bluuebunny/crossref_metadata_2025 huggingface dataset:
Phototactic behavior of Daphnia and the continuous monitoring of water quality: Interference of fish kairomones and food quality
Authors: Kieu Nhan Dang , Michels Erik , De Meester Luc
Published: March 2010

We carried out a laboratory study to evaluate the sensitivity of phototactic behavior of Daphnia magna to sublethal concentrations of pentachlorophenol (PCP) and copper. More specifically, we determined whether the sensitivity of a D. magna clone to those pollutants is influenced by food quality and the presence of fish kairomones. Test animals were fed either unicellular green algae (Scenedesmus acutus) or fresh baker's yeast (Saccharomyces cerevisiae) and were cultured in the presence or absence of fish kairomones. Four concentrations of PCP (0.4, 0.8, 1.2, and 1.6 mg/L PCP) and one concentration of copper (0.02 mg/L Cu2+) in International Standards Organisation (ISO, Geneva, Switzerland) standard medium were applied in the experiments. Animals were exposed for 3 h to the pollutants prior to the experiments. In the absence of fish kairomones, a strong negative relationship between the phototactic index and nominal sublethal concentrations of PCP was found in animals fed either algae or yeast. The sensitivity of the Daphnia clone to sublethal concentrations of PCP was, however, less clear cut in animals fed yeast than in animals fed algae. The detection limit was 0.4 mg/L PCP with algae as food but was as high as 1.2 mg/L PCP when yeast was used as food. The ability to detect sublethal concentrations of copper and PCP using phototactic behavior was lost when the clones were cultured in the presence of fish kairomones. At a concentration of 0.02 mg/L Cu2+ and in the absence of fish kairomones, the D. magna clone tested became significantly less positively phototactic than in the control treatment regardless of the quality of the food used to culture the test animals. These results suggest that assays using the phototactic behavior of Daphnia to monitor water quality should use genetically stable (clonal) material, positively phototactic, and insensitive to the presence of fish kairomones.
Class III metallothioneins in response to cadmium toxicity in the marine microalga Tetraselmis suecica (Kylin) Butch
Authors: Pérez-Rama Mónica , López Concepción Herrero , Alonso Julio Abalde , Vaamonde Enrique Torres
Published: March 2010

Microalgae are one of the most important organisms in our ecosystems being seriously affected by metal pollution. However, the microalgae Tetraselmis suecica (Kylin) Butch is tolerant to cadmium; the concentration of this metal that reduces the population growth to 50% of the control growth level is 5.8 mg/L after 96 h of exposure. In this study, class III metallothioneins were investigated for their involvement as a possible tolerance mechanism in this microalga when exposed to cadmium. A set of these molecules was purified from these microalgal cells after exposure to the metal. These polypeptides were analyzed by capillary zone electrophoresis, which is a technique that allows the length of the metallothioneins synthesized by this microalga to be known. The T. suecica cells were able to synthesize class III metallothioneins of three to six subunits of (γ-Glu-Cys). The most abundant polypeptide possessed four subunits, and (γ-Glu-Cys)6-Gly was the largest polypeptide synthesized by this microalga and detected by this technique. Tolerance to cadmium as a function of increasing polypeptide length is also discussed.
Ultimate biodegradation of alkylphenol ethoxylate surfactants and their biodegradation intermediates
Authors: Staples Charles A , Naylor Carter G , Williams James B , Gledhill William E
Published: March 2010

The ultimate biodegradation of the commercial products nonylphenol ethoxylates (NPE9), octylphenol ethoxylates (OPE9), and their biodegradation intermediates, NPE1.5, OPE1.5, NP, and OP, was measured using conventional methods. The extent of biodegradation was also determined by gas chromatography/mass spectrometry (GC/MS) and high-performance liquid chromatography (HPLC) analysis of metabolites and measurement of dissolved organic carbon. Optimized pseudo–first order degradation rate constants and half-lives were calculated from these data and from previously published data, using Larson's equation for surfactant degradation kinetics. Ultimate aerobic biodegradation of alkylphenol ethoxylates and their biodegradation intermediates has now been examined using acclimated wastewater treatment plant sludge as the microbial seed, household wastewater treatment systems, and unacclimated fresh water, seawater, and soil. Ultimate biodegradation half-lives ranged from about one to four weeks and provide definitive evidence for the extensive biodegradability of alkyphenol ethoxylates (APE) surfactants and their metabolites and their lack of persistence in the environment.
Use ofUlva lactucato identify ammonia toxicity in marine and estuarine sediments
Authors: Pelletier Marguerite C , Ho Kay T , Cantwell Mark , Kuhn-Hines Anne , Jayaraman Saro , Burgess Robert M
Published: March 2010

Toxicity identification evaluation (TIE) methods are being developed for use with whole sediments. Although a phase I TIE method has been developed to characterize ammonia toxicity in aqueous samples using the marine macroalga Ulva lactuca, the relationship between amphipod and mysid mortality and uptake by U. lactuca of bedded sediment ammonia had not been explored. Additionally, it was not known how interactions in whole sediments between metal and organic contaminants with U. lactuca and ammonia would affect TIE interpretation. The current study showed that ammonia toxicity to amphipods and mysids was reduced significantly in marine sediments in the presence of U. lactuca. The alga slightly affected metal concentrations but did not alter the concentration of organic contaminants in either overlying or interstitial waters. Conversely, ammonia uptake by U. lactuca was not affected by the presence of metal or organic contaminants in the sediments. When used with other TIE manipulations, U. lactuca can be utilized in a whole-sediment, phase I TIE to remove toxicity due to ammonia.
Biomimetic solid-phase microextraction to predict body residues and toxicity of chemicals that act by narcosis
Authors: Leslie Heather A. , Oosthoek Annelies J. P. , Busser Frans J. M. , Kraak Michiel H. S. , Hermens Joop L. M.
Published: March 2010

