bluuebunny/crossref_metadata_2025_split huggingface dataset:
Primer and interviews: Diverse connections between primary cilia and Hedgehog signaling
Authors: Kiefer Julie C. 
Published: March 2010

AbstractOn the surface, the Hedgehog (Hh) pathway and primary cilia make strange bedfellows. Hh is a dynamic regulator of a myriad of developmental processes, ranging from spinal cord and limb patterning to lung branching morphogenesis. By contrast, immotile primary cilia were long considered ancestral holdovers with no known function. Considering the disparate perceptions of these two phenomena, the relatively recent discovery that there is a symbiotic‐like relationship between Hh and cilia was unexpected. This primer covers the basics of primary cilia and Hh signaling, highlighting variations in ways they are connected across species, and also discusses the evolutionary implications of these findings. Roles of cilia in signal transduction are analyzed further in an interview with Søren T. Christensen, PhD, and Andrew S. Peterson, PhD, in the A Conversation With the Experts section. Developmental Dynamics 239:1255–1262, 2010. © 2010 Wiley‐Liss, Inc.
Metallo‐Controlled Dynamic Molecular Tweezers: Design, Synthesis, and Self‐Assembly by Metal‐Ion Coordination
Authors: Ulrich Sébastien , Petitjean Anne , Lehn Jean‐Marie 
Published: March 2010

AbstractThe introduction of controllable dynamic features into synthetic receptors represents a step towards “smart” adaptive nanodevices. We report herein our studies on the construction of dynamic molecular tweezers in which the binding of a substrate is allosterically controlled through shape switching of the receptor induced by metal‐ion coordination. 1D, 2D NMR spectroscopy and X‐ray crystallography were used to identify the nature of the metallosupramolecular entity generated. The presence of large aromatic naphthalene diimide moieties on the scaffold of the molecular tweezers strongly influences their coordination‐driven self‐assembly. It was found that these additional stacking interactions lead to the cooperative formation of a homocomplex, to the self‐sorted assembly of a hetero complex, and to the binding of non‐coordinating aromatic guests.
Fecal genotyping and contaminant analyses reveal variation in individual river otter exposure to localized persistent contaminants
Authors: Guertin Daniel A. , Harestad Alton S. , Ben-David Merav , Drouillard Ken G. , Elliott John E. 
Published: March 2010

AbstractThe present study investigated polyhalogenated aromatic hydrocarbon (PHAH) concentrations in feces of known river otters (Lontra canadensis) along the coast of southern Vancouver Island, British Columbia, Canada. Specifically, we combined microsatellite genotyping of DNA from feces for individual identification with fecal contaminant analyses to evaluate exposure of 23 wild otters to organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenylethers (PBDEs). Overall, feces collected from otters in urban/industrial Victoria Harbor had the greatest concentrations of nearly all compounds assessed. Fecal concentrations of OCPs and PBDEs were generally low throughout the region, whereas PCBs dominated in all locations. Re-sampling of known otters over space and time revealed that PCB exposure varied with movement and landscape use. Otters with the highest fecal PCB concentrations were those inhabiting the inner reaches of Victoria Harbor and adjacent Esquimalt Harbor, and those venturing into the harbor systems. Over 50% of samples collected from eight known otters in Victoria Harbor had total-PCB concentrations above the maximum allowable concentration as established for Eurasian otter (Lutra lutra) feces, with a geometric mean value (10.6 mg/kg lipid wt) that exceeded the reproductive toxicity threshold (9 mg/kg lipid wt). Those results are consistent with our findings from 1998 and 2004, and indicate that the harbors of southern Vancouver Island, particularly Victoria Harbor, are a chronic source of PCB exposure for otters. The present study further demonstrates the suitability of using otter feces as a noninvasive/destructive biomonitoring tool in contaminant studies, particularly when sampling of the same individuals at the local population-level is desired. Environ. Toxicol. Chem. 2010;29:275–284. © 2009 SETAC
Estimating the acute toxicity of waterborne chemicals in trout from measurements of median lethal dose and the octanol-water partition coefficient
Authors: Hodson Peter V. , Dixon D. George , Kaiser Klaus L. E. 
Published: March 2010

