bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ethoxyresorufin-O-deethylase induction in trout exposed to mixtures of polycyclic aromatic hydrocarbons
Authors: Basu Niladri , Billiard Sonya , Fragoso Nuno , Omoike Anselm , Tabash Samir , Brown Stephen , Hodson Peter 
Published: March 2010

AbstractThis study investigated whether ethoxyresorufin-O-deethylase (EROD) activity in rainbow trout exposed to mixtures of polycyclic aromatic hydrocarbons (PAHs) could be predicted from induction equivalency factors (IEF). The test PAHs were classified into strong and weak inducers on the basis of similar exposure-response curves. Induction equivalency factors of strong inducers, based on benzo[k]fluoranthene (BkF) as the reference compound, ranged from 0.03 to 0.16. Trout exposed to mixtures of strong inducers (2, 4, and 6 equipotent parts) at 0.32-, 1.0-, or 3.2-nM BkF-equivalents showed exposure-dependent increases in EROD activity, consistent with an additive interaction. The extent of activity did not vary greatly among mixtures and single PAHs at a given induction equivalent quantity (IEQ). Induction equivalency factors could not be calculated for weak inducers because the range of induction was too low. Hence, each weak inducer was added to mixtures at concentrations that induced EROD activity fivefold. These mixtures appeared additive because binary and quaternary mixtures caused about 10- and 20-fold induction, respectively. Strong inducers mixed the same way also showed additivity. In contrast, EROD induction by mixtures containing both strong and weak PAHs was 800 to 900% greater than expected, suggesting synergistic interactions. Therefore, if mixtures are composed of PAHs that behave similarly, IEFs may be a suitable approach for assessing risk. However, for mixtures that contain PAHs of differing potency and efficacy, bioassays will be a more reliable measure of risk than IEFs.
Description and evaluation of a short-term reproduction test with the fathead minnow (Pimephales promelas)
Authors: Ankley Gerald T , Jensen Kathleen M , Kahl Michael D , Korte Joseph J , Makynen Elizabeth A 
Published: March 2010

AbstractDue to the time and expense associated with full life-cycle testing, most current toxicity tests with fish do not explicitly consider reproductive output as an endpoint but, rather, focus on early life-stage survival and development. However, some classes of chemicals could adversely impact reproduction at concentrations below those that affect development. Further, estimates of the effects of toxic compounds on reproductive output can be critical to the ecological risk assessment process. In this manuscript, we describe a short-term reproduction test with the fathead minnow (Pimephales promelas) and evaluate the test using two model reproductive toxicants, methoxychlor (an estrogenic compound) and methyltestosterone (an androgenic chemical). The test is initiated with reproductively mature animals and is comprised of a pre-exposure phase of 14 to 21 d, followed by a chemical exposure of up to 21 d. During and at completion of the test, several endpoints related to reproductive fitness and endocrine function are assessed. Both chemicals evaluated in our study caused a significant decrease in fecundity of the fish at nominal concentrations of 5.0 μg/L (methoxychlor) and 0.2 mg/L (methyltestosterone). Methoxychlor decreased plasma concentrations of one or more steroids (testosterone, 11-ketotestosterone, β-estradiol) in both sexes and caused a significant induction of plasma vitellogenin in males, a response consistent with activation of the estrogen receptor by the pesticide (or its metabolites). Methyltestosterone decreased plasma concentrations of sex steroids and adversely affected gonadal status (as evaluated by relative weight and histopathology) in both sexes. The androgenic nature of methyltestosterone was clearly expressed as masculinization of exposed females via formation of nuptial tubercles, structures normally present only in reproductively active males. The chemical also caused a significant induction of plasma vitellogenin in both males and females; this unexpected estrogenic response was most likely due to aromatization of the androgen to a form capable of binding to the estrogen receptor. These studies demonstrate the utility of this short-term assay for identifying chemicals that exert reproductive toxicity through alterations in endocrine systems controlled by estrogens and androgens.
Effects of eight polycyclic aromatic compounds on the survival and reproduction of the springtail Folsomia fimetaria L. (collembola, isotomidae)
Authors: Sverdrup Line E , Kelley Axel E , Krogh Paul Henning , Nielsen Torben , Jensen John , Scott-Fordsmand Janeck J , Stenersen JørgenN 
Published: March 2010