A biomimetic extraction technique using solid-phase microextraction (SPME) fibers has been developed for the risk assessment of contaminants with a narcotic mode of action. Our goal is to apply this technique in the future for the prediction of total baseline toxicity of environmental water and effluent samples. Validation of this method requires establishing the relationship between contaminant accumulation and toxicity in biota and accumulation in the surrogate solid phase (the SPME fiber coating). For this purpose, we determined the median lethal concentration (LC50) values for Chironomus riparius midge larvae exposed to two halogenated aromatic compounds separately and measured body residues in the exposed larvae. Solid-phase microextraction fibers with an 85-μm polyacrylate (PA) coating served as the surrogate hydrophobic phase, mimicking the uptake of the compounds by midge larvae. The toxicant concentrations in SPME fibers measured directly by gas chromatography/mass spectrometry (GCMS) or calculated from the SPME fiber—water partition coefficient, KSPME, were related to the toxicant concentrations found in midge larvae. Our results demonstrated that the biomimetic SPME method enables the estimation of body residues in biota and prediction of the degree of baseline toxicity of a water medium.
A pesticide surface water mobility index and its relationship with concentrations in agricultural drainage watersheds
Authors: Chen Wenlin , Hertl Peter , Chen Sunmao , Tierney Dennis
Published: March 2010

An index to benchmark pesticide mobility relevant to surface water runoff and soil erosion (surface water mobility index, or SWMI) was derived based on two key environmental fate parameters: degradation half-life and organic carbon-normalized soil/water sorption coefficient (Koc). Values assigned with the index of each individual compound correlate well with the concentration trend of 13 pesticides monitored in six Lake Erie, USA, tributaries from 1983 to 1991. Regression using a power function of SWMI fits concentration data well at various percentiles in the database for each tributary and all six tributaries combined, with r2 ranging from 0.71 to 0.94 for the concentrations at the 95th percentile. Good agreement was also obtained between SWMI and the timeweighted annual mean concentrations (r2 = 0.67–0.87). Although concentrations at or near peaks tend to be driven by rare hydrological events (intense precipitation immediately after application), SWMI explains the peak concentration data generally well (r2 = 0.53–0.86). The SWMI-concentration relationship was further evaluated with two other pesticide monitoring databases: the U.S. Geological Survey National Water Quality Assessment Program White River Study Unit (1991–1996) at Hazelton, Indiana, USA, and the Syngenta (previously Novartis) Voluntary Monitoring Program with Community Water Systems at the Higginsville City Lake, Missouri, USA (1995–1997). The ability of the proposed SWMI to discriminate pesticide runoff mobility and its correlation with surface water monitoring data can be significant in the development of screening methodologies and data-based models for government agencies and/or practitioners in general facing increasing pressure to assess pesticide occurrence in aquatic environments.
Effects of agricultural runoff on native amphibians in the Lower Fraser River Valley, British Columbia, Canada
Authors: de Solla Shane R. , Pettit Karen E. , Bishop Christine A. , Cheng Kimberly M. , Elliott John E.
Published: March 2010

Hatching success, deformity rates, and survivorship of northern red-legged frogs (Rana aurora) and northwestern salamanders (Ambystoma gracile) were assessed at three agricultural and three reference sites in the Sumas Prairie, British Columbia, Canada. In 1997 and 1998, eggs of both species and eggs of R. aurora, respectively, were placed in Nytex mesh cages (Irwindale, CA, USA) in roadside ditches at each site. Concurrently in 1997, eggs of R. aurora were reared in the laboratory but were exposed to water samples from each of the study sites. Hatching success was significantly lower at all agricultural sites compared to the reference sites for both species. However, no differences were observed in hatching success among sites for eggs of R. aurora reared in the laboratory. Water chemistry differed among all sites, but the largest differences were between reference and agricultural sites. Ammonia (maximum of 1.27 mg/L), total phosphate (maximum of 8.14 mg/L), and biological oxygen demand (maximum of 79.00 mg/L) were high at some of the agricultural sites during the development period. Results suggest that agricultural runoff may contribute to lower reproductive success and ultimately to reduced population viability of amphibian populations in the Lower Fraser Valley (BC, Canada).
Integrated biomarker response: A useful tool for ecological risk assessment
Authors: Beliaeff Benoit , Burgeot Thierry
Published: March 2010

A battery of biomarkers is often used to evaluate the effects of exposure to chemical contaminants and detect responses to environmental stress. Unfortunately, field application of biomarkers is subject to various constraints (e.g., the availability of living material) that can limit data acquisition and prevent the use of multivariate methods during statistical analysis. In these circumstances, a simple method is needed to summarize biomarker responses and simplify their interpretation in biomonitoring programs. The present study used star plots to display results for the panel of biomarkers used for each station and survey. Integrated biomarker response (IBR) was then computed as the star plot area. Star plots using IBR values instead of biomarker data make it possible to visualize between-site and/or between-survey differences for comparison with exposure conditions. This approach was applied to sites in the Baltic Sea and the Seine Estuary, English Channel. In both cases, IBR values were visually compared to polycyclic aromatic hydrocarbons (PAH) or polychlorobiphenyls (PCB) levels measured in mussel or fish tissues. The IBR, as an indicator of environmental stress, appears to be a useful tool for scientists and managers in assessing ecological risk.
Toxicity of the explosives 2,4,6-trinitrotoluene, hexahydro-1,3,5-trinitro-1,3,5-triazine, and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine in sediments toChironomus tentansandHyalella azteca: Low-dose hormesis and high-dose mortality
Authors: Steevens Jeffery A. , Duke B. Maurice , Lotufo Guilherme R. , Bridges Todd S.
Published: March 2010

