bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hepatic ethoxyresorufin-O-deethylase activity and inducibility in wild populations of double-crested cormorants (Phalacrocorax auritus)
Authors: Davis Jay A , Fry D Michael , Wilson Barry W 
Published: March 2010

AbstractMicroplate fluorometric techniques were used to measure ethoxyresorufin O-deethylase (EROD) activity in hepatic microsomes and primary hepatocyte cultures from individual wild double-crested cormorant (Phalacrocorax auritus) embryos. Embryos were collected in 1993 and 1994 from Humboldt Bay and San Francisco Bay (CA, USA) and a reference site in coastal Oregon (USA). Median microsomal EROD activities in embryos collected from San Francisco Bay (in both 1993 and 1994) and from Humboldt Bay (1994) were four- to eightfold higher than the reference site median (Kruskal–Wallis, p &lt; 0.05). This degree of induction suggests that cormorant embryos in the two California locations were exposed to concentrations of dioxinlike compounds that are at the threshold for toxic effects in this species. Substantial variation in the EROD response in cultured hepatocytes was observed between individuals, populations, and the two bird species tested (cormorants and chickens [Gallus gallus]). Although most of the cormorant individuals displayed a consistent dose–response profile, a few individuals were uninducible, showing no appreciable increase over basal activity with increasing dose of inducer. Composite dose–response curves for two cormorant colonies appeared to be divergent in spite of small sample sizes, indicating that inducibility can also vary at the population level. These observations suggest that considerable variability in pollutant metabolism and sensitivity associated with single enzyme systems may exist within wild populations and species.
Biomagnification of polychlorinated biphenyls through a riverine food web
Authors: Zaranko Danuta T , Griffiths Ronald W , Kaushik Narinder K 
Published: March 2010

AbstractFrom 1989 to 1993, biota collected from Pottersburg Creek, London, ON, Canada were analyzed for total polychlorinated biphenyls (PCBs) and lipids. Data were analyzed by analysis of covariance (ANCOVA) with lipid as the covariate, to investigate station, time, and trophic effects on PCB accumulation in aquatic organisms. All three variables were highly significant (p &lt; 0.0001). PCB concentrations in biota decreased along the length of the creek away from the point source. PCB concentrations in biota collected in July 1993 were not significantly different from concentrations in biota collected in July 1990 (p &gt; 0.16), suggesting that sources into the creek have not been alleviated. The relationship between PCBs and lipid for biota from Pottersburg Creek suggests that organisms accumulate PCBs relative to their position in the food web (p &lt; 0.0001). Fish and leeches occupying the top of the food web accumulated more PCBs than organisms occupying a lower trophic position (crayfish and oligochaetes/chironomids), indicating that biomagnification through trophic transfer (i.e., the uptake of a chemical through ingestion) is the primary mechanism governing contaminant levels in biota and not bioconcentration (i.e., the uptake of a chemical from water).
The calux (chemical-activated luciferase expression) assay adapted and validated for measuring TCDD equivalents in blood plasma
Authors: Murk Albertinka J , Leonards Pim E G , Bulder Astrid S , Jonas Arjen S , Rozemeijer Marcel J C , Denison Michael S , Koeman Jan H , Brouwer Abraham 
Published: March 2010

