bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of atrazine and nitrate on northern leopard frog (Rana pipiens) larvae exposed in the laboratory from posthatch through metamorphosis
Authors: Allran John Wesley , Karasov William H 
Published: March 2010

Abstract
A ecent ecological rsk assessment of the herbicideatrazinefound that theecosystemsat greatest risk within North America are the streams, rivers, and reservoirs of the midwestern corn-growing regions. Habitats adjacent to application areas could be exposed to high levels of atrazine during periods of amphibian activity such as breeding and migration. Because fertilizer application coincides both spatially and temporally with atrazine application in agricultural areas, we tested the effects of atrazine and nitrate on northern leopard frog (Rana pipiens) larvae in the laboratory. Larvae were exposed to atrazine (0, 20, and 200 μg/L) and nitrate (0, 5, and 30 mg NO3-N/L) from first-feeding stage through metamorphosis in a factorial design. Atrazine concentrations in metamorphosed juveniles were approximately six times the concentration in the water, indicating bioconcentration of atrazine by larvae. Atrazine, nitrate, and their interaction had no significant effect on development rate, percent metamorphosis, time to metamorphosis, percent survival, mass at metamorphosis, or hematocrit. However, nitrate slowed growth of larvae. Though this growth inhibition is statistically significant, it is probably not biologically important when compared with natural variation in the environment. Thus, concentrations of atrazine and nitrate commonly found in the environment do not appear to pose a significant threat to R. pipiens larvae through direct toxicity.
Concentration dependency of biota-sediment accumulation factors for chlorinated dibenzo-p-dioxins and dibenzofurans in dungeness crab (Cancer magister) at marine pulp mill sites in British Columbia, Canada
Authors: Cretney Walter J , Yunker Mark B 
Published: March 2010

AbstractBiota-sediment accumulation factors (BSAFs) for some chlorinated dibenzo- p -dioxin and dibenzofuran congeners (PCDD/Fs) in Dungeness crab (Cancer magister) hepatopancreas and associated sediments are concentration independent as required by equilibrium partition models. In particular 2, 3, 7, 8-tetrachlorodibenzo-p -dioxin (2, 3, 7, 8-TCDD), 2, 3, 7, 8-tetrachlorodibenzofuran, the 2, 3, 7, 8-substituted pentachlorodibenzofurans, and the non-2, 3, 7, 8-hexachlorodibenzofurans (HxCDFs) seem to fall into this group. The BSAFs for other isomers exhibit significant, nonlinear variations with sediment or crab PCDD/F concentrations. For some of these other isomers (e.g., the non-2, 3, 7, 8 TCDDs and possibility the 2, 3, 7, 8-substituted HxCDFs), association of a variable fraction of the total present with soot carbon may provide a satisfactory explanation for the concentration behavior. For the HxCDDs we propose that the nonlinear concentration behavior may arise from the thermodynamic properties of fluids confined in hydrophobic voids within particulate and colloidal material produced by the pulp mills. The nonlinear relationship between BSAFs and PCDD/F concentrations greatly complicates prediction of the potential for dioxin and furan bioaccumulation in crabs and the formulation of sediment quality criteria. We provide a nonlinear equation relating toxic equivalency and sediment concentrations.
Simulation study of characteristics of statistical estimators of inhibition concentration
Authors: Bailer A John , Elmore Ryan T , Shumate B Joseph , Oris James T 
Published: March 2010

Abstract
Statistical estimators of the concentrations associated with specified levels of reproductive toxicity in the aquatic organism Ceriodaphnia dubia are presented and compared. The first estimator, the ICp or inhibition concentration approach, was based on a nonparametric estimation routine that assumed responses monotonically declined with increasing concentrations. This estimator also assumed that linear interpolation between mean responses associated with consecutive concentration groups was reasonable. The second estimator, the RIp or reproductive inhibition concentration approach, was based on a parametric concentration-response model. This model assumed that the number of young is a Poisson or negative, binomially distributed, random variable, and that the mean number of young could be modeled using an exponential term involving a polynomial in the test concentrations. Confidence intervals for both these estimators were obtained using variants of a bootstrap resampling procedure. The properties of these estimators, namely bias, mean squared error, and coverage probabilities, were compared in a Monte Carlo simulation study. The results from this study suggested that over a broad range of realistic conditions, the confidence intervals associated with the ICp estimator failed to maintain nominal coverage probabilities, whereas the confidence intervals associated with the RIp estimator performed as nominally stated under most conditions. Finally, correct specification of the model concentration-response pattern was observed to be important for estimating inhibition concentrations with small bias and variability.
Innovative techniques for harmful algal toxin analysis
Authors: Pierce Richard H , Kirkpatrick Gary J 
Published: March 2010