AbstractMeasurements of the median lethal dose (LD50) of chemicals to fish provide a simpler, faster and less expensive alternative to median lethal concentrations (LC50s). Since dose is controlled, LD50s may be a better basis for structure-activity relationships. However, LC50s are used extensively in aquatic hazard assessments. Therefore, LC50s and LD50s for rainbow trout of 48 organic chemicals were measured to determine whether LC50 could be predicted from LD50. A simple linear regression of log-transformed data provided the best fit (r = 0.70), but it accounted for only 50% of the variability in LC50s. LC50s were also strongly correlated with measures of molecular size [molecular weight (MW; r = −0.90) and Parachor (r = −0.89)] and of water-lipid partitioning [octanol-water partition coefficient (Kow; r = −0.73)]. Hence, inclusion of these factors in a multiple regression analysis was examined. Since MW and Parachor were negatively correlated with LD50 (r = −0.61 and −0.60, respectively), they were not true independent variables and were not used. However, there was no relationship of Kow with LD50, and a multiple regression analysis using both LD50 and Kow predicted LC50 with greater certainty (r = 0.92) than did either factor alone. Therefore, LC50 can be predicted from LD50 when partitioning of a chemical from water to lipid is recognized.
QSAR investigation of benzene toxicity to fathead minnow using molecular connectivity
Authors: Hall Lowell H. , Maynard Ellen L. , Kier Lemont B. 
Published: March 2010

AbstractThe topological methods of molecular connectivity and kappa shape analysis have been applied to a set of 65 substituted benzenes and their toxicities to fathead minnow Pimephales promelas. The three variables 1χ, 1kα and 6χvp along with an ortho/para-dinitro indicator variable yield a QSAR equation with r = 0.940, s = 0.26 and F = 114. This equation is then used to estimate toxicities for 22 compounds not in the original data set. Twelve of the predicted compounds contain substituents in the original data set but 10 contain substituents new to the data, including fluoro-, cyano- and acyl-.
Modeling the fate of chemicals in an aquatic environment: The use of computer spreadsheet and graphics software
Authors: Southwood Jeanette M. , Harris Reed C. , MacKay Don 
Published: March 2010

AbstractThe Quantitative Water Air Sediment Interaction (QWASI) model, based on the concept of fugacity, is used to develop quantitative descriptions of the fate of chemicals in aquatic environments using LOTUS 1-2-3 software on a microcomputer. This software package is shown to provide a powerful, easy to use framework in which to use QWASI to simulate the reported fate of three chemicals: tertiary butylphenyl diphenyl phosphate, 3,4-dichloroaniline and chloroform. For each chemical, the graphics capabilities and interactive features of LOTUS 1-2-3 are used to guide the modeler regarding the influence of various processes on the fate of the chemical and determine appropriate variables on which to focus to improve the simulation.
Identification of ammonia as an important sediment-associated toxicant in the lower fox River and green bay, Wisconsin
Authors: Ankley Gerald T. , Katko Albert , Arthur John W. 
Published: March 2010

AbstractToxicity of sediment pore water from 13 sites in the lower Fox River/Green Bay watershed was assessed using a number of test species. Sediment pore water from the 10 lower Fox River sites exhibited acute toxicity to fathead minnows (Pimephales promelas) and Ceriodaphnia dubia, and pore water samples from all 13 sites were chronically toxic to C. dubia. Sediment pore water from seven of the sampling sites was toxic to Selenastrum capricornutum, but none of the samples were toxic to Photobacterium phosphoreum. Toxicity characterization, identification and confirmation procedures indicated that a significant amount of the acute toxicity of the pore water to fathead minnows and C. dubia was due to ammonia. The identification of ammonia, a naturally occurring compound in sediments, as a potentially important sediment-associated toxicant has implications for sediment toxicity assessment and control, not only in the Fox River and Green Bay, but in other freshwater and marine systems as well.
The effects of nine diet and water combinations on the culture health ofCeriodaphnia dubia
Authors: Patterson Paul W. , Dickson Kenneth L. , Waller William T. , Rodgers John H. 
Published: March 2010

