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Aryl Hydrocarbon (aryl + hydrocarbon)

Distribution by Scientific Domains
Life Sciences100%

Terms modified by Aryl Hydrocarbon

  • aryl hydrocarbon hydroxylase
    		•
  • aryl hydrocarbon receptor
    		•

    Selected Abstracts

    Evaluating polycyclic aromatic hydrocarbons using a yeast bioassay

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2007
    Abeer Alnafisi
    Abstract Sixteen polycyclic aromatic hydrocarbons (PAHs) were evaluated for the ability to activate aryl hydrocarbon (Ah) receptor signaling in a yeast-based bioassay. Individual PAHs were classified as inactive or as weakly, moderately, or strongly active based on induction of human Ah receptor signaling. Indeno[1,2,3- cd]pyrene, chrysene, benzo[a]anthracene, benzo[a]pyrene, benzo[j]fluoranthene, and benzo[k]fluoranthene were the most potent activators of human Ah receptor signaling. Various mixtures of PAHs had additive or synergistic effects in the bioassay. Environmental samples from the New Orleans (Louisiana, USA) and Detroit (Michigan, USA) areas that were previously analyzed for PAH composition and quantity were tested in this bioassay. Weak but statistically significant relationships were found when the analytically measured levels of PAHs were correlated with sample dilutions that gave 25% effective concentration signaling levels in the Ah receptor assay. We conclude that this Ah receptor signaling assay may be useful for preliminary biomonitoring of samples for PAHs and other Ah receptor ligands. [source]

    Evaluation of the methoxytriazine herbicide prometon using a short-term fathead minnow reproduction test and a suite of in vitro bioassays

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2006
    Daniel L. Villeneuve
    Abstract Prometon is one of the most consistently detected herbicides in the U.S. environment. However, no previous assessment of the potential for prometon or related methoxytriazine herbicides to act as endocrine-disrupting chemicals has been conducted. This study used an array of in vitro bioassays to assess whether prometon, atraton, terbumeton, or secbumeton might act as potent (ant)agonists of the aryl hydrocarbon, estrogen, androgen, or glucocorticoid receptors or as aromatase inhibitors or inducers in vitro. Potential effects of prometon were also evaluated using a 21-d fathead minnow reproduction assay. Concentrations of methoxytriazines, as great as 1 mg/L (4.4 ,M), did not induce significant dioxin-like responses in H4IIE-luc cells, estrogenic responses in MVLN cells, or androgen or glucocorticoid receptor,mediated responses in MDA-kb2 cells, nor did the methoxytriazines significantly affect aromatase activity in vitro. In the fathead minnow assay, exposure to 20, 200, or 1,000 ,g prometon/L significantly reduced the weight of the male fat pad (an androgen-responsive tissue) relative to body weight. Exposure to 20 ,g prometon/L significantly increased female plasma testosterone concentrations, but the effect was not observed at greater concentrations. Overall, prometon did not significantly reduce fecundity over the 21-d exposure, nor were other endpoints, including plasma vitellogenin and estradiol concentrations, brain and ovary aromatase activity, and male tubercle index, significantly affected. Evidence from our work suggests that prometon may cause subtle endocrine and/or reproductive effects in fathead minnows, but no clear mechanism of action was observed. The relevance of these effects to hazard assessment for the pesticide is uncertain. [source]

    Induction of cytochrome P4501A in African brown house snake (Lamprophis fuliginosus) primary hepatocytes

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2006
    Markus Hecker
    Abstract Ahough there have been numerous sudies involving fish, birds, and mammals, little is known about the response of the cytochrome P4501A system of snakes to halogenated aromatic hydrocarbons (HAHs). The present study describes the induction of ethoxyresorufin- O -deethylase (EROD) in primary hepatocytes of the African brown house snake (Lamprophis fuliginosus). Hepatocytes were exposed in multiwell plates to 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) and four different non- ortho -substi-tuted coplanar polychlorinated biphenyls (PCBs 77, 81, 126, and 169). Exposure to TCDD and PCB 126 resulted in a dose-dependent increase in EROD activity, with maximum inducible EROD activities of 177 ± 56 (mean ± SEM) and 101.1 ± 55 pmol/min/mg protein for TCDD and PCB 126, respectively. None of the other PCBs caused a measurable induction of EROD, which suggests reduced inducibility of snake hepatocytes compared to some vertebrate taxa. Median effective concentrations (EC50s) were 0.16 ± 0.03 nM for TCDD and 8.25 ± 4.14 nM for PCB 126. The relative potency (REP20,80) range for PCB 126 was 0.044 to 0.046. Compared to results from in vitro systems using other vertebrate species, both the maximum inducibility and the REPs estimated for L. fuliginosus were within the same range as those reported for mammals and the more sensitive bird species but were greater than the values reported for most fish species. In conclusion, induction of EROD activity in primary hepatocytes appears to be a useful approach for evaluating the dioxin-like potencies of aryl hydrocarbon,receptor agonists in snakes. The test system offers a method for rapid screening of reptilian responsiveness to these compounds using smaller numbers of organisms than with in vivo studies, an important consideration for many declining reptile species. [source]

    Monitoring river sediments contaminated predominantly with polyaromatic hydrocarbons by chemical and in vitro bioassay techniques