The toxicity of the explosives 2,4,6-trinitrotoluene (TNT); hexahydro-1,3,5-trinitro-1,3,5-triazine (royal demolition explosive [RDX]); and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (high-melting explosive [HMX]), was evaluated in spiked sediment with two freshwater invertebrates. The midge Chironomus tentans and the amphipod Hyalella azteca demonstrated significant toxic effects after exposure to TNT and its degradation products, 1,3,5-trinitrobenzene (TNB) and 2,4-diamino-6-nitrotoluene (2,4-DANT). Significant reductions in survival of C. tentans exposed to TNT, TNB, and 2,4-DANT were observed at nominal sediment concentrations as low as 200 mg/kg. Hyalella azteca was more sensitive to TNT, TNB, and 2,4-DANT than the midge, where significant reductions in survival were observed at nominal concentrations of 50, 100, and 200 mg/kg, respectively. Survival of the midge and the amphipod was unaffected after exposure to RDX or HMX at the highest concentrations of 1,000 and 400 mg/kg, respectively. Growth of the midge, measured as total weight, was significantly reduced by 2,4-DANT. However, significantly increased growth was observed after exposure to sublethal concentrations of RDX and HMX. Although significant reductions in amphipod survival were observed at high concentrations of TNB, growth was significantly increased at sublethal concentrations. The results of the current investigation suggest that organisms exposed to explosives at contaminated sites may be affected at concentrations less than 25 mg/kg through hormetic growth enhancement and at higher concentrations through increased mortality.
Accumulation and elimination of 16 polycyclic aromatic compounds in the earthworm (Eisenia fetida)
Authors: Matscheko Nadja , Lundstedt Staffan , Svensson Linda , Harju Jvikael , Tysklind Mats
Published: March 2010

Acumulation and elimination of different polycyclic aromatic compounds (PACs) were studied in earthworms (Eisenia fetida) exposed to contaminated soil from an old gasworks site. In total, 12 polycyclic aromatic hydrocarbons (PAHs), two N- and S-heterocyclic PACs, and two PAC-quinones were included in the study. Peak-shaped accumulation curves were found for many of the compounds. After 19 d of exposure, the ratio between concentrations in worm lipids and soil organic matter was 0.02 on average. The half-lives of the PACs were relatively long, between 2 and 11d. The elimination rate constants, k2, correlated both with literature-derived octanol-water partition coefficients (Kow) for PAHs (r2 = 0.93) and the computed polarizability (r2 = 0.88) of all the compounds. The elimination rate constants of PAHs are comparable to those of PCBs found in earlier studies, and the linear regression coefficient, r2, of k2 against Kow for PAHs and PCBs together was 0.93.
Uptake of intact zinc-ethylenediaminetetraacetic acid from soil is dependent on plant species and complex concentration
Authors: Collins Richard N. , Merrington Graham , McLaughlin Mike J. , Knudsen Chris
Published: March 2010

Pot experiments were conducted with barley (Hordeum vulgare L.), potato (Solanum tuberosum L.), Indian mustard (Brassica juncea L.), and white lupin (Lupinus albus L.) to determine the nature of Zn mobilization, uptake, and root-shoot transport from a Zn-contaminated soil in the presence of increasing concentrations of ethylenediaminetetraacetic acid (EDTA; 0.0–3.4 mmole/kg soil). Increasing EDTA concentrations lead to a greater proportion of soil-solution Zn being detected as the ZnEDTA complex. However, a significant increase in the concentration of soil-solution Zn was only observed after the addition of 3.4 mmole EDTA/kg soil. At this application rate, regardless of the plant species, 97 ± 9% (± SD) of the increase in soil-solution Zn could be accounted for by chelation/desorption, and 89 ± 9% of total Zn in solution was measured as ZnEDTA. Although the complex was detected in the xylem exudate of B. juncea after 0.34 mmole EDTA/kg soil had been added, ZnEDTA was only found in the xylem exudate of the other plant species following the highest application rate of EDTA. In this case, the accumulation of Zn and the concentration of ZnEDTA in the xylem sap of B. juncea were significantly greater than those of H. vulgare and S. tuberosum. Measurements of plant transpiration following the addition of EDTA indicated that B. juncea experienced greater physiological stress in the presence of high concentrations of EDTA. It was therefore concluded that two different mechanisms of ZnEDTA uptake existed for these plant species. Based on a review of the literature, it was hypothesized that uptake of ZnEDTA by B. juncea occurred only after physiological damage to its root system, whereas uptake by H. vulgare and S. tuberosum was via an apoplastic pathway (passive extracellular transport into the xylem).
Persistent organochlorine residues and their bioaccumulation profiles in resident and migratory birds from North Vietnam
Authors: Minh Tu Binh , Kunisue Tatsuya , Yen Nguyen Thi Hong , Watanabe Mafumi , Tanabe Shinsuke , Hue Nguyen Duc , Qui Vo
Published: March 2010

