bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of a flow-through in situ environmental chamber to study microbial adaptation processes in riverine sediments and periphyton
Authors: Shimp Robert J. , Schwab Burney S. 
Published: March 2010

Abstract
Adaptation of sediment-associated and periphytic microbial communities to the quaternary ammonium surfactant dodecyltrimethylammonium chloride (C12-TMAC) was assessed using an in situ environmental chamber. The chamber was placed on the bottom of the Little Miami River (Ohio) and consisted of six channels that were aligned so the river water flowed through them. Concentrated C12-TMAC was dosed to the channels to achieve nominal concentrations of 0 (control), 0.25 and 25 mg/L. Periodically, samples of sediment and periphyton were removed and the biodegradation of C12-TMAC was measured. Results demonstrated that the in situ system was a useful method for assessing the impact of chemicals on aquatic microbial communities. Adaptation to C12-TMAC occurred in both sedimentary and periphytic compartments within 5 to 10 d of exposure. Both biodegradation potential (Vmax) and first-order biodegradation rate constants (K1) increased 15- to 60-fold relative to activity in the control channel. Adaptation was accompanied by an increase in the most-probable number (MPN) of C12-TMAC degraders. However, the increase in MPN was not directly proportional to the increase in biodegradation activity. Results from this work were comparable to previous research using laboratory microcosms, indicating that such laboratory systems are comparatively accurate models of field-measured adaptation responses.
In situ mineralization of chlorinated phenols by pelagic bacteria in lakes of differing humic content
Authors: Tranvik Lars , Larsson Per , Okla Lennart , Regnell Olof 
Published: March 2010

Abstract
The microbial mineralization of phenol and three chlorinated phenols (3,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the water column of 23 pristine, oligotrophic lakes of different humic content was investigated. During short-term (∼2 d) in situ incubations of water samples amended with 14C-labeled phenolic compounds, the fraction of the added pollutant mineralized to 14CO2 was positively correlated with water color (an estimate of humic content) and the total organic carbon concentration of the water. The rate of mineralization per bacterial cell was not correlated with humic content, due to increased bacterial abundance with increasing humic content. Hence, the higher mineralization rate in humic lakes than in clear-water lakes was probably a result of higher bacterial abundance rather than being an effect of bacterial cells having a higher potential for the degradation of such compounds.
In situ and laboratory sediment toxicity testing with ceriodaphnia dubia
Authors: Sasson-Brickson Gemini , Burton G. Allen 
Published: March 2010

Abstract
Ecological assessments of sites containing hazardous wastes are improved by field testing. In situ exposures of Ceriodaphnia dubia were conducted in a stream impacted by several effluents, a combined sewer overflow and a creosote treatment operation. Sediments contained high levels of metals and polynuclear aromatic hydrocarbons. Fish and macroinvertebrate community indices were depressed. Ceriodaphnia dubia were placed in sediment exposure chambers in the stream for 48 h and also exposed to sediments that were simultaneously collected in the laboratory. Percent survival was generally higher in situ as compared to static laboratory exposures; however, overlying water toxicity was lower in laboratory assays. Average survival rates in elutriate fractions were slightly higher than interstitial or solid-phase exposures, and filtration reduced both elutriate and interstitial fraction toxicity. In situ sediment exposures proved to be sensitive indicators of both degraded and nondegraded stream conditions. Results show traditional sample collection and laboratory toxicity test methods may alter the water and sediment toxicity that occurs in situ. This highlights the importance of laboratory validation and in situ testing in aquatic safety assessments.
Degradation of aromatic compounds bound to humic acid by the combined action of sunlight and microorganisms
Authors: Amador José A. , Alexander Martin , Zika Rod G. 
Published: March 2010