AbstractCulture health of Ceriodaphnia dubia was evaluated for organisms cultured with all combinations of three foods and three waters. The criteria used to assess health of cultures included adult and neonate weights, time required to produce first broods, neonate production, adult survival, and resistance to hexavalent chromium. Diet-water combinations that produced the most neonates were not found to produce adults that were more resistant to chromium than those that produced fewer neonates. Of those evaluated, a diet of Selenastrum capricornutum and a yeast-trout food-cereal leaf mixture was best for culturing and testing Ceriodaphnia. The best tested synthetic culture water was a mixture of nine parts reconstituted hard water and one part bottled mineral water.
Comparison of microbial trophic interactions in aquatic microcosms designed for the testing of introduced microorganisms
Authors: Kroer Niels , Coffin Richard B. , Jørgensen Niels O.G. 
Published: March 2010

AbstractTwo aquatic microcosms of different complexity were calibrated with a eutrophic lake. The simple microcosm consisted of an intact sediment core with overlying water. The complex microcosm was compartmentalized (phytoplankton tank, grazer tank, and sediment cores) to allow manipulation of individual components of the microbial food web. The comparison showed that whereas average phytoplankton biomass and productivity were approximately 30% lower in microcosms, biomass and activity of the heterotrophs (bacteria and nanoflagellates) were equal to or higher (up to 40% higher) than the corresponding field values. Important components of the microbial loop were represented in both microcosms. In the field and simple microcosm, approximately 30% of the phytoplankton production was cycled through the microbial loop, whereas close to 50% was fluxed through the loop in the complex model. Similarly, bacterial production amounted to almost the same fraction of the primary production in the simple microcosm and the field (16 and 18%, respectively) but 29% in the complex model. The percentage of the primary production that ended up as nanoflagellate production, on the other hand, was almost similar in all systems (0.4%). These data indicate that while the simple microcosm was the better surrogate of the field, variability between replicate microcosms of the complex model was lower (10-25% and 25-41 % for the complex and simple models, respectively). The choice of model, therefore, depends on the questions asked. The results suggest that the trophic-level analysis is useful in calibration studies of microcosms intended for testing of microorganisms.
Purification of the 70-kDa heat-shock protein from catfish liver: Immunological comparison of the protein in different fish species and its potential use as a stress indicator
Authors: Abukhalaf Imad K. , Zimmerman Earl G. , Dickson Kenneth L. , Masaracchia Ruthann A. , Donahue Manus J. , Covington Sean 
Published: March 2010

AbstractThe heat-shock protein or stress-70 family was isolated from catfish liver. The homogeneity of the purified protein was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Fish subjected to whole-body hyperthermia contained the constitutive and the heat-inducible stress-70 with approximate molecular weights of 70 and 68 kDa, respectively. The final purification product from livers of catfish raised under normal temperature was only the constitutive stress-70. Western blot analysis with rabbit antiserum prepared against purified catfish (Ictalurus punctatus) liver stress-70 showed that the antibody cross-reacted with liver, muscle, and gill tissue homogenates of fathead minnows (Pimephales promelas), red shiners (Cyprinella lutrensis), black bass (Micropterus salmoides), and bluegill (Lepomis macrochirus), with various intensities suggesting that stress-70s from different tissues of various fish species share common antigenic determinants of the protein. This substantiates that the antigen/antibody approach of stress-70 is useful as a stress indicator and, consequently, as a potential biomarker for water quality.
Ratios between acute aquatic toxicity and effects on population growth rates in relation to toxicant mode of action
Authors: Roex Erwin W M , Van Gestel Cornelis A M , Van Wezel Annemarie P , Van Straalen Nico M 
Published: March 2010

AbstractEnvironmental risk assessment of chemicals is mostly based on the results of standardized toxicity tests. To obtain environmental quality criteria, extrapolation factors are used that depend on the amount and quality of available data. These extrapolation factors do not, however, take into account the mode of action of the compound tested or the life history of the test organism. In this study, we analyzed the variability in acute-to-chronic ratios (ACRs) for various chemicals in relation to their mode of action. Chemicals were classified as nonpolar narcotics, polar narcotics, specifically acting compounds, and heavy metals. As an acute endpoint, the LC50 was used; as a chronic endpoint, the lowest test concentration at which the natural rate of population increase (r) is affected, or LOEC(r), was used. Data were derived from the on-line literature. Nonpolar narcotic chemicals demonstrate the smallest variation in ACRs, and acute tests can be used to derive chronic endpoints for this class. For the other classes, the variation in ACRs is larger. Fish species especially show a relatively large ACR. For heavy metals, differences in the mode of action may play an important role in explaining differences in ACRs. For the other three classes, however, it is less reliable to predict chronic toxicity using the results of acute tests. In general, differences in species sensitivity rather than in mode of action for the chemical seem to determine differences in ACRs.
Toxicity of Anacostia River, Washington, DC, USA, sediment fed to mute swans (Cygnus olor)
Authors: Beyer W Nelson , Day Daniel , Melancon Mark J , Sileo Louis 
Published: March 2010

AbstractSediment ingestion is sometimes the principal route by which waterfowl are exposed to environmental contaminants, and at severely contaminated sites waterfowl have been killed by ingesting sediment. Mute swans (Cygnus olor) were fed a diet for 6 weeks with a high but environmentally realistic concentration (24%) of sediment from the moderately polluted Anacostia River in the District of Columbia, USA, to estimate the sediment's toxicity. Control swans were fed the same diet without the sediment. Five organochlorine compounds were detected in the treated diets, but none of 22 organochlorine compounds included in the analyses was detected in livers of the treated swans. The concentrations of 24 polynuclear aromatic hydrocarbons measured in the treated diet were as high as 0.80 mg/kg, and they were thought to have been responsible for the observed induction of hepatic microsomal monooxygenase activity in livers. A concentration of 85 mg/kg of lead in the diet was enough to decrease red blood cell ALAD activity but was not high enough to cause more serious effects of lead poisoning. The dietary concentrations of Al, Fe, V, and Ba were high compared to the concentrations of these elements known to be toxic in laboratory feeding studies. However, the lack of accumulation in the livers of the treated swans suggested that these elements were not readily available from the ingested sediment. We did not study all potential toxic effects, but, on the basis of those that we did consider, we concluded that the treated swans were basically healthy after a chronic exposure to the sediment.
Formation of copper complexes in landfill leachate and their toxicity to zebrafish embryos
Authors: Fraser Jonathon K , Butler Catherine A , Timperley Michael H , Evans Clive W 
Published: March 2010

AbstractToxic metal organic complexeshavenot been found in natural waters, although someorganicacids form bioavailable lipophilic and metabolite-type metal complexes. Landfill leachates usually contain organic acids and in the urban environment these leachates, when mixed with storm waters containing Cu, could be a source of toxic Cu organic complexes in streams and estuaries. We investigated the formation of Cu complexes in the leachate from an active urban landfill and found that some of the complexes formed were toxic to zebrafish embryos. High and low nominal molecular weight (NMWT) fractions; &gt;5,000 Da and &lt;700 Da, of leachate both formed Cu complexes with almost identical Cu complexing characteristics but the toxicity was due solely to the low NMWT complexes formed in the &lt;700 Da fraction. Chemical equilibrium modelling with MINTEQA2 and H and Cu complex conditional association constants and ligand concentrations obtained from pH and Cu titrations with a Cu ion-selective electrode and van den Berg–Ruzic analyses of the titration data was used to calculate the copper speciation in the embryo test solutions. This calculated speciation, which was confirmed by measurements of Cu2+ in the test solutions, enabled the toxicity due to the free Cu ion and to the Cu complexes to be distinguished.
Utility of organophosphorus hydrolase for the remediation of mutagenicity of methyl parathion
Authors: Cho Tae-Hyeon , Wild James R , Donnelly Kirby C 
Published: March 2010

