bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of chloride on silver uptake by two green algae, Pseudokirchneriella subcapitata and Chlorella pyrenoidosa
Authors: Lee Dae-Young , Fortin Claude , Campbell Peter G. C. 
Published: November 2004

Abstract
Silver bioavailability in the presence of chloride was estimated from short-term (≤60 min) uptake experiments with two green algae, Pseudokirchneriella subcapitata and Chlorella pyrenoidosa. In the first experiment, silver uptake was monitored under two concentration regimes in which total dissolved silver ([Ag]tot) and [Cl] were manipulated to maintain [Ag+] at a constant value (10 nM). Comparable uptake rates were measured for both treatments despite the dramatic changes in [Cl] and [Ag]tot. In the second experiment, ambient [Ag]tot was held constant (10 or 115 nM), but [Cl] was varied (0.005-50 mM) to explore the whole range of silver chloro-complexes. Intracellular silver varied markedly along the [Cl] gradient and exhibited a clear, positive correlation with ambient [Ag+] for both algae. We conclude that the biotic ligand model reliably describes silver bioavailability in the presence of chloride for the two test algae and that its applicability depends on the relative magnitudes of silver fluxes through the unstirred diffusion layer and across the cell membrane, with the latter being affected by the presence or absence of a Cu(I) transporter. In the presence of chloride, no evidence was found for the internalization of silver via anion transport or passive diffusion of the neutral mono-chloro-complex, AgCl0.
Some fundamental (and often overlooked) considerations underlying the free ion activity and biotic ligand models
Authors: Hassler Christel S. , Slaveykova Vera I. , Wilkinson Kevin J. 
Published: November 2004

Abstract
Trace metal bioavailability is often evaluated on the basis of steady-state models such as the free ion activity model (FIAM) and the biotic ligand model (BLM). Some of the assumptions underlying these models were verified by examining Pb and Zn uptake by the green microalga Chlorella kesslerii. Transporter bound metal ({M-Rcell}) and free ion concentrations ([MZ+]) were related to experimentally determined uptake fluxes (Jint). Although the BLM and FIAM correctly predicted Pb uptake in the absence of competing ions, they failed to predict competitive interactions with Ca2+, likely because of modifications of the algal surface charge and the active nature of Ca2+ transport. Zinc transport is also active; in this case, both the internalization rate constant (kint) and the equilibrium constant for the binding of Zn to the transport sites (KZn-Rcell) varied as a function of [Zn2+] in the bulk solution. For this reason, Zn uptake could not be modeled by the steady-state models either in the presence or absence of competitors (Cd and Ca). Furthermore, the role of Cu on Pb and Zn adsorption and uptake could not be predicted by either model because of secondary effects on the algal physiology and membrane permeability. Finally, a 17°C reduction in temperature resulted in a two-to fivefold decrease in membrane permeability of the metals, an observation that also is unaccounted for by either the FIAM or BLM. This paper emphasizes the limitations of the models in well-controlled laboratory systems with the goal of extrapolating the results to complex environmental systems.
Effects of the antifungal imidazole ketoconazole on CYP1A and CYP3A in rainbow trout and killifish
Authors: Hegelund Tove , Ottosson Karin , Rådinger Madeleine , Tomberg Peter , Celander Malin C. 
Published: November 2004

Abstract
The use of N-substituted imidazoles is widespread, and imidazole and triazole fungicides have been detected in the aquatic environment and shown to bioaccumulate in fish. We have investigated effects of the model imidazole, ketoconazole, on drug-metabolizing cytochrome P450 (CYP) forms. We focused on cytochrome P4501A (CYP1A) and cytochrome P4503A (CYP3A) expression and activities in juvenile rainbow trout and in adult killifish. The CYP1A expression (mRNA, protein) and activity was induced in rainbow trout, whereas in killifish no effect of ketoconazole on CYP1A protein expression was observed. A biphasic dose-response relationship was observed between ketoconazole exposure and hepatic CYP1A-mediated ethoxyresorufin O-deethy-lase (EROD) activity in rainbow trout in vitro and in vivo, implying that higher doses of ketoconazole inhibit CYP1A activities. Slight induction of CYP3A protein levels was observed in rainbow trout exposed in vivo to ketoconazole. However, the CYP3A-mediated benzyloxy-4-[trifluoromethyl]-coumarin (BFC) O-debenzyloxylase activity was reduced in rainbow trout and killifish treated with ketoconazole. In vitro inhibition studies confirmed that ketoconazole was a potent inhibitor of both CYP3A and CYP1A enzyme activities in these species. This study showed that ketoconazole induced CYP1A and CYP3A expression in rainbow trout. However, the most pronounced effect of ketoconazole was a 60 to 90% decrease in CYP3A catalytic activities in rainbow trout and in killifish.
Assessment of mercury in waters, sediments, and biota of New Hampshire and Vermont lakes, USA, sampled using a geographically randomized design
Authors: Kamman Neil C. , Lorey Peter M. , Driscoll Charles T. , Estabrook Robert , Major Andrew , Pientka Bernie , Glassford Ed 
Published: November 2004