AbstractA study was conducted of the degradation of aniline-humic acid and phenol-humic acid complexes by sunlight and the subsequent mineralization by microorganisms. Irradiation of anilinehumic acid and phenol-humic acid complexes in sunlight resulted in a loss of UV light absorbance and the formation of low-molecular-weight products. Sunlight irradiation of the aniline-humic acid complexes had no effect on their subsequent mineralization. The rate and extent of mineralization of the phenol-humic acid complexes were enhanced by sunlight irradiation. The mineralization of phenol-humic acid complexes increased with integrated solar flux and was proportional to the percentage of the original complex that was converted to low-molecular-weight photoproducts. The effects of solar irradiation on molecular-weight distribution of the complexes appear to be independent of the organic compound used to form the complex. The effects of irradiation on microbial mineralization of the complexes are different for different organic compounds.
Cytochrome P450E (P450IA) induction and inhibition in winter flounder by 3,3′,4,4′-tetrachlorobiphenyl: Comparison of response in fish from georges bank and narragansett bay
Authors: Monosson Emily , Stegeman John J. 
Published: March 2010

Abstract
Induction of liver microsomal cytochrome P450 by 3,3′,4,4′-tetrachlorobiphenyl (TCB) was evaluated in winter flounder from two different sites, one offshore (Georges Bank) and one coastal (Narrow River, Narraganseti, Rhode Island). Immunoblot analysis of liver microsomes with monoclonal antibody 1–12–3 to scup P450E (P450IA1) revealed P450IA protein content of 0.01 nmol/mg in Georges Bank fish that were not treated with TCB. By comparison, untreated Narrow River fish had an 80-fold greater content of immunodetected P450IA protein, indicating a strong environmental induction in these fish. In Georges Bank fish the total (spectrophotometrically measured) microsomal P450 content and the content of P450IA protein were induced progressively by intraperitoneal doses of TCB ranging from 0.1 to 10.0 mg/kg. Ethoxyresorufin-O-deethylase (EROD) specific activity (activity per mg protein) was also progressively induced, but the catalytic efficiency or turnover number (i.e., activity/nmol P450IA) was less in fish given the greater doses of TCB. In Narrow River fish TCB treatment resulted in no significant change (at P ≤ 0.05) in total microsomal P450 content or in P450IA protein content, although they tended to be less (total P450) or greater (P450IA) in fish given the greater doses. The EROD activity per mg protein was less in Narrow River fish given greater TCB doses than it was in control fish. EROD activities per nmol of P4501A protein in control Narrow River fish were less than those in any treatment group of Georges Bank fish and tended to diminish even further with TCB treatment. The results show that 3,3′,4,4′-TCB induces P450IA in winter flounder and that TCB acts in vivo to inhibit the activity of P450IA enzyme by mechanisms not yet known. The lower catalytic efficiency of P450IA enzyme in Narrow River fish than in Georges Bank fish indicates that P450IA inhibition, whether caused by TCB or some other agent, does occur in the environment. The data also indicate that prior condition, including existing environmental induction, can strongly influence the responses of P450IA protein to additional chlorobiphenyl exposure.
Desorption of chlorinated hydrocarbons from phytoplankton
Authors: Autenrieth Robin L. , Depinto Joseph V. 
Published: March 2010

AbstractStudies were conducted to investigate the desorptive characteristics of hexachlorobenzene (HCB) and 2,4,5,2′,4′,5′-hexachlorobiphenyl (HCBP) sorbed to algal and sediment suspensions by using three approaches: batch equilibration, air purging and competitive exchange. In both short-term and extended batch desorptions, sorption partition coefficients were consistently greater than desorption partition coefficients. Air-purging removed virtually all of the sorbed HCBP within 2 h, exhibiting a two-component release pattern for all tested sorbents. In competitive sorption tests, HCB originally sorbed to suspended sediments was released to be taken up by algae. These studies indicate the importance of sorbent type in the magnitude and strength of sorption for two hydrophobic compounds.
The use of the physiological energetics of Gammarus pulex to assess toxicity: A study using artificial streams
Authors: Maltby Lorraine 
Published: March 2010

