| 1. |
- Bluhm, Kerstin, et al.
(författare)
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Impacts of Different Exposure Scenarios on Transcript Abundances in Danio rerio Embryos when Investigating the Toxicological Burden of Riverine Sediments
- 2014
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Ingår i: PLOS ONE. - San francisco, USA : Public Library of Science. - 1932-6203. ; 9:9
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Recently, a proof-of-concept study revealed the suitability of transcriptome analyses to obtain and assess changes in the abundance of transcripts in zebrafish (Danio rerio) embryos after exposure to organic sediment extracts. The present study investigated changes in the transcript abundance in zebrafish embryos exposed to whole sediment samples and corresponding organic extracts in order to identify the impact of different exposure pathways on sediment toxicity.Materials and Methods: Danio rerio embryos were exposed to sublethal concentrations of three sediment samples from the Danube River, Germany. The sediment samples were investigated both as freeze-dried samples and as organic extracts. Silica dust and a process control of the extraction procedure were used as references. After exposure, mRNA was isolated and changes in profiles of gene expression levels were examined by an oligonucleotide microarray. The microarray results were compared with bioassays, chemical analysis of the sediments and profiles of gene expression levels induced by several single substances.Results and Discussion: The microarray approach elucidated significant changes in the abundance of transcripts in exposed zebrafish embryos compared to the references. Generally, results could be related to Ah-receptor-mediated effects asconfirmed by bioassays and chemical analysis of dioxin-like contaminants, as well as to exposure to stress-inducing compounds. Furthermore, the results indicated that mixtures of chemicals, as present in sediment and extract samples, result in complex changes of gene expression level profiles difficult to compare with profiles induced by single chemical substances. Specifically, patterns of transcript abundances were less influenced by the chemical composition at the sampling site compared t the method of exposure (sediment/extract). This effect might be related to different bioavailability of chemicals.Conclusions: The apparent difference between the exposure scenarios is an important aspect that needs to be addressed when conducting analyses of alterations in the expression level of mRNA.
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| 2. |
- Böttcher, Melanie, et al.
(författare)
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Comparison of in vitro and in situ genotoxicity in the Danube River by means of the comet assay and the micronucleus test
- 2010
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Ingår i: Mutation research. Genetic toxicology and environmental mutagenesis. - Amsterdam, Neteherlands : Elsevier. - 1383-5718 .- 1879-3592. ; 700:1-2, s. 11-17
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Tidskriftsartikel (refereegranskat)abstract
- Genotoxicity can be correlated with adverse reproductive effects or may even result in elevated extinction risk for particular species of an ecosystem. It may thus be a valuable tool for screening of pollution and potential environmental harm. Since many genotoxicants tend to adsorb on to particulate matter, sediments and suspended materials are of particular interest for genotoxicity screening under field conditions. In order to correlate the genotoxic potential of sediments with genetic damage in fish, rainbow-trout liver (RTL-W1) cells were exposed in vitro to acetone extracts of sediments collected at 10 selected sites along the upper Danube River and analyzed in the comet and micronucleus assays. These in vitro results were compared with micronucleus formation in erythrocytes of the European barbel (Barbus barbus) caught int he field. The two in vitro bioassays showed excellent correlation, indicating comparability of genotoxic potentials in vitro. Sampling sites could be clearly differentiated with respect to severity of effects, with Rottenacker as the most heavily contaminated site, Ehingen and Schwarzach as moderately genotoxic,and with the weakest effects in the tributary Lauchert. All other sediment extracts showed intermediate genotoxic or clastogenic effects. In situ, micronucleus formation in barbel erythrocytes indicated severe genotoxicity at Rottenacker, moderate effects at Ehingen, but minor contamination at Riedlingen and Sigmaringen. In situ observations thus showed excellent correlation with corresponding in vitro tests and document the ecological relevance of in vitro studies with sediment extracts. With respect to the ecological status of the Danube River, the results overall indicate a moderate to severe genotoxic potential with a highly differential localization.
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| 3. |
- Kosmehl, Thomas, et al.
