bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detecting Adaptive Trait Introgression BetweenIris fulvaandI. brevicaulisin Highly Selective Field Conditions
Authors: Martin Noland H , Bouck Amy C , Arnold Michael L 
Published: January 2006

AbstractThe idea that natural hybridization has served as an important force in evolutionary and adaptive diversification has gained considerable momentum in recent years. By combining genome analyses with a highly selective field experiment, we provide evidence for adaptive trait introgression between two naturally hybridizing Louisiana Iris species, flood-tolerant Iris fulva and dry-adapted I. brevicaulis. We planted reciprocal backcross (BC1) hybrids along with pure-species plants into natural settings that, due to a flooding event, favored I. fulva. As expected, I. fulva plants survived at much higher rates than I. brevicaulis plants. Backcross hybrids toward I. fulva (BCIF) also survived at significantly higher rates than the reciprocal backcross toward I. brevicaulis (BCIB). Survivorship of BCIB hybrids was strongly influenced by the presence of a number of introgressed I. fulva alleles located throughout the genome, while survivorship in the reciprocal BCIF hybrids was heavily influenced by two epistatically acting QTL of opposite effects. These results demonstrate the potential for adaptive trait introgression between these two species and may help to explain patterns of genetic variation observed in naturally occurring hybrid zones.
Drosophila melanogaster P-glycoprotein: A membrane detoxification system toward polycyclic aromatic hydrocarbon pollutants
Authors: Vaché Christel , Camares Olivier , De Graeve Fabienne , Dastugue Bernard , Meiniel Annie , Vaury Chantal , Pellier Serge , LEoz-Garziandia Eva , Bamdad Mahchid 
Published: January 2006

Abstract
Polycyclic aromatic hydrocarbons (PAHs) are well-known ubiquitous environmental contaminants. Permeability gly-coprotein (P-gp) is a transmembrane detoxification efflux pump transporting various lipophilic xenobiotics, such as PAHs, out of the cells. The existence of a P-gp detoxification system inducible by PAHs was investigated in Drosophila melanogaster. Western blot experiments showed that D. melanogaster expressed a 140-kDa P-gp in Sl2 cells, embryos, and adult flies. Permeability glycoprotein was expressed in adult flies in the head, abdomen, and thorax and sublocalized in the sexual and olfactory organs. Flow cytometry experiments using Drosophila Sl2 cells in the presence of PAHs and target P-gp drug compounds revealed that Drosophila P-gp acted as an efflux detoxification pump. In Drosophila exposed to benzo[a]pyrene or to ambient air polluted by higher or lower PAH concentrations, P-gp expression was clearly showed a dose-dependent increase response. The P-gp induction was detected both in adult flies and in different fly parts, such as the head, thorax, and antennae. Drosophila P-gp acts as a membrane barrier against PAH pollutants.
Tree swallow (Tachycineta bicolor) exposure to polychlorinated biphenyls at the Kalamazoo River superfund site, Michigan, USA
Authors: Neigh Arianne M. , Zwiernik Matthew J. , Bradley Patrick W. , Kay Denise P. , Park Cyrus S. , Jones Paul D. , Newsted John L. , Blankenship Alan L. , Giesy John P. 
Published: January 2006

AbstractIn 1990, a portion of the Kalamazoo River in Michigan, USA, was designated a Superfund site because of the presence of polychlorinated biphenyls (PCBs) in the sediment and floodplain soils. During a four-year period from 2000 to 2003, several avian species were monitored for reproductive effects and concentrations of PCBs in tissues attributed to food chain transfer from contaminated sediments. The tree swallow (Tachycineta bicolor) was chosen as a model receptor for contamination of passerine species. A top-down methodology was used to evaluate the bioaccumulation of PCBs, including non-ortho and mono-ortho congeners, in tree swallow eggs, nestlings, and adults at the Kalamazoo River area of concern (KRAOC) and at an upstream reference site. Generally, a sixfold difference in tissue concentrations of total PCBs was observed between the two sites with concentrations in eggs and nestlings at the KRAOC ranging from 0.95 to 15 μg PCB/g wet weight. Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQsWHO-Avian) for PCBs, based on bird-specific World Health Organization toxic equivalence factors, were 10- to 30-fold greater in the KRAOC than at the reference location. Egg and nestling TEQsWHO-Avian ranged from 0.21 to 2.4 ng TEQ/g wet weight at the KRAOC. Hazard quotients calculated from literature-derived toxicity reference values were below 1.0 at both the target and the reference site based on the no-observed-adverse-effect level and the lowest-observed-adverse-effect level.
Speciation of aqueous methylmercury influences uptake by a freshwater alga (Selenastrum capricornutum)
Authors: Gorski Patrick R. , Armstrong David E. , Hurley James P. , Shafer Martin M. 
Published: January 2006