AbstractA method was developed to isolate lipophilic compounds efficiently from small aliquots of blood plasma and test these for total dioxin-like toxic potency using recombinant rat (H4IIE) and mouse (Hepa1c1c7) hepatoma cell lines, containing the firefly (Photinus pyralis) luciferase gene under trans-activational control of the aryl hydrocarbon receptor (AhR). For this experiment, blood plasma was used originating from eider ducks (Somateria mollissima) that had been dosed with 3,3′,4,4′-tetrachlorobiphenyl (PCB-77) or with the technical PCB-mixture Clophen A50. For each sample the CALUX (chemical-activated luciferase expression) response of both the fat-containing organic extract and the fat-free, cleaned extract were compared with data from chemical analyses of these samples. The CALUX responses for the extracts were converted into so-called CALUX TEQs (TCDD equivalents), using a 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) standard curve. The CALUX TEQs in both fatty and cleaned extracts correlated significantly with PCB-77 or PCB-153 levels (depending on the dosage group) determined in blood plasma using gas chromatography–mass spectrometry (GC-MS). For PCB-77 a toxic equivalency factor (TEF) of 1.5 × 10−3 was calculated based on these correlations. In addition, PCB-118 and PCB-156 levels in abdominal fat (assessed with GC with electron capture detection) and hepatic ethoxyresorufin O-deethylase activities correlated well with the CALUX TEQs in both fatty and cleaned blood plasma extracts, suggesting the TEQ levels in blood offer a good measure for internal dose. Plasma cholesterol and triglyceride levels were determined as a measure of lipid content, in 10-μl aliquots of blood plasma using enzymatic spectrophotometric determination. In conclusion, we have demonstrated that the CALUX assay is a rapid, sensitive assay for assessing the toxic potency of (mixtures of) AhR-active compounds in small aliquots of blood plasma. The limit of detection for the CALUX assay is currently less than 0.1 fmol (32 fg) TEQ, which corresponds with the amount of TEQs present in 0.1 to 1 ml of blood plasma in environmentally exposed species or man.
Cereal aphid and parasitoid survival in a logarithmically diluted deltamethrin spray transect in winter wheat: Field-based risk assessment
Authors: Longley Martin , Jepson Paul C 
Published: March 2010

Abstract
Dose rates of the pyrethroid insecticide deltamethrin were optimized for aphid control and the conservation of beneficial parasitoids in winter wheat. A logarithmic dose sprayer was used to apply concentrations ranging from twice the recommended field rate to a concentration representing one-fiftieth of the field rate. Volumetric analysis of colored dye deposits quantified the partitioning of pesticide through the crop canopy and was used to calculate direct exposure rates of aphid colonies and residue concentration on different plant structures contacted by foraging parasitoids. Aphid parasitoids, from the genus Aphidius, were found to be more at risk from exposure to insecticide residues than were their aphid hosts under the given bioassay conditions. However, the toxicity of deltamethrin residues on flag leaves was found to dissipate over a 5-d period after application. Deltamethrin provided significant aphid control at dose rates greater than 1 g a.i./ha (or at approximately one-sixth of the recommended field rate). At low concentrations of deltamethrin, aphids survived in the lower crop strata within low toxicity refuges. The implications of these refugia and the spatial redistribution of prey and host populations following spray application for the success of biological control agents are discussed.
Temporal biomarker responses in wild passerine birds exposed to pesticide spray drift
Authors: Cordi Britt , Fossi Cristina , Depledge Michael 
Published: March 2010

Abstract
A field study was conducted to assess the degree of exposure experienced by nestling and adult great tits, (Parus major) to spray drift of pirimicarb and dimethoate. Nondestructive assays of serum esterases, serum butyrylcholinesterase (BChE), and carboxylesterase (CbE) were used as exposure biomarkers and measurements of weight gain and survival were made to assess adverse biological effects. Nest boxes were placed in hedgerows bordering fields sprayed with pesticides (either pirimicarb or dimethoate). One hedge was sprayed directly with pirimicarb to simulate maximum drift effect. Two hedges were left untreated to serve as control areas. The concentrations of the two insecticides were within the recommended dose for cereals. Significant inhibition of BChE activity was detected within 24 h in adult birds exposed to drift of dimethoate and in adult birds from the hedge sprayed directly with pirimicarb. Highly significant correlations were found between the weight of unexposed nestlings and BChE and CbE activity, indicating that a developmental increase in enzyme activities is correlated with the growth rate of the nestlings. Inhibition in nestling BChE activity was found in all treated hedges after 24 h. A tendency of reduced weight gain was found in nestlings both between 0 to 24 h and 24 to 48 h after treatment in all the treated hedges compared to nestlings from the control hedge (p &gt; 0.07). These results indicate the potential of pesticide drift to reduce growth rate and survival of juvenile wild passerine birds.
Photoactivation and toxicity of mixtures of polycyclic aromatic hydrocarbon compounds in marine sediment
Authors: Swartz Richard C , Ferraro Steven P , Lamberson Janet O , Cole Faith A , Ozretich Robert J , Boese Bruce L , Schults Donald W , Behrenfeld Michael , Ankley Gerald T 
Published: March 2010

