bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of gut contents on dry weight estimates ofChironomus tentanslarvae: Implications for interpreting toxicity in freshwater sediment toxicity tests
Authors: Sibley Paul K , Monson Philip D , Ankley Gerald T 
Published: March 2010

AbstractGut contents have long been recognized as a potentially important source of bias in studies concerned with estimating contaminant body burdens in benthic macroinvertebrates. In this study, we show that gut-associated, inorganic material may also lead to significant overestimates of weight in Chironomus tentans larvae in sediment toxicity tests and thus influence statistical interpretation of effects on growth with this organism. Two methods were evaluated regarding their potential to correct for the proportion of larval dry weight contributed by gut contents: purging and determination of ash-free dry weight (afdw). Each method was assessed in a series of 10-d growth tests using (1) clean sand and clay substrates with a restricted particle size distribution (mean particle size: 8, 146, 218, 306, 448, and 592 μm), and (2) sediments collected from both clean and contaminated field sites encompassing a wide range in particle size distribution. Both purging and afdw determination resulted in significant reductions in the dry weight of larvae in most substrates &lt;306 μm and in the field-collected sediments. In these treatments, 7–59% of the dry weight of fourth instar larvae was comprised of inorganic material contained within the digestive tract. Sediment organic carbon was also important; the contribution of gut contents to larval dry weight in a highly organic (23.6%) sediment was only 7.9% despite a small particle size distribution (mean = 149 μm). Correction for ingested material changed the rank order of treatment means in all tests and reduced the number of statistically significant outcomes for many treatment comparisons. Both methods reduced variability (lower standard deviation) associated with mean dry weight estimates, although variability was generally greater with purging than with the afdw method. Based on the results of this study, we recommend that afdw, not dry weight, be used to determine the weight of C. tentans larvae in 10-d and life-cycle tests with this organism.
Acetylcholinesterase inhibition and altered locomotor behavior in the carabid beetlePterostichus cupreus.A linkage between biomarkers at two levels of biological complexity
Authors: Jensen Charlotte S , Garsdal Lone , Baatrup Erik 
Published: March 2010

AbstractThe establishment of cause–effect relationships is fundamental for the interpretation and the predictive value of biomarker responses measured at all levels of biological complexity. In the present study, the biochemical exposure biomarker acetylcholin-esterase (AChE) inhibition was related to locomotor behavior, representing a general effect biomarker at the organismal level. Both sexes of the carabid beetle Pterostichus cupreus were intoxicated with three doses of the organophosphorous insecticide dimethoate. Five elements of their locomotor behavior were measured for 4 h employing computer-aided video tracking, whereupon the whole body AChE activity was measured in the individual beetle. AChE inhibition was strongly correlated with dimethoate dose in both sexes. Alterations in the locomotor behavior were directly correlated with AChE inhibition in male beetles, which responded by reducing the time in locomotion, average velocity, and path length and by increasing the turning rate and frequency of stops. Females responded similarly at the two highest doses, whereas their locomotor behavior was not significantly different from the control group at the lowest dimethoate dose, suggesting a sex-dependent difference in behavioral sensitivity to minor AChE depressions. The results demonstrate that automated measurements of locomotor behavior is at least as sensitive an endpoint to organophosphate poisoning as the AChE assay. Further, the correlation between the molecular and behavioral responses in individual beetles indicates a mechanistic relationship between the two biomarkers.
Effects of simulated solar radiation on the bioaccumulation of polycyclic aromatic hydrocarbons by the duckweed Lemna gibba
Authors: Duxbury Cheryl L , Dixon D George , Greenberg Bruce M 
Published: March 2010