AbstractThe global increase in frequency and intensity of harmful algal blooms (HABs) has led to more frequent incidence of seafood-borne illnesses and adverse impacts on natural resources. In response, public health agencies worldwide have mobilized to initiate HAB monitoring programs. To meet this demand, innovative analytical techniques are being developed that provide rapid and reliable detection of the causative organisms and the toxins produced. Modifications to conventional chromatography and mass spectrometry have greatly improved sensitivity and selectivity of these methods toward naturally occurring phycotoxins. Bioassay techniques using live organisms are giving way to molecular and cellular methods that measure the toxicologically significant activity of the toxin molecules. Molecular probes are being applied to distinguish species-specific RNA and DNA sequences for rapid identification of HAB-causing organisms. The direction of this new technology is to develop rapid and reliable screening methods for phycotoxins and the causative organisms to provide protection for public health, aquaculture, and natural resources. New methods also are being developed for detecting minute amounts of toxin molecules in microenvironments, leading to understanding the toxicokinetics and toxicological functions of the toxins.
Immunohistochemical localization of cytochrome P4501A induced by 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126) in multiple organs of northern leopard frogs,Rana pipiens
Authors: Huang Yue-Wern , Stegeman John J , Woodin Bruce R , Karasov William H 
Published: March 2010

AbstractMonoclonal antibody 1 12–3(MA1 12–3)recognizesanepitopeexclusivetocytochromeP450sinsubfamily1A (CYP1A) from all vertebrates tested so far, including one amphibian species. In this study, we first tested the utility of MAb 1–12-3 for detection of presumed CYP1A proteins in hepatic microsomes of northern leopard frogs treated without or with 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126). Statistical analysis showed that ethoxyresorufin-O-deethylase (EROD) activities and CYP1A equivalents in treated groups were significantly increased at doses &gt;2.3 mg/kg compared with the control groups (p &lt; 0.05), and the increases were maintained for at least four weeks. This result confirmed that MAb 1–12-3 can be used for detection of CYP1A in northern leopard frogs and indicated that CYP1A is the primary catalyst for EROD in this species. In a subsequent experiment, sections of organs of PCB 126-treated frogs were immunohistochemically stained with MAb 1–12-3 to identify localization of the CYP1A in different cell types. The CYP1A staining was seen prominently in hepatocytes and epithelium of nephronic duct, while capillaries close to gastric epithelium and submucosal vascular epithelium in both stomach and intestine exhibited moderate to strong staining. The CYP1A was immunodetected in coronary endothelium and the vascular endothelium of lung and gonad. In skin, mild staining was seen in epithelial cells of mucous glands and serous glands and in vascular endothelium, demonstrating induction of CYP1A in the dermal layer.
Biological response to variation of acid-volatile sulfides and metals in field-exposed spiked sediments
Authors: Boothman Warren S , Hansen David J , Berry Walter J , Robson Deborah L , Helmstetter Andrea , Corbin Jeffrey M , Pratt Sheldon D 
Published: March 2010

AbstractVertical and temporal variations of acid-volatile sulfides (AVS) and simultaneously extracted metals (SEM) in sediment can control biological impacts of metals. To assess the significance of these variations in field sediments, sediments spiked with cadmium, copper, lead, nickel, and zinc were deployed in Narragansett Bay for four months and recolonization by benthic organisms investigated. In surface sediments, concentrations of AVS decreased with time whenever AVS exceeded SEM but remained unchanged when AVS was less than SEM; in subsurface sediments, concentrations increased slightly. Concentrations of total SEM decreased with time only in surface sediments in which SEM exceeded AVS. Metals were not detected in interstitial waters of sediments where AVS exceeded SEM but were significant when SEM exceeded AVS and followed the order of solubilities of their sulfides. Concentrations in interstitial waters decreased with time, but exceeded U.S. Environmental Protection Agency chronic water quality criteria for 56 to 119 d. After 119 d, faunal assemblages in all treatments were similar to controls. Lack of biological response was related to vertical distributions of AVS and SEM. Biological exposure took place in near-surface sediments, where AVS exceeded SEM in even the highest treatments. Therefore, concentrations of metals in interstitial waters were low and consequently biological impacts were undetectable.
Uptake of polycyclic aromatic hydrocarbon compounds by the gills of the bivalve mollusk Elliptio complanata
Authors: Birdsall Karen , Kukor Jerome J , Cheney Marcos A 
Published: March 2010