AbstractThe direct toxicity and photoinduced toxicity of sediment-associated acenaphthene, phenanthrene, fuoranthene, and pyrene were determined for the marine amphipod Rhepoxynius abronius. The four polycyclic aromatic hydrocarbons (PAHs) were spiked into sediment in a concentration series of either single compounds or as approximately equitoxic mixtures of all four compounds. Standard 10-d sediment toxicity tests were conducted under fluorescent lighting. After 10 d, survivors were exposed for 1 h to ultraviolet (UV) radiation in the absence of sediment and then tested for their ability to bury in uncontaminated sediment. The 10-d median lethal concentrations (LC50s) were 2.31 mg acenaphthene/g organic carbon (OC), 2.22 mg phenanthrene/g OC, 3.31 mg fluoranthene/g OC, and 2.81 mg pyrene/g OC These LC50s were used to calculate the sum of toxic units (ΣTU) of the four PAHs in the approximately equitoxic mixtures. The ΣTU LC50 was then calculated for the mixture treatments. If the toxicologic interaction of a mixture of contaminants is additive, ΣTU LC50 =1.0. The observed LC50 (1.55 ΣTU) was slightly, but significantly, greater than unity, indicating that the interaction of PAHs in the mixture was less than additive. Exposure to UV radiation enhanced the toxic effects of fluoranthene and pyrene, but did not affect the toxicity of acenaphthene and phenanthrene. Effects of UV radiation on the toxicity of the mixture of four PAHs could be explained by the photoactivation of fluoranthene and pyrene alone. These results are consistent with predictions based on photophysical properties of PAH compounds.
Biodegradation of organic compounds sequestered in organic solids or in nanopores within silica particles
Authors: Hatzinger Paul B , Alexander Martin 
Published: March 2010

AbstractA study was conducted using model solids to determine whether the time-dependent decline in availability for biodegradation of organic pollutants in soil might result from the entrapment of these compounds in porous or nonporous solids. A strain of Pseudomonas mineralized phenanthrene in solid alkanes containing 18 to 32 carbons, three waxes, and low-molecular-weight polycaprolactone, polyethylene, and polypropylene. The rates were appreciably slower than when the substrate was not initially present within these nonporous solids. From 1.4 to 63.4% of the polycyclic aromatic hydrocarbon added to the solids was mineralized in 90 d. The rates and extents of partitioning of phenanthrene varied markedly among the solids. The rates of partitioning and biodegradation of phenanthrene initially present in the alkanes were positively correlated. The bacterium rapidly and extensively mineralized phenanthrene provided in calcium alginate beads containing varying amounts of soluble soil organic matter. The rates and extents of phenanthrene mineralization declined as the percentage of the substrate in the nanopores within silica particles increased, but the reductions in rate, extent, or both were less pronounced than with nonporous solids. The rate of 4-nitrophenol biodegradation also declined with increasing percentages of the compound in these nanopores. The data are consistent with hypotheses that the sequestration and consequent decrease in bioavailability of organic compounds that persist in soil result from their partitioning into organic matter or their presence within nanopores in soil.
Polychlorinated biphenyl congeners and selected organochlorines in lake superior fish, USA
Authors: Gerstenberger Shawn L , Gallinat Mike P , Dellinger John A 
Published: March 2010

AbstractWalleye, whitefish and whitefish livers, lake trout, and siscowet lake trout were collected from the Apostle Islands Region of Lake Superior. Carp were obtained from a Lake Michigan tributary near Oshkosh, Wisconsin, USA. Each fish species was analyzed for 89 polychlorinated biphenyl congeners, 12 selected organochlorines, and total lipids. Congener profiles varied greatly between the fish species. Carp and whitefish contained tri- and tetra-chlorobiphenyl congeners, such as 28 + 31, 63, and 66+95 in the highest concentrations. Siscowet trout contained the more heavily chlorinated penta-, hexa-, and hepta-chlorobiphenyl congeners such as 153, 89, 138 + 163, 180, 182 + 187, and 170. In addition to the highly chlorinated PCB congeners routinely examined in Great Lakes fish, many lower chlorinated, ortho-substituted PCB congeners are also commonly found. These lower chlorinated congeners have known effects in laboratory animals but may be overlooked by analytical techniques in which Aroclor standards or mixtures of selected congeners are used for quantitation. A congener-specific approach including both the lower chlorinated ortho-substituted PCB congeners and the more highly chlorinated congeners should be implemented to better assess the interactions and toxicities of individual congeners and other persistent compounds.
Remobilization and export of cadmium from lake sediments by emerging insects
Authors: Currie Robert S , Fairchild Wayne L , Muir Derek C G 
Published: March 2010

AbstractEmerging insects including, Diptera, Odonata, Ephemeroptera, and Trichoptera were collected from Lake 382(L382) in 1991 and 1992 to estimate quantitatively the export of Cd by aquatic insects from a natural system having elevated Cd concentrations in the water and sediment. L382 is a Canadian Shield lake, located within the Experimental Lakes Area in northwestern Ontario, that received experimental additions of Cd from 1987 to 1992. Emerging Diptera (mostly Chironomidae), Odonata, and Ephemeroptera had mean Cd concentrations of 1.41, 0.11, and 0.30 μg/g wet weight, respectively. An estimated 1.32 to 3.90 g of Cd per year were exported from the sediments of L382 depending on the estimate of production rates used for these groups of insects. Approximately 0.05 to 0.17% of the whole-lake Cd load in L382 sediments was exported annually or 0.12 to 0.39% of the epilimnion Cd sediment load. Insect emergence may have resulted in greater Cd export from L382 relative to losses via the outflow. Cadmium exported from the sediments by insects may be remobilized and become more available to aquatic organisms or enter the terrestrial ecosystem and become available to insectivores.
Acetylcholinesterase and ATPase activities in erythrocyte ghosts are not affected by 1,2,4-trichlorobenzene: Implications for toxicity by narcotic chemicals
Authors: van Wezel Annemarie P , Schmitz Marion G J , Tielens Aloysius G M 
Published: March 2010

AbstractThe membrane concentration at which 1 2,4-trichlorobenzene (1,2,4-triCBz) affects the functioning of diverse membrane proteins and the partition coefficient of 1,2,4-triCBz between ghosts and water were studied. Earlier studies showed that the fluidity of phospholipids is increased at concentrations of 20 to 60 mmol/kg lipid and that lethality by narcosis in an organism occurs at concentrations of 40 to 160 mmol/kg lipid, irrespective of the physicochemical properties of the nonpolar narcotic chemical. Concentrations in a horse erythrocyte membrane of 110 to 1,100 mmol/kg lipid did not affect the activity of the Na+/K+ ATPase and Mg2+ ATPase. Acetylcholinesterase functioning was not disturbed at membrane concentrations of 33 to 330 mmol/kg lipid. Therefore, disturbance of the membrane proteins studied is not the mechanism by which narcotic chemicals act. The functioning of these membrane proteins is not affected by the change in phospholipid fluidity that is known to occur in organisms that die due to exposure to narcotic chemicals. In vitro bioassays often contain a high concentration of lipids in the system. With hydrophobic test compounds, the concentration of the test compound in the exposure medium at the start of the experiment is much higher than the exposure concentration at equilibrium. Therefore, effects in in vitro bioassays should not be expressed in terms of the exposure concentration at the start of the experiment.
Identification and confirmation of ammonia toxicity in contaminated sediments using a modified toxicity identification evaluation approach
Authors: Van Sprang Patrick A , Janssen Colin R 
Published: March 2010