Concentrations of persistent organochlorines (OCs), such as polychlorinated biphenyls (PCBs), 1 1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), and chlordane compounds (CHLs), were determined in whole-body homogenates of resident and migratory birds collected from the Red River estuary, North Vietnam, during March and October 1997. Contamination pattern was in the order of DDTs > PCBs > HCHs > CHLs > HCB in both resident and migratory birds. Residue concentrations, according to the feeding habit, showed little variability, which may reflect relatively similar trophic levels of the bird species analyzed. Resident birds accumulated greater concentrations of DDTs as compared to migrants. In contrast, HCH residues were greater in migratory species. Higher proportions of p,p′-DDT to total DDT concentrations were found in many species of residents and migrants, indicating recent exposure to technical DDT in northern Vietnam. Congener-specific PCB analysis showed the predominance of penta- and hexachlorobiphenyls in all the species analyzed. Estimation of hepatic microsomal enzyme activities suggested higher metabolic capacity for PCB congeners in shore birds from Vietnam as compared to higher-trophic predator birds and marine mammals. Comparison of OC residues in avian species in Asia-Pacific revealed that DDT residues in resident birds in North Vietnam are among the highest values reported for the countries surveyed, suggesting recent usage of DDT in Vietnam. Available data for birds, fish, and bivalves from the recent Asia-Pacific Mussel Watch Program suggested that Vietnam might be a potential source of DDT contamination in Asian developing countries. To our knowledge, this is the first study of the OC accumulation in avian species from Vietnam.
Toxicity of metal mixtures to a tropical freshwater alga (Chlorellasp.): The effect of interactions between copper, cadmium, and zinc on metal cell binding and uptake
Authors: Franklin Natasha M. , Stauber Jennifer L. , Lim Richard P. , Petocz Peter
Published: March 2010

The individual and combined effects of copper, cadmium, and zinc on the cell division rate of the tropical freshwater alga Chlorella sp. were determined over 48 to 72 h. Metal mixtures were prepared based on multiples of their single-metal median effective concentration (EC50) values, i.e., toxic units (TU) using a triangular mixture design with five toxicant levels (0, 0.75, 1.0, 1.25, and 1.5 TU). Single-metal EC50 values after a 72-h exposure were 0.11, 0.85, and 1.4 μM for copper, cadmium, and zinc, respectively. Significant interactions were observed for all metal combinations after 48 and 72 h. An equitoxic mixture of Cu 1 Cd was more than concentration additive (synergistic) to the growth of Chlorella sp., while combinations of Cu + Zn, Cd + Zn, and Cu + Cd + Zn were all less than concentration additive or were antagonistic. To determine the effect of each metal on the uptake of the other, extracellular (membrane-bound) and intracellular metal concentrations, both alone and in mixtures, were compared. The increased growth inhibition observed for mixtures of Cu + Cd was due to higher concentrations of cell-bound and intracellular copper in the presence of cadmium compared with copper alone (i.e., cadmium-enhanced copper uptake). In contrast, both extra- and intracellular cadmium concentrations were reduced in the presence of copper. In mixtures of Cu + Zn, copper also inhibited the binding and cellular uptake of zinc, which resulted in decreased toxicity. Zinc had no appreciable effect on the uptake of copper by Chlorella sp. Our results suggest that all three metals share some common uptake and transport sites on Chlorella cells and that copper out competes both cadmium and zinc for cell binding. Determination of metal cell distribution coefficients (Kd) confirmed that Kd values for cadmium and zinc in single-metal exposures decreased in the presence of copper.
Measuring the bioavailability of two hydrophobic organic compounds in the presence of dissolved organic matter
Authors: Akkanen Jarkko , Kukkonen Jussi V. K.
Published: March 2010

Bioavailability of benzo[a]pyrene (BaP) and 3,3′,4,4′-tetrachlorobiphenyl (TCB) was studied in natural lake water containing dissolved organic matter (DOM). Lake water was diluted to give a dissolved organic carbon (DOC) range of 1 to 20 mg/L. Partition coefficients for the model compounds were assessed at different DOM concentrations and over time with three different methods, namely equilibrium dialysis and reverse-phase and liquid-liquid extraction. In addition, biological partition coefficients were estimated from the difference in the bioconcentration of the model compounds in Daphnia magna in the presence and absence of DOM. Results showed that bioavailability of the model compounds was reduced by the presence of DOM. The equilibrium dialysis method gave the best estimates for bioavailability of the model compounds when compared with biologically determined values. Both the reverse-phase and the liquid-liquid extraction overestimated the bioavailable fraction. The more pronounced overestimation of bioavailable fraction of TCB suggested that the sorption of TCB was not only lower but the interaction was also weaker than that of BaP. Increasing DOM concentration produced lower partition coefficients and the effect seemed to be more pronounced when measured by the reverse-phase and the extraction methods.
Activity and population dynamics of heterotrophic and ammonia-oxidizing microorganisms in soil surrounding sludge bands spiked with linear alkylbenzene sulfonate: A field study
Authors: Brandt Kristian Koefoed , Krogh Paul Henning , Sørensen Jan
Published: March 2010