AbstractUptake of methylmercury (MeHg) by the alga Selenastrum capricornutum was measured in fresh water batch culture bioassays. The concentration of MeHg in the alga increased rapidly (within 15 min), reached a maximum by 6 h, and then declined because of growth dilution. The alga's rapid growth rate (doubling time, ∼10 h) contributed to the importance of growth dilution. Conditional first-order rate constants were calculated for uptake (k1 = 6.95 × 10−9 L/cell/h) and growth (kG = 0.07/h). A competitive synthetic ligand, disodium ethylenediaminetetra-acetate, formed strong complexes with MeHg and reduced MeHg uptake, consistent with the biotic ligand model. A conditional equilibrium formation constant (K) for the MeHg–algae complex was estimated to be approximately 1016 and was used to model the influence of natural ligands on MeHg bioavailability. Model results suggested MeHg would be most bioavailable at concentrations of dissolved organic matter (DOM) less than 10 mg/L and increasingly unavailable at higher DOM concentrations for the specific humic acid modeled. Similarly, at molar concentrations of sulfide (and, possibly, metal–sulfide clusters) equal to approximately half the MeHg concentration, MeHg was predicted to be unavailable to algae because of the formation of strong 2:1 MeHg–sulfide complexes.
Evaluating the risk to aquatic ecosystems posed by leachate from tire shred fill in roads using toxicity tests, toxicity identification evaluations, and groundwater modeling
Authors: Sheehan Patrick J. , Warmerdam John M. , Ogle Scott , Humphrey Dana N. , Patenaude Stacey M. 
Published: January 2006

AbstractThe risk to adjacent aquatic systems posed by leachates from scrap tires used in engineering applications has not been characterized adequately. Toxicity testing, toxicity identification evaluation (TIE), and groundwater modeling were used to determine the circumstances under which tire shreds could be used as roadbed fill with negligible risk to aquatic organisms in adjacent water bodies. Elevated levels of iron, manganese, and several other chemicals were found in tire shred leachates. However, chronic toxicity tests with Ceriodaphnia dubia and fathead minnows (Pimephales promelas) showed no adverse effects caused by leachates collected from tire shreds installed above the water table. Exposure to leachates collected from tire shreds installed below the water table resulted in significant reductions to both survival and reproduction in C. dubia. The TIE results indicated that exposure to soluble metals (likely ferrous iron primarily) and the formation of iron hydroxide precipitates on this invertebrate species likely were the causes of the observed effects. The available chemistry data show that iron concentrations in the affected groundwater decreased substantially within a short distance (0.61 m) downgradient of tire shred fill. Based on geochemical modeling, the use of tire shreds in applications below the water table is appropriate in settings where dissolved oxygen is greater than 2.0 mg/L, pH is greater than 5.8, and a downgradient buffer of approximately 3.0 m exists between the fill and the surface water. For settings with lower dissolved oxygen concentrations or lower pH, results of groundwater modeling indicate that a greater buffer distance (∼11 m) is needed to dilute the leachate to nontoxic levels under various soil and groundwater conditions solely through advection and dispersion processes.
Effect of short-term exposure to methyl-tert-butyl ether andtert-butyl alcohol on the hatch rate and development of the African catfish,Clarias gariepinus
Authors: Moreels David , Lodewijks Pieter , Zegers Hans , Rurangwa Eugène , Vromant Nico , Bastiaens Leen , Diels LUdo , Springael Dirk , Merckx Roel , Ollevier Frans 
Published: January 2006

