bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bioassay-driven analysis of chewing tobacco extracts
Authors: Chou Chin C. , Hee Shane S. Que 
Published: March 2010

Abstract
The aims were to develop a method to simulate extraction of toxic components into human saliva, to identify these components through bioassay-driven analyses using the Microtox® test, and to quantify the toxic compounds. Chewing tobacco extractions into artificial saliva simulated oral chewing conditions. The Microtox bioassay-directed subfractionation scheme identified acutely toxic components in chewing tobacco extracts. GC-MS identified and quantified the toxic components. The subfractionation (pH 7 extraction, pH 2 extraction, then pH 10 extraction using organic solvents) scheme was shown to be comparable to biological digestive sequences and to simulate nicotine bioavailability. The low toxicity of artificial saliva allowed development of a sensitive bioassay. Nicotine was the major acutely toxic agent detected. Classification by Draize ocular irritative categories showed that leached nicotine concentrations were mildly to moderately irritating. Thus, the Microtox test can be used to detect irritative compounds and subfractions, and can be potentially applied to saliva biological monitoring in humans.
Community-level field method for testing the toxicity of contaminated sediments in estuaries
Authors: Watzin Mary C. , Roscigno Pasquale F. , Burke W. David 
Published: March 2010

Abstract
The objective of this study was to demonstrate a method for testing the toxicity of contaminated sediments under field conditions. An artificial sediment that matches field sediment in grain-size distribution and organic matter content was mixed from 11 components and used as the test substrate. Clean sediments and sediments spiked with zinc (∼8,000 mg/kg) were exposed in the field on a holding rack anchored on the bottom of Mobile Bay, Alabama. The abundance and diversity (species richness) of benthic invertebrate recruits were used as indicators of sediment quality. The number of recruits was significantly reduced by the presence of zinc in one-week exposures.
Modeling the accumulation of three waterborne chlorinated ethanes in fathead minnows (Pimephales promelas): A physiologically based approach
Authors: Lien Gregory J. , Nichols John W. , McKim James M. , Gallinat Carol A. 
Published: March 2010

AbstractA physiologically based kinetic model was used to predict the accumulation of a homologous series of chlorinated ethanes in fathead minnows (Pimephales promelas). Uptake and accumulation of these compounds are described in terms of a few fundamental physiological, morphological, and physicochemical parameters. Chemical residues in 30-d-old fathead minnows exposed to 1,1,2,2-tetrachloroethane, pentachloroethane, and hexachloroethane were used to evaluate model performance. The predicted and observed accumulations of the chlorinated ethanes were in close agreement. A quantitative assessment of the major factors regulating the exchange of these compounds indicates that the cutaneous surface may be an important route of uptake in small fish.
Transgenic hsp 16-Lacz strains of the soil nematode caenorhabditis elegans as biological monitors of environmental stress
Authors: Stringham Eve G. , Candido E. Peter M. 
Published: March 2010

Abstract
Caenorhabditis elegans is a small, free-living hermaphroditic nematode that is widely used for the investigation of basic biological phenomena at the genetic and molecular levels. The hsp16 genes in this system encode a family of stress-inducible 16-kDa proteins. Stable transgenic nematode lines were derived that carry fusions of the hsp16 genes to the Escherichia coli lacZ reporter gene. These transgenic strains express high levels of β-galactosidase in the nucleus, in response to a heat shock or to a variety of chemical stressors. Agents tested to date that induce the stress response in these animals include Cd2+, Cu2+, Hg2+, Pb2+, Zn2+, AsO2−, and the herbicide paraquat. Some of these agents yield distinct tissue patterns of stress induction (e.g., Pb2+ in the posterior pharynx, Cd2+ throughout the pharynx, Hg2+ in intestine), suggesting that classification of stress agents in complex mixtures may be a useful feature of this biomonitoring system. Using a soluble β-galactosidase substrate, an assay was developed that allows the magnitude of the stress response to be measured. Stress reporter gene induction always occurred below the LC50 of the test substance, suggesting that this assay is a more sensitive and rapid indicator of stress than current LC50 assays using Caenorhabditis elegans.
Mitochondrial dna diversity of brown bullhead from contaminated and relatively pristine sites in the great lakes
Authors: Murdoch Mary H. , Hebert Paul D. N. 
Published: March 2010