Abstract
We report on mercury (Hg) contamination in waters, sediments, and biota of Vermont and New Hmpshire (USA) lakes measured during 1998—2000, using a geographically randomized design. Waters and sediments of 92 lakes were sampled for mercury, methylmercury, and ancillary parameters. Yellow perch (Perca flavescens) muscle tissues were analyzed for mercury on 47 of these lakes. Interannual variation in mercury was limited; only epilimnetic Hg was elevated by approximately 1.5 ng/L in 1998 over remaining years because of wet weather. Aqueous total and methylmercury concentrations were elevated in both dystrophic and eutrophic lakes over other types. Yellow perch tissue concentrations were elevated by 0.218 μg/g in dystrophic lakes over other types and were very low in eutrophic lakes. Fish tissue mercury concentrations showed no relationship to hypolimnetic or sediment mercury or methylmercury. A statistical model indicated that yellow perch tissues in 40.2 ± 13% of lakes were likely to exceed the U.S. Environmental Protection Agency (U.S. EPA) methylmercury criterion of 0.3 μg/g, and yellow perch from New Hampshire were twice as likely to exceed the criterion as those from Vermont. Results of this study provide a regional-scale baseline against which the success of future reductions in mercury emissions can be assessed.
Bioconcentration, biotransformation, and elimination of polycyclic aromatic hydrocarbons in sheepshead minnows (Cyprinodon variegatus) Exposed to Contaminated Seawater
Authors: Jonsson Grete , Bechmann Renee K. , Bamber Shaw D. , Baussant Thierry 
Published: November 2004

Abstract
Sheepshead minnows (Cyprinodon variegatus) were continuously exposed to two concentrations of polycyclic aromatic hydrocarbons (PAHs) dissolved in seawater (Σ PAH = 7.57 and 72.31 μg/L) for 36 d, followed by 8 d of depuration. The PAHs studied were naphthalene (NPH or C0-NPH), phenanthrene (PHE or C0-PHE), pyrene (PYR), 2-methylnaphthalene (C1-NPH), 1,3-dimethylnaphthalene (C2-NPH), 2-isopropylnaphthalene (C3-NPH), 9-methylphenanthrene (C1-PHE), and 9-ethylphenanthrene (C2-PHE). Uptake rate constants (k1) for NPHs increased with increasing degree of alkylation and log value of the octanol/water partition coefficient (Kow), whereas k1 values for three- and four-ring PAHs were lower despite their high log Kow values. Elimination rate constants (k2) for the homologue series of NPHs and PHEs generally increased with decreasing degree of alkylation and log Kow values. However, the depuration time did not directly correlate with the molecular size for nonalkylated PAHs. Bioconcentration factors (BCFs) were estimated from the ratio of k1 to k2 and also directly from PAH concentrations in fish tissue and water samples, and the factors generated by the two methods were very similar. A significant positive correlation was determined between log BCFs and log Kow values for the series of C0- through C3-NPH at both low (r2 = 0.985, p = 0.0077) and high (r2 = 0.956, p = 0.022) exposures, although this correlation was not determined for all the PAHs studied. As a result of increased metabolism and/or reduced bioavailability with increasing lipophilic character, the estimated BCFs for C0- through C2-PHE and PYR were generally lower than those for C0- through C3-NPH. The two exposure levels revealed minor variations in k1 and k2 values for parent PAHs and in the temporal pattern of PAH metabolite concentrations in bile. The present results indicate that the presence and nature of alkyl groups have a significant influence on the kinetics and metabolism of PAHs in fish.
Sulfide as a confounding factor in toxicity tests with the sea urchin Paracentrotus lividus: Comparisons with chemical analysis data
Authors: Losso Chiara , Novelli Alessandra Arizzi , Picone Marco , Ghirardini Annamaria Volpi , Ghetti Pier Francesco , Rudello Danilo , Ugo Paolo 
Published: November 2004