Abstract
Polycyclic aromatic hydrocarbons (PAHs) and herbicides are important contaminants of world water systems with effects on aquatic organisms. The uptake of naphthalene, anthracene, and chrysene by gills of the bivalve mollusk Elliptio complanata was determined. Additionally, the effects of paraquat, atrazine, alachlor, 2,4-dichlorophenoxyacetic acid (2,4-D), and 2,4-dinitrophenol on the uptake of these compounds were also determined. The results indicate (1) the uptake of anthracene is approximately equivalent to that of chrysene and the uptake of either of these compounds is higher than that of naphthalene; (2) comparisons of uptakes with that of inulin, which occupies only extracellular space, show that all compounds studied are taken up; (3) the uptakes of naphthalene, anthracene, and chrysene are initially altered by the presence of herbicides such as paraquat, alachlor, 2,4-D, atrazine, and 2,4-dinitrophenol.
Characterization of the acute toxicity of photoactivated fluoranthene to glochidia of the freshwater mussel,Utterbackia imbecillis
Authors: Weinstein John E 
Published: March 2010

AbstractThe acute photoactivated toxicity of fluoranthene to the glochidial larvae of the paper pondshell, Utterbackia imbecillis, was characterized in the laboratory using three sets of experiments. Toxicokinetic studies revealed that glochidia rapidly bioaccumulated fluoranthene, reaching an apparent steady state in 4 h. Based on a two-compartment model, uptake (Ku) and depuration (Kd) rate constants were 1394 ml/g/h and 0.769/h, respectively. However, experimental data suggested the presence of a fast and slow depuration compartment with a Kd of 0.290 and 0.031/h, respectively. Replicate 24-h acute toxicity tests designed to determine the overall sensitivity of glochidia to photoactivated fluoranthene were conducted under simulated sunlight (ultraviolet [UV]-A = 69.0 ±1.0 μW/cm2) (mean ± standard deviation [SD]). Mean median lethal concentrations (LC50) of fluoranthene at 8, 16, and 24 h were 5.59 ± 0.59, 4.09 ± 0.57, and 2.45 ± 0.45 μg/L, respectively. Mean median lethal doses (LD50) at the same time periods were 14.76 ± 2.17, 11.66 ± 2.82, and 6.98 ± 1.31 μg/g dry weight, respectively. Acute toxicity tests designed to elucidate the relationship between the rate of mortality and UV intensity were conducted under one of four different UV intensities (UV-A = 15, 31, 50, and 68 μW/cm2). Regression analysis revealed that the time-dependent mortality of glochidia was inversely related to the product of initial tissue residue of fluoranthene and UV intensity. These findings suggest that glochidia of freshwater mussels are among the most sensitive organisms tested to date to photoactivated fluoranthene and the time-dependent mortality of glochidia can accurately be predicted through evaluation of the product of fluoranthene tissue residue and the light intensity to which the glochidia is exposed.
Enhanced mineralization of benzo[a]pyrene in the presence of nonaqueous phase liquids
Authors: Kanaly Robert A. , Bartha Richard , Watanabe Kazuya , Harayama Shigeaki 
Published: March 2010

AbstractBacterial mineralization of [7- 14C]benzo[a]pyrene (BaP) to 14CO2 was enhanced by the presence of nonaqueous phase liquids (NAPLs). Mineralization of BaP was affected differently by different NAPLs, and the mode of enhancement of mineralization by a NAPL most likely occurred by a combination of cometabolic and physical effects. Mineralization was enhanced to the greatest extent when BaP was dissolved in a high-boiling distillation product of diesel fuel.
Chronic effects of silver exposure on ion levels, survival, and silver distribution within developing rainbow trout (Oncorhynchus mykiss) embryos
Authors: Guadagnolo Christine M , Brauner Colin J , Wood Chris M 
Published: March 2010