Abstract
The effects of eight polycyclic aromatic compounds on the survival and reproduction of the collembolan Folsomia fimetaria L. were investigated in a well-characterized Danish agricultural soil. With the exception of acridine, polycyclic aromatic hydrocarbons (PAHs) and neutral N-, S-, and O-monosubstituted analogues showed similar toxicities to soil collembolans when the results were expressed in relation to total soil concentrations (mg/kg). The estimated concentrations resulting in a 10% reduction of reproductive output (EC10 values) were based on measured initial concentrations and were for acridine 290 mg/kg, carbazole 10 mg/kg, dibenzofuran 19 mg/kg, dibenzothiophene 7.8 mg/kg, fluoranthene 37 mg/kg, fluorene 7.7 mg/kg, phenantrene 23 mg/kg, and pyrene 10 mg/kg. When the EC10 values were converted to soil pore-water concentrations, they showed a highly significant correlation (r2 = 0.71, p &lt; 0.01) to no-observed-effect concentrations for the freshwater crustacean Daphnia magna, as estimated by a quantitative structure activity relation (QSAR) for baseline toxicity (nonpolar narcosis). Only carbazole and acridine were more than two times more toxic (4.9 and 3.1, respectively) than expected from the Daphnia QSAR data. The latter result indicates that the toxicity of the tested substances is close to that expected for compounds with nonpolar narcosis as the mode of action. However, the relatively large uncertainties in the extrapolation method prevent final conclusions from being drawn.
Effects of endophyte status of tall fescue tissues on the earthworm (Eisenia fetida)
Authors: Humphries Susan S , Gwinn Kimberly D , Stewart Arthur J 
Published: March 2010

Abstract
A cryptic fungal endophyte, Neotyphodium coenophialum, infects most tall fescue (Festuca arundinacea) pastures in the United States. Cattle, sheep, and horses that consume the endophyte-infected grass can suffer fescue toxicosis caused by toxic alkaloids in the infected plants. The effects of the endophyte on mammalian herbivores have been well documented, but less is known regarding the quality of the grass (infected vs noninfected) as a food material for soil invertebrates. We conducted 21-d tests with earthworms (Eisenia fetida) to determine the nutritional quality of endophyte-infected and noninfected tall fescue leaf and root tissues. Earthworm survival, growth, and reproduction were measured in each treatment combination of tissue type and infection status. Earthworm survival was 100% in all treatments. Tall fescue tissue type (leaf vs root) and infection status (present or absent) both significantly affected E. fetida growth and reproduction. The earthworms grew and had moderate levels of reproduction in replicates containing tall fescue leaf tissue as the sole food source regardless of the endophyte-infection status, but earthworms lost weight and had less reproduction in replicates where tall fescue root tissue was the sole food source. An unexpected effect of infection status on earthworm growth in the tall fescue leaf-tissue treatments was also evident: mean growth of E. fetida with access to endophyte-infected leaf tissue as the sole food source was 3.6-fold greater than mean growth of E. fetida with access to noninfected leaf tissue as the sole food source. Knowledge regarding the relative effects of endophyte status of tall fescue on soil organisms may allow the development of more effective environmental management strategies at sites where tall fescue is being considered for use in phytoremediation or for vegetative cover. Investigators working with tall fescue should be alert to the possibility of endophyte-mediated effects of tall fescue on other organisms and, at a minimum, should provide information regarding the grass's infection status when reporting the results of studies that involve use of tall fescue.
Synergistic effects of a photooxidized polycyclic aromatic hydrocarbon and copper on photosynthesis and plant growth: Evidence that in vivo formation of reactive oxygen species is a mechanism of copper toxicity
Authors: Babu T Sudhakar , Marder Jonathan B , Tripuranthakam Sridevi , Dixon D George , Greenberg Bruce M 
Published: March 2010