Abstract
Sperm cell and embryo toxicity tests with the sea urchin Paracentrotus lividus were performed to assess the toxicity of sulfide, which is considered a confounding factor in toxicity tests. For improved information on the sensitivity of these methods to sulfide, experiments were performed in the same aerobic conditions used for testing environmental samples, with sulfide concentrations being monitored at the same time by cathodic stripping voltammetry. New toxicity data for sulfide expressed as median effective concentration (EC50) and no-observed-effect concentration (NOEC) are reported. The EC50 value for the embryo toxicity test (total sulfide at 0.43 mg/L) was three times lower than for the sperm cell test (total sulfide at 1.20 mg/L), and the NOEC values were similar (on the order of total sulfide at 10−1 mg/L) for both tests. The decrease in sulfide concentration during the bioassay as a consequence of possible oxidation of sulfide by dissolved oxygen was determined by voltammetric analysis, indicating a half-life of about 50 min in the presence of gametes. To check the influence of sulfide concentrations on toxicity effects in real samples, toxicity (with the sperm cell toxicity test) and chemical analyses also were performed in pore-water samples collected with an in situ sampler in sediments of the Lagoon of Venice (Italy). A highly positive correlation between increased acute toxicity and increased sulfide concentration was found. Examination of data revealed that sulfide is a real confounding factor in toxicity testing in anoxic environmental samples containing concentrations above the sensitivity limit of the method.
Effects of atrazine on fathead minnow in a short-term reproduction assay
Authors: Bringolf Robert B. , Belden Jason B. , Summerfelt Robert C 
Published: November 2004

Abstract
Atrazine is the most extensively used herbicide in the United States. Part-per-million concentrations of atrazine have been reported in agricultural runoff. It is detectable in surface waters and precipitation throughout the year, and it has been found in groundwater sources of drinking water. Recent studies indicate that atrazine may be a potent endocrine-disrupting compound in frogs exposed to part-per-billion (μg/L) concentrations. For these reasons, the effects of atrazine (5 and 50 μg/L) on several endpoints related to reproductive fitness were examined in fathead minnows (Pimephales promelas) in a 21-d static exposure. Estradiol (0.5 μg/L) was included as a positive-control treatment. Endpoints examined in adult fish during and after the exposures included survival, egg production, number of spawns, eggs/spawn, relative gonad weight, gonad histology, number of nuptial tubercles, and plasma vitellogenin concentration. Eggs produced during the exposures were hatched and reared in control water. The percentages of embryos fertilized and hatched as well as larval survival were evaluated. Decreasing trends were observed in relative testis weight, testis maturity, and percentage embryo fertilization. These trends suggest that further investigation is warranted, but the differences in these and other endpoints were not statistically significant in the atrazine-exposed fish. Nearly all endpoints concerning fish exposed to estradiol were significantly different from atrazine-exposed fish and control fish. These results suggest that atrazine did not have strong estrogenic effects in adult fathead minnows and did not cause overt reproductive toxicity at environmentally relevant concentrations.
Effect of dissolved organic matter source on acute copper toxicity to Daphnia magna
Authors: De Schamphelaere Karel A. C. , Vasconcelos Flavio M. , Tack Filip M. G. , Allen Herbert E. , Janssen Colin R. 
Published: November 2004