Abstract
Light (particularly ultraviolet B) results in photomodification of polycyclic aromatic hydrocarbons (PAHs) to products with increased polarity and water solubility and enhanced toxicity relative to the parent compounds. The uptake and depuration kinetics of three representative PAHs, anthracene (ANT), phenanthrene (PHE), and benzo [a]pyrene (BAP), and their photomodified products were determined for Lemna gibba. The 14C-labeled PAHs were delivered to the plants in their aqueous growth medium either via a dimethylsulfoxide (DMSO) carrier or adsorbed directly to sand placed in the medium. Assimilation was carried out under simulated solar radiation (SSR) and in darkness. The potential sites of PAH action within the plants were defined by identifying the subcellular location of both intact and photomodified PAHs following assimilation. Lemna gibba had a high capacity for intact ANT, PHE, and BAP in the dark regardless of the two routes of delivery. Depuration was also rapid. Net assimilation of all three PAHs in the dark was always higher when the chemicals were delivered with DMSO than from sand, although first-order kinetics were apparent with both delivery systems. The relative levels of assimilation were PHE &gt; ANT &gt; BAP. Polycyclic aromatic hydrocarbons were rapidly assimilated under SSR, albeit net assimilation for both the intact and photomodified forms was generally lower under SSR compared with darkness. This was also reflected in the bioconcentration factors, which were highest in darkness for each PAH and dropped significantly under SSR and after photomodification. Both intact and photooxidized PAHs accumulated preferentially in the thylakoids and microsomes of L. gibba, suggesting these to be the subcellular compartments most at risk from PAH damage.
Early life-stage mortalities of Japanese medaka (Oryzias latipes) exposed to polychlorinated diphenyl ethers
Authors: Metcalfe Chris D , Metcalfe Tracy L , Cormier James A , Huestis Susan Y , Niimi Art J 
Published: March 2010

AbstractPolychlorinated diphenyl ethers (PCDEs) are a group of compounds that resemble polychlorinated dibenzofurans in structure that have been detected at ppb concentrations in fish from the Great Lakes. The objective of this project was to determine the toxicological significance of PCDE residues in fish. PCDE congener 77 (3,3′,4,4′-tetrachlorodiphenyl ether), congener 71 (2,3′,4′,6-tetrachlorodiphenyl ether), congener 118 (2,3′,4,4′,5-pentachlorodiphenyl ether), and congener 105 (2,3,3′,4,4′-pentachlorodiphenyl) were tested for toxicity with early life stages (ELS) of Japanese medaka, Oryzias latipes. These embryotoxicity data showed that the mono-ortho congeners 105 and 118 and the non-ortho congener 77 were embryotoxic to medaka. However, the toxic equivalency factors (TEFs) estimated for congeners 105, 77, and 118 relative to 2,3,7, 8-TCDD were relatively low at 0.00056, 0.00003, and 0.00001, respectively. PCDE compounds were isolated in a fraction prepared from a bulk extract of Lake Ontario lake trout. In this fraction, congeners 99 (2,2′,4,4′,5-pentaCDE), 153 (2,2′,4,4′,5,5′-hexaCDE), 154 (2,2′,4,4′,5,6′-hexaCDE), and 163 (2,3,3′,4′,5, 6-hexaCDE) comprised 81.3% of total PCDEs, while congeners 77, 71, 118, and 105 comprised only 1.1% of total PCDEs. The LC50 for embryotoxicity of this fraction was equivalent to 15.5 ng/ml of total PCDEs. Toxicopathic lesions noted in medaka embryos exposed to either individual PCDEs or the lake trout extract included vascular hemorrhage but no edematous lesions. Medaka fry did not exhibit symptoms of hyperexcitability prior to death, as has been noted for ELS of lake trout exhibiting “swim-up syndrome.” These data indicate that PCDEs in Lake Ontario lake trout have the potential to induce toxic effects in early life stages of fish. However, the medaka mortalities were not consistent with observations of either “blue-sac disease” or swim-up syndrome observed in some natural populations of Great Lakes salmonids.
Extrapolation factors for small samples of pesticide toxicity data: Special focus on LD50 values for birds and mammals
Authors: Luttik Robert , Aldenberg Tom 
Published: March 2010

Abstract
For the registration procedure of pesticides it is necessary to have specific information and testing data in order to conduct an ecological hazard/risk assessment. The hazard/risk assessment for acute exposure is usually based on a quotient method, where the estimated environmental concentration is compared with the lowest available 50% lethal dose (LD50) value. Generally there are only one or two LD50s available for birds and mammals, and an underestimation of the potential hazard/risk could be a real possibility. In this article, we propose to estimate a hazardous dose for 5% of the species (HD5) for LD50 data, corresponding with the hazardous concentration for 5% of the species for the no-observed effects concentration (NOEC) data. In addition we describe a method for calculating safety factors that can be used in the case of small sample sizes, especially those smaller than 4 and including n = 1. The safety factors to be applied to the geometric mean of the LD50s for a median estimate of the HD5 of birds and mammals are 5.7 and 3.8, respectively. The safety factors for the 95% confidence limit of the HD5 of birds for n = 1, 2, and 3 are 33, 20, and 16, respectively. For mammals these safety factors are 15, 10, and 8.
Review of the environmental behavior and fate of methyl tert-butyl ether
Authors: Squillace Paul J , Pankow James F , Korte Nic E , Zogorski John S 
Published: March 2010