(författare)
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A combined DNA-microarray and mechanism-specific toxicity approach with zebrafish embryos to investigate the pollution of river sediments
- 2012
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Ingår i: Reproductive Toxicology. - Oxford, United Kingdom : Elsevier. - 0890-6238 .- 1873-1708. ; 33:2, s. 245-253
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Tidskriftsartikel (refereegranskat)abstract
- The zebrafish embryo has repeatedly proved to be a useful model for the analysis of effects by environmental toxicants. This proof-of-concept study was performed to investigate if an approach combining mechanism-specific bioassays with microarray techniques can obtain more in-depth insights into theecotoxicity of complex pollutant mixtures as present, e.g., in sediment extracts. For this end, altered gene expression was compared to data from established bioassays as well as to results from chemical analysis. Mechanism-specific biotests indicated a defined hazard potential of the sediment extracts, and microarray analysis revealed several classes of significantly regulated genes which could be related to the hazard potential. Results indicate that potential classes of contaminants can be assigned to sediment extracts by both classical biomarker genes and corresponding expression profile analyses of known substances. However, it is difficult to distinguish between specific responses and more universal detoxification of the organism.
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| 4. |
- Fassbender, Christopher, et al.
(författare)
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Gene-TEQ-a standardized comparative assessment of effects in the comet assay using genotoxicity equivalents
- 2012
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Ingår i: Journal of Environmental Monitoring. - Cambridge, United Kingdom : The Royal Society of Chemistry. - 1464-0325 .- 1464-0333. ; 14, s. 1325-1334
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Tidskriftsartikel (refereegranskat)abstract
- Existing methods for the comparison of genotoxic effects in the comet assay bear considerable disadvantages such as the problem to link information about concentration dependence and severity of effects. Moreover, given the lack of standardized protocols and the use of various standards, it may be extremely difficult to compare different studies. In order to provide a method for standardized comparative assessment of genotoxic effects, the concept of genotoxicity equivalents (Gene-TEQ) was developed. As potential reference compounds for genotoxic effects, three directly acting (N-methyl-N0-nitro-N-nitrosoguanidine (MNNG), methyl-methanesulfonate, and N-methyl-N-nitrosourea) and three indirectly acting (cyclophosphamide, dimethylnitrosamine, and 4-nitroquinoline-oxide) genotoxic substances were compared with respect to their cytotoxic (neutral red) and genotoxic (cometassay) concentration–response profiles in the permanent fish cell line RTL-W1. For further comparison, two sediment extracts from the upper Danube River were investigated as environmental samples. Based on the results of cytotoxicity and genotoxicity testing, MNNG was selected as the reference compound. At several exposure levels and durations, genotoxic effects of both the other pure substances and the environmental samples were calculated as percentages of the maximum MNNGeffect and related to the absolute MNNG effect (EC values). Thus, genotoxicity equivalent factors(Gene-TEQs) relative to MNNG could be calculated. Gene-TEQs can easily be applied to puresubstances, mixtures and field samples to provide information about their toxicity relative to the reference compound. Furthermore, the Gene-TEQ concept allows a direct comparison of environmental samples from different laboratories.
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| 5. |
- Grund, Stefanie, et al.
(författare)
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Assessment of fish health status in the Upper Danube River by investigation of ultrastructural alterations in the liver of barbel Barbus barbus
- 2010
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Ingår i: Diseases of Aquatic Organisms. - Luhe, Germany : Inter-Research. - 0177-5103 .- 1616-1580. ; 23, s. 235-248
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Tidskriftsartikel (refereegranskat)abstract
- Despite intensive efforts and tightened guidelines for improvement of water quality over the last 2 decades, declines of fish populations have been reported for several rivers around the world. The present study forms part of a comprehensive weight-of-evidence approach, which aims to identify potential causes for the decline in fish catches observed in the Upper Danube River. The major focus of the present study is the investigation of the health status of wild barbel Barbus barbus L. collected from 3 locations along the Danube River, which experienced different levels of contamination. Whereas the comparison of the condition factor (CF) of field fish with that of control fish revealed no differences, ultrastructural investigations indicated severe disturbance of hepatic cell metabolism in field fish from the more contaminated sites Rottenacker and Ehingen, compared to both control fish and field fish from the less contaminated site Riedlingen. The ultrastructural analysis provided information about reactions of e.g. the rough endoplasmic reticulum, peroxisomes, andmitochondria, indicating an impaired health status of barbel at the sampling sites Rottenacker and Ehingen. Even though a straightforward cause-effect relationship between sediment contamination and ultrastructural alterations could not be established, based on a meta-analysis and toxicity assays it may be suggested that sediment-bound xenobiotics at least partly account for the hepatocellular changes. A relationship between impaired fish health status and the decline of fish catches along the Upper Danube River cannot be excluded.