AbstractHeavy metals and polycyclic aromatic hydrocarbons (PAHs) are often cocontaminants in industrialized environments, yet little is known about either the extent or mechanisms of their cotoxicity. To address this shortfall, the combined effects of an oxygenated PAH, 1,2-dihydroxyanthraquinone (1,2-dhATQ), and a heavy metal, Cu2+, on photosynthesis and growth of the duckweed (Lemna gibba) were evaluated. Using assays of chlorophyll a fluorescence and photosystem I activity, 1,2-dhATQ inhibited electron transport at the cytochrome b6/f complex. Conversely, Cu2+ alone (at low concentrations) had little effect on photosynthesis. When Cu2+ was combined with 1,2-dhATQ, an increase in transient and steady-state chlorophyll a fluorescence quenching occurred relative to 1,2-dhATQ alone. Treatment of isolated thylakoid membranes with 1,2-dhATQ inhibited whole-chain linear electron transport, measured as O2 consumption using methyl viologen as the electron acceptor. However, Cu2+ plus 1,2-dhATQ resulted in active O2 consumption with or without methyl viologen as an electron acceptor. From these data, we conclude that 1,2-dhATQ renders the plastoquinone pool to a highly reduced state by inhibiting at cytochrome b6/f Then, Cu2+ is able to mediate the transfer of electrons from reduced plastoquinone to O2, forming reactive oxygen species. At the whole-organism level, when Cu2+ and 1,2-dhATQ were mixed at concentrations that resulted in the above-mentioned impacts on photosynthesis, synergistic inhibition of plant growth was observed. This suggests a catalytic mechanism of toxicity for redox active metals, a process that could be instrumental in explaining their impacts at low concentrations.
Comparison of metal uptake rate and absorption efficiency in marine bivalves
Authors: Wang Wen-Xiong 
Published: March 2010

Abstract
Recent studies have quantified extensively metal assimilation efficiency from ingested food sources in aquatic invertebrates. Metal absorption efficiency (α) from the dissolved phase is analogous to metal assimilation efficiency, but it remains poorly defined and quantified. In this study, the α of four trace metals [Cd, Cr(VI), Se(IV), and Zn] was determined in three species of marine bivalves (green mussel [Perna viridis], black mussel [Septifer virgatus], and clam [Ruditapes philippinarum]). Individual bivalves were first measured for their clearance rates, followed by measurements of the metal influx rate, after which the metal α and the uptake rate constant (Ku) were then computed. Among the four metals considered; the highest Ku and α were found for Zn, followed by Cd &gt; Cr(VI) &gt; Se(IV). The Ku values were comparable between the two mussels but were 1.8- to 3.3-fold lower in the clams. Interspecific difference in metal Ku was strongly related to, but intraspecific difference in Ku was not affected by, the bivalve's clearance rate. Interspecific difference in metal α was smaller than the metal Ku and was independent of the clearance rate, whereas the intraspecific difference in metal α correlated with the individual variations of the clearance rate. Within each bivalve species, a significant negative correlation was found between the metal α and the clearance rate, implying that an individual pumping a greater amount of water was coupled to a lower α. Significant correlation between the α of four metals was also documented in all three species of bivalves. Thus, metal bioavailability from the aqueous phase was directly related to the physiological conditions of the animals. Both the aqueous chemistry and the physiology of the animals can be important in affecting metal bioavailability from the dissolved phase.
Degradation products of a phenylurea herbicide, diuron: Synthesis, ecotoxicity, and biotransformation
Authors: Tixier Céline , Sancelme Martine , Sancelme Martine , Bonnemoy Frédérique , Cuer Annie , Veschambre Henri 
Published: March 2010

Abstract
The degradation products of diuron (photoproducts and metabolites), already described in the literature, were synthesized in order to carry out further investigations. Their ecotoxicity was determined using the standardized Microtox® test, and most of the derivatives presented a nontarget toxicity higher than that of diuron. Therefore, the biotransformation of these compounds was tested with four fungal strains and a bacterial strain, which were known to be efficient for diuron transformation. With the exception of the 3,4-dichlorophenylurea, all the degradation products underwent other transformations with most of the strains tested, but no mineralization was observed. For many of them, the biodegradation compound for which the toxicity was important was 3,4-dichlorophenylurea. This study underlines the importance of knowing the nature of the degradation products, which has to be kept in mind while analyzing natural water samples or soil samples.
Ubiquitous observations of enhanced solid affinities for aromatic organochlorines in field situations: Are in situ dissolved exposures overestimated by existing partitioning models?
Authors: Bucheli Thomas D , Gustafsson Örjan 
Published: March 2010