Abstract
Rainbow trout embryos were chronically exposed to silver (as AgNO3) in moderately hard water (120 mg CaCO3/L, 0.70 mM Cl−, 1.3 mg/L dissolved organic matter, 12.3 ± 0.1 °C) at nominal concentrations of 0.1, 1, and 10 μg/L (measured = 0.117 ± 0.008, 1.22 ± 0.16, and 13.51 ± 1.58 μg/L, respectively) to investigate the effects on mortality, ionoregulation, and silver uptake and distribution of the embryo. Mortalities in the low concentrations (0.1 and 1.2 μg/L) were not significantly different from controls throughout embryonic development (days 1–32 postfertilization). Mortalities of embryos in the 13.5-μg/L treatment reached 56% by day 32 postfertilization (33% when accounting for control mortality), by which time more than 50% of surviving embryos had hatched. Accumulation of silver in whole embryos of 1.2- and 13.5-μg/L treatments reached the highest concentrations of 0.13 and 0.24 μg/g total silver, respectively, by day 32, but whole embryo silver burden was not correlated with mortality. Silver concentrations in different compartments of the whole embryo (chorion, dissected embryo, and yolk) were greatest just before hatch and were higher in the chorion for all experimental treatments. Up to 85% of total whole embryo silver content was bound to the chorion, which acts as a protective barrier during silver exposure. Whole embryo Na+ concentration in the 13.5-μg/L treatment was significantly reduced relative to controls from days 23 to 32 postfertilization, and levels in the embryo were reduced by 40% at day 32 postfertilization, indicating that silver toxicity in the whole embryo is associated with an ion regulatory disturbance that is similar to the acute effect of AgNO3 in juvenile and adult trout.
A simple Tenax® extraction method to determine the availability of sediment-sorbed organic compounds
Authors: Cornelissen Gerard , Rigterink Henk , ten Hulscher Dorien E M , Vrind Bea A , van Noort Paul C M 
Published: March 2010

Abstract
A simple method to determine the availability of sediment-sorbed organic contaminants was developed and validated. For 10 polycyclic aromatic hydrocarbons, 4 polychlorinated biphenyls, and 9 chlorobenzenes in 6 sediments, we measured the fraction extracted by Tenax® in 6 and 30 h. These fractions were compared with the rapidly desorbing fractions determined by consecutive Tenax extraction. Extraction by Tenax for 30 h completely removed the rapidly desorbing fraction plus some part of the slowly desorbing fraction. The fraction removed after 30 h was about 1.4 times the rapidly desorbing fraction. The fraction extracted by Tenax after 6 h is about 0.5 times the rapidly desorbing fraction for chlorobenzenes (CBs)/polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). The rapidly desorbing fraction probably represents the fraction of sorbed organic compound that poses actual risks for transport to (ground) water and determines the uptake by organisms and that can be microbially degraded. Extraction by Tenax for 6 h provides an easy way to address these issues more accurately than does the measurement of total concentrations.
Effect of mercury andGpi-2genotype on standard metabolic rate of eastern mosquitofish (Gambusia holbrooki)
Authors: Tatara, Christopher Paul , Newman Michael C , Mulvey Margaret 
Published: March 2010

AbstractPrevious studies demonstrated differential mortality among mosquitofish of different Gpi-2 genotypes during acute mercury and arsenate exposures. Mercury-exposed mosquitofish also had Gpi-2 genotype-specific differences in glycolytic and Krebs cycle metabolite pools. The mortality and metabolite data suggested that mosquitofish bearing specific Gpi-2 genotypes might differ in metabolic efficiency, with less efficient Gpi-2 genotypes having higher standard metabolic rates (SMRs) and shorter times to death during acute mercury exposure. Effect of Gpi-2 genotype on SMR was assessed with a factorial arrangement of six Gpi-2 genotypes and two exposure sequences (Control — Control; Control — 100 μg/L Hg). The SMRs were estimated by measuring oxygen consumption using an indirect, closed-circuit, computer-controlled respirometer. A 48-h exposure to 100 μg/L of mercury resulted in a 16.7% elevation of SMR above control levels (p = 0.001). The Gpi-2 genotype and the number of heterozygous loci per individual had no significant effect on SMR in mercury-exposed mosquitofish. The experimental results do not support the hypothesis that Gpi-2 genotype-specific differences in glycolytic and Krebs cycle metabolite pools and mortality in mosquitofish exposed to mercury are associated with differences in SMR.
Assessment of chloroaniline toxicity by the submitochondrial particle assay
Authors: Argese Emanuele , Bettiol Cinzia , Agnoli Francesca , Zambon Alfonso , Mazzola Martina , Ghirardini Annamaria Volpi 
Published: March 2010

AbstractThe effects on mitochondrial respiration of 15 chloroanilines were recorded by using the in vitro response of submi-tochondrial particles (SMP) from beef heart mitochondria. The bioassay procedure for SMP is based on the process of reverse electron transfer, which can be negatively affected by inhibitors of electron transport, by uncouplers, and by chemicals that impair membrane integrity. The EC50 values, determined for the tested chloroanilines, indicate a general tendency of increasing toxicity with increasing chlorine substitution. In order to validate the results obtained and to evaluate the capability of the SMP assay to reproduce the toxic effects of the examined compounds on different freshwater species, the EC50 values were compared with literature data from other biological assays regarding both in vitro systems and whole organisms. A good correlation was found in particular with two widely used testing systems, the Microtox® and the ##Tetrahymena# assays. In addition, quantitative structure-activity relationships (QSARs) were established between the EC50 values and various molecular descriptors for hydrophobic, steric, and electronic interactions. The results obtained were utilized to elucidate the mechanism of toxic action of chloroanilines, which are commonly reported to act by the polar narcosis mode of action. Moreover, they confirmed that the SMP assay can be a useful tool for studying the toxicity of chemicals that act nonspecifically by impairing membrane structure and functions.
Reevaluating the free-ion activity model of trace metal toxicity toward higher plants: Experimental evidence with copper and zinc
Authors: Parker David R , Pedler Judith F , Ahnstrom Zoe Ann S. , Resketo Margaret 
Published: March 2010

AbstractAcrossa diverse spectrum of organisms, the absorption and toxicity of trace elements are usually correlated with the activity of the free metal ion, but reported exceptions to this generalization are increasing. For the first time, we tested the validity of the free-ion activity model (FIAM) in the case of terrestrial plants and organic acids that may be abundant in the soil solution and rhizosphere. Short-term (48-h) root elongation of wheat (Triticum aestivum L.) in a simple medium (2 mM CaCl2, pH 6.0) was used to probe the toxicity of Cu and Zn in the presence of malonate, malate, and citrate. Precautions were taken to prevent biodegradation of the organic acids, and its absence was confirmed by ion chromatography. Copper speciation was verified using a Cu-selective ion electrode, and published stability constants were modified to improve agreement between measured and calculated Cu2+ activities. With additions of both malonate and malate, Cu toxicity was alleviated but not to the extent predicted by the FIAM; the Cu-ligand complexes seemingly contributed to the toxicity. No such departures were observed with citrate and Cu nor with any of the three ligands in combination with Zn. Thus, exceptions to the FIAM occur with higher plants as well as with aquatic biota but do not seem to occur in a predictable or systematic fashion with respect to metal or organic acid under investigation. Several possible explanations for the observed departures from the FIAM are discussed, including the possibility of accidental cotransport of metal and ligand into the cytoplasm.
Effects of copper on olfaction of colorado pikeminnow
Authors: Beyers Daniel W , Farmer Michael S 
Published: March 2010

Abstract
Effects of copper on olfaction of Colorado pikeminnow (Ptychocheilus lucius) were investigated by exposing fish for 24 or 96 h, then evaluating olfactory ability using a behavioral assay and observing olfactory structures using scanning electron microscopy (SEM). The behavioral assay measured a response known as fright reaction. Failure of exposed fish to demonstrate a fright reaction in the presence of skin homogenate assumed to contain fright pheromone was considered evidence of copper-induced loss of olfactory ability. Regression analysis was used to describe the response of fish as a function of copper concentration at each exposure duration. Olfactory ability declined with increasing copper concentration. For copper concentrations less than 66 μg/L, olfaction was more sensitive to exposure at 24 h than at 96 h. This result suggests that physiological adaptation and recovery of sensory ability occurred despite continuous exposure in the 96-h treatment. Protective mechanisms induced by exposure may have reduced sensitivity to copper by 96 h. Systematic surveys using SEM to detect presence or absence of olfactory receptors confirmed results of behavioral assays. Copper concentrations in one river inhabited by Colorado pikeminnow were compared with effective concentrations estimated by regression. Comparisons suggest that ambient copper concentrations may occasionally inhibit olfaction of wild fish.