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| 6. |
- Hinger, Gunnar, et al.
(författare)
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Some heterocyclic aromatic compounds are Ah receptor agonists in the DR-CALUX assay and the EROD assay with RTL-W1 cells
- 2011
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 18:8, s. 1297-1304
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Heterocyclic aromatic compounds containing nitrogen, sulfur, or oxygen heteroatoms (NSO-HET) have been detected in air, soil, marine, and freshwater systems. However, only few publications are available investigating NSO-HET using in vitro bioassays. To support better characterization of environmental samples, selected NSO-HET were screened for dioxin-like activity in two bioassays. Methods The present study focuses on the identification and quantification of dioxin-like effects of 12 NSO-HET using the DR-CALUX assay, and the 7-ethoxyresorufin-O-deethylase (EROD) assay with the permanent fish liver cell line RTL-W1. Changes of the total medium compound concentrations during the test procedure due to, e.g., sorption or volatilization were quantified using GC/MS. Results The NSO-HET benzofuran, 2,3-dimethylbenzofuran, dibenzofuran, dibenzothiophen, acridine, xanthene, and carbazole caused a response in the DR-CALUX assay. Only benzofuran and 2,3-dimethylbenzofuran were also positive in the EROD assay. All other compounds were inactive in the EROD assay. Relative potency (REP) values ranged from (2.80 +/- 1.32) center dot 10(-8) to (3.26 A +/- 2.03) A center dot 10(-6) in the DR-CALUX and from (3.26 A +/- 0.91) A center dot 10(-7) to (4.87 A +/- 1.97) A center dot 10(-7) in the EROD assay. Conclusions The REP values were comparable to those of larger polycyclic aromatic hydrocarbons, e.g., fluoranthene and pyrene. Thus, and because of the ubiquitous distribution of heterocyclic aromatic compounds in the environment, the provided data will further facilitate the bioanalytical and analytical characterization of environmental samples towards these toxicants.
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| 7. |
- Holbech, Henrik, et al.
(författare)
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Comparison of zebrafish (Danio rerio) and fathead minnow (Pimephales promelas) as test species in the Fish Sexual Development Test (FSDT).
- 2012
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Ingår i: Comparative Biochemistry and Physiology - Part C. - : Elsevier BV. - 1532-0456 .- 1878-1659. ; 155:2, s. 407-15
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Tidskriftsartikel (refereegranskat)abstract
- Results are presented from a validation (with 5 laboratories) of the Fish Sexual Development Test (FSDT) developed to detect endocrine disrupters (EDs) and included in the OECD (Organisation for Economic Co-operation and Development) working program. The aromatase-inhibiting fungicide prochloraz was tested in zebrafish (Danio rerio) and fathead minnow (Pimephales promelas). The fish were exposed during sexual differentiation and development from 0 to 60 days post hatch (dph). After exposure, the vitellogenin (VTG) concentrations were quantified in head/tail homogenate and the sex ratio was determined (defined as female, male, intersex or undifferentiated). NOEC/LOEC and EC(x) designs were compared to optimize the test approach. Results show that both species are highly sensitive to prochloraz during sexual development. They respond by skewing of the sex ratio towards male phenotype and by a VTG decline in females. The NOEC/LOEC approach is preferred because sex ratio is difficult to analyze with a regression model. The mean NOEC/LOEC for prochloraz on the sex ratio was 43.3/134 μg/L and 101/293 μg/L for zebrafish and fathead minnow, respectively. The mean NOEC/LOEC on the decline in female VTG concentration was 65/110 μg/L and ~30/68 μg/L respectively. In conclusion, zebrafish and fathead minnow are suitable species in the FSDT and their sexual differentiation is equally labile to EDs.
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| 8. |
- Keiter, Steffen, 1971-, et al.