Abstract
This paper investigates the ability of the traditional organic matter partitioning (OMP) model to predict the solid–water distribution, and hence the dissolved exposures, of hydrophobic organic compounds (HOCs) in real field situations. Observed organic-carbon-normalized partitioning coefficients ((Koc)obs) of polychlorinated biphenyls, polychlorinated benzenes, polychlorinated dibenzo-dioxins and -furans, and p,p′-dichlorodiphenyltrichlorethane (DDT) with metabolites were selected from the literature and compared with their respective OMP model estimates. For all compound classes and in a majority of the investigated cases, (Koc)obs values were significantly larger than predicted. This translated into factors of overestimated dissolved exposures ranging from 1 to 1,000. Various reasons are discussed for the discrepancies between predictions and actual observations, such as the effect of the diagenetic state and other properties of the particulate organic matter. The greater enhancement in (Koc)obs of planar over nonplanar compounds suggests in certain cases that efficient interactions with aromatic soot phases may be significant. For an improved predictability of (Koc)obs and dissolved exposures of HOCs in the real environment, the inclusion of soot and possibly other distinct subfractions of bulk organic carbon into an extended solid–water partitioning model may be considered.
Monitoring river sediments contaminated predominantly with polyaromatic hydrocarbons by chemical and in vitro bioassay techniques
Authors: Vondráček Jan , Machala Miroslav , Minksová Kateřina , Bláha Luděk , Murk Albertinka J , Kozubík Alois , Hofmanová Jiřina , Hilscherová Klára , Ulrich Robert , Ciganek Miroslav , Neča Jiří , Švrčková Daniela , Holoubek Ivan 
Published: March 2010

AbstractExtracts of sediment samples collected from the Morava River and its tributaries (Czech Republic) were examined for mutagenic, dioxin-like, and estrogenic activities. Moreover, the human leukemic HL-60 cell line was tested as a potential model for the detection of effects of environmental contaminants on cell proliferation and differentiation processes. Analytical data indicate that the sediments were contaminated predominantly with polycyclic aromatic hydrocarbons (PAHs) and phthalate esters. The sums of concentrations of 16 U.S. Environmental Protection Agency priority PAHs ranged from 0.8 to 13.2 μg/g and those of phthalates reached up to 3,000 ng/g, while only low levels of chlorinated hydrocarbons were found. The main goal of the present study was to determine effects of PAH prevalence on in vitro bioassays, with special emphasis on dioxin-like activity. The dioxin-like activity was tested using a reporter gene assay based on chemical-activated luciferase expression (the CALUX assay). Significant dioxin-like activity (2.6—40.1 μg/g benzo[a]pyrene equivalents and 5.9—48.2 ng/g 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents) was detected in all samples, and the results obtained with various exposure times or with both crude and PAH-deprived extracts indicate that the response was probably caused almost exclusively by the presence of high concentrations of PAHs. This corresponds with results of chemical analyses and indicates that various exposure times would allow a discrimination between dioxin-like activities of persistent compounds and easily metabolized aryl hydrocarbon (Ah) receptor inducers. Only sediment extracts containing the highest concentrations of PAHs were mutagenic, as determined by the umu assay. Estrogenic activity was found in several samples (4.75–22.61 pg/g estradiol equivalents) using cells stably transfected with an estrogen-responsive element linked to a luciferase promoter. Noncytotoxic doses of extracts had no effects on HL-60 cell proliferation, while two of the tested crude extracts significantly enhanced their all-trans retinoic acid-induced differentiation. These activities were not associated with phthalate esters and/or PAHs. Our results indicate that cellular and biochemical in vitro assays based on various specific modes of action may yield data complementary to results of mutagenicity tests and that they could be useful in environmental risk assessment. High levels of PAHs are apparently associated with dioxin-like and mutagenic activities rather than with estrogenic activity.
Fluoride concentrations in antler bone of roe deer (Capreolus capreolus) indicate decreasing fluoride pollution in an industrialized area of western Germany
Authors: Kierdorf Uwe , Kierdorf Horst 
Published: March 2010