AbstractMethyl tert-butyl ether (MTBE), a synthetic chemical used as a fuel additive, has been detected more frequently in the environment than previously. In this study, we examine the effects of MTBE (up to 100 mg/L) and its primary metabolite tert-butyl alcohol (TBA) (up to 1,400 mg/L) on the hatch rate and larval development of the African catfish Clarias gariepinus. Exposure to higher MTBE concentrations resulted in deformed eyes, mouthparts, and spinal cord and in increased larval mortality. Methyl tert-butyl ether exposure had no significant impact on egg viability, whereas TBA induced a decline of hatch rate. The MTBE can be regarded as a pollutant with toxicological effects on catfish larvae at concentrations above 50 mg/L. Although such concentrations greatly surpass present-day concentrations found in surface water (0.088 mg/L), concentrations up to 200 mg/L have been detected in groundwater.
Sorption kinetics of toluene in humic acid: A computational approach
Authors: Shih Yang-Hsin , Wu Shian-Chee , Lin Jyh-Shing , Lee Lien-Feng 
Published: January 2006

Abstract
Molecular dynamics, a computational technique aiming to describe the time-dependent movement of molecules, has been applied to study the sorption kinetics of volatile organic contaminants in soil organic matter. The molecular dynamics simulation results obtain reasonably accurate estimates of diffusion rates and activation energy of the penetration of a volatile organic compound molecule into a model humic substance. The sorption rate of toluene to humic acid decreases with the density of the humic acid matrix and increases with temperature. All the present results indicate that the sorption of toluene into humic acid is mainly diffusion controlled. Finally, the present studies have shown that molecular dynamics of volatile organic compounds in humic substances yields meaningful results, which help in the understanding of diffusion at the molecular level and which facilitate the problem-solving capability for removing the contaminants from the soils.
Chlorfenapyr and mallard ducks: Overview, study design, macroscopic effects, and analytical chemistry
Authors: Albers Peter H. , Klein Patrice N. , Green David E. , Melancon Mark J. , Bradley Brian P. , Noguchi GEORGE 
Published: January 2006

Abstract
The first commercial pesticide derived from a class of compounds known as halogenated pyrroles was registered for use in the United States in 2001. Chlorfenapyr degrades slowly in soil, sediment, and water and is highly toxic to birds. Information on biochemical or histological endpoints in birds is lacking; therefore, a two-year study was conducted to provide information needed to develop diagnostic criteria for chlorfenapyr toxicosis. In the first year, male mallard ducks were fed concentrations of 0, 2, 5, or 10 ppm technical chlorfenapyr or 5 ppm of a formulated product in their diet during a 10-week chronic exposure study. Survival, body weight, feed consumption (removal), behavior, and molt progression were monitored. Feed and liver were analyzed for chlorfenapyr and two metabolites. Five of 10 ducks in the 10-ppm group died, and neurotoxic effects were observed in the 5-and 10-ppm groups. Feed removal increased for ducks receiving chlorfenapyr and body weights of 5- and 10-ppm ducks were reduced. Loss of body fat, muscle atrophy, and bile retention were suggestive of metabolic disruption or a decreased ability to digest and absorb nutrients. Liver and kidney weights and liver and kidney weight/body weight ratios exhibited a positive response to concentrations of chlorfenapyr in the diet. Emaciation and elevated organ weight/body weight ratios are candidates for a suite of indicators of chronic chlorfenapyr exposure. Liver is the preferred tissue for chemical confirmation of exposure.
Effects of copper on enchytraeids in the field under differing soil moisture regimes
Authors: Maraldo Kristine , Christensen Bent , Strandberg Beate , Holmstrup Martin 
Published: January 2006

AbstractThe aims of this study were to investigate the combined effects of drought stress and copper pollution on enchytraeids under natural conditions in the field and to compare the results of laboratory toxicity tests with results of the field study. Such studies were conducted to increase the understanding of interactions between chemicals and natural stressors and assess the predictive value of standardized laboratory tests with enchytraeids. The combined effect of copper and summer drought on enchytraeids was investigated in an old copper-contaminated field site at Hygum, Denmark, in three areas with different copper burdens. Each area consisted of five plots, which were divided into two subplots: one control and one drought subplot in which precipitation was excluded for a 45-d period during summer. Enchytraeids were sampled in spring (before the enforced drought began) and in autumn (after recovery from drought). Clear effects of copper were evident in both the field and the laboratory experiment. The field population density and species composition was highly affected by copper at concentrations in the range 300 to 500 mg Cu/kg dry soil and higher. In particular, a greatly impoverished species diversity was found in the copper-polluted areas. The effects of copper in the field compared reasonably well with the results of the laboratory tests. Surprisingly, possible effects of summer drought in the field were not detected in the autumn sampling, perhaps because of rapid recovery of the enchytraeid populations in both unpolluted and copper-polluted areas.
Triclosan in a North Texas wastewater treatment plant and the influent and effluent of an experimental constructed wetland
Authors: Waltman Elise Lyn , Venables Barney J. , Waller William T. 
Published: January 2006

