh and saline water showed no reduction in surface oxidation with time, yet exposure of these nanotubes to saline and NOM reduced human cell toxicity markedly.

In the last decades a dramatic loss of Apis mellifera hives has been reported in both Europe and USA. Research in this field is oriented towards identifying a synergy of contributing factors, i.e. pathogens, pesticides, habitat loss and pollution to the weakening of the hive. Cadmium (Cd) is a hazardous anthropogenic pollutant whose effects are proving to be increasingly lethal. Among the multiple damages related to Cd contamination, some studies report that it causes immunosuppression in various animal species. The aim of this paper is to determine whether contamination by Cd, may have a similar effect on the honey bees’ immunocompetence. Our results, obtained by immune challenge experiments and confirmed by structural and ultrastructural observations show that such metal causes a reduction in immunocompetence in 3 days Cd exposed bees. As further evidence of honey bee response to Cd treatment, Energy Dispersive X-ray Spectroscopy (X-EDS) has revealed the presence of zinc (Zn) in peculiar electron-dense granules in fat body cells. Zn is a characteristic component of metallothioneins (MTs), which are usually synthesized as anti-oxidant and scavenger tools against Cd contamination. Our findings suggest that honey bee colonies may have a weakened immune system in Cd polluted areas, resulting in a decreased ability in dealing with pathogens.

The discharge of oil well produced water (PW) provides a constant source of contaminants to the marine environment including polycyclic aromatic hydrocarbons, alkylated phenols, metals and production chemicals. High concentrations of PW cause adverse effects to exposed biota, including reduced survival, growth and reproduction. Here we explore the effects of PW on immune function in the blue mussel, Mytilus edulis. Mussels were exposed for 21 days to sublethal PW concentrations (0.125-0.5%) and cellular parameters were measured. Cell viability, phagocytosis and cytotoxicity were inhibited after exposure to 0.25% and 0.5% PW, whilst the 0.125% PW treatment produced significant increases in these biomarker responses. This biphasic response was only observed after 7 days exposure; longer exposure periods led to a reduction in immune parameters. Results indicate that PW concentrations close to the discharge point cause modulation to cellular immunity. The implications for longer-term disease resistance are discussed. Exposure to produced water alters immune function in the sentinel species Mytilus edulis.

To investigate the consequences of acidification and metal accumulation on the biology of aquatic bryophytes, the acid-tolerant liverwort Scapania undulata (L.) Dum. and the acid-sensitive moss Rhynchostegium riparioides (Hedw.) Cardot were transplanted from one stream to two other streams of differing acidity (pH 5.20 and 6.38). The bryophytes were collected in a circumneutral (pH 6.57) stream in the Vosges Mountains. Metal accumulation was semi-quantitatively measured in shoots by energy dispersive TEM X-ray spectroscopy (EDXS). After 1 month, the two species remained green without alteration signs. Although no marked ultrastructural damage was observed in either species, some cells seemed to be necrotic, with flattened chloroplasts, in R. riparioides. Lipid droplet accumulation was observed in some leaf cells of S.undulata when transplanted to the most acidic stream. Metal was mostly localised in the cell wall, and was only sometimes detected in small vacuoles. Under acidic conditions, R. riparioides showed the highest relative amount of Al and the lowest amount of Fe, whereas the acid-tolerant bryophyte species S. undulata contained more Fe and less Al. The capability to limit the uptake of metals into the cytoplasm varies according to the bryophyte species. This could be an explanation of the tolerance of S. undulata to acidification.

The present study aims to evaluate the comparative effects of methyl parathion and hexaconazole on genotoxicity, oxidative stress, antioxidative defence system and photosynthetic pigments in barley (Hordeum vulgare L. variety karan-16). The seeds were exposed with three different concentrations, i.e. 0.05, 0.1 and 0.5 % for 6 h after three pre-soaking durations 7, 17 and 27 h which represents G₁, S and G₂ phases of the cell cycle, respectively. Ethyl methane sulphonate, a well-known mutagenic agent and double distilled water, was used as positive and negative controls, respectively. The results indicate significant decrease in mitotic index with increasing concentrations of pesticides, and the extent was higher in methyl parathion. Chromosomal aberrations were found more frequent in methyl parathion than hexaconazole as compared to their respective controls. Treatment with the pesticides induced oxidative stress which was evident with higher contents of H₂O₂ and lipid peroxidation, and the increase was more prominent in methyl parathion. Contents of total phenolics were increased; however, soluble protein content showed a reverse trend. Among the enzymatic antioxidants, activities of superoxide dismutase and peroxidase were significantly up-regulated, and more increase was noticed in hexaconazole. Increments in total chlorophyll and carotenoid contents were observed up to 0.1 % but decreased at higher concentration (0.5 %), and the reductions were more prominent in methyl parathion than hexaconazole as compared to their respective controls. Methyl parathion treatment caused more damage in the plant cells of barley as compared to hexaconazole, which may be closely related to higher genotoxicity and oxidative stress.