Recent research has documented soil microorganisms to be rather sensitive to linear alkylbenzene sulfonates (LAS), which may enter the soil environment in considerable quantities following sewage sludge disposal. We here report field effects of LAS on selected microbial populations present in a sandy soil surrounding well-defined sludge bands spiked with high but realistic LAS levels (7.1 or 31.3 g/kg). Surprisingly, LAS had no effect on heterotrophic respiration in the sludge compartment per se but stimulated activity and metabolic quotient (microbial activity per unit of biomass) in the surrounding soil. By contrast, autotrophic ammonia oxidation was initially inhibited in the LAS-spiked sludge. This led to dramatic transient increases of NH+4 availability in the sludge and surrounding soil, subsequently stimulating soil ammonia oxidizers. As judged from a Nitrosomonas europaea bioluminescence toxicity assay, however, LAS or other sludge components never accumulated to toxic levels in the soil compartments and the LAS tolerance of the indigenous microbes further remained unchanged following LAS exposure. LAS effects on the investigated microbial populations largely occurred during the first two months and were confined to soil closer than 30 mm from LAS-spiked sludge. Our results strongly suggest that disposal of LAS-contaminated sludge does not pose a major risk to the function of the soil microbial community under field conditions.
Quantitative measurement of fathead minnow vitellogenin mRNA using hybridization protection assays
Authors: Thomas-Jones Emma , Walkley Neal , Morris Ceri , Kille Peter , Cryer Jennifer , Weeks Ian , Woodhead J. Stuart
Published: March 2010

We have developed a novel test system for the quantitative assessment of gene transcription. The procedure involves the use of chemiluminescent-labeled oligonucleotide probes in a hybridization protection assay (HPA) format. We have used this technology to measure changes in vitellogenin mRNA to demonstrate the impact of estrogen exposure in the juvenile fathead minnow (Pimephales promelas). Marked changes in mRNA expression were observed in response to intraperitoneal injection of 17β-estradiol demonstrating the utility of this technique for the identification and monitoring of toxic responses to xenobiotics.
Arsenic speciation in the earthworms Lumbricus rubellus and Dendrodrilus rubidus
Authors: Langdon Caroline J. , Piearce Trevor G. , Feldmann Jörg , Semple Kirk T. , Meharg Andrew A.
Published: March 2010

Two species of earthworm, Lumbricus rubellus Hoffmeister and Dendrodrilus rubidus (Savigny) collected from an arsenic-contaminated mine spoil site and an uncontaminated site were investigated for total tissue arsenic concentrations and for arsenic compounds by liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). For L. rubellus, whole-body total tissue arsenic concentrations were 7.0 to 17.0 mg arsenic/kg dry weight in uncontaminated soil and 162 to 566 mg arsenic/kg dry weight in contaminated soil. For D. rubidus, whole-body tissue concentrations were 2.0 to 5.0 mg arsenic/kg dry weight and 97 to 321 mg arsenic/kg dry weight, respectively. Arsenobetaine was the only organic arsenic species detected in both species of earthworms, with the remainder of the extractable arsenic being arsenate and arsenite. There was an increase in the proportion of arsenic present as arsenobetaine in the total arsenic burden. Lumbricus rubellus and D. rubidus have similar life styles, both being surface living and litter feeding. Arsenic speciation was found to be similar in both species for both uncontaminated and contaminated sites, with dose-dependent formation of arsenobetaine. When L. rubellus and D. rubidus from contaminated sites were incubated in arsenic-free soils, the total tissue burden of arsenic diminished. Initially, L. rubellus from the tolerant populations (from the contaminated site) eliminated arsenic in the first 7 d of exposure before accumulating arsenic in tissues, whereas nontolerant populations (from the uncontaminated site) accumulated arsenic linearly. The tolerant and nontolerant L. rubellus eliminated tissue arsenic linearly over 21 d when incubated in uncontaminated soil.
Developmental phytotoxicity of metal oxide nanoparticles to Arabidopsis thaliana
Authors: Lee Chang Woo , Mahendra Shaily , Zodrow Katherine , Li Dong , Tsai Yu-Chang , Braam Janet , Alvarez Pedro J.J.
Published: March 2010

Phytotoxicity is an important consideration to understand the potential environmental impacts of manufactured nanomaterials. Here, we report on the effects of four metal oxide nanoparticles, aluminum oxide (nAl2O3), silicon dioxide (nSiO2), magnetite (nFe3O4), and zinc oxide (nZnO), on the development of Arabidopsis thaliana (Mouse-ear cress). Three toxicity indicators (seed germination, root elongation, and number of leaves) were quantified following exposure to each nanoparticle at three concentrations: 400, 2,000, and 4,000 mg/L. Among these particles, nZnO was most phytotoxic, followed by nFe3O4, nSiO2, and nAl2O3, which was not toxic. Consequently, nZnO was further studied to discern the importance of particle size and zinc dissolution as toxicity determinants. Soluble zinc concentrations in nanoparticle suspensions were 33-fold lower than the minimum inhibitory concentration of dissolved zinc salt (ZnCl2), indicating that zinc dissolution could not solely account for the observed toxicity. Inhibition of seed germination by ZnO depended on particle size, with nanoparticles exerting higher toxicity than larger (micron-sized) particles at equivalent concentrations. Overall, this study shows that direct exposure to nanoparticles significantly contributed to phytotoxicity and underscores the need for eco-responsible disposal of wastes and sludge containing metal oxide nanoparticles. Environ. Toxicol. Chem. 2010;29:669–675. © 2009 SETAC
Bioavailability of a natural lead-contaminated invertebrate diet to zebrafish
Authors: Boyle David , Amlund Heidi , Lundebye Anne-Katrine , Hogstrand Christer , Bury Nic R.
Published: March 2010