Abstract
A sublethal assay based on the energy budget of the freshwater amphipod Gammarus pulex has been developed. Gammarus “scope for growth” can be used both as a laboratory test and as an in situ bioassay. This paper provides a short review of the technique and investigates a way in which it may be simplified for field deployment. The usefulness of this modified technique for determining the toxicity of an organic compound and its relative sensitivity compared to other measures of toxicity was investigated by using an artificial stream system.
A phytoassay procedure using fluorescence induction
Authors: Caux P.-Y. , Blaise C. , Leblanc P. , Tache M. 
Published: March 2010

Abstract
A bioassay protocol has been developed to obtain the essential phytotoxicological data on toxicants influencing the electronic transport chain of the photosynthetic light reactions. The purpose of this study was to determine the principal physical factors affecting the photosynthetic fluorescence induction response (Kautsky effect) of algae grown in microplates. It was found that levels of relative fluorescence units (R.F.U.s) varied heterogeneously in a microplate whose 96 wells were inoculated with a culture of Selenastrum capricornutum at constant inoculum conditions for a period of 4 d. In order to account for this, the following parameters were analyzed: effect of evaporation processes, cell concentration, algal culture volume, probe distance, adjacent well proximity, plate well shape, and plate opaqueness. It was found that intraplate variation of R.F.U. levels occurred as a result of media evaporation from peripheral wells. R.F.U. levels were directly proportional to the culture cell concentration and to the culture cell volume but indirectly proportional to the culture distance from the light harvesting probe. R.F.U.s from black microplates gave a lower response but with less variation than those from translucent microplates.
Effects of environmental and experimental design factors on culturing and toxicity testing of Ceriodaphnia dubia
Authors: Cooney J.D. , Lenoble B.J. , Pollock T.L. , Smith G.J. , Degraeve G.M. , Moore E.L. 
Published: March 2010

Abstract
The U S. Environmental Protection Agency (EPA) has developed a 7-d toxicity test to evaluate effects of effluents on Ceriodaphnia dubia survival and reproduction. This study evaluated effects of laboratory culture and test procedures on Ceriodaphnia dubia survival and reproduction Parameters such as temperature, food concentration, beaker size, solution-renewal frequency, light quality, illumination, photoperiod, water type, and test organism age were evaluated to determine how these culture and test parameters affected individual culturing success and acceptability and reproducibility of toxicity test results. Test parameters proposed by the EPA were evaluated under controlled laboratory conditions by varying levels of individual environmental or experimental design parameters to determine an acceptable range of responses for survival and reproduction, both with and without a reference toxicant For those parameters not specified by the EPA (e.g, water hardness, light quality), commonly used ranges for those parameters were evaluated.
Results provided a decision matrix of acceptable ranges for individual environmental and experimental design parameters that were used to optimize the test parameters for conducting 7-d effluent tests with Ceriodaphnia dubia Overall, of the studied test parameters, renewal frequency and photopenod were the primary factors affecting culture and toxicity test success In this study, the EPA restriction on Ceriodaphnia dubia age at test initiation was not critical, as long as all organisms were &lt;24 h old and randomly distributed among the test concentrations
Sources of error in screening by flow cytometry for the effects of environmental mutagens
Authors: Tiersch Terrence R. , Wachtel Stephen S. 
Published: March 2010

Abstract
Flow cytometry is often used to detect DNA aneuploidy and mosaicism associated with malignancy or genetic damage. Yet DNA aneuploidy and mosaicism detected by flow cytometry may be more apparent than real. In contrast to the DNA mass observed for blood, we consistently found markedly different values and higher variability for DNA mass among other tissues collected from the same animal. Prepared mixtures of blood and other cells generated multiple fluorescence peaks identical to those that might be expected for aneuploid mosaicism. Moreover, analysis of tissues such as feather pulp, which contains a combination of cell types, yielded multiple fluorescence peaks that were not observed when blood alone was analyzed. Thus care should be exercised in classifying DNA values from different tissues as normal or abnormal, because the appearance of supernumerary fluorescence peaks might not always indicate the presence of abnormal cell populations.
Effects of the presence and absence of various fractions of dissolved organic matter on the toxicity of fenvalerate to Daphnia magna
Authors: Hodge Valerie A. , Fan Gary T. , Solomon Keith R. , Kaushik Narinder K. , Leppard Gary G. , Burnison B. Kent 
Published: March 2010