(författare)
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DanTox-a novel joint research project using zebrafish (Danio rerio) to identify specific toxicity and molecular modes of action of sediment-bound pollutants
- 2010
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Ingår i: Journal of Soils and Sediments. - Heidelberg, Germany : Springer. - 1439-0108 .- 1614-7480. ; 10:4, s. 714-717
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The European Water Framework Directive aimsto achieve a good ecological and chemical status in surface water of European rivers by the year 2015. Since sediments and particulate matter act as secondary sources for pollutants, applied sediment toxicology is perceived to play a major rolefor obtaining new knowledge that can contribute to successful attainment of the goal. However, the existing bioassays for sediment toxicity analyses do not provide sufficient data concerning bioavailability of environmental pollutants. In this regard, there is an urgent need to combine sediment contact assays with gene expression analysis to investigate mechanism-specific sediment toxicity.Purpose: The aim of the novel joint research project is todevelop a eukaryotic test system, which can be used to investigate the ecotoxicological effects of contaminated sediments on gene expression level (DNA-array and RT-PCR).Current ecotoxicological research customarily involves a battery of bioassays to cover different toxicological endpoints (e.g., teratogenicity, genotoxicity, mutagenicity, Ah-receptor mediated toxicity, neurotoxicity). In contrast, methods that detect alterations in gene expression offer deeper insight by elucidating how chemical exposure and/or environmental challenge affect multiple metabolic pathways leading to these particular kinds of toxic response. Gene expression profiles reflect the way cells and organisms adapt or respond to a changing environment.Conclusion: The present project aspires to increase the fundamental molecular and physiological knowledge concerning the mode of action of environmental toxicants in zebrafish (Danio rerio). By working with partners from the academic and research institutions as well as from industry and waterway regulations, the success of this basic research-driven joint project in terms of development and implementation of novel sediment toxicity methods will be realized.
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| 9. |
- Otte, Jens, et al.
(författare)
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Contribution of Priority PAHs and POPs to Ah Receptor-Mediated Activities in Sediment Samples from the RiverElbe Estuary, Germany
- 2013
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Ingår i: PLOS ONE. - San Francisco, USA : Public Library Service. - 1932-6203. ; 8:10
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Tidskriftsartikel (refereegranskat)abstract
- The estuary of the River Elbe between Hamburg and the North Sea (Germany) is a sink for contaminated sediment and suspended particulate matter (SPM). One major concern is the effect of human activities on the hydrodynamics, particularlythe intensive dredging activities in this area that may result in remobilization of sediment-bound pollutants. The aim of this study was to identify pollutants contributing to the toxicological risk associated with re-suspension of sediments in the Elbe Estuary by use of an effect-directed analysis that combines chemical and biological analyses in with specific fractionation techniques. Sediments were collected from sites along the Elbe Estuary and a site from a small harbor basin of the Elbe Estuary that is known to be polluted. The sixteen priority EPA-PAHs were quantified in organic extracts of sediments. In addition, dioxin equivalents of sediments were investigated by use of the 7-ethoxyresorufin O-deethylase assay with RTL-W1 cells and the Ah receptor-mediated luciferase transactivation assay with H4IIE-luc cells. Quantification of the 16 priorityPAHs revealed that sediments were moderately contaminated at all of the sites in the Elbe River Estuary (,0.02–0.906 mg/gdw). Sediments contained relatively small concentrations of dioxin equivalents (Bio-TEQ) with concentrations ranging from15.5 to 322 pg/g dw, which were significantly correlated with dioxin equivalents calculated based on toxicity referencevalues and concentrations of PAH. The concentration of Bio-TEQ at the reference site exceeded 200,000 pg/g dw. In apotency balance the 16 PAHs explained between 47 and 118% of the Bio-TEQ in the luciferase assay, which can be explained by the constant input of PAHs bound to SPM from the upper course of the Elbe River into its estuary. Successful identification of a significant portion of dioxin-like activity to priority PAHs in complex environmental samples such assediments has rarely been reported.
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| 10. |
- Peddinghaus, Sabrina, et al.
(författare)
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Quantitative assessment of the embryotoxic potential of NSO-heterocyclic compounds using zebrafish (Danio rerio)
- 2012
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Ingår i: Reproductive Toxicology. - Oxford, United Kingdