bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glutathione-dependent metabolism in fish and rodents
Authors: Wallace Kendall B. 
Published: March 2010

Abstract
Hepatic glutathione (GSH) concentration was significantly higher in rats and mice compared to either fathead minnows or rainbow trout. In rodents, the concentration of GSH approximated the Km of hepatic glutathione peroxidase (GPx), whereas in fish GSH concentration was less than the Km of GPx. The significantly lower Km for oxidized glutathione (GSSG) of glutathione reductase compared to the Km for GSH of the peroxidase is consistent with the large ratio of reduced-to-oxidized glutathione in all four species. The concentration of GSH in rodent liver far exceeds the Km for hepatic glutathione-S-transferase (GST), which contrasts with that observed for fish. Furthermore, the greater activity of renal gamma-glutamyl transpeptidase in rodents compared to fish suggests that, once formed, glutathione conjugates are rapidly hydrolyzed, leading to greater mer-capturic acid production in rats and mice. Collectively, these data suggest that rodents are quite capable of conducting GSH-dependent detoxification of prooxidants and electrophiles, whereas in fish GSH-dependent metabolism appears to be self-limited by the availability of endogenous GSH. Accordingly, the data suggest that fish may be disproportionately more susceptible than rodents to xenobiotics that are eliminated principally by GSH-dependent metabolic detoxification.
A multitrophic level evaluation of sediment toxicity in waukegan and indiana harbors
Authors: Allen Burton G. , Stemmer Betty L. , Winks Kelly L. , Ross Philippe E. , Burnett Louann C. 
Published: March 2010

AbstractThe toxicity of sediments from three Waukegan Harbor sites, two Indiana Harbor sites and one reference site (Homer Lake) were evaluated using a multitrophic level test battery. The test battery consisted of the following assays: Daphnia magna 48-h survival, Ceriodaphnia dubia 48-h survival, Hyalella azteca 48-h survival, Selenastrum capricornutum 48-h growth inhibition and enzymatic activity of the indigenous microbial community (alkaline phosphatase, electron transport system activity, ß-galactosidase and ß-glucosidase). All assays, with the exception of S. capricornutum, were conducted using both whole sediments and elutriate (water-extractable) fractions. The test battery effectively discriminated between sites in most cases. However, response patterns varied slightly between macrofaunal and microbial responses and between whole sediment and elutriate phase responses. C. dubia was the most sensitive and H. azteca the least sensitive macrofaunal test species. Microbial community assays showed a greater range of responses, thus providing for greater discrimination between test sites. ß-galactosidase and ß-glucosidase were the most sensitive microbial assays. The acute toxicity response patterns verified sites containing the highest levels of contaminants at Waukegan Harbor and detected contamination in Indiana Harbor. Differences between degree and/or pattern of response and whole sediment versus elutriate toxicity patterns demonstrated both the usefulness and necessity of a multitrophic level toxicity test battery in sediment quality assessments.
Biochemical responses in aquatic animals: A review of determinants of oxidative stress
Authors: Di Giulio Richard T. , Washburn Peter C. , Wenning Richard J. , Winston Gary W. , Jewell Catherine S. 
Published: March 2010

AbstractThe study of biochemical responses in aquatic animals comprises a vigorous area of inquiry within ecotoxicology for a number of reasons, including the perceived need for basic research in the field, the desire for highly sensitive biomarkers useful for biomonitoring and the particular concern for elevated rates of neoplasia observed in some aquatic systems. In this paper, an approach only recently investigated by aquatic toxicologists will be described and reviewed in detail. This approach is based on theories of oxyradical generation and subsequent oxidative stress in biological systems. Of particular concern to environmental toxicologists with respect to these phenomena are the abilities of a number of common and diverse compounds to undergo enzymatically facilitated redox cycling in cells and thereby generate oxyradicals under aerobic conditions. Mechanisms of oxyradical generation, toxicological consequences of these processes and endogenous antioxidant defense systems are described. In addition, methodologies for studying these phenomena are discussed and recent studies demonstrating their applicability to aquatic toxicology are reviewed.
Reactions of selected nucleophiles with 2-chloropropenal, a mutagenic constituent of softwood kraft chlorination effluent
Authors: Tachibana Sanro , Santodonato Joseph , Dence Carlton W. 
Published: March 2010

Abstract2-Chloropropenal (2-chloroacrolein), a constituent of softwood kraft chlorination effluent that gives strongly positive results in the Salmonella mutagenicity assay (Ames Test), was reacted with various nucleophiles and the resulting effect on mutagenicity monitored. Nucleophiles such as hydroxide ion and sulfur dioxide (HSO−3, SO3) proved very effective in reducing the mutagenicity of aqueous 2-chloropropenal solutions. The application of other strong nucleophiles, (glutathione, pyrrolidine and sodium thiosulfate) to 2-chloropropenal also produced substantial benefits in terms of mutagenicity reduction. Further experimentation revealed that the loss of mutagenicity was not the result of the removal of organically bound chlorine but rather the removal of the ethylenic group in 2-chloropropenal, possibly as a consequence of undergoing Michael-type 1,4-addition reactions with the various nucleophiles. In the treatment of 2-chloropropenal with alkali (pH 9), additional condensation of the acrolein derivative to a polymer was demonstrated by gel permeation chromatography.
Biochemical analysis of allozyme copper and cadmium tolerance in fish using starch gel electrophoresis
Authors: Chagnon Norman L. , Guttman Sheldon I. 
Published: March 2010

Abstract
The in vitro effects of copper and cadmium on fish enzyme activity were assayed by combining the metals with the biochemical stains used to resolve these enzyme systems on starch gels. The effects of copper and cadmium on the activity of PGM-2, GPI-2 and IDH-2 enzymes in mosquitofish were assayed using stain-metal mixtures containing 2.0 ml 0.1 m CuSO4 · 5H2O or 0.1 m CdSO4. Enzymes whose activities were effected by copper in this initial test were resolved using a series of stain-metal mixtures containing copper at lower concentrations to determine effect threshold concentration ranges and to determine concentration ranges that might produce differential effects on activity among allozymes of a single protein. Interspecific differences in the effect of copper on the activity of PGM-2 enzyme variants were examined for 17 fish species from seven locations.
Copper was found to effect the activity of PGM-2, GPI-2, and IDH-2 enzymes in mosquitofish and intraspecific and interspecific differences existed in the copper sensitivity of enzymes in a number of the fish species tested. Allozyme phenotypes at the PGM-2 locus in mosquitofish observed on test gels (0.9 mg Cu/L) suggests that two isoalleles, one copper-tolerant and one copper-sensitive, are present at this locus.
Microbial degradation of nitrogen, oxygen and sulfur heterocyclic compounds under anaerobic conditions: Studies with aquifer samples
Authors: Kuhn Elmar P. , Suflita Joseph M. 
Published: March 2010

AbstractThe potential for anaerobic biodegradation of 12 heterocyclic model compounds was studied. Nine of the model compounds were biotransformed in aquifer slurries under sulfate-reducing or methanogenic conditions. The nitrogen and oxygen heterocyclic compounds were more susceptible to anaerobic biodegradation than those compounds containing a sulfur heteroatom. Carboxy-substituted compounds were anaerobically metabolized more readily than unsubstituted or methylated analogues. In methanogenic incubations, 47 to 84% of the expected amount of carbon in pyridine, 4-picoline, nicotinic acid and 2-thiophene carboxylic acid was recovered as methane. In contrast, only small amounts of methane were detected in aquifer slurries amended with compounds containing an oxygen heteroatom, even though a decrease in the parent substrate concentration occurred. Pyridine, 2-picoline and 4-picoline were biotransformed within three months under sulfate-reducing conditions. However, longer incubation times were required for the degradation of these substrates in methanogenic aquifer slurries. A literature survey reveals the widespread contamination of ground waters with heterocyclic compounds from waste management practice and fossil-fuel-related industries.
Aqueous chlorination of resorcinol
Authors: Heasley Victor L. , Burns Michael D. , Kemalyan Nathan A. , McKee Tawnya C. , Schroeter Hinako , Teegarden Brad R. , Whitney Scott E. , Wershaw Robert L. 
Published: March 2010

