bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro induction of ethoxyresorufin-O-deethylase and porphyrins by halogenated aromatic hydrocarbons in avian primary hepatocytes
Authors: Sanderson J Thomas , Kennedy Sean W , Giesy John P 
Published: March 2010

AbstractEthoxyresorufin-O-deethylase (EROD) and porphyrin induction responses of primary hepatocytes to halogenated aromatic hydrocarbons (HAHs) were examined in newly hatched domestic chickens, herring gulls, ring-billed gulls, double-crested cormorants, and Forster's terns. Concentration–response relationships were determined for both biochemical responses in hepatocyte preparations derived from individual avian livers (except for the tern). The choice of vehicle used to dose chicken hepatocytes greatly affected the potencies and efficacies of HAHs. Dimethyl sulfoxide resulted in median effective concentration (EC50) values for EROD induction that were between 10 and 15 times less than isooctane (isooctane was used throughout the study). Neither vehicle induced EROD activity by itself. Concentration-dependent increases in EROD activity were observed with several HAHs, and their potencies (EC50 values) were compared to that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) within each hepatocyte preparation to determine relative potency factors (RPFs). Differences in sensitivity to these responses were observed among individuals within each of the species and among species. Median EC50 values (nM) for EROD induction by TCDD were 0.72, 13, 20, 25, and 150 for the chicken, cormorant, ring-billed gull, herring gull, and tern hatchling, respectively. Relative potency factors for several HAHs were different, in both ranking and potency, from those generally derived in mammalian hepatocytes. Porphyrin accumulation was observed occasionally with the most potent aryl hydrocarbon receptor agonists, but most HAHs were not tested at concentrations sufficiently high to observe a consistent response. This study provides information on interindividual and interspecies differences in responsiveness to TCDD-like compounds and provides species-specific RPFs that may prove useful for the purpose of hazard and risk assessment for fish-eating birds.
Accumulation and depuration of sediment-sorbed C12- and C16-polychlorinated alkanes by oligochaetes (Lumbriculus variegatus)
Authors: Fisk Aaron T , Wiens Susanna C , Webster G R Barrie , Bergman Åke , Muir Derek C.G 
Published: March 2010

Abstract
Oligochaetes (Lumbriculus variegatus) were exposed to sediment spiked with four 14C-polychlorinated alkanes (PCAs) (C12H20C16 [56% Cl by weight], C12H16Cl10 [69% Cl], C16H31Cl3 [35% Cl], and C16H21Cl13 [69% Cl]) to measure bioaccumulation parameters and biotransformation. Chlorinated paraffins are industrial products that consist of thousands of different PCAs. Chlorinated paraffins are hydrophobic (log octanol–water partition coefficients [Kows] &gt; 5.0) and are reported to have relatively high concentrations in sediment compared with other persistent organochlorines; however, no data exist on their bioavailability from sediment. The PCAs C12H20Cl6, C12H16Cl10, and C16H31Cl3 were readily available to sediment-ingesting oligochaetes, whereas C16H21Cl13 had lower bioavailability. Uptake rates of the C12-PCAs were greater than the C16-PCAs, but half-lives (t½s) were greater for the C16-PCAs (t½ = 30-33 d) than for the C12-PCAs (t½ = 12-14 d). Biota–sediment accumulation factors were &gt;1 for C12H20Cl6, C12H16Cl10, and C16H31Cl3, but &lt;1 for C16H21Cl13. Comparison of toluene-extractable and -nonextractable 14C suggest that PCAs were biotransformed in aerobic sediments and by oligochaetes, and that the susceptibility to degradation in sediments decreases with increasing chlorine content. The relative abundance of individual PCAs may differ between sediment and benthic invertebrates because of differences in the bioaccumulation and degradation of PCAs of varying carbon chain length and chlorine content.
Energetic and behavioral responses by the common goby,Pomatoschistus microps(krøyer), exposed to linear alkylbenzene sulfonate
Authors: Christiansen Per Dahl , Brozek Morten , Hansen Benni Winding 
Published: March 2010