Abstract
Brown bullhead were sampled from contaminated and relatively pristine sites to determine whether there was any association between genetic diversity and site contamination. Nine sites were sampled in the lower Great Lakes: five from Areas of Concern (identified by the International Joint Commission as having significant environmental degradation) and four from relatively clean areas of similar habitat type. Genetic variation was surveyed in the mitochondrial genome using restriction fragment length polymorphisms. Sixteen restriction enzymes were used to identify 42 distinct mitochondrial DNA haplotypes among 163 fish. Eight pairwise comparisons of populations at contaminated vs. clean sites showed that genetic diversity estimates were always lower in populations from contaminated sites. The most parsimonious explanation is that reduced diversity is a result of stochastic reductions in population size that have culled much of the genetic diversity from populations. Although contaminated sites support large populations of brown bullhead, historical environmental degradation at these sites may have reduced population size in the past, resulting in reduced present-day genetic diversity.
Actions and interactions of temperature, ph and photoperiod on mercury bioaccumulation by nymphs of the burrowing mayfly Hexagenia rigida, from the sediment contamination source
Authors: Odin M. , Feurtet-Mazel A. , Ribeyre F. , Boudou A. 
Published: March 2010

Abstract
Based on a three-compartment system — water, natural sediment, Hexagenia rigida nymphs — an experimental study was set up, using a complete factorial design, to quantify the actions and interactions of three abiotic factors (temperature: 10, 18, and 26°C; photoperiod: 6, 12, and 18 h per day; pH: 5.0 and 7.5) on inorganic mercury (HgCl2) and methylmercury (CH3HgCl) bioaccumulation by Hexagema rigida (whole organism and gills). The two chemical forms of the metal were initially introduced into the sediment; the exposure duration was 15 d. Total Hg burdens measured at the whole-organism level revealed a very high bioaccumulation capacity of this burrowing mayfly species and important differences between the two contamination conditions of the sediment source, a factor close to 20 observed in favor of methylmercury, for similar exposure conditions. Among the three abiotic factors taken into account, temperature and water-column pH played an important role on Hg bioaccumulated by the nymphs, when considered in isolation and in interaction. An increase in temperature from 10 to 26°C gave rise to an increase in Hg bioaccumulation, with the higher differences close to a factor of 1.7. On the other hand, acidification of the water column from 7.5 to 5.0 led to a decrease in the amounts of the metal accumulated by Hexagenia rigida. These effects were similar for the two Hg compounds, but they were more pronounced when the experimental units were contaminated by methylmercury. This comparative analysis of the amounts of metal bioaccumulated by whole organism and by the gills, estimates of nymph activity within the sediment, and results from earlier lab studies have generated several hypotheses on the involved mechanisms. We propose that ingested sediment is the predominant route of exposure and that the gut acts as a selective barrier that favors organic Hg absorption.
Comparison of whole-sediment, elutriate and pore-water exposures for use in assessing sediment-associated organic contaminants in bioassays
Authors: Harkey Gail A. , Landrum Peter F. , Klaine Stephen J. 
Published: March 2010