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2001
    Jan Vondrá
    Abstract Extracts of sediment samples collected from the Morava River and its tributaries (Czech Republic) were examined for mutagenic, dioxin-like, and estrogenic activities. Moreover, the human leukemic HL-60 cell line was tested as a potential model for the detection of effects of environmental contaminants on cell proliferation and differentiation processes. Analytical data indicate that the sediments were contaminated predominantly with polycyclic aromatic hydrocarbons (PAHs) and phthalate esters. The sums of concentrations of 16 U.S. Environmental Protection Agency priority PAHs ranged from 0.8 to 13.2 ,g/g and those of phthalates reached up to 3,000 ng/g, while only low levels of chlorinated hydrocarbons were found. The main goal of the present study was to determine effects of PAH prevalence on in vitro bioassays, with special emphasis on dioxin-like activity. The dioxin-like activity was tested using a reporter gene assay based on chemical-activated luciferase expression (the CALUX assay). Significant dioxin-like activity (2.6,40.1 ,g/g benzo[a]pyrene equivalents and 5.9,48.2 ng/g 2,3,7,8-tetrachlorodibenzo- p -dioxin equivalents) was detected in all samples, and the results obtained with various exposure times or with both crude and PAH-deprived extracts indicate that the response was probably caused almost exclusively by the presence of high concentrations of PAHs. This corresponds with results of chemical analyses and indicates that various exposure times would allow a discrimination between dioxin-like activities of persistent compounds and easily metabolized aryl hydrocarbon (Ah) receptor inducers. Only sediment extracts containing the highest concentrations of PAHs were mutagenic, as determined by the umu assay. Estrogenic activity was found in several samples (4.75,22.61 pg/g estradiol equivalents) using cells stably transfected with an estrogen-responsive element linked to a luciferase promoter. Noncytotoxic doses of extracts had no effects on HL-60 cell proliferation, while two of the tested crude extracts significantly enhanced their all- trans retinoic acid-induced differentiation. These activities were not associated with phthalate esters and/or PAHs. Our results indicate that cellular and biochemical in vitro assays based on various specific modes of action may yield data complementary to results of mutagenicity tests and that they could be useful in environmental risk assessment. High levels of PAHs are apparently associated with dioxin-like and mutagenic activities rather than with estrogenic activity. [source]

    Xenobiotic activity in serum and sperm chromatin integrity in European and inuit populations

    MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 4 2008
    Tanja Krüger
    Abstract Lipophilic persistent organic pollutants (POPs) are ubiquitous in the environment and suspected to interfere with hormone activities and reproduction. In previous studies we demonstrated that POP exposure can affect sperm DNA integrity and differences between Inuits and Europeans in sperm DNA integrity and xenobiotic activity were observed. The aim of this study was to investigate possible relations between human sperm chromatin integrity and the xenobiotic serum activity of lipophilic POPs assessed as effects on the estrogen (ER), androgen (AR), and/or aryl hydrocarbon (AhR) receptors. Human sperm chromatin integrity was assessed as DNA fragmentation index (%DFI) and high DNA stainability (%HDS) using the flow cytometric sperm chromatin structure assay (SCSA). Xenobiotic receptor activities were determined using chemically activated luciferase gene expression (CALUX) assay. The study included 53 Greenlandic Inuits and 247 Europeans (Sweden, Warsaw (Poland) and Kharkiv (Ukraine)). A heterogeneous pattern of correlations was found. For Inuits, ER and AhR activities and %DFI were inversely correlated, whereas a positive correlation between AR activity and %DFI was found for Europeans. In contrast, no correlation between receptor activities and %HDS was observed for Inuits but for Europeans positive and negative correlations were observed between ER and AR activities and %HDS, respectively. We suggest that the different patterns of xenobiotic serum activities, in combination with diet associated factors and/or genetics, might be connected to the observed differences in sperm chromatin integrity between the Inuits and Europeans. Mol. Reprod. Dev. 75: 669,680, 2008. © 2007 Wiley-Liss, Inc. [source]

    Aryl hydrocarbon bioaccessibility to small mammals from arctic plants using in vitro techniques

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2007
    Sarah A. Armstrong
    Abstract Through their diet, herbivores inhabiting contaminated sites may be chronically exposed to a variety of aryl hydrocarbons (e.g., dioxins and polycyclic aromatic hydrocarbons [PAHs]). However, little is known about how differences in morphology and physiology among plant species alter the environmental accumulation of aryl hydrocarbons or their release and subsequent activity in the gastrointestinal tract of herbivores after ingestion. In the present study, the activity of aryl hydrocarbons during digestion was examined using six Arctic plant species growing in impacted and reference sites near Inuvik, Northwest Territories, Canada. The plant species studied were black spruce (Picea mariana), labrador tea (Ledum groenlandicum), bog birch (Betula glandulosa), green alder (Alnus crispa), water sedge (Carex aquatilis), and little-tree willow (Salix arbusculoides). Plants were digested using a simulator of the upper digestive tract, and aryl hydrocarbon release was evaluated using an aryl hydrocarbon-receptor assay. Bioaccessible aryl hydrocarbon activity varied among the plant species tested. The species with the greatest activity was green alder, and the species with the least activity was black spruce. Further investigation revealed that digested plant extracts may antagonize the aryl hydrocarbon receptor and prevent bioactivation of the aryl compound benzo[a]pyrene. Thus, PAH risk from the ingestion of vegetation varies among plant species and may depend on antagonists present in the vegetation. [source]