Introduction More attention has been paid to tetracycline contamination in view of its rapid increasing concentration in the environment. Therefore, it is important to set up rapid, simple, and accurate methods for monitoring tetracycline ecotoxicity. Methods In the present study, a hydroponics experiment was conducted to examine toxic effects of tetracycline at the concentration range of 0.5 to 300 mg L⁻¹ on growth, antioxidative, and genetic indices of wheat (Triticum aestivum L.). Results The results indicated that tetracycline at 0.5-10 mg L⁻¹ could stimulate seed germination, cell mitotic division, and growth of wheat seedlings and did not induce a significant increase in the activity of antioxidative enzymes. However, tetracycline at the high concentrations (10-300 mg L⁻¹) could significantly inhibit these parameters in the concentration-dependent manner, including germination percentage (≥100 mg L⁻¹), shoot height (≥100 mg L⁻¹), root length (≥50 mg L⁻¹), and mitotic index (≥50 mg L⁻¹), and increased the activity of antioxidative enzymes (≥25 mg L⁻¹) in the dose-dependent manner, including superoxide dismutase, catalase, and peroxidase. Tetracycline at 5 mg L⁻¹ and above significantly augmented chromosome aberration frequency and malondialdehyde (MDA) content. On the other hand, MDA has positive correlation with the inhibition rates of seed germination, root length, shoot length, mitotic index, and antioxidative enzyme activities. Conclusion Tetracycline may have potential physiological, biochemical, and genetic toxicity to plant cells, and chromosome aberration and MDA might be sensitive bioindicators for tetracycline contamination than the other plant characteristics.

Background, aim and scope Mixed pollution with trace elements and organic industrial compounds is characteristic for many spill areas and dumping sites. The danger for the environment and human health from such sites is large, and sustainable remediation strategies are urgently needed. Phytoremediation seems to be a cheap and environmentally sound option for the removal of unwanted compounds, and the hyperaccumulation of trace elements and toxic metals is seemingly independent from the metabolism of organic xenobiotics. However, stress reactions, ROS formation and depletion of antioxidants will also cause alterations in xenobiotic detoxification. Here, we investigate the capability of plants to detoxify chlorophenols via glutathione conjugation in a mixed pollution situation. Materials and methods Typha latifolia and Phragmites australis plants for the present study were grown under greenhouse conditions in experimental ponds. A Picea abies L. suspension culture was grown in a growth chamber. Cadmium sulphate, sodium arsenate and lead chloride in concentrations from 10 to 500 µM were administered to plants. Enzymes of interest for the present study were: glutathione transferase (GST), glutathione reductase, ascorbate peroxidase and peroxidase. Measurements were performed according to published methods. GST spectrophotometric assays included the model substrates CDNB, DCNB, NBC, NBoC and the herbicide Fluorodifen. Results Heavy metals lead to visible stress symptoms in higher plants. Besides one long-term experiment of 72 days duration, the present study shows time and concentration-dependent plant alterations already after 24 and 72 h Cd incubation. P. abies spruce cell cultures react to CdSO₄ and Na₂HAsO₄ with an oxidative burst, similar to that observed after pathogen attack or elicitor treatment. Cd application resulted in a reduction in GSH and GSSG contents. When a heavy metal mixture containing Na₂HAsO₄, CdSO₄ and PbCl₂ was applied to cultures, both GSH and GSSG levels declined. Incubation with 80 µM arsenic alone doubled GSSG values. Based on these results, further experiments were performed in whole plants of cattail and reed, using cadmium in Phragmites and cadmium and arsenic in Typha as inducers of stress. In Phragmites australis, GST activities for CDNB and DCNB were significantly reduced after short-term Cd exposure (24 h). In the same samples, all antioxidant enzymes increased with rising heavy metal concentrations. Typha latifolia rhizome incubation with Cd and As leads to an increase in glutathione reductase and total peroxidase activity and to a decrease in ascorbate peroxidase activity. Measurements of the same enzymes in leaves of the same plants show increased GR activities, but no change in peroxidases. GST conjugation for CDNB was depressed in both cattail rhizomes and leaves treated with Cd. After As application increased, DCNB enzyme activities were detected. Discussion T. latifolia and P. australis are powerful species for phytoremediation because they penetrate a large volume of soil with their extensive root and rhizome systems. However, an effective remediation process will depend on active detoxifying enzymes, and also on the availability of conjugation partners, e.g. glutathione and its analogues. Species-specific differences seem to exist between the regulations of primary defence enzymes like SOD, catalase, peroxidases, whereas others prefer to induce the glutathione-dependent enzymes. As long as the pollutant mix encountered is simple and dominated by heavy metals, plant defence might be sufficient. When pollution plumes contain heavy metals and organic xenobiotics at the same time, this means that part of the detoxification capacity, at least of glutathione-conjugating reactions, is withdrawn from the heavy metal front to serve other purposes. In fact, glutathione S-transferases show strong reactions in stressed plants or in the presence of heavy metals. The spruce cell culture was a perfect model system to study short-term responses on heavy metal impact. Overall, and on the canopy level, this inhibitory effect might result in a lower detoxification capacity for organic pollutants and thus interfere with phytoremediation. Conclusions We present evidence that pollution with heavy metals will interfere with both the oxidative stress defence in plants, and with their ability to conjugate organic xenobiotics. Despite plant-species-dependent differences, the general reactions seem to include oxidative stress and an induction of antioxidative enzymes. Several processes seem to depend on direct binding of heavy metals to enzyme proteins, but effects on transcription are also observed. Induction of xenobiotic metabolism will be obtained at high heavy metal concentrations, when plant stress is elevated. Recommendations and perspectives Plants for phytoremediation of complex pollution mixtures have to be selected according to three major issues: uptake/accumulation capacity, antioxidative stress management, and detoxification/binding properties for both the trace elements and the organic xenobiotics. By way of this, it might be possible to speed up the desired remediation process and/or to obtain the desired end products. And, amongst the end products, emphasis should be laid on industrial building materials, biomass for insulation or biogas production, but not for feed and fodder. Each of these attempts would increase the chances for publicly accepted use of phytoremediation and help to cure the environment.