Abstract
An investigation of the aqueous chlorination (NaOCl) of resorcinol is reported. The following intermediates were detected in moderate to high yield at different pH values and varying percentages of chlorination: 2-chloro-, 4-chloro-, 2,4-dichloro-, 4,6-dichloro- and 2,4,6-trichlororesorcinol. Only trace amounts of the intermediates were detected when the chlorination was conducted in the presence of phosphate buffer. This result has significant implications since resorcinol in phosphate buffer has been used as a model compound in several recent studies on the formation of chlorinated hydrocarbons during chlorination of drinking water. Relative rates of chlorination were determined for resorcinol and several of the chlorinated resorcinols. Resorcinol was found to chlorinate only three times faster than 2,4,6-trichlororesorcinol. The structure 2,4,6-trichlororesorcinol was established as a monohydrate even after sublimation. A tetrachloro or pentachloro intermediate was not detected, suggesting that the ring-opening step of such an intermediate must be rapid.
Environmental persistence and fate of fenoxaprop-ethyl
Authors: Toole Amy P. , Crosby Donald G. 
Published: March 2010

Abstract
The environmental persistence and fate of ethyl 2-[4-[(6-chloro-2-benzoxazolyl)oxy]phen-oxy]propanoate (fenoxaprop-ethyl), a herbicide proposed for selective control of grasses in California rice, have been investigated under laboratory and field conditions. In the field, it dissipated rapidly from both water and soil, with half-lives in water &lt;4 h and soil residues below detectability within 6 d. The photolysis half-life in sterile, distilled water was 269 · 19 h; in field water a combination of microbial and photochemical reactions resulted in a half-life of 29 · 2 h. Products included the corresponding acid, 6-chlorobenzoxazolinone, ethyl 2-(4-hydroxyphenoxy)propanoate and 2-(4-hydroxyphenoxy)propanoic acid. Hydrolysis was slow at pH 6.1 and 7.4 but resulted in a half-life of only 8.3 h at pH 9.1. Fenoxaprop-ethyl is essentially nonvolatile (Henry's Law constant = 3 × 10−7) and was bound moderately to soil (Koc = 6800). These properties represent a near optimum for pesticide persistence.
Comparison of on-site and laboratory toxicity tests: Derivation of site-specific criteria for un-ionized ammonia in a Colorado transitional stream
Authors: Nimmo Del Wayne R. , Link Denise , Parrish Loys P. , Rodriguez Glenn J. , Wuerthele William , Davies Patrick H. 
Published: March 2010

AbstractAcute tests with fathead minnows (Pimephales prornelas Rafinesque), johnny darters (Etheostoma nigrum Rafinesque), white suckers (Catostomus commersoni Lacépède) and acute and chronic tests with Ceriodaphnia dubia were conducted to evaluate whether characteristics of the St. Vrain River in Colorado would ameliorate or enhance toxicity of un-ionized ammonia compared to laboratory (well) water and LC50 values found in the literature. Concurrently, tests were conducted on dilutions of Longmont, Colorado, wastewater to evaluate its toxicity in differing ammonia concentrations. Tests were conducted at two temperatures (approximately 6 and 20°C) to simulate seasonal differences.LC50s for fishes in the St. Vrain River water were similar to LC50s in laboratory water, indicating there was no site water effect. LC50s derived for fishes tested in warm conditions were within a factor of about two or three of literature values. However, the constituents in or characteristics of the wastewater appeared to enhance ammonia toxicity. Literature values (LC50s) for resident aquatic organisms and the new LC50 value for johnny darters tested on-site were used to derive site-specific criteria for un-ionized ammonia. Greater sensitivities of species to ammonia at cold versus warm temperatures suggests that colder, low-flow conditions may be a critical period for warm-water aquatic communities with regard to ammonia toxicity.
Suppression of secretory rosette formation by PCBs in Lumbricus terrestris: An earthworm assay for humoral immunotoxicity of xenobiotics
Authors: Rodriguez-Grau Jorge , Venables Barney J. , Fitzpatrick Lloyd C. , Goven Arthur J. , Cooper Edwin L. 
Published: March 2010

Abstract
Research is part of an effort to develop surrogate immunoassays with the earthworm Lumbricus terrestris to assess immunotoxic potential of xenobiotics to mammals. Objective was to determine if an earthworm humoral immunoassay, secretory (S) rosette formation by coelomic leukocytes, is sensitive to a known mammalian immunotoxin, the polychlorinated biphenyl (PCB) Aroclor 1254®. Results are presented in terms of PCB exposure and tissue levels during uptake/depuration. Using 5-d filter paper contact exposure, LC50 and LD50 were 300 m̈g/cm2 and 1,140 m̈g/g dry mass. Nominal PCB exposure concentration of 5.0 m̈g/cm2 and actual tissue levels of 76 m̈g/g dry mass were sufficient to suppress S-rosette formation. Suppression and return of function followed PCB levels in coelomic leukocytes, the presumed site of toxicity. Compared to published mammalian data on immunoglobulin suppression by PCBs, the earthworm immunoassay appeared to be more sensitive.
Swimming behavior as an indicator of sublethal toxicity in fish
Authors: Little Edward E. , Finger Susan E. 
Published: March 2010