Abstract
A review of pertinent equations and current research indicates that when gasoline oxygenated with methyl tert-butyl ether (MTBE) comes into contact with water, large amounts of MTBE can dissolve. At 25°C, the water solubility of MTBE is about 5,000 mg/L for a gasoline that is 10% MTBE by weight, whereas for a nonoxygenated gasoline, the total hydrocarbon solubility in water is typically about 120 mg/L. Methyl tert-butyl ether sorbs only weakly to subsurface solids; therefore, sorption does not substantially retard the transport of MTBE by ground water. In addition, MTBE generally resists biodegradation in ground water. The half-life of MTBE in the atmosphere can be as short as 3 d in a regional airshed. In the air, MTBE tends to partition into atmospheric water, including precipitation. However, the washing out of gas-phase MTBE by precipitation will not, by itself, greatly alter the gas-phase concentration of the compound in the air. The partitioning of MTBE to precipitation can nevertheless result in concentrations as high as 3 μg/L or more in urban precipitation and can contribute to the presence of MTBE in surface and ground water.
Variation of the stability of complexes of Al(III) with a fulvic acid extracted from a humic cambisol soil in the pH range three to five
Authors: Esteves da Silva Joaquim C G , Machado Adélio A S C , Ramos M Angeles , Arce Florencio , Rey Francisco 
Published: March 2010

Abstract
The interaction of the aluminum ion [Al(III)] with the major constituent of soil organic matter, fulvic acids (FA), was investigated in the acid pH range. The complexation of a FA extracted from a humic cambisol soil (at a concentration of 80 mg/L) when titrated with Al(III) were monitored directly by synchronous fluorescence (SyF) spectroscopy at five pH values (3.0, 3.5, 4.0, 4.5, and 5.0), at 25°C and with 0.1 N KNO3. Inverted second derivative SyF data were preprocessed by a self-modeling mixture analysis method to obtain fluorescence enhancement profiles as a function of the increasing Al(III) concentration. Assuming that the concentration of complexes formed between Al(III) and FA is proportional to the fluorescence intensity, these profiles were adjusted to a 1:1 complexation model and the following conditional stability constants (log Kc) were calculated (standard deviation in parenthesis), pH = 3.0, 4.3 (1); pH = 3.5, 4.3 (1); pH = 4.0, 5.0 (1); pH = 4.5, 5.1 (3); and pH = 5.0, 5.3 (2). These constants show that the stability of the complexes decreases markedly at pH &lt; 4. The environmental implication of this result is that an increase in the extent of the dissociation of the Al(III) + FA complexes is expected at pH &lt; 4, increasing the free Al(III) concentration and probably its ecotoxicity.
Percent methylmercury and organic mercury in tissues of marine mammals and fish using different experimental and calculation methods
Authors: Wagemann Rudolf , Trebacz Ewa , Hunt Robert , Boila Gail 
Published: March 2010

Abstract
Muscle and liver tissues of marine mammals and fish were extracted with methylene chloride–hexane (DCM-hexane) or toluene and the extracts were analyzed for organic mercury by cold vapor atomic absorption spectroscopy (CVAAS) and for methylmercury by gas liquid chromatography with an electron capture detector (GC-ECD). Total mercury in tissues was determined by CVAAS. Methylmercury and organic mercury concentrations in muscle agreed with each other and with total mercury for both marine mammals and fish, indicating that on average 100% of the total mercury in this tissue was in the form of methylmercury. Either total mercury or organic mercury determined by CVAAS was found to be a valid measure of the average methylmercury concentration in muscles of marine mammals and fish. In liver, the CVAAS method produced higher mercury values (15% organic mercury) than the GC-ECD method (6% methylmercury), methylmercury being only 38% of organic mercury. From this, the presence of organic mercury compound(s) other than methylmercury was inferred. The CVAAS method produced a biased estimate of methylmercury in liver; an accurate measure of methylmercury in this tissue was obtained by GC-ECD, either with DCM-hexane or with toluene extraction. The DCM-hexane extract could be directly analyzed by CVAAS for organic mercury while toluene required an additional back-extraction step for such a determination. In calculating the average percentage of methylmercury and organic mercury in a sample, three different calculation methods were used. Only one of them, linear, robust regression analysis produced acceptable results when the variables (MeHg, organic Hg, total Hg) were significantly correlated. The other two methods overestimated the mean percentage under these conditions.
Short-term tissue distribution, depuration and possible gene expression effects of [3H]TCDD exposure in soft-shell clams (Mya arenaria)
Authors: Rhodes Linda D , Gardner George R , Van Beneden Rebecca J 
Published: March 2010