AbstractBioassays have frequently been used as tools to simulate exposure of benthos to sediment-associated contaminants in hazard assessments. Due to the problems involved with estimating bioavailability in whole-sediment bioassays, aqueous fractions such as elutriates and pore water have been substituted for whole-sediment exposures. The objective of this research was to compare and evaluate the bioavailability of representative neutral hydrophobic contaminants in whole sediments and in aqueous extracts of whole sediment (elutriate and pore water) in simultaneous bioassays, using three representative indicator species, Diporeia spp., Chironomus riparius larvae, and Lumbriculus variegatus. Aqueous extracts of whole sediment did not accurately represent the exposure observed in whole sediment. Generally, the aqueous extracts underexposed organisms compared to whole sediment, even after adjusting accumulation to the fraction of organic carbon in the test media. Accumulation comparisons among whole-sediment, elutriate, and pore-water exposures depended on sampling time. At some sampling times for some contaminants, differences in accumulation between a particular aqueous extract and whole sediment were not significant; however, these similarities were not observed for all species at the particular sampling time. Bioaccumulation and contaminant clearance data suggest that a number of factors such as the indicator species, exposure media, and chemical/physical properties of individual contaminants are responsible for the accumulation differences observed among the tested media. Normalizing bioaccumulation to the amount of organic carbon in a source compartment adjusted for bioavailability differences of only some contaminants. We suggest that the bioavailability of contaminants such as those tested cannot be accurately predicted in bioassays that expose organisms to aqueous representations of whole sediment.
Assessment of the toxic potential of PCB congener 81 (3,4,4′,5-tetrachlorobiphenyl) to fish in relation to other non-ortho-substituted pcb congeners
Authors: Harris G.E. , Kiparissis Y. , Metcalfe C.D. 
Published: March 2010

Abstract
PCB congener 81 (3,4,4′,5-tetrachlorobiphenyl) has been detected in fish tissues from various sites in North America. The embryotoxicity of this compound to medaka (Oryzias latipes) and the induction of hepatic aryl hydrocarbon hydroxylase (AHH) in rainbow trout (Oncorhynchus mykiss) were determined to assess the toxic potency of this compound relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and two other non-ortho-substituted PCB compounds, congener 77 (3,3′,4,4′-tetrachlorobiphenyl) and congener 126 (3,3′,4,4′,5-pentachlorobiphenyl). The TCDD toxic equivalency factors (TEFs) estimated for congener 81 from two end points in the medaka embryotoxicity assay were 0.0014 (from mortality data) and 0.006 (from swim bladder inflation data). The TEF estimated for congener 81 from data on AHH induction in rainbow trout was 0.004. All TEFs were greater than those estimated for congener 77 but were less than the TEFs estimated for congener 126. On the basis of these toxicity data, it is suggested that this congener may contribute significantly to the toxic burden of planar halogenated aromatic hydrocarbons in fish.
Toxicokinetics and toxicity of sediment-associated pyrene to lumbriculus variegatus (oligochaeta)
Authors: Kukkonen Jussi , Landrum Peter F. 
Published: March 2010

Abstract
The oligochaete Lumbriculus variegatus has been proposed for whole-sediment bioassays to assess sediment contamination. Our work examines Lumbriculus variegatus exposure to pyrene-dosed Lake Michigan sediment at 0.4 ng g−1 and 64, 132, 206, and 269 μg g−1. Both bioaccumulation and survival were followed to enhance Lumbriculus variegatus development as a bioassay organism. Lumbriculus variegatus accumulated sediment-associated pyrene rapidly and achieved apparent steady state within 48 to 168 h. The pyrene uptake clearances (ks, g sed g−1 animal h−1) ranged from 0.039 to 0.132 and decreased with increasing pyrene concentration. At high pyrene concentrations, the worms avoided the sediment, which reduced accumulation and likely minimized the mortality response. In addition, the effect of organism loading on bioaccumulation was determined at different animal densities, 1:10, 1:50, and 1:100 g dry weight Lumbriculus variegatus:g sediment organic carbon, and a sediment pyrene concentration of 0.4 ng g−1. Surprisingly, the bioaccumulation declined as organism density decreased. Pyrene elimination was rapid in clean sediment (ke = 0.026 ± 0.002 h−1) but was much slower in water (ke = 0.0043 ± 0.0007 h−1). Bioavailability apparently declined for exposures in sediment stored 1.5 months, based on the estimate of ke from nonlinear regression compared to direct measures of elimination. The apparent decline was attributed to both a decline in lipid content during the experiment and changes in pyrene bioavailability. Finally, for bioaccumulation studies, gut purging at a set time (e.g., 24 h) may result in an underestimate of contaminant concentration in organisms. An elimination study with extrapolation to the initial body burden can ensure that biases due to incomplete elimination of gut contents and body burden losses during the purging process are minimized.
Exposure of fish to biologically treated bleached-kraft effluent. 2. Induction of hepatic cytochrome P4501A in mountain whitefish (Prosopium williamsoni) and other species
Authors: Kloepper-Sams P.J. , Benton E. 
Published: March 2010