Abstract
Swimming behavior of fish is impaired by exposure to a diversity of contaminants. Gross aberrations in swimming can be qualitatively assessed while subtle changes in swimming behavior arising from sublethal exposures can be detected through a more detailed analysis of this response. Compared to other swimming behavior variables, the physical capacity to swim against water flow tends to be affected at relatively high toxicant concentrations and often presages mortality. Orientation to water flow, however, is altered at sublethal concentrations. Frequency of activity is a more sensitive measure in detecting contamination than measurements of survival alone. Alterations in swimming behavior have been detected during exposures to various contaminants at concentrations as low as 0.7 to 5% of their LC50 values and at concentrations that subsequently inhibited growth after longer periods of exposure. Analysis of swimming patterns provides even higher resolution for analysis of swimming behavior, and increased availability of the instrumentation necessary for such measurements should facilitate use of this approach. Fish swimming activity can easily be incorporated in test protocols to expand the sensitivity of standard toxicity tests.
A behavioral screening assay for Daphnia Magna: A method to assess the effects of xenobiotics on spacial orientation
Authors: Goodrich Mark S. , Lech John J. 
Published: March 2010

Abstract
We have developed a short-term, low-cost method of detecting changes in the orientative ability of Daphnia magna in response to xenobiotics. The method employs the reaction, a migration along the gradient, of D. magna to a light intensity gradient. The method was derived from techniques established to simulate and analyze migration patterns of zooplankton in the natural environment. Each test uses a minimum of 100 1- to 3-d old Daphnia exposed to a directional light beam within a circular chamber. The chamber is divided into eight sections, each containing 45° of arc. These quadrants can be isolated from each other, thus isolating eight groups of migrating Daphnia. Each test results in three endpoints: an average direction for the migration (mean angle), an index of the magnitude of random, undirected migration (r value) and a percentage of nonresponse. The method was validated by showing a positive dose-related response to a known neurotoxin, lindane. The method is sensitive to lindane, producing effects on orientation even at a concentration as low as 50 ppb. The effect of lindane was a dramatic increase in the random migration of dosed Daphnia, showing a less directed migration pattern than control. Implications of developing a behavioral test with Daphnia and its correlation with the natural environment are discussed, as well as its incorporation into the general toxicity screening strategy. Interpretative and comparative statistical analysis of the method's endpoints are presented and discussed.
Behavioral toxicity syndromes: A promising tool for assessing toxicity mechanisms in juvenile fathead minnows
Authors: Drummond Robert A. , Russom Christine L. 
Published: March 2010

Abstract
Fathead minnows (Pimephales promelas) were exposed to acutely toxic concentrations of organic chemicals under flow-through conditions at 25°C for 96 h. Changes in behavior and morphology were systematically recorded to develop a plan for classifying these chemicals. On this basis, three behavioral toxicity syndromes were evident. Each syndrome appears to represent a different general mode of toxic action. The hypoactivity syndrome, reflecting narcosis, is characterized by depressed locomotor activity, loss of startle response and very dark body coloration. The hyperactivity syndrome, representing metabolic dysfunction (e.g., uncouplers of oxidative phosphorylation), is characterized by greatly accelerated locomotor activity, overreaction to stimuli and increased ventilatory activity. The physical deformity syndrome, indicative of neurological dysfunction (e.g., AChE inhibition), is characterized by a high incidence of convulsions, tetany, scoliosis/lordosis and hemorrhage in the vertebral area. This classification approach also should be useful to help delineate specific, underlying mechanisms or sites of chemical action.
Behavioral responses of marked snails as indicators of water quality
Authors: Burris Janet A. , Bamford Martha S. , Stewart Arthur J. 
Published: March 2010