AbstractThe pesticide methyl parathion (MP) is widely distributed in the environment and is chemically similar to nerve agents used in chemical warfare. Detoxification of this class of compounds is a critical environmental concern. Toxicity of MP is primarily associated with the inhibition of cholinesterase activity and resulting effects on the nervous system. Methyl parathion can also induce a genotoxic effect in bacterial and mammalian cells. However, the major metabolite of MP degradation, p-nitrophenol (PNP), is generally considered less toxic. This study reports on the evaluation of the genotoxic effect of MP, PNP, and a 1:1 MP:PNP mixture, and the utility of an organophosphorus hydrolase (OPH) enzyme for degradation of MP. Although MP induced a positive genotoxic response in Salmonella typhimurium TA100 at a dose of 1,000 μg per plate, PNP and a 1:1 mixture of PNP and MP did not induce a positive response. Methyl parathion dissolved in Luria-Bertani broth containing 5% methanol was treated with genetically engineered intact Escherichia coli cells expressing OPH activity. Significant rates of MP biodegradation were observed in the liquid culture. Within 55 h, an average 95.5% of the MP was converted to PNP as measured spectrophotometrically. The genotoxic potential of extracts of OPH-treated and untreated MP-amended media was measured with S. typhimurium strain TA100. The untreated media induced a dose-dependent genotoxic response at a dose equivalent to 54 ml of medium (MP 0.025 mg/ml) per plate, whereas the OPH-treated media failed to induce a genotoxic response. Chemical analysis indicated that about 90% of MP was removed from the media by treatment with OPH enzyme. These studies indicate that the OPH enzyme is capable of degrading MP and eliminating its genotoxic potential in liquid culture.
Evaluation of the efficacy of extrapolation population modeling to predict the dynamics ofAmericamysis bahiapopulations in the laboratory
Authors: Kuhn Anne , Munns Wayne R , Champlin Denise , McKinney Richard , Tagliabue Mark , Serbst Jonathan , Gleason Timothy 
Published: March 2010

AbstractAn age-classified projection matrix model has beendeveloped to extrapolate the chronic (28–35 d) demographic responses of Americamysis bahia (formerly Mysidopsis bahia) to population-level response. This study was conducted to evaluate the efficacy of this model for predicting the population behavior of A. bahia held (for more than three generations) under controlled laboratory exposure conditions. The research involved the performance of a standard life-cycle test and a multigenerational (greater than three mysid generations, 55 d) assay using A. bahia to experimentally evaluate model predictions regarding population-level risks of chemical exposure. The organic compound para-nonylphenol was chosen as the chemical stressor in these assays. This compound is a ubiquitous contaminant and suspected endocrine disruptor. Utilizing data obtained during the standard life-cycle test, aggregate estimates of population growth rate (λ) and measured p-nonylphenol concentration were used to develop an exposure-response model of population-level effects. These estimates provided the basis of predictions for the long-term dynamics of mysid populations exposed to p-nonylphenol. The veracity of the mysid population model was evaluated through quantitative comparisons of model predictions based on the life-cycle test with dynamics of the experimental populations (multigenerational assay results). The results indicate that the population model was able to project within a few micrograms per liter the concentration where population-level effects would begin to occur (projected 16 μg/L from the model vs measured 19 μg/L from the multigenerational assay).
Phenolic toxicity—detection and classification through the use of a recombinant bioluminescentEscherichia coli
Authors: Choi Sue Hyung , Gu Man Bock 
Published: March 2010

AbstractA genetically engineered Escherichia coli strain, DPD2540, containing a fabA::luxCDABE fusion that gives a bioluminescent output when membrane fatty acids are limited was used to determine the extent to which phenolics result in the limitation of membrane fatty acids. Tested phenolics were found to be classifiable into two groups according to the bioluminescent response they elicited and their pKa. A dose-dependent bioluminescent response, due to fatty acid limitation, was seen for phenolics with pKa values greater than seven, which exist mainly in the protonated form (HA), while no significant bioluminescent response was seen, compared with the control, for phenolics with pKa values lower than seven, which exist almost entirely as A−. A newly modified distribution model for phenolic compounds in the cellular membrane is proposed and used to predict the bioluminescent response induced by group I phenolics and the cellular toxicity for both groups. The [HA]*, obtained with this model, shows good correlation with the various bioluminescent responses produced by group I phenolics. It was also found that the distribution ratio between the medium and the cell membrane, K1, calculated as well using the proposed model, is a good representative parameter for the cellular toxicity of the phenolic compounds according to their substituted groups when compared with the conventional method of using the octanol-water partition coefficient, log Kow. As a new parameter, the critical concentration was also shown to be a good representative of the cellular toxicity for group I phenolics to the Escherichia coli cells.