Dietary metals are increasingly recognized as key determinants of total metal burdens in fish, yet their ecotoxicological significance remains unclear. In this study, a pairwise experimental design was used to assess reproductive performance of zebrafish (Danio rerio) fed diets supplemented with a natural Pb-enriched polychaete, Nereis diversicolor. Zebrafish were fed 1% flake food (dry wt diet/wet wt fish/d), 1% brine shrimp, and 1% N. diversicolor collected from either Gannel estuary, Cornwall, United Kingdom (UK), an estuary with legacy Pb contamination, or Blackwater estuary, Essex, UK, a reference site with low background metal concentrations, for 63 d. Mean daily dietary doses of Pb were 0.417 and 0.1 mg/kg/d (dry wt feed:wet wt fish) for fish fed N. diversicolor from Gannel and Blackwater estuaries, respectively. With the exception of Ag, which was higher for fish fed N. diversicolor from Gannel estuary, there were no differences in daily dietary exposures to other metals (As, Cd, Cu, Fe, and Zn) between treatment groups. Fish fed Pb-enriched Gannel N. diversicolor exhibited no significant impairment to incidence of spawning, numbers of eggs per breeding pair or hatch rate of embryos compared with pre-exposure levels, when N. diversicolor was omitted from the dietary regimen. Nevertheless, metal analysis revealed significant increases in whole-body Pb burdens of male fish fed polychaetes from Gannel estuary, Ag in female fish fed Gannel worms, and Ag and Cd in male fish fed the Blackwater worms. These data demonstrate that Pb naturally incorporated in N. diversicolor is bioavailable to fish, and fish exhibit sex-dependent dietary metal accumulation patterns, but after 63 d of the experimental feeding regimen, reproductive performance was unaffected. Environ. Toxicol. Chem. 2010;29:708–714. © 2009 SETAC
Molecular docking and comparative molecular similarity indices analysis of estrogenicity of polybrominated diphenyl ethers and their analogues
Authors: Yang Weihua , Liu Xiaohua , Liu Hongling , Wu Yang , Giesy John P. , Yu Hongxia
Published: March 2010

Molecular docking and three-dimensional quantitative structure–activity relationships (3D-QSAR) were used to develop models to predict estrogenicity of polybrominated diphenyl ethers (PBDEs), para-hydroxylated polybrominated diphenyl ethers (para-HO-PBDEs), and brominated bisphenol A compounds to the human estrogen receptor α (hERα). Based on the molecular conformations developed from the molecular docking, predictive comparative molecular similarity indices analysis (CoMSIA) models were developed. The results of CoMSIA modeling with region focusing included were: leave-one-out (LOO) cross-validated coefficient q2(LOO) = 0.722 (all 26 compounds), q2(LOO) = 0.633 (the training set, 20 compounds), q2(LMO, two groups) = 0.520 ± 0.155 (26 compounds), q2(LMO, five groups) = 0.665 ± 0.068 (26 compounds), predictive r2, r2pred = 0.686 (the test set, 6 compounds), and Q2EXT = 0.678. The 3D-QSAR can be used to infer the activities of compounds with similar structural characteristics. The interaction mechanism between compounds and the hERα was explored. Hydrogen bonding of the compound with Glu353 in the hERα is an important determinant of the estrogenic activity of para-HO-PBDEs and brominated bisphenol A. Environ. Toxicol. Chem. 2010;29:660–668. © 2009 SETAC
Evaluation of the amphibian metamorphosis assay: Exposure to the goitrogen methimazole and the endogenous thyroid hormone L-thyroxine
Authors: Coady Katherine , Marino Troy , Thomas Johnson , Currie Rebecca , Hancock Gregg , Crofoot Jackie , McNalley Lindsay , McFadden Lisa , Geter David , Klecka Gary
Published: March 2010

The U.S. Environmental Protection Agency (U.S. EPA) has included an amphibian metamorphosis assay (AMA) to detect thyroid active chemicals in Tier 1 testing of their endocrine screening program. To understand the variability, specificity, and reliability of the key endpoints of this assay, two exposure studies with Xenopus laevis tadpoles were conducted with two known thyroid-active compounds, namely, methimazole or L-thyroxine, for a total of 21 d. In addition, various increased-flow-rate treatments were included in the exposures to evaluate the effects of physical stress on metamorphic development. The endpoints examined in the exposures were wet weight, snout–vent length, hind-limb length, developmental stage, and thyroid and gonadal histopathology. As expected, the results indicated that both methimazole and L-thyroxine were thyroid active in the AMA, hind-limb length and thyroid histopathology being the most sensitive endpoints of thyroid activity. Tadpoles that were exposed to the various physical stressors in these experiments showed no signs of altered metamorphic development, and exposure to the thyroid-active compounds had no effect on the developing gonad of X. laevis. Taken together, these results support the use of the AMA as a Tier 1 endocrine screen for detection of potential thyroid pathway activity; however, the lack of a true negative response (no-effect) during the validation process prevents a full evaluation of this assay's specificity at this time. Environ. Toxicol. Chem. 2010;29:869–880. © 2009 SETAC
Influence of deltamethrin on nonspecific cellular and humoral defense mechanisms in rainbow trout (Oncorhynchus mykiss)
Authors: Siwicki Andrzej K. , Terech-Majewska Elzbieta , Grudniewska Joanna , Malaczewska Joanna , Kazun Krzysztof , Lepa Agnieszka
Published: March 2010