Abstract
The protective effect of dissolved organic matter (DOM) on metal toxicity to aquatic organisms has been reported by numerous authors. Bioavailability models such as the biotic ligand model (BLM) thus account for this factor to predict metal toxicity to aquatic organisms. Until now, however, few attempts have been made to assess the effect of the DOM source on metal speciation and toxicity and, accordingly, on BLM predictions. The aims of this study were to investigate to what extent DOMs differ in their ability to decrease acute copper toxicity to the cladoceran Daphnia magna and to evaluate if ultraviolet (UV) absorbance measurements may be a simple and effective method to incorporate DOM variability into the acute Cu-BLM for D. magna. Acute toxicity tests were carried out in artificial test water enriched with DOMs isolated from six locations in Europe and North America and in seven natural European surface waters. The acute Cu-BLM for D. magna was then used to estimate the copper complexing capacity of each DOM (expressed as % active fulvic acid, %AFA). A factor of 6 difference was observed between the lowest and the highest copper complexing capacity. A significant linear relationship was observed between the UV-absorbance coefficient at 350 nm (ε350) and the %AFA. Linking this relationship to the acute Cu-BLM resulted in a significant improvement of the predictive capacity of this BLM. Without accounting for this relationship, 90% of the predicted 48-h 50% effective concentrations (EC50) were within a factor of 2 of the observed EC50s; taking this relationship into account, 90% of the EC50s were predicted with an error of less than factor 1.3. The present study and other studies seem to indicate that UV absorbance may be a good measure of biologically and toxicologically relevant differences in copper binding behavior of DOM.
Effects of zinc pyrithione and copper pyrithione on microbial community function and structure in sediments
Authors: Petersen Dorthe Groth , Dahllof Ingela , Nielsen Lars Peter 
Published: November 2004

Abstract
The effects of the new antifouling biocides, zinc pyrithione (ZPT) and copper pyrithione (CPT), onmicrobial communities in estuarine sediments were studied in microcosms. As functional endpoints, fluxes of nutrients (NO−3, NH+4, HPO2−4, Si(OH)4) and protein synthesis ([14C]leucine incorporation) were used, whereas molecular fingerprinting methods (polymerase chain reaction/denaturing gradient gel electrophoresis) were used to describe the bacterial community structure. The lowest-observed-effect concentration (LOEC) for ZPT was 0.001 nmol/g dry sediment for the phosphate flux and total DNA content, whereas the LOEC for CPT was 0.1 nmol/g dry sediment for the nitrate flux and total DNA content. Nitrate fluxes increased significantly following additions of both ZPT and CPT, whereas ammonium fluxes decreased significantly after ZPT addition, suggesting changes in the nitrification and denitrification processes. The total DNA content decreased significantly following addition of both ZPT and CPT, but at the highest addition of ZPT (10 nmol ZPT/g dry sediment), an increase in total DNA content was found. Increased protein synthesis and bacterial diversity were also observed at this concentration of ZPT, suggesting growth of tolerant opportunistic species.
Laboratory and field responses to cadmium: An experimental study in effluent-dominated stream mesocosms
Authors: Brooks Bryan W , Stanley Jacob K. , White Jessica C , Turner Philip K. , Wu K. Benjamin , La Point Thomas W. 
Published: November 2004

Abstract
Although select stream flows in the southwestern United States are dominated by effluent discharges, metal hazards have not been experimentally evaluated in effluent-dominated streams. Lotic mesocosms were designed to assess cadmium effects on multiple levels of biological organization, to determine relevance to regulatory criteria of standard laboratory toxicity tests, and to link laboratory tests to stream responses. Replicate streams were treated with 15 or 143 μg/L Cd during a 10-d study. Streams were sampled on days 0 and 10 for benthic macroinvertebrates, periphyton, and ecosystem metabolism. Concurrent Ceriodaphnia dubia and Pimephales promelas laboratory tests were performed with water from streams. Individual organism, population, and community response variables were affected by 143 μg/L Cd but not by the 15-μg/L treatment level. A biotic ligand model for cadmium predicted a 48-h median effective concentration (EC50) value of 280 μg/L Cd for C. dubia in these effluent-dominated streams; an EC50 value of 38.3 μg/L Cd was estimated for C. dubia in tests performed with reconstituted hard water. Our findings generally support use of the biotic ligand model for establishing site-specific, acute water quality criteria for cadmium. However, future effluent-dominated stream research is required to evaluate relationships between chronic cadmium exposure and organismal and community responses.
An enzyme-linked immunosorbent assay for lipovitellin quantification in copepods: A screening tool for endocrine toxicity
Authors: Volz David C. , Chandler G. Thomas 
Published: November 2004