AbstractToxicity identification of sediment pore waters from four sites in the Upper Scheldt (Belgium) was assessed using a simplified and discriminative toxicity identification evaluation procedure. The samples from all locations exhibited acute toxicity toward the freshwater crustacean Thamnocephalus platyurus. Toxicity was removed or considerably reduced by the cation exchange resins and air stripping at pH 11. In addition, the toxicity of the pore waters was found to be highly pH dependent. Increased toxicity was observed at higher pH levels, whereas reduced toxicity was found at lower pH levels. Based on these results, ammonia was suggested as the main toxic agent. The presence of ammonia concentrations exceeding the 24-h median lethal concentration and comparison of the toxicity characterization profiles of the pore waters with those of the suspected toxicant supported this hypothesis. Furthermore, a significant positive correlation between the observed toxicity of the pore waters and the expected toxicity (due to the presence of the suspected toxicant) confirmed ammonia as the true toxic agent. Finally, the ratio between the expected ammonia toxicity and the observed toxicity from the characterization tests was approx. 1, meaning that all or most of the observed toxicity was caused by the presence of one toxicant (i.e., ammonia). The developed toxicity identification evaluation procedure is suggested as a usefull tool for the identification and confirmation of toxicants in contaminated sediments.
Possible effects of polychlorinated biphenyls on sex determination in rainbow trout
Authors: Matta Mary Baker , Cairncross Charles , Kocan Richard M 
Published: March 2010

Abstract
Aqeous exposure of newly hatched rainbow trout (Oncorhynchus mykiss) larvae to Aroclor 1260 resulted in altered sex ratios and severe gonadal abnormalities in juvenile females. The proportion of females decreased from 41.9% in combined controls to 31.6 to 36.1% in groups that accumulated 2.5 μg/g Aroclor 1260 after 3-h immersions, although this decrease was not statistically significant (p = 0.057). A total of 18.2% of the females in the treatment group that accumulated 2.1 μg/g Aroclor 1260 had abnormal gonads as compared to 2.7% in combined controls (p = 0.001). Abnormalities were characterized by inconsistent or extremely limited development of oocytes. Although further work is required to validate these results, this study suggests that environmentally realistic tissue concentrations of Aroclor 1260 may disrupt sexual development in female trout.
Vitellogenin as a biomarker for xenobiotic estrogens in an amphibian model system
Authors: Palmer Brent D , Huth Leslie K , Pieto Dana L , Selcer Kyle W 
Published: March 2010

Abstract
A number of chemicals released into the environment have the potential to interfere with physiological and developmental processes by disrupting endocrine pathways. Among the best known of these endocrine disruptors are compounds that mimic the action of the steroid hormone 17β-estradiol. These xenobiotic estrogens are believed to pose health risks to both humans and wildlife. Our laboratories are designing in vivo bioassays for xenobiotic estrogens based on induction of the egg-yolk precursor protein vitellogenin. Vitellogenin is normally produced by the liver of adult female nonmammalian vertebrates under estrogen stimulation. In immature or male animals, which have low levels of endogenous estrogens, vitellogenin can serve as a reliable biomarker for exposure to xenobiotic estrogens. Our model system used the African clawed frog, Xenopus laevis, an ideal species for laboratory screening of endocrine disruptors. Xenopus laevis vitellogenin was purified by diethylaminoethyl (DEAE) chromatography and used to generate polyclonal antibodies in rabbits. The resulting antiserum was used to develop an enzyme-linked immunosorbent assay (ELISA) for measurement of serum vitellogenin. Frogs were exposed to compounds by immersion in order to mimic environmental exposure to aquatic contaminants. Initially, frogs were immersed in the potent estrogenic agent diethyl-stilbestrol (DES) at a concentration of 1 ppm for 11 d to test the efficacy of the immersion protocol. Diethylstilbestrol exposed animals showed substantial induction of serum vitellogenin, indicating that the frogs are capable of responding to estrogenic agents present in their aquatic environment. Vitellogenin induction was then investigated for chlordane, dieldrin, endosulfan, and toxaphene, compounds that have been shown through in vitro assays to be weakly estrogenic when administered individually but more strongly estrogenic in combination. Adult male frogs were immersed in water containing the compounds (1 ppm, 11 d), both singly and in paired combinations. Endosulfan proved toxic at this concentration. Toxaphene- and dieldrin-treated frogs showed significant levels of vitellogenin induction, while chlordane-treated animals did not differ from controls. There was no evidence of a synergistic response between any of the combinations. This research demonstrates the utility of vitellogenin as a biomarker for exposure to estrogenic agents. The assays developed could be used to screen chemicals for estrogenic properties, to test waters for the presence of estrogenic agents, or to assess wildlife exposure to environmental estrogens.