Abstract
The antimicrobial triclosan was analyzed in unfiltered samples from influent, effluent, and receiving stream and before and after a pilot-scale constructed wetland at a North Texas municipal wastewater treatment plant. Triclosan concentrations were reduced by 97 to 99% by the activated sludge treatment plant. Effluent concentrations were further reduced by passage through the constructed wetland, but receiving stream concentrations were not statistically significantly different from effluent concentrations. Effluent concentrations of triclosan were seasonal with highest concentrations occurring during the summer months. The effluent-dominated receiving stream maximum concentrations during summer months were below reported algal no-observed-effect concentrations based on biomass and growth rate but exceeded concentrations reported to cause shifts in algal community structure.
Metallothionein gene expression and protein levels in triploid and diploid oysters Crassostrea gigas after exposure to cadmium and zinc
Authors: Marie Véronique , Gonzalez Patrice , Baudrimont Magalie , Boutet Isabelle , Moraga Dario , Bourdineaud Jean-Paul , Boudou Alain 
Published: January 2006

Abstract
Quantitative real-time polymerase chain reaction (PCR) was used to compare for the first time the differential expression of metallothionein (MT) isoform genes, together with biosynthesis of the total MT proteins, in the gills of triploid and diploid juvenile Pacific oyster Crassostrea gigas in response to cadmium (Cd) and zinc (Zn) exposure. Oysters were exposed to Cd (0.133 μM), Zn (15.3 μM), and Cd+Zn for 14 d. Results showed similar response capacities to metal exposures in the two populations. No significant difference was revealed in terms of MT gene expression, MT protein synthesis, and Cd accumulation. However, triploid oysters bioaccumulated Zn 30% less efficiently than diploid oysters. Among the three MT isoform genes, CgMT2 appeared to be more expressed than CgMT1, whereas CgMT3 appeared to be anecdotal (106 times lower than CgMT2). CgMT2 and CgMT1 gene expression levels were increased sevenfold in the presence of Cd, whereas Zn appeared to have no effect. A twofold increase in MT protein levels occurred in response to Cd exposure. Discrepancies between mRNA and protein levels suggest that in C. gigas MT are regulated at the transcriptional level, as well as at the translational level.
Metabolism of uniconazole-P in water-sediment systems under illumination
Authors: Kodaka Rika , Sugano Terumi , Katagi Toshiyuki 
Published: January 2006

AbstractAerobic soil metabolism of uniconazole-P ([S]-E-1-[4-chlorophenyl]-4,4-dimethyl-2-[1,2,4-triazole-1-yl]-penten-3-ol) and the effect of illumination on metabolic profiles were studied in the water–sediment system when spiked to water. Uniconazole-P was gradually partitioned to the sediment with an aquatic half-life of 6.9 d in darkness with formation of bound residues. Illumination of the system from a xenon lamp (&gt;290 nm) greatly accelerated the degradation of uniconazole-P via photoinduced isomerization between E- and Z-isomers with a subsequent intramolecular cyclization, and its aquatic half-life was greatly reduced to 0.6 d. Kinetic analysis based on compartment models suggested the possible contribution of photodegradation at the water-sediment interface, leading to more formation of the cyclized derivative in the sediment.
Application of toxicity identification evaluation to sediment in a highly contaminated water reservoir in southeastern Brazil
Authors: Araújo Rosalina P. A. , Botta-Paschoal Clarice M. R. , Silvério Patrícia F. , Almeida Fernanda V. , Rodrigues Paulo F. , Umbuzeiro Gisela A. , Jardim Wilson F. , Mozeto Antonio A. 
Published: January 2006