The influence of deltamethrin on the innate immunity in rainbow trout was examined. Fish were immersed in deltamethrin at doses of 1, 2, and 4 µg/L for 30 min. The results showed that deltamethrin at doses of 2 and 4 µg/L decreased phagocytic activity of spleen macrophages and proliferative response of pronephros lymphocytes at days 1, 2, and 5 after immersion. Deltamethrin at these doses decreased the lysozyme activity, total protein, and immunoglobulin levels in serum. The greatest immunosuppressive influence of deltamethrin at dose 4 µg/L was observed at the end of the study. Environ. Toxicol. Chem. 2010;29:489–491. © 2009 SETAC
Impact of microcystin containing diets on physiological performance of Nile tilapia (Oreochromis niloticus) concerning stress and growth
Authors: Ziková Andrea , Trubiroha Achim , Wiegand Claudia , Wuertz Sven , Rennert Bernhard , Pflugmacher Stephan , Kopp Radovan , Mareš Jan , Kloas Werner
Published: March 2010

Diets containing Microcystis with considerable amounts of the cyanotoxin microcystin-LR (MC-LR) were fed to determine their impact on the physiological performance of the omnivorous Nile tilapia (Oreochromis niloticus) with regard to stress and growth performance. Four different diets were prepared based on a commercial diet (control, MC-5% [containing 5% dried Microcystis biomass], MC-20% [containing 20% dried Microcystis biomass], and Arthrospira-20% [containing 20% dried Arthrospira sp. biomass without toxin]) and fed to female Nile tilapia. Blood and tissue samples were taken after 1, 7, and 28 d, and MC-LR was quantified in gills, muscle, and liver by using high-performance liquid chromatography (HPLC). Only in the liver were moderate concentrations of MC-LR detected. The stress hormone cortisol and glucose were analyzed from plasma, suggesting that all modified diets caused only minor to moderate stress, which was confirmed by analyses of hepatic glycogen. In addition, the effects of the different diets on growth performance were investigated by determining gene expression of hypophyseal growth hormone (GH) and hepatic insulin-like growth factor-I (IGF-I). For all diets, quantitative reverse transcription-polymerase chain reaction (RT-qPCR) demonstrated no significant effect on gene expression of the major endocrine hormones of the growth axis, whereas classical growth data, including growth and feed conversion ratio, displayed slight inhibitory effects of all modified diets independent of their MC-LR content. However, no significant change was found in condition or hepatosomatic index among the various diets, so it seems feasible that dried cyanobacterial biomass might be even used as a component in fish diet for Nile tilapia, which requires further research in more detail. Environ. Toxicol. Chem. 2010;29:561–568. © 2009 SETAC
Effect of nitrite on early-life stages of common carp (Cyprinus carpio L.)
Authors: Kroupova Hana , Prokes Miroslav , Macova Stanislava , Penaz Milan , Barus Vlastimil , Novotny Ladislav , Machova Jana
Published: March 2010

A one-month chronic exposure of common carp larvae and embryos to nitrite revealed significant (p < 0.01) differences in total accumulated mortality in fish exposed to 33, 67, and 330 mg/L NO 2− compared with controls. At the highest concentration, all fish died within 8 d of exposure. On the basis of accumulated mortality in the experimental groups, lethal concentrations of nitrite were estimated at 29 d LC50 = 88 mg/L NO 2−; lowest-observed-effect concentration (LOEC) = 28 mg/L NO 2−; and no-observed-effect concentration (NOEC) = 7 mg/L NO 2−. Fulton's condition factor values were significantly lower in fish from all experimental groups compared with controls. By day 12, fish exposed to 33 and 67 mg/L NO 2− had significantly lower mass and total length compared with controls. No significant negative effects of nitrite at the concentrations tested (0.7–330 mg/L NO 2−, at 10 mg/L Cl−) on hatching or embryo viability were demonstrated, but significant differences in early ontogeny among groups were noted. Fish from all the concentrations showed a dose-related delay in development compared with the controls. Lordosis, kyphosis, scoliosis, and body shortening were observed at all concentrations and in controls, as was yolk sac deformation and edema, eye deformation, and cardiac edema. The incidence of these malformations was positively correlated with nitrite concentration. Histopathology revealed epidermal spongiosis; edema and hyperplasia of the gill epithelium, including hypertrophy and hyperplasia of eosinophilic granular cells (chloride cells); and interstitial edema of skeletal muscle in fish exposed to 67 mg/L NO 2−. Similar, but milder, changes were observed at lower nitrite concentrations. Environ. Toxicol. Chem. 2010;29:535–540. © 2009 SETAC
Bacterial community dynamics in high and low bioavailability soils following laboratory exposure to a range of hexahydro-1,3,5-trinitro-1,3,5-triazine concentrations
Authors: Anderson Jennifer A.H. , Cañas Jaclyn E. , Long Monique K. , Zak John C. , Cox Stephen B.
Published: March 2010

Few studies have examined the potential long-term effects of high concentrations of hexahydro-1,3,5-trinitro-1,3,5-triaxine (RDX) on bacterial communities in soil. In the present study, a sandy loam soil and a silt loam soil (high and low bioavailability, respectively) were artificially contaminated with RDX (0, 50, 500, 1,500, 5,000, 10,000, and 15,000 mg/kg soil). Bacterial communities from each treatment were monitored over 63 d to characterize the effects of RDX exposure on bacterial activity, biomass, functional diversity (Biolog microtiter plates), and structural diversity (denaturing gradient gel electrophoresis of 16S rDNA). Bacterial communities native to the high bioavailability soil were inherently different than bacterial communities native to the silt loam soil, not only in terms of bacterial activity and biomass, but also in terms of bacterial community functional and structural diversity. Soil RDX contamination was correlated with decreased bacterial biomass in the silt loam soil treatments and with decreased bacterial activity in the sandy loam soil treatments on day 7. Soil RDX contamination did not cause a significant shift in the functional diversity of the bacterial communities native to the silt loam soil, but was correlated with a shift in identities of substrates used by bacterial communities native to the sandy loam soil on day 7. Bacterial community structure was insensitive to the gradient of RDX concentrations at the beginning of the incubation. However, the identities of carbon substrates used by bacterial communities in both soil types were affected by long-term incubation with RDX. Environ. Toxicol. Chem. 2010;29:38–44. © 2009 SETAC
Polychlorinated biphenyl elimination rates and changes in chemical activity in hibernating amphibians
Authors: Angell Robin A. , Haffner G. Douglas
Published: March 2010

The present study examined polychlorinated biphenyl (PCB) elimination rates in overwintering green frogs (Rana clamitans) to determine if changes in chemical activity occurred during hibernation. Adult green frogs were dosed with a 1:1:1 ratio of Aroclors 1248:1254:1260 in sunflower oil and allowed to enter into hibernation. Frogs were collected at four time points over the course of 85 days. Significant PCB elimination rates ranged from 0.0027 to 0.0376 d−1. A negative correlation was found between KOW and elimination rate. Over the course of the present study, a decrease in total body percent lipid was measured. There was an overall increase in fugacity of higher KOW compounds corresponding to the relatively rapid decrease in lipid content. Congeners in metabolic group 2 (meta-para vicinal hydrogen atoms) were preferentially eliminated over those in metabolic group 3 (ortho-meta vicinal hydrogen atoms), suggesting that biotransformation was occurring during hibernation. It was concluded that metabolic activity during hibernation, associated with water temperature, was sufficiently high to reduce lipid concentrations and increase chemical activity in emerging adults. Environ. Toxicol. Chem. 2010;29:700–707. © 2009 SETAC
Mercury concentrations in landlocked Arctic char (Salvelinus alpinus) from the Canadian Arctic. Part I: Insights from trophic relationships in 18 lakes
Authors: Gantner Nikolaus , Power Michael , Iqaluk Deborah , Meili Markus , Borg Hans , Sundbom Marcus , Solomon Keith R. , Lawson Greg , Muir Derek C.
Published: March 2010

Concentrations of mercury (Hg) have increased slowly in landlocked Arctic char over a 10- to 15-year period in the Arctic. Fluxes of Hg to sediments also show increases in most Arctic lakes. Correlation of Hg with trophic level (TL) was used to investigate and compare biomagnification of Hg in food webs from lakes in the Canadian Arctic sampled from 2002 to 2007. Concentrations of Hg (total Hg and methylmercury [MeHg]) in food webs were compared across longitudinal and latitudinal gradients in relation to δ13C and δ15N in periphyton, zooplankton, benthic invertebrates, and Arctic char of varying size-classes. Trophic magnification factors (TMFs) were calculated for the food web in each lake and related to available physical and chemical characteristics of the lakes. The relative content of MeHg increased with trophic level from 4.3 to 12.2% in periphyton, 41 to 79% in zooplankton, 59 to 72% in insects, and 74 to 100% in juvenile and adult char. The δ13C signatures of adult char indicated coupling with benthic invertebrates. Cannibalism among char lengthened the food chain. Biomagnification was confirmed in all 18 lakes, with TMFs ranging from 3.5 ± 1.1 to 64.3 ± 0.8. Results indicate that TMFs and food chain length (FCL) are key factors in explaining interlake variability in biomagnification of [Hg] among different lakes. Environ. Toxicol. Chem. 2010;29:621–632. © 2009 SETAC
Cytotoxicity, calcium release, and pH changes generated by novel calcium phosphate cement formulations
Authors: Khashaba Rania M. , Lockwood Petra E. , Lewis Jill B. , Messer Regina L. , Chutkan Norman B. , Borke James L.
Published: March 2010

Few published studies describe the biological properties of calcium phosphate cements (CPCs) for dental applications. We measured several biologically relevant properties of 3 CPCs over an extended (8 wk) interval. Monocalcium phosphate, calcium oxide, and synthetic hydroxyapatite were combined with either modified polyacrylic acid, light‐activated modified polyalkenoic acid, or 35% w/w polymethyl vinyl ether maleic acid to obtain Types I, II, and III CPCs, respectively. Set cements were placed in direct contact with L929 fibroblasts for up to 8 weeks. Media Ca+2 and pH were determined by atomic absorption spectroscopy and pH electrode respectively. Cell mitochondrial function was measured by MTT assay. Type I cements suppressed mitochondrial activity > 90% (vs. Teflon controls), but significantly (p < 0.05) improved to control levels over 8 weeks. Type II cements suppressed mitochondrial activity > 90% at all times. Type III cements elevated mitochondrial activity significantly after 7 wks. The pH profiles approached neutrality by 24 h, and all cements released calcium into the storage medium at all periods (24 h ‐ 8 wk). We concluded that several types of cements had long‐term biological profiles that show promise for dental applications. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010