AbstractInduction of the hepatic detoxification enzyme cytochrome P4501A has been observed in fish exposed to bleached-kraft mill effluents (BKME). P4501A content was examined in three species of wild fish exposed to BKME in a western Canadian river as part of an extensive program that included chemical monitoring, fish population studies, and other fish biochemical and physiological measurements. The Rocky Mountain whitefish Prosopium williamsoni exhibited marked induction of P4501A compared to reference whitefish, as measured by both catalytic activity and immunoreactive protein content. Similar P4501A induction was observed 4 d after reference fish were treated with 20 mg/kg β-naphthoflavone. Whitefish P4501A levels have declined from a peak in spring 1991, following mill process modifications and concurrent with reductions in body burdens of hydrophobic compounds. Whitefish collected near the mill, moved upstream of effluent discharges, and held for 8 d showed no significant loss of hepatic P4501A-related (ethoxyresorufin O-deethylase, EROD) enzyme activity or P4501A protein levels. For spring 1991, correlations were found between EROD activity and measures of chronic exposure to BKME (e.g., muscle 2,3,7,8-tetrachlorodibenzo-p-dioxin content), but not between EROD and measures of acute exposure (e.g., bile content of resin acids or chlorophenolic metabolites). These and other lines of evidence indicate that the P4501A-inducing agent(s) at this site may be neither waterborne nor rapidly eliminated. A second species, longnose sucker (Catostomus catostomus), collected near the mill exhibited modest (two- to threefold) P4501A induction. For both species, no significant correlations between P4501A induction and trends in other biological responses were found, as described in a companion paper. Burbot (Lota lota) had hepatic EROD activities generally in the range of reference values, despite substantial exposure to mill-related compounds. In contrast to studies at historically degraded pulp mill sites, P4501A induction is the only major biological response observed to date at this site. As P4501A induction is not related to adverse effects, it could be best classified as an indicator of exposure to BKME.
Exposure of fish to biologically treated bleached-kraft mill effluent. 3. Fish habitat and population assessment
Authors: Swanson S.M. , Schryer R. , Shelast R. , Kloepper-Sams P.J. , Owens J.W. 
Published: March 2010

AbstractPopulations of mountain whitefish (Prosopium williamsoni) and longnose sucker (Catostomus catostomus) exposed to bleached-kraft mill effluent (BKME) in the Wapiti/Smoky river system in northwestern Alberta were compared to similar populations in a reference river system (the upper North Saskatchewan River). Fish species distribution and relative abundance patterns were linked to natural events such as floods and low flows, and to habitat quality. There was no evidence that fish were avoiding the effluent plume area; relative abundance was often highest near the effluent discharge due to use of this area for overwintering and rearing. Radiotelemetry and recapture studies indicated that fish movements could be both rapid and extensive, occurring during spawning periods and at other times of the year. Thus, exposure could not be assumed to be related to capture location alone; separate exposure measures were necessary. Populations of exposed mountain whitefish and longnose sucker were growing and reproducing successfully. Higher condition factors in exposed longnose suckers and greater mesenteric fat stores in exposed individuals of both species were not accompanied by any apparent disruption in allocation of energy to reproduction or growth. The age structure of the populations showed that there had been no losses of age classes through reproductive or recruitment failures, and growth curves were indistinguishable from reference curves. There were no correlations between indicators of exposure and population-level effects. Important natural phenomena, including a one-hundred-year flood and natural upstream/downstream habitat gradients, affected species distribution and were correlated with some population parameters such as condition factors and relative gonad size.
Use of life tables and lc50 tests to evaluate chronic and acute toxicity effects of copper on the marine copepod tisbe furcata (baird)
Authors: Bechmann Renée Katrin 
Published: March 2010

Abstract
Cohorts of the epiphytic marine copepod Tisbe furcata were chronically exposed to copper in life-table experiments to test whether ecologically relevant impacts can occur at sublethal concentrations. Data on fecundity, longevity, and rate of development were used to calculate rm – the intrinsic rate of natural increase. Acute toxicity tests (96-h LC50 tests) were done to compare the concentrations of copper affecting individual lethality and population biology. The LC50 value for Tisbe furcata nauplii was 2.8 μM copper (178 μg/L). The results from the life-table experiments show that 0.9 μM copper (32% of LC50) can cause significant negative effects on demographic parameters (total production of nauplii, life span, and reproductive period for fertile females) and reduce the percentage of fertile females leading to a 61% reduction of rm. However, rm was still positive at 0.9 μM copper, and the net reproductive rate (Ro) indicated a fivefold increase in population size from one generation to the next. Although there were no significant effects of copper at 0.5 μM (18% of LC50), there was a negative trend in almost all the demographic parameters, indicating that the observed 10% reduction of rm at this concentration was an effect of copper. For the substances tested so far with both acute LC50 tests and life-table experiments, rm was not reduced at concentrations below LC50/10. When life-table experiments are used as part of environmental hazard assessments, concentrations below LC50/10 should be tested to detect substances that are potentially harmful to the environment at sublethal concentrations, rather than testing concentrations close to LC50.
Adsorption and desorption hysteresis of pahs in surface sediment
Authors: Fu Gongmin , Kan Amy T. , Tomson Mason 
Published: March 2010

Abstract
The overall objective of this research is to investigate the desorption reversibility of two PAHs (naphthalene and phenanthrene) from sediment materials Batch adsorption and desorption experiments were designed to minimize the contribution of experimental artifacts The sorbent was sediment obtained from Johnson Ranch (Lula, OK) that contained 92% sand, 6% silt, 2% clay, and 0 27% organic matter Batch adsorption and desorption experiments with radiolabeled chemicals were conducted at various pH levels and ionic strengths, solute concentrations ranging over several orders of magnitude, and equilibrium times up to five months These model pollutants appear to be readily adsorbed by sediment, but a portion of the bound pollutants resists desorption The adsorption is rapid and predictable using published Koc and Kow relationships From 30 to 50% of the adsorbed amount resists desorption The resistant fraction can be desorbed in water only at rates one to three orders of magnitude slower than previous observations or theories It is hypothesized that some multistep chemical or mechanical effects promote soil aggregation and/or entrapment of pollutants in the soil organic matter during adsorption
Production of a novel recombinant cell line for use as a bioassay system for detection of 2,3,7,8-tetrachlorodibenzo-P-dioxin-like chemicals
Authors: El-Fouly M.H. , Richter C. , Giesy J.P. , Denison M.S. 
Published: March 2010

AbstractExposure to specific halogenated aromatic hydrocarbons (HAHs), such as 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD), can produce a wide variety of species- and tissue specific toxic and biological effects The presence of HAHs in environmental samples as complex mixtures has made it difficult to predict the biological and toxic potency of these chemicals We have used aspects of the molecular mechanism of action of these chemicals to develop a species-specific bioassay system for detection of bioactive HAHs in complex mixtures Here we describe construction and utilization of a recombinant expression vector that responds to these HAHs with the induction of an easily measurable gene product, heat-stable human placental alkaline phosphatase (PAP) This vector contains the PAP gene under TCDD-inducible control of four dioxin-responsive DNA enhancer elements HAH inducible expression of PAP from the recombinant vector occurs in a dose- and Ah-receptor- (AhR-) dependent manner Stable transfection of this vector into mouse hepatoma cells has produced a novel cell line in which AhR-dependent induction of gene expression can easily be measured This transfected cell line can readily be used for detection and relative quantitation of AhR agonists in complex mixtures of environmental and biological samples and for identification and characterization of novel AhR agonists