AbstractBehavioral responses of the common stream-dwelling operculate snail Elimia clavaeformis were used to provide information about streamwater quality in in situ tests. These snails were found to be advantageous for such tests because they can be collected easily, individually marked, and transferred to other stream sites for release and recapture experiments.In noncontaminated stream sites, Elimia tended to disperse upstream. The rate of net movement was variable, but typically ranged from 0.5 to 5 m/d. Water velocity and food level influenced the movement patterns of the snails in 24- and 48-h field experiments in noncontaminated stream sites. Rates of movement in the laboratory were temperature dependent, and increased from about 1.0 cm/min at 9°C to 2.2 cm/min at 24°C.In contaminated streams, snails showed clear evidence of stress: They moved downstream, and in some sites either withdrew into the shell or were unable to retract the foot or attach to a substrate. The maximum distance that Elimia traveled downstream in 24 h in a contaminated stream site was 17.5 m.In laboratory streams, Elimia moved downstream when exposed to 0.02 mg/L total residual chlorine (TRC); the time required to immobilize these snails declined rapidly as TRC concentration increased. Behavioral characteristics of snails that may be useful for water quality assessments include turnover time (the time needed for a snail to right itself after being turned onto its back), the rate and direction of dispersal or immobilization.
Toxicokinetics of selected polycyclic aromatic hydrocarbons in rainbow trout following different routes of exposure
Authors: Kennedy Christopher J. , Law Francis C. P. 
Published: March 2010

Abstract
The toxicokinetics and bioavailabilities of 2-methylnaphthalene (2-MN), fluorene and pyrene were studied in rainbow trout (Salmo gairdners) implanted with an indwelling cannula in the dorsal aorta. After intraarterial injection of one of the polycyclic aromatic hydrocarbons (PAHs) (10 mg/kg) to trout, chemical concentration in the blood was found to decline triphasically with time. The terminal half-lives of elimination from the blood for 2-MN, fluorene and pyrene were 9.6, 10.5 and 12.8 h, respectively. The toxicokinetics of the PAHs in trout were best described by a three-compartment open model with the central compartment and the deep peripheral compartment representing the blood and fatty tissues of trout, respectively. The PAHs were metabolized by trout mainly to water-soluble metabolites which were excreted into the urine and bile. When trout were exposed to water containing 2-MN, fluorene or pyrene (0.5 mg/L), the chemical was detected almost immediately in the blood. The apparent bioavailabilities of 2-MN, fluorene and pyrene in trout were 20, 36 and 35%, respectively. In contrast, little or no unchanged chemical was detected in the blood of trout following intragastric administration of 2-MN, fluorene or pyrene (50 mg/kg). These results indicate that the PAHs are absorbed systemically by trout via the branchial route at rates much faster than that of the oral route.
Rate-limiting barriers to xenobiotic uptake by the gill
Authors: Hayton William L. , Barron Mace G. 
Published: March 2010

Abstract
Waterborne xenobiotics enter fish and other aquatic species primarily by transfer across the gill epithelium. Potential barriers to uptake include water flow across the gill, diffusion across the gill epithelium and the overlying aqueous stagnant layer and blood flow through the gill (cardiac output). In general, for any particular chemical, only one of the barriers is operative with the resistance offered by the others being negligible. The rate-limiting barrier is determined by the physico- and biochemical properties of the substance: molecular size, lipophilicity, binding to blood proteins and formed elements. The resistance of each barrier is affected differently by variables such as temperature, molecular size, lipophilicity and body size of the animal. When the resistance offered by the gill barriers is low, uptake may be controlled by transfer to storage tissues, e.g., by blood flow to adipose tissue.
A simple flow-limited model for exchange of organic chemicals at fish gills
Authors: Erickson Russell J. , McKim James M. 
Published: March 2010

AbstractA mathematical model for the exchange of organic chemicals by fish gills was formulated based solely on the limitations imposed by the flows of water and blood into the gills. For large rainbow trout, this model was found to closely follow the magnitude and trends of observed gill uptake rates over a range of octanol/water partition coefficient from 1 to 106. Observations averaged only about 30% less than model predictions. This modest lack-of-fit is presumably due to the effects of diffusional barriers and ionization which would further limit uptake, although uncertainties in model parameters and data are likely also partly responsible. This analysis suggests that these basic physiological parameters are of major importance in the regulation of exchange at fish gills and should be accounted for in more detailed toxicokinetic models. Also, this simple model could by itself be useful for approximate assessments of accumulation of organic chemicals by fish.