AbstractA short-term, waterborne exposure and depuration study of Mya arenaria to [3H]tetrachlorodibenzo-p-dioxin([3H]TCDD) was performed. Gill, digestive gland, foot, and gonad were sampled up to 2 weeks after a 24-h exposure to a low dose (10 parts per trillion [pptr]) or high dose (2,000 pptr) of [3H]TCDD in the water. In the gill, peak concentrations occurred at the beginning of depuration (406 and 8,658 pg/g wet weight, low- and high-dose groups, respectively), whereas peak concentrations in the digestive gland and foot were found 12 to 24 h after exposure (digestive gland, 539 and 9,369 pg/g wet weight; foot, 146 and 2,718 pg/g wet weight; low- and high-dose groups, respectively). In contrast, tissue concentrations in the gonad increased through the post-exposure period; at 2 weeks after exposure, tissue concentrations were highest in the gonad (243 and 3,012 pg/g wet weight, low-and high-dose groups, respectively). Examination of gill and gonad by differential display polymerase chain reaction identified potential alterations in expression of genes that may be associated with increased cell cycling or translation initiation. This study shows that M. arenaria can accumulate TCDD in the gonad from an acute exposure, and it identifies several M. arenaria genes whose expression may be altered by TCDD exposure.
Exposure to β-sitosterol alters the endocrine status of goldfish differently than 17β-estradiol
Authors: MacLatchy Deborah , Peters Lisa , Nickle John , Van Der Kraak Glen 
Published: March 2010

Abstract
Wild fish exposed to bleached kraft-mill effluent (BKM) have a variety of reproductive dysfunctions. BKM contains β-sitosterol, a presumed phytoestrogen. In this study, goldfish were exposed for 12 d to concentrations of β-sitosterol typical of BKME (75, 300, 600, and 1,200 μg/L) and to 17β-estradiol (E2) (75 and 300 μg/L) for comparative purposes. In general, plasma reproductive steroid levels in males and females were decreased by β-sitosterol treatment. E2 exposure significantly increased plasma steroid levels. Basal in vitro production of testosterone (T) and pregnenolone by testes of β-sitosterol-treated fish were either unchanged or decreased, while human chorionic gonadotropin (hCG)-stimulated T and pregnenolone production were decreased. 25-OH Cholesterol treatment stimulated only pregnenolone production. In E2-treated fish, basal, hCG- and 25-OH cholesterol-treated testes had either unchanged or increased T and pregnenolone production. Steroids of β-sitosterol fish increased in response to Ovaprim (salmon GnRH and the dopamine receptor antagonist domperidone) to a lesser degree than in control fish. Overall, gonadotropin II (GtH-II) levels were not changed by β-sitosterol treatment. In E2-treated fish, plasma GtH-II levels were decreased; plasma GtH-II following Ovaprim injection was unchanged. Gonadal cholesterol levels were decreased in the 1,200-μg/L β-sitosterol-treated fish but were unchanged in E2-treated fish. These results suggest that decreases in plasma steroids by β-sitosterol are possibly due to alterations in cholesterol availability to P450scc (enzyme that converts cholesterol to pregnenolone) or P450scc activity. β-Sitosterol also appears to affect gonadal steroidogenesis between pregnenolone and T. These findings strengthen the suggestion that β-sitosterol could be a contributing factor to the reproductive dysfunctions observed in BKME-exposed fish.
Metabolic androgenization of female Daphnia magna by the xenoestrogen 4-nonylphenol
Authors: Baldwin William S , Graham Stephen E , Shea Damian , LeBlanc Gerald A 
Published: March 2010

