| 1. |
- Andersson, Erik, et al.
(author)
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Incomplete degradation of polycyclic aromatic hydrocarbons in soil inoculated with wood rotting fungi and their effect on the indigenous soil bacteria.
- 2003
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In: Rangeland Ecology & Management. - : Wiley. - 1550-7424. ; 22:6, s. 1238-1243
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Journal article (peer-reviewed)abstract
- Soil artificially contaminated with fluorene, phenanthrene, pyrene, and benz[a]anthracene was inoculated with the wood-rotting fungi Pleurotus ostreatus and Antrodia vaillantii. During 12 weeks of incubation, polycyclic aromatic hydrocarbon (PAH) degradation and the formation of persistent degradation products were monitored by chemical analysis. In addition, the effect on the indigenous soil bacteria was studied by plate count techniques and by measuring the concentration of bacteria-specific phospholipid fatty acids (PLFAs). In both soils inoculated with fungi, the PAH degradation was enhanced compared to the control soil without fungi. The white-rot fungus P. ostreatus accelerated the degradation rate radically the first weeks, while the effect of the brown-rot fungus was more pronounced at later stages during the 12-week study. In a soil with no amendments, the final degradation result was similar to that in the soil with added fungi, although the degradation pattern for the individual PAHs was different. Furthermore, the degradation by P. ostreatus was accompanied by an accumulation of PAH metabolites, that is, 9-fluorenone, benz[a]anthracene-7,12-dione, and two compounds identified as 4-hydroxy-9-fluorenone and 4-oxapyrene-5-one, that was not seen in the other soils. The inoculation with the white-rot fungus also had a large negative effect on the indigenous soil bacteria. This could be an important drawback of using the white-rot fungus P. ostreatus in soil bioremediation since a sequential fungal–bacterial degradation probably is needed for a complete degradation of PAHs in soil. In the soil inoculated with A. vaillantii, on the other hand, no metabolites accumulated, and no negative effects were observed on the indigenous microorganisms.
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| 2. |
- Andersson, Patrik, et al.
(author)
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Multivariate modeling of polychlorinated biphenyl-induced CYP1A activity in hepatocytes from three different species : ranking scales and species differences
- 2000
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In: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 19:5, s. 1454-1463
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Journal article (peer-reviewed)abstract
- Cytochrome P4501A–induced activity of 20 selected polychlorinated biphenyls (PCBs) was evaluated by measuring ethoxyresorufin-O-deethylase and methoxyresorufin-O-demethylase activities induced in the hepatocytes of cynomolgus monkeys, male castrated pigs, and chicken embryos. Quantitative structure-activity relationships have been established, including 52 physi-cochemical parameters and different measures of the dose-response curves. Relative effect potencies are predicted for the 154 tetra-to hepta-PCBs and reported for the most potent congeners according to both EC50 and maximal response values. Important physicochemical parameters of the PCBs as related to the modeled activity are parts of their ultraviolet absorption spectra, the Henry's law constant, the ionization potential, and the octanol-water partition coefficient. Interspecies differences were found in terms of varied sensitivity to different structural subgroups of the compounds. The chicken hepatocyte assay showed the most specific structure-activity relationship, with high activity for the non-ortho PCBs, whereas the pig hepatocytes responded even for some di- to tetra-ortho PCBs. An interspecies response, the principal induction potency, is presented for the 41 most potent PCBs. These responses showed strong correlation with the toxic equivalency factors and are likely to be useful in risk assessment of the compounds.
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| 3. |
- Bengtsson, Göran, et al.
(author)
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Reduced grazing rates in Daphnia pulex caused by contaminants: Implications for trophic cascades
- 2004
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In: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 23:11, s. 2641-2648
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Journal article (peer-reviewed)abstract
- Ecotoxicological endpoints based on behavioral traits (e.g., predator avoidance, feeding, and locomotion) may be more sensitive and give more insights into patterns of sublethal toxicity than survivorship tests. In this study, the density-dependent grazing rate of Daphnia pulex pre-exposed to p,p'-dichlorodiphenyldichloroethylene (DDE) (insecticide metabolite) and glyphosate (herbicide), via water or a vector, Scenedesmus spp., was assayed in laboratory experiments. The phytoplankton biomass was estimated from the chlorophyll content, and the pesticide uptake and turnover pattern in Daphnia and Scenedestnus were determined from parallel experiments with a radiolabeled source. Scenedestnus spp. relative net growth rate was inversely and linearly related to the density of the grazer. Daphnia pulex exhibited significant reductions in grazing rate: 30% for those pre-exposed to p,p'DDE via water and 40% for D. pulex pre-exposed to glyphosate via Scenedesmus spp. Through the process of trophic cascading, this impaired grazing allowed Scenedesmus spp. to grow at higher rates, 70 and 60%, respectively. The reduced grazing efficiencies were associated with the treatments that gave the highest body burden of p,p'-DDE (70 mug/g dry wt) and the lowest of glyphosate (13 mg/g dry wt). The pattern of results suggests a toxic effect of p,p'-DDE on D. pulex and a growth enhancement of Scenedesmus spp. in response to nitrogen and phosphorus in glyphosate excreted by D. pulex.