AbstractThe acute toxicity of linear alkylbenzene sulfonate (LAS) on the common goby (Pomatoschistus microps), an estuarine fish, was established during a 96-h static exposure. The median lethal concentration was 2.6 ± 0.49 mg LAS/L (mean ± 95% confidence limit). The acute behavioral responses to LAS at different concentrations were excess mucus secretion and apathy at 1.0 mg/L; air gulping, distension of the mouth and opercula, change in pigmentation, and erratic swimming at 2.0 to 3.0 mg/L; and loss of balance and reactivity at ≤4.0 mg/L. The frequency of operculum opening increased with increasing LAS concentrations and appeared at 4.0 mg/L, with a significant doubling in relation to the frequency observed in control fish (p = 0.025). The physiological responses by P. microps after prolonged exposure to sublethal and environmentally realistic concentrations of LAS (0.05-1.0 mg/L) were observed under semistatic conditions in the laboratory. Ingestion, respiration, and growth were also measured during 28 d of exposure. A significant decrease in growth and respiration was found at 0.1 mg LAS/L (p = 0.049 and 0.033, respectively), but ingestion was not affected. The effect concentrations for growth and respiration represent the lowest-observed-effect concentrations, which are both lower than values previously reported for fish. Gross conversion efficiency was affected negatively at 1.0 mg LAS/L (p = 0.001). Pomatoschistus microps is recommended as a suitable and relevant test organism for ecotoxicological experiments.
A simple apparatus for administering 2,3,7,8-tetrachlorodibenzo-p-dioxin to commercially available pelletized fish food
Authors: Fernandez Joseph D , Denny Jeffrey S , Tietge Joseph E 
Published: March 2010

Abstract
A simple apparatus for loading chemicals onto commercially available, pelletized fish food is described. An analysis of several food nutrients indicated the procedure using n-hexane (50 ml n-hexane:200 g food) had an inconsequential influence on their concentrations, i.e., only lauric acid and margaroleic acid exhibited reductions ≥ 10%, 25%, and 17%, respectively. Of 35 batches of food laden with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), only 40% of the loadings were within 10% of the desired value. However, in terms of the within-batch variability, all loadings exhibited a coefficient of variation (CV) ≤15%, and over 60% of the loadings exhibited a CV ≤10%.
Mercury and plants in contaminated soils: 1. Uptake, partitioning, and emission to the atmosphere
Authors: Leonard Todd L , Taylor George E , Gustin Mae S , Fernandez George C.J 
Published: March 2010

Abstract
The uptake, distribution, and subsequent emission of mercury to the atmosphere were investigated in five plant species (Lepidium latifolium [L.], Artemisia douglasiana [Bess in Hook], Caulanthus sp. [S. Watson], Fragaria vesca [L.], and Eucalyptus globulus [Labill]) with different ecological and physiological attributes. Transfer coefficients for mercury in the soil-plant system were calculated. Plant-to-atmosphere emissions of mercury were determined using a controlled environment gas-exchange system and ranged from 10 to 93 ng/m2/h in the light; emissions in the dark were an order of magnitude less. Transfer coefficients for mercury within the soil-plant system increased acropetally (root-to-leaf axis) by orders of magnitude. Estimated mercury emissions from plants in the Carson River Drainage Basin of Nevada over the growing season (0.5 mg/m2) add to the previously reported soil mercury emissions (8.5 mg/m2), resulting in total landscape emissions of 9 mg/m2. For L. latifolium, 70% of the mercury taken up by the roots during the growing season was emitted to the atmosphere. For every one molecule of mercury retained in foliage of L. latifolium, 12 molecules of mercury were emitted. Within this arid ecosystem, mercury emissions are a dominant pathway of the mercury cycle. Plants function as conduits for the interfacial transport of mercury from the geosphere to the atmosphere, and this role is undervalued in models of the behavior of mercury in terrestrial ecosystems and in the atmosphere on a global scale.
Hydrolysis of genotoxic methyl-substituted oxiranes: Experimental kinetic and semiempirical studies
Authors: Kirkovsky Leonid I , Lermontov Sergei A , Zavorin Sergei I , Sukhozhenko Ivan I , Zavelsky Vladimir I , Thier Ricarda , Bolt Hermann M 
Published: March 2010