Abstract
Vrtebrates and invertebrates metabolize testosterone to a variety of less-polar derivatives that elicit varying degrees of androgenicity as well as polar elimination products. We have developed a model, using the cladoceran Daphnia magna, with which the ability of xenobiotics to alter steroid hormone metabolism can be assessed and possible physiologic consequences evaluated during a 3-week assay. This model was used to assess the effects of the xenoestrogen 4-nonylphenol on steroid-metabolic processes. Exposure of daphnids to 100 μg/L 4-nonylphenol for 48 h caused a significant increase in the accumulation of radioactivity derived from [14C]testosterone provided to the exposure media. More definitive analyses demonstrated that both 25 and 100 μg/L 4-nonylphenol disrupted components of the testosterone metabolic pathway that would lead to a decrease in the metabolic elimination of testosterone and an increase in the accumulation of androgenic derivatives. Exposure of daphnids to 100 μg/L 4-nonylphenol significantly decreased fecundity of the organisms while having no effect on survival of the parental organisms. Comparison of metabolic and reproductive effects of 4-nonylphenol revealed that 71 μg/L, the reproductive chronic value, would reduce the metabolic elimination of testosterone by approximately 50%. This relationship is consistent with that which we have reported for other toxicants and identifies a mechanism, in addition to estrogenicity, that may contribute to the reproductive toxicity of this compound.
Exposure of atlantic salmon parr (Salmo salar) to a combination of resin acids and a water soluble fraction of diesel fuel oil: A model to investigate the chemical causes of Pigmented Salmon Syndrome
Authors: Croce Bronwen , Stagg Ronald M 
Published: March 2010

AbstractPigmented Salmon Syndrome is a pollutant-induced hemolytic anemia and hyperbilirubinemia. As part of an investigation of this condition, S2 Atlantic salmon parr (Salmo salar) were exposed to a diesel fuel oil, water soluble fraction (WSF) in combination with a mixture of three resin acids (isopimaric, dehydroabietic, and abietic acids) in a continuous-flow freshwater system. The total nominal concentrations of resin acids in the exposure tanks were 10, 50, and 100 μg/L; the diesel WSF was generated in situ and provided a mean hydrocarbon concentration of 2.0 ±0.1 mg/L (n = 12) during the 9-d exposure period. Exposure to the diesel WSF alone depressed liver bilirubin UDP-glucuronosyl transferase (UDPGT) activity and induced phenol UDPGT activity. Exposure to the diesel WSF in the absence or presence of resin acids induced liver cytochrome P4501A and increased the concentrations in the plasma of the enzymes lactate dehydrogenase, alkaline phosphatase, and glutamic oxaloacetic transaminase. The combined exposure to diesel WSF with either 50 or 100 μg/L total resin acid caused significant elevations in the concentrations of bilirubin in the plasma and many of these fish had yellow pigmentation on the ventral surface and around the gill arches. The results demonstrate that exposure to combinations of two groups of contaminants can result in the manifestation of toxic effects not apparent from exposure to either of these chemicals in isolation.
Tadpole swimming performance and activity affected by acute exposure to sublethal levels of carbaryl
Authors: Bridges Christine M 
Published: March 2010

AbstractGeneral activity and swimming performance (i.e., sprint speed and distance) of plains leopard frog tadpoles (Rana blairi) were examined after acute exposure to three sublethal concentrations of carbaryl (3.5, 5.0, and 7.2 mg/L). Both swimming performance and spontaneous swimming activity are important for carrying out life history functions (e.g., growth and development) and for escaping from predators. Measured tadpole activity diminished by nearly 90% at 3.5 mg/L carbaryl and completely ceased at 7.2 mg/L. Sprint speed and sprint distance also decreased significantly following exposure. Carbaryl affected both swimming performance and activity after just 24 h, suggesting that 24 h may be an adequate length of exposure to determine behavioral effects on tadpoles. Slight recovery of activity levels was noted at 24 and 48 h post-exposure; no recovery of swimming performance was observed. Reduction in activity and swimming performance may result in increased predation rates and, because activity is closely associated with feeding, may result in slowed growth leading to a failure to emerge before pond drying or an indirect reduction in adult fitness. Acute exposure to sublethal toxicants such as carbaryl may not only affect immediate survival of tadpoles but also impact critical life history functions and generate changes at the local population level.