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| 4. |
- Bergknut, Magnus, et al.
(author)
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Assessment of the availability of polycyclic aromatic hydrocarbons from gasworks soil using different extraction solvents and techniques
- 2004
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In: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 23:8, s. 1861-1866
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Journal article (peer-reviewed)abstract
- This study was designed to assess the availability of polycyclic aromatic hydrocarbons (PAHs) present at a gasworks site to different soil remediation techniques. The study examined the effect on PAH availability of using different organic solvents, the degree of pretreatment, and the extraction time. In total, 25 PAHs (with two to six fused rings) and five carbonyl derivatives were measured. The results indicated that the PAHs and their derivatives were bound loosely to the surface of the studied soil and that there were no significant kinetic boundaries associated with the extraction of the PAHs. Furthermore, it was concluded that the studied soil was not suitable for bioremediation, as the concentration of PAHs with low molecular weight were limited. However, pressurized liquid extraction (PLE) with methanol as the solvent extracted 97% of all PAHs and PAH-derivatives, indicating that extraction may be effective as part of a soil remediation technique for old gasworks soils.
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| 5. |
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| 6. |
- Hegelund, Tove, 1971, et al.
(author)
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Effects of the antifungal imidazole ketoconazole on CYPIA and CYP3A in rainbow trout and killifish
- 2004
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In: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 23:5, s. 1326-1334
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Journal article (peer-reviewed)abstract
- The use of N-substituted imidazoles is widespread, and imidazole and triazole fungicides have been detected in the aquatic environment and shown to bioaccumulate in fish. We have investigated effects of the model imidazole, ketoconazole, on drug-metabolizing cytochrome P450 (CYP) forms. We focused on cytochrome P4501A (CYP1A) and cytochrome P4503A (CYP3A) expression and activities in juvenile rainbow trout and in adult killifish. The CYP1A expression (mRNA, protein) and activity was induced in rainbow trout, whereas in killifish no effect of ketoconazole on CYP1A protein expression was observed. A biphasic dose-response relationship was observed between ketoconazole exposure and hepatic CYP1A-mediated ethoxyresorufin O-deethylase (EROD) activity in rainbow trout in vitro and in vivo, implying that higher doses of ketoconazole inhibit CYP1A activities. Slight induction of CYP3A protein levels was observed in rainbow trout exposed in vivo to ketoconazole. However, the CYP3A-mediated benzyloxy-4-[trifluoromethyl]-coumarin (BFC) O-debenzyloxylase activity was reduced in rainbow trout and killifish treated with ketoconazole. In vitro inhibition studies confirmed that ketoconazole was a potent inhibitor of both CYP3A and CYP1A enzyme activities in these species. This Study showed that ketoconazole induced CYP1A and CYP3A expression in rainbow trout. However, the most pronounced effect of ketoconazole was a 60 to 90% decrease in CYP3A catalytic activities in rainbow trout and in killifish.
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| 7. |
- Jonsson, Susanne, 1965-, et al.