Abstract
The kinetics of acid-catalyzed hydrolysis of seven methylated aliphatic epoxides—R1R2C(O)CR3R4 (A: R1=R2=R3=R4=H; B: R1=R2=R3=H, R4=Me; C: R1=R2=H, R3=R4=Me; D: R1=R3=H, R2=R4=Me(trans); E: R1=R3=H, R2=R4=Me(cis); F: R1=R3=R4=Me, R2=H; G: R1=R2=R3=R4=Me)—has beens studied at 36 ± 1.5°C. Compounds with two methyl groups at the same carbon atom of the oxirane ring exhibit highest rate constants (keff in reciprocal molar concentration per second: 11.0 ± 1.3 for C, 10.7 ± 2.1 for F, and 8.7 ± 0.7 for G as opposed to 0.124 ± 0.003 for B, 0.305 ± 0.003 for D, and 0.635 ± 0.036 for E). Ethylene oxide (A) displays the lowest rate of hydrolysis (0.027 M−1 s−1). The results are consistent with literature data available for compounds A, B, and C. To model the reactivities we have employed quantum chemical calculations (MNDO, AM1, PM3, and MINDO/3) of the main reaction species. There is a correlation of the logarithm keff with the total energy of epoxide ring opening. The best correlation coefficients (r) were obtained using the AM1 and MNDO methods (0.966 and 0.957, respectively). However, unlike MNDO, AM1 predicts approximately zero energy barriers for the oxirane ring opening of compounds B, C, F, and G, which is not consistent with published kinetic data. Thus, the MNDO method provides a preferential means of modeling the acidic hydrolysis of the series of methylated oxiranes. The general ranking of mutagenicity in vitro, A &gt; B &gt; C, is in line with the concept that this sequence also gradually leaves the expoxide reactivity optimal for genotoxicity toward reactivities leading to higher biological detoxifications.
Digestive determinants of benzo[a]pyrene and phenanthrene bioaccumulation by a deposit-feeding polychaete
Authors: Penry Deborah L , Weston Donald P 
Published: March 2010

AbstractThe uptake of hydrophobic contaminants from ingested sediment can contribute significantly to body burdens of deposit feeders, and feeding behavior and digestive physiology can play important roles in bioaccumulation. We examined the uptake of polycyclic aromatic hydrocarbons (PAHs) by the deposit-feeding polychaete Abarenicola pacifica in experiments in which worms were first acclimated to low or high organic carbon sediments with 0.08 or 0.45% total organic carbon, respectively and then transferred to low or high organic carbon test sediments contaminated with radiolabeled phenanthrene or benzo[a]pyrene. Ingestion rate was a strong determinant of rates (benzo[a]pyrene) or extents (phenanthrene) of PAH uptake. Ingestion rate measurements are essential in many types of bioaccumulation studies because differences in ingestion rates between sediment types may confound some traditional measures of bioavailability. Physiological acclimation to the low or high organic carbon sediments did not appear to affect PAH uptake from the test sediments, but acclimation did affect biotransformation capabilities, particularly for phenanthrene.
Pigmented skin tumors in gizzard shad (Dorosoma cepedianum) from the south-central United States: Range extension and further etiological studies
Authors: Geter David R , Hawkins William E , Means Jay C , Ostrander Gary K 
Published: March 2010

Abstract
Previous studies reported skin tumors diagnosed as pigmented subcutaneous spindle-cell neoplasms in 22% of gizzard shad (Dorosoma cepedianum) from Lake of the Arbuckles, Oklahoma, USA. Those studies could not confirm chemical carcinogens or retroviruses as etiological agents. The present study reports the neoplasms in 20% of shad from two additional lakes, Lake Murray and Lake Texoma in south-central Oklahoma, extending the range of the lesion. No neoplasms were found in shad from a reference site, Lake Carl Blackwell, Oklahoma. Further investigations into the etiology of the lesions were conducted. Significant levels of potentially carcinogenic trace elements in the water, sediment, or tissues were not identified by inductively coupled plasma mass spectrometry. Radioactivity, analyzed by liquid scintillation counting of radon and gross alpha/beta radiation, was not above background levels. Genetic marker and band-sharing analysis by random amplified polymorphic DNA and double-stringency polymerase chain reaction could not separate tumor-bearing shad from nontumor-bearing ones. Of 2,128 shad examined, 387 exhibited lesions, with a significantly higher number occurring dorsally (79.5%) than ventrally (20.5%). Overall, this study showed the epizootic is not limited to a single lake and tended to rule out some known carcinogens and radioactivity as proximate causes of the epizootic.
Relationship between oxygen consumption and sediment-water fluxes of heavy metals in coastal marine sediments
Authors: Shine James P , Ika Raveendra , Ford Timothy E 
Published: March 2010