Abstract
In order to reconstruct temporal changes in ambient fluoride levels in the industrialized Ruhr area (western Germany), we analyzed the bone fluoride content of 167 antlers of roe deer (Capreolus capreolus) killed between 1951 and 1999 in the northern part of this region. Individual values ranged between 110 and 8,178 mg F−/kg ash, and there was an overall marked decrease over the sampling period. Average bone fluoride concentrations in antlers from the periods 1980 through 1989 (geometric mean [95% confidence interval]: 1,490 [1,193–1,861] mg/kg ash) and 1990 through 1999 (753 [644–882] mg/kg ash) differed significantly (p &lt; 0.001) and were both significantly (p &lt; 0.001) lower than those from the periods 1951 through 1969 (3,720 [3,227–4,288] mg/kg ash) and 1970 through 1979 (2,573 [2,203–3,006] mg/kg ash). The findings are seen as indicative of a progressively reduced atmospheric fluoride deposition into the study area, caused by effective emission-control measures in Germany and neighboring countries. Because antlers are replaced annually, grow during a fixed period of some months, and are regularly collected and kept as trophies, they are well suited as monitoring units for analyzing temporal trends in environmental pollution by fluoride and other bone-seeking pollutants.
Reproductive, biochemical, physiological, and population responses in perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) downstream of two elemental chlorine-free pulp and paper mills
Authors: Karels Aarno , Markkula Eveliina , Oikari Aimo 
Published: March 2010

Abstract
Perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) populations in a state of late vitellogenesis were studied downstream of two pulp and paper mills and at upstream references in southern Lake Saimaa, Finland. The mills used elemental chlorine-free bleaching and activated sludge effluent treatment technologies. The exposure of fish to pulp mill effluents, as measured by concentrations of chlorophenolics in the bile and liver ethoxyresorufin-O-deethylase (EROD) activity, was low and almost similar to the references. Nevertheless, bile resin acid concentrations in exposed perch and roach (260–320 μg/ml) and bile β-sitosterol concentrations in exposed roach (1.5–3.5 μg/ml) were, respectively, 10 to 30 times and 2 to 5 times higher compared with the references. Reproductive parameters like plasma 17β-estradiol and testosterone levels were lower in exposed male and female perch but the same in roach. Vitellogenin concentrations in plasma and liver cytosol of roach were similar. Gonad weight and fecundity were lower in exposed female perch but similar in roach. The relative liver weight was higher in exposed roach but not in perch. The body condition and immunologic parameters in fish were the same. The growth and age at maturity of exposed perch and roach were similar to the references. The size and age distribution of perch in the recipient of one of the mills was shifted toward smaller and younger fish. Our results show that several reproductive variables were altered in late vitellogenic perch in the vicinity of the mills, but they were not altered in roach.
Aquatic reclamation in the Athabasca, Canada, oil sands: Naphthenate and salt effects on phytoplankton communities
Authors: Leung Sherwin Sik-Cheung , MacKinnon Mike D , Smith Ralph E H 
Published: March 2010

Abstract
Microcosm experiments with natural indigenous phytoplankton communities were conducted to assess the effects of waters from oil sands extraction processes, emphasizing the naphthenate and salt constituents. Process waters of varying ages (zero to eight years), remediation histories, and chemical composition were obtained from outdoor mesocosms and inoculated with phytoplankton assemblages from a reference lake in the study area. Community composition measures, including percentage model affinity (PMA) and canonical correspondence analysis (CCA), revealed significant community effects of water from systems less than five years old, with naphthenate concentrations greater than 20 mg/L, compared to water from the reference lake. Canonical correspondence analysis, PMA, and regression analyses further showed that naphthenate concentration was significantly correlated with community structure. Using CCA, groups of taxa characteristic of waters with &gt;20 mg/L naphthenates (including Botryococcus braunii, Gloeococcus schroeteri, Cosmarium depressum, Chrysococcus rufescens, Chromulina spp., Ochromonas spp., and Keratococcus spp.) were identified. Salinity, as reflected in conductivity, was positively correlated with naphthenate concentration and itself appeared to influence the community structure. The results confirmed an important role for naphthenates in ecological effects of process waters from oil sands mining, but the influence of covarying factors such as salinity requires further investigation.