(author)
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Toxicity of mono- and diesters of o-phthalic esters to a crustacean, a green alga, and a bacterium
- 2003
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In: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 22:12, s. 3037-3043
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Journal article (peer-reviewed)abstract
- The degradation of phthalic acid diesters may lead to formation of o-phthalic acid and phthalic acid monoesters. The ecotoxic properties of the monoesters have never been systematically investigated, and concern has been raised that these degradation products may be more toxic than the diesters. Therefore, the aquatic toxicity of phthalic acid, six monoesters, and five diesters of o-phthalic acid was tested in three standardized toxicity tests using the bacteria Vibrio fischeri, the green algae Pseudokirchneriella subcapitata, and the crustacean Daphnia magna. The monoesters tested were monomethyl, monoethyl, monobutyl, monobenzyl, mono(2-ethylhexyl), and monodecyl phthalate, while the diesters tested were dimethyl, diethyl, dibutyl, butylbentyl, and di(2-ethylhexyl)phthalate, which were assumed to be below their water solubility. The median effective concentration (EC50) values for the three organisms ranged from 103 mg/L to >4,710 mg/L for phthalic acid, and corresponding values for the monoesters ranged from 2.3 mg/L (monodecyl phthalate in bacteria test) to 4,130 mg/L (monomethyl phthalate in bacteria test). Dimethyl and diethyl phthalate were found to be the least toxic of the diesters (EC50 26.2–377 mg/L), and the toxicity of the other diesters (butylbenzyl and dibutyl phthalate) ranged from 0.96 to 7.74 mg/L. In general, the phthalate monoesters (degradation products) were less toxic than the corresponding diesters (mother compounds).
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| 8. |
- Jönsson, E. Maria, et al.
(author)
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Cell-specific CYP1A expression and benzo(a)pyrene adduct formation in gills of rainbow trout (Oncorhynchus mykiss ) following CYP1A induction in the laboratory and in the field
- 2004
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In: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 23:4, s. 874-882
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Journal article (peer-reviewed)abstract
- The effect of cytochrome P4501A (CYP1A)induction on cell-specific benzo[a]pyrene (BaP) adduct formation was studied in rainbow trout (Oncorhynchus mykiss) gills. Fish preexposed to β-naphthoflavone (βNF) or caged in a polluted river were exposed to waterborne 3H-benzo[a]pyrene (3H-BaP). The 3H-benzo[a]pyrene adducts in the gill filaments were localized by autoradiography and CYP1A protein by immunohistochemistry. Ethoxyresorufin O-deethylase (EROD) activity was measured using a gill filament-based ex vivo assay. Branchial 3H-BaP binding and EROD activity were enhanced by exposure to βNF or to the river water, and completely blocked by the CYP1A inhibitor ellipticine. The predominant sites of adduct formation were in epithelium of the secondary lamellae and in epithelium of the efferent edge of the gill filament. In βNF-exposed fish, the strongest CYP1A immunoreactivity was observed in differentiating cells and in pillar cells. In fish caged in the polluted river, strong CYP1A immunoreactivity was found in most cells in the secondary lamellae, whereas the primary lamellae were almost devoid of immunoreactivity. Our results reveal a discrepancy between the localization of CYP1A protein and BaP adducts in the gill. Consequently, other factors, such as bioavailability of waterborne polycyclic aromatic hydrocarbons (PAHs) to the target cells, are important for the localization of PAH adducts in the gill.
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| 9. |
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| 10. |
- Landberg, Tommy, et al.
(author)
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Interclonal variation of heavy metal interactions inSalix viminalis
- 2002
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In: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 21:12, s. 2669-2674
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Journal article (peer-reviewed)abstract
- In the complex chemistry of soil, interactions between metals can be expected and these affect the uptake of the metals by the plants. The role of the metal–metal interaction may vary between different plants. This study was performed to investigate if variations exist in the interactions between Cd, Cu, and Zn on toxicity and accumulation of these metals in different clones of Salix viminalis. Two studies were performed. First, to study interaction at uptake, 10 clones with high or low accumulation capacity of Cd, Cu, and Zn, respectively, were treated with 0.3 μM Cd, 0.1 μM Cu, and 3 μM Zn (all three metals at the same time or separately). Second, to study the effect of one of the metals on the sensitivity of the plant to the other metals, three clones with high or low sensitivity to each of the three metals were used in a modified Weibull analysis. Examination of the results shows that interclonal variation exists in effects of metal interaction on metal accumulation and sensitivity exists. The uptake experiment showed that accumulation of Cu was decreased by the other metals, but only in clones with high Cu-accumulating properties because of decreased net uptake of Cu. The accumulation of Zn in roots was increased two- to threefold in all clones in the presence of the other metals because of a decreased translocation of Zn to the shoot. The accumulation of Cd was not changed by the presence of the other metals in any of the clones. The second experiment showed that the effect of interactions between the different metals on metal toxicity was present in all clones but appeared most frequently in the clone with high Zn resistance. Synergistic effects between Cu and Zn in the Zn-resistant clone suggested that this clone had evolved an additional site of toxic action that was absent in the other clones.
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