Abstract
The relationship between benthic oxygen demand and the sediment–water flux of six heavy metals (cobolt [Co], nickel [Ni], copper [Cu], zinc [Zn], cadmium [Cd], and lead [Pb]) was examined at two locations: New Bedford Harbor and Buzzards Bay, Massachusetts, USA. Dissolved metal fluxes were measured in laboratory microcosms incubated in the dark at in situ temperatures, and microcosms were collected over different seasons to examine temporal and spatial variability in the fluxes. The net flux of all metals was generally out of the sediments. However, at low rates of benthic oxygen demand, net flux of Pb and Co was into the sediments. When data from the two sites are combined, regression of metal fluxes (normalized to sediment metal content) against benthic oxygen demand was significant for all metals (r2 = 0.58-0.85), with all slopes significantly different from zero. The flux values (normalized to sediment metal content) ranged from -1.4 (mmole/m2/d)/(mole/mole C)sediment for Zn during winter to 42 (mmole/m2/d)/(mole/mole C)sediment for Cd during summer months. The magnitude of the fluxes generally showed the following relationship: Cd &lt; Zn &lt; Co, Ni, Cu &lt; Pb, indicating higher relative mobility for Cd and lower mobility for Pb. The estimated annual fluxes of metals to New Bedford Harbor and Buzzards Bay amount to ˜0.06% (Pb) to 25% (Cd) of the inventory of metals in the top 2 cm of sediments and can equal the inventory of metals in the water column on a time scale as short as 7 d for Zn.
Distribution and composition of polycyclic aromatic hydrocarbons within experimental microcosms treated with liquid creosote
Authors: Bestari K T Jim , Robinson Richard D , Solomon Keith R , Steele Tracey S , Day Kristen E , Sibley Paul K 
Published: March 2010

Abstract
Temporal changes in the distribution and relative composition of 15 priority polycyclic aromatic hydrocarbons (PAHs) in water, sediment, and absorbed to polyvinylchloride (PVC) strips were assessed following direct application of liquid creosote to aquatic microcosms. Fourteen microcosms were treated with nominal creosote concentrations ranging from 0.06 to 109 mg/L and two microcosms served as controls. Quantitative analysis of PAHs was performed using high-performance liquid chromatography equipped with a fluorescence detector. Post-treatment concentration of PAHs in water decreased exponentially with time. At 2 d posttreatment, total PAHs (∑ PAH) ranged from 7.3 μg/L (lowest treatment) to 5,803.2 μg/L (highest treatment); by 84 d, ∑ PAH in the same microcosms was reduced to between 0.8 μg/L and 13.9 μg/L, respectively. The relative composition of PAHs in the water also changed with time; at 2 d posttreatment, ∑ PAH in the lowest treatment (7.3 μg/L) reflected contribution from nine PAHs, whereas only two PAHs contributed to this concentration (0.8 μg/L) at 84 d. Low and high molecular weight (mol. wt.) PAHs were lost first from the water column, followed by PAHs of intermediate mol wt. In sediments, a dose-dependent increase in ∑ PAH was observed above 0.59 mg/L creosote up to 28 d, followed by a decline thereafter in all but the highest treatment. Total PAHs in sediment ranged from 0.91 μg/g (lowest treatment) to 63.9 μg/g (highest treatment) at 28 d. A dose-dependent relationship was also observed in PVC strips, with ∑ PAH on PVC ranging from 0.05 to 88 μg/cm2 at 31 d and 0.04 to 18.4 μg/cm2 at 58 d posttreatment. A mass balance evaluation showed that 88.3% of PAHs was lost from the system after 1 month, indicating that liquid creosote is attenuated relatively quickly in aquatic environments.
Physiologically based toxicokinetic model for maternal transfer of 2,3,7,8-tetrachlorodibenzo-p-dioxin in brook trout (Salvelinus fontinalis)
Authors: Nichols John W , Jensen Kathleen M , Tietge Joseph E , Johnson Rodney D 
Published: March 2010

AbstractA physiologically based toxicokinetic (PB-TK) model was developed to describe the uptake, distribution, and elimination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in female brook trout during a 6-month feeding and depuration study. Dietary uptake was modeled under two assumptions, uptake proceeds to equilibrium between blood exiting the intestinal tract and the contents of the intestinal tract, and uptake is limited by desorption of TCDD from gut contents and/or diffusion from the lumen into tissues. Model outputs were evaluated by comparison with measured TCDD residues. The best model fit to the data was obtained by imposing a moderate diffusion limitation on gut uptake. Of the parameters that comprise the gut submodel, whole body residue predictions were most sensitive to changes in the diffusion rate constant and fecal egestion rate. Chemical residues in fat were indicative of an internal disequilibrium with other tissues during the loading phase of the study. Accurate simulations of this behavior were obtained using a diffusion-limited tissue description. Chemical residues in liver, muscle, and ovaries were adequately described by assuming that uptake and elimination were blood flow limited. Spawning probably resulted in a small increase in whole body TCDD concentration and did not appear to represent an important route of chemical elimination. These results suggest that field-derived whole body TCDD residues could be used to estimate residues in developing ovaries of brook trout to within a factor of two, provided that whole body and ovary lipid content were known.
Metal and phytochelatin content in phytoplankton from freshwater lakes with different metal concentrations
Authors: Knauer Katja , Ahner Beth , Xue Han Bin , Sigg Laura 
Published: March 2010