Abstract
Vitellogenin (VTG) has been widely used as a biomarker of estrogenic exposure in fish, leading to the development of standardized assays for VTG quantification. However, standardized quantitative assays for invertebrate, particularly crustacean, lipovitellin (also known as vitellin [VTN]) are lacking. In this study, a fluorescence-based VTN enzyme-linked immunosorbent assay (ELISA) was developed to quantify microquantities of VTN in the estuarine, sediment-dwelling copepod Amphiascus tenuiremis. This ELISA utilizes a VTN-specific polyclonal antibody developed against amphipod (Leptocheirus plumulosus) embryo VTN and exhibits specificity toward female copepod proteins. In routine assays, the working range of the ELISA was 31.25 to 1,000 ng/ml (75–25% specific binding/maximum antibody binding [B/B0]) with a 50% B/B0 intra- and interassay variation of 3.9% (n = 9) and 12.5% (n = 26), respectively. This ELISA is capable of detecting VTN as low as 2 ng/ml, and can accurately detect VTN in as few as four copepods. The ELISA significantly discriminated positive (gravid female) and negative (male) samples, and was suitable for screening endocrine toxicity in copepods. Stage-I juvenile copepods were individually reared to adults in aqueous microvolumes of the phenylpyrazole insecticide, fipronil, and whole-body homogenate extracts were assayed for VTN levels. Fipronil-exposed virgin adult females, but not males, exhibited significantly higher levels of VTN relative to control males and females. This crustacean VTN ELISA is likely useful for evaluating endocrine activity of environmental toxicants in copepods and other crustacean species.
Effects of chronic waterborne nickel exposure on two successive generations of Daphnia magna
Authors: Pane Eric F. , Mcgeer James C. , Wood Chris M. 
Published: November 2004

Abstract
In a 21-d chronic toxicity test in which an F0 generation of Daphnia magna were exposed to waterborne Ni, the no-observable-effect concentration (for survival, reproduction, and growth) was 42 μg Ni L−1, or 58% of the measured 21-d median lethal concentration (LC50) of 71.9 μg Ni L−1 (95% confidence interval, 56.5–95.0). Chronic exposure to 85 μg Ni L−1 caused marked decreases in survival, reproduction, and growth in F0 animals. In the F1 generation (daphnids born of mothers from the chronically exposed F0 generation), animals chronically exposed to 42 μg Ni L−1 for 11 d weighed significantly less (20%) than controls, indicating increased sensitivity of F1 animals. Additionally, in this successive generation, significant decreases in whole-body levels of metabolites occurred following exposure to both 42 μg Ni L−1 (decreased glycogen and adenosine triphosphate [ATP]) and 21 μg Ni L−1 (decreased ATP). No significant changes were observed in whole-body total lipid, total protein, and lactate levels at any concentration. Whereas F1 neonates with mothers that were exposed to 21 μg Ni L−1 showed increased resistance to acute Ni challenge, as measured by a significant (83%) increase in the acute (48-h) LC50, F1 neonates with mothers that were exposed to 42 μg Ni L−1 were no more tolerant of acute Ni challenge than control animals were. Nickel accumulations in F1 animals chronically exposed to 21 and 42 μg Ni L−1 were 11- and 18-fold, respectively, above control counterparts. The data presented suggest that chronic Ni exposure to two successive generations of D. magna lowered the overall energy state in the second generation. Whereas the quantity of neonates produced was not affected, the quality was; thus, environmentally meaningful criteria for regulating waterborne Ni concentrations in freshwater require consideration of possible multigenerational effects.
Eiders (Somateria mollissima) obtain nodularin, a cyanobacterial hepatotoxin, in baltic sea food web
Authors: Sipiä Vesa O. , Karlsson Krister M. , Meriluoto Jussi A. O. , Kankaanpää Harri T. 
Published: November 2004

Abstract
Nodularin (NODN) is a cyclic pentapeptide hepatotoxin produced by the cyanobacterium Nodularia spumigena, which occurs regularly in the Baltic Sea during the summer season. Nodularia blooms have caused several animal kills in the Baltic Sea area, and NODLN has been found in mussels and fish caught from the northern Baltic Sea in 1996 to 2002. We analyzed liver samples of common eider (Somateria mollissima) for NODLN by enzyme-linked immunosorbent assay (ELISA) and liquid chromatography/mass spectrometry (LC-MS). Eiders feed extensively on mussel and can be exposed to NODLN by contaminated mussels. Fifteen eiders were shot and collected from three different sites in the western Gulf of Finland (northern Baltic Sea) in August and September 2002. Analyses by ELISA and LC-MS showed that eider liver samples contained 3 to 180 μg NODLN/kg dry weight and 0.1 to 5.8 μg NODLN/liver (dry wt). This is the first documentation of NODLN in seabirds and additional evidence for the transfer of NODLN in different parts of the Baltic Sea food web.