Abstract
Toxicity of fenvalerate to Daphnia magna, in the presence of particulate or dissolved organic matter, was investigated. Dissolved organic matter (DOM) was isolated from Jack Lake, Ontario (JL-DOM), and separated into four size fractions. A sample of fibrils from Lake St. George, Ontario, and two model substances, pectin and polygalacturonic acid, represented DOM of algal origin. Chlamydomonas reinhardii was included as a source of particulate organic matter for comparison. Daphnia magna (≤48 and ≤24 h old) was exposed to treatments of fenvalerate plus these sources of DOM. The end point of the static 48-h bioassays was the inability of daphnids to swim during a 10-s period after gentle prodding. Results from treatments with JL-DOM (10 × natural concentrations) and fibrils (4 mg/L) were analyzed independently. The EC50 of fenvalerate plus &gt;0.2 μM JL-DOM (0.22 μg/L) was significantly lower than that of the &gt;10-kD-molecular-weight fraction (1.99 μg/L), but neither was different from fenvalerate alone (0.91 μg/L). There were no significant differences between treatments including lake fibrils, pectin or polygalacturonic acid, or between age groups. No bioassays using Daphnia magna and algal fibrils as a source of DOM have been conducted previously. An adhesion phenomenon occurred between Daphnia magna and the DOM (JL-DOM and fibrils) in the presence of fenvalerate. DOM and fibrils aggregated on the spine and antennae of the daphnids, which impaired the ability of the organisms to swim. Adhesion increased as the concentration of fenvalerate increased but was absent in controls. This phenomenon may confound the results of bioassays that use immobility as an end point. Adhesion could be an important sublethal effect of fenvalerate, affecting daphnid survival and its role as a food source in aquatic systems.
Impurity variations in a carbon black: Characterization by the ames Salmonella mutagenicity assay and polycyclic aromatic hydrocarbon analysis
Authors: Agurell Eva , Löfroth Göran 
Published: March 2010

Abstract
Samples of a furnace carbon black, N-330, were collected from the production line during a period of three years. Following extraction with benzene and solvent exchange, the mutagenic response was determined with the Ames Salmonella assay in the TA98 and TA100 strains with and without addition of S9. The samples were mainly mutagenic in the presence of S9, showing that polycyclic aromatic hydrocarbons (PAHs) were the major mutagenic impurities. The mutagenic response varied 30-fold among the samples. Analysis of PAHs in the range from phenanthrene to coronerie also showed a wide variation between samples being correlated to the mutagenic response. The large concentration differences of impurities between batches implies that a single batch cannot be used for generalized toxicological studies. The presence of PAH and mutagenic impurities in the investigated carbon black is a significant source of these environmental pollutants compared to another source of concern, automobile exhaust.
Relationships between behavior and the inhibition of acetylcholinesterase in birds exposed to organophosphorus pesticides
Authors: Hart Andrew D. M. 
Published: March 2010

Abstract
Effects of sublethal acute doses of the organophosphate chlorfenvinphos on the behavior of captive starlings (Sturnus vulgaris) were investigated in four experiments. Effects were more complex and occurred at lower levels of exposure than in previous avian studies. Altered posture was associated with inhibition of brain acetylcholinesterase (AChE) activity to less than about 88% of the normal level. Reductions in flying and singing, and increased resting, were associated with inhibition of AChE to below 61 % normal. Substantial recovery of normal behavior occurred within 5 h of treatment. Feeding activity was reduced for over 8 h in birds with AChE inhibited to less than about 73% normal, accompanied by a proportionate loss of body weight. Flying activity was initially depressed for 1 to 2 h but then increased above normal levels. Singing of isolated males in response to the playback of recorded song decreased in proportion to the inhibition of AChE. Performance of a foraging task was unaffected by inhibition of AChE to as little as 57% normal. A review of relevant studies suggests that only broad generalizations, of limited practical value, can be made about the relationship between AChE inhibition and behavioral effects.
Stability of residues and brain cholinesterase activity in carcasses of northern bobwhite exposed to three organophosphate insecticides
Authors: Johnson Gregory D. , Palmer David A. , Krueger Henry O. , Fischer David L. 
Published: March 2010