Abstract
The tace metal (Cu, Zn, Cd, Mn) and phytochelatin(an intracellular chelator for metal ions) cellular content were determined in phytoplankton samples originating from four lakes (Greifen, Sempach, Lucerne, and Orta). The lakes differ in their metal concentrations and in other conditions (pH, trophic state, organic matter). Total and intracellular contents of Cu and Cd were related to the experimentally determined free metal ion concentration and the total and intracellular content of Mn to the dissolved Mn. The intracellular Zn content was tightly regulated over a broad range of [Zn2+]. Phytochelatin concentrations were measurable in phytoplankton communities from three of the lakes, in spite of low levels of free Cu, Zn, and Cd ion concentrations. Culture experiments showed that the concentration of intracellular phytochelatin in Scenedesmus subspicatus and in a natural algal community increased upon addition of copper in a similar concentration range as in the lakes. Phytochelatin concentrations were below detection in the phytoplankton collected from the highly contaminated Lake Orta, perhaps suggesting that this algal community has adapted in some other way to high metal concentrations. Although we only sampled a few lakes, the lack of any clear relationship between phytochelatin and metal concentrations calls into question the feasibility of using phytochelatins as a bioindicator of metal exposure in lakes.
Biota–sediment accumulation and trophic transfer factors for extremely hydrophobic polychlorinated biphenyls
Authors: Maruya Keith A , Lee Richard F 
Published: March 2010

AbstractPolychlorinated biphenyls (PCBs) in fish, invertebrates, and sediment from a contaminated tidal creek system in coastal Georgia (USA) were traced to Aroclor 1268, a mixture of hepta through decachlorinated homologs (x̄CI = 8.5) used at a former chlor/alkali plant adjacent to the study site. The base 10 logarithm of the octanol/water partition coefficient (Kow) for the 15 most abundant Aroclor 1268 components in these samples ranged from 6.7 to &gt;9. The composite mean biota–sediment accumulation factor (BSAF) for these congeners was 3.1, 0.81, and 0.28 for yearling striped mullet, spotted sea trout, and grass shrimp, respectively, species representing three trophic levels of the local food web. Individual congener BSAFs were negatively correlated (p ≤ 0.05) with log Kow for all three species. The composite mean trophic transfer factor (TTFlip), defined as the ratio of lipid-normalized PCB concentrations in fish to grass shrimp, was higher for mullet (12) than for sea trout (2.9). Individual TTFlip values were two to three times higher for Cl7 and Cl8 homologs that were substituted at all four ortho positions, suggesting a difference in PCB retention based on chlorine substitution patterns. The relative magnitude of BSAFs and TTFlip values indicated that sediment-ingesting forage species like mullet efficiently accumulate PCBs and are an important link in the food web transfer of sediment-associated contaminants in this system. The negative linear relationships between BSAF and log Kow established in this study are among the first to be reported in the field for extremely hydrophobic PCBs.
Nondestructive indicator of ethoxyresorufin-O-deethylase activity in embryonic fish
Authors: Nacci Diane , Coiro Laura , Kuhn Anne , Champlin Denise , Munns Wayne , Specker Jennifer , Cooper Keith 
Published: March 2010

AbstractMany environmental contaminants of concern produce aryl hydrocarbon (Ah) receptor-mediated effects often assessed as ethoxyresorufin-O-deethylase (EROD) activity. We modified a standardized embryonic and larval fish bioassay using an estuarine fish species (Fundulus heteroclitus) to include measurement of fluorescence in the urinary bladders of living embryos as a nondestructive indicator of EROD activity. This fluorescence was observed only in embryos exposed to the EROD substrate and Ah receptor agonists and was consistent in fluorescence characteristics with the EROD product, resorufin. Aryl hydrocarbon receptor-agonist exposures at sublethal concentrations in the parts per billion range, produced significant increases in EROD fluorescence in embryos as young as 3 d postfertilization. These findings are consistent with the conclusion that this fluorescence method is a specific and sensitive nondestructive indicator of Ah receptor-mediated effects in an embryonic fish. As such, this simple method may be useful for assessing effects of environmental contaminants on the early development of fishes and to link molecular indicators with organism-level responses.