AbstractRasgão Reservoir, located close to the Metropolitan region of São Paulo, Brazil, has been analyzed previously, and its sediment was found to be highly toxic, with high levels of metals and polycyclic aromatic hydrocarbons and a complete absence of benthic life. Polychlorinated biphenyls also were present, as was mutagenic activity, detected with the Salmonella/microsome assay. Because of the extremely complex mixture of contaminants in these sediments, a toxicity identification evaluation was performed on the pore water and elutriate using Ceriodaphnia dubia and Vibrio fischeri. Toxicity characterization, identification, and confirmation procedures were performed in one representative sample of the reservoir, and the results indicated that ammonia was the main cause of the toxicity detected with C. dubia in both sediment pore water and elutriate. Chemical analysis corroborated this observation by revealing un-ionized ammonia concentrations as high as 5.14 mg/L in pore water and 2.06 mg/L in elutriate. These high ammonia levels masked possible toxicity caused by other classes of compounds. The toxicity detected with V. fischeri decreased with the time of sample storage and was related to the organic fraction of the pore water and the elutriate, in which compounds such as benzothiazole and nonylphenol were detected.
Characterization of putative ligands for a fish gonadal androgen receptor in a pulp mill effluent
Authors: Larsson D. G. Joakim , Adolfsson-Erici Margaretha , Thomas Peter 
Published: January 2006

AbstractFish exposed to pulp and paper mill effluents often become masculinized. A plausible hypothesisis that this is caused by activation of androgen receptors. The present study aimed to investigate if ligands for the fish gonadal androgen receptor (AR2) are present in pulp mill effluent and to characterize/identify these compounds. Extracts of both primary and biologically treated effluents from a Swedish kraft pulp mill were fractionated chemically. Fractions were tested in competitive binding assays for AR2 from ovaries of the Atlantic croaker (Micropogonias undulatus). Primary effluent contained 96 ng dihydrotestosterone equivalents/L, whereas biologically treated effluent was 16 times less potent. Further fractionations and assays of binding activities were performed on the primary effluent. Eight final fractions displaced androgen in the binding assay, and gas chromatography/mass spectrometry (GC/MS) analyses revealed that these contained 37 detectable compounds that were not present in inactive fractions. The majority were moderately polar compounds between 200 and 400 g/mol with hydroxyl/carbonyl groups. Two compounds were ruled out because of their lack of binding to AR2. The mass spectra of a third compound matched that of 4-hydroxy-3 (2-(4-hydroxy-3methoxophenyl)ethyl)-5-metoxyacetophenon, but the remaining candidates could not be fully identified. A search for 21 known steroidal AR2 ligands showed that progesterone, a relatively strong AR2 ligand, was present in the primary effluent (1.6 μg/L) but was removed during the biological treatment step. The detection of multiple fractions with significant binding activity indicates that a variety of compounds in effluents have the potential to masculinize fish near pulp mills via an androgen receptor-mediated mechanism.
Organochlorine compounds (polychlorinated biphenyls and pesticides) and polycyclic aromatic hydrocarbons in populations of Hexaplex trunculus affected by imposex in the Lagoon of Venice, Italy
Authors: Maran Chiara , Centanni Elena , Pellizzato Francesca , Pavoni Bruno 
Published: January 2006

Abstract
Concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides, and polycyclic aromatic hydrocarbons (PAHs) were measured in gastropods from the Lagoon of Venice, Italy. The visceral coil and the rest of the soft body of organisms (Hexaplex trunculus) sampled at two stations inside the lagoon and three stations on the seaward side were analyzed to evaluate their contamination levels. Preferential accumulation of PCBs and pesticides in the visceral coil (&gt;80%) compared with the rest of the soft body was observed, whereas on average, PAHs showed no preferential partitioning. Differences between levels of organochlorine contaminants in the gastropods highlighted a gradient of pollution from the stations inside the lagoon (PCBs, 45–363 ng/g; pesticides, 4–51 ng/g) to the sea (PCBs, 13–131 ng/g; pesticides, 2–29 ng/g). The possible role of the three classes of contaminants, in addition to that of organotin compounds (OTCs), previously analyzed in the same samples, in causing one of the anatomic modifications because of imposex in this gastropod also was studied. A modeling approach by partial least squares (PLS) in latent variables was applied to explain the penis length of imposex-affected females with concentrations of organic pollutants. The synergistic role of PCBs, pesticides, and OTCs was evidenced, whereas the contribution of PAHs appeared to be very low.