Abstract
Presence of pesticide residues in animal tissues and inhibition of brain cholinesterase (ChE) activity are often used to document exposure of animals to organophosphorus and carbamate insecticides and determine if the animal's death resulted from exposure. Carcasses found during field studies can be several days old; therefore, it is important to determine how residue and ChE levels change over time after death. Objectives of this study were to determine pesticide residues in tissues and/or brain acetylcholinesterase (AChE) activity of northern bobwhite (Colinus virginianus) exposed to either sulprofos, methamidophos, or azinphos-methyl, and the extent to which residue and AChE levels change with decomposition of carcasses under field conditions. Test compounds were administered orally by gavage and/or in the diet to northern bobwhite at previously determined sublethal and lethal exposure levels. Birds surviving the dose were sacrificed and placed in crop fields. Carcasses were recovered following 0-, 24-, 48-, and in some cases 96-h intervals and analyzed for residues. Brain AChE activity was also determined for birds exposed to sulprofos. Residues were detected in all exposed birds and varied with dose. Results indicate that pesticide residues and brain AChE levels were stable under field conditions at least up to 48 to 96 h following death.
Chromosome damage in wild rodents inhabiting a site contaminated with aroclor 1254
Authors: Shaw-Allen Patricia L. , McBee Karen 
Published: March 2010

Abstract
An in situ investigation of structural chromosomal damage in wild rodents from a site contaminated with Aroclor 1254 was undertaken to compare effects observed in nature to those documented in previous laboratory studies. Laboratory assays indicate that Aroclor 1254 does not cause structural damage to chromosomes. However, the many variables at work in actual waste-site environments and receptor populations led us to question whether exposures under natural conditions could potentially lead to different results using the same assay systems. Individuals of three rodent species, Peromyscus leucopus, Sigmodon hispidus, and Reithrodontomys fulvescens, were collected from the contaminated site and three matched, pristine reference sites. Standard somatic metaphase chromosome preparations from bone marrow were examined for chromosomes lesions. Comparisons were made between conspecifics from the Aroclor-contaminated site and the reference sites. Significant increases in chromosome damage were not observed in animals from the Aroclor-contaminated site, indicating agreement between laboratory assays and an in situ application of this assay system.
Effects of ionizing radiation on breeding swallows at current radiation protection standards
Authors: Zach Reto , Hawkins Janice L. , Sheppard Steve C. 
Published: March 2010

Abstract
A field study was carried out involving breeding tree swallows (Tachycineta bicolor) to see whether human protection standards are also adequate for birds, as implied by an International Commission on Radiological Protection 1977 assumption. The swallows were provided with a grid of nest boxes with radiation levels up to 45 times the background level, or 6 μGy/h. Swallows were permitted to settle freely in the boxes for breeding, regardless of radiation level. The breeding performance was exceptionally high and was not influenced by experimental radiation exposure. The results were similar for the growth performance of nestlings. Thus numerous, apparently healthy young were raised to fledging in a radiation environment that corresponded to an annual dose of up to 50 mSv, which is the current limit for human occupational exposure. The corresponding limit for the public is lower, at 5 mSv/a. The results show that swallows are not affected during the nesting season by radiation doses above the limits for humans, provided birds and humans share a similar radiation environment.
The relationship of total copper 48-H LC50s toDaphnia magnadry weight
Authors: Lazorchak James M. , Waller William T. 
Published: March 2010

AbstractA study was conducted with Daphnia magna to determine the effect of neonate weight loss or lack of weight gain on experimentally derived copper 48-h LC50s. Standard unfed tests as well as algal-fed (Selenastrum capricornutum) tests were used to look at weight loss and gain. No significant relationship was found between amount of weight loss and copper LC50s. However, dry weight of unfed and algal-fed control organisms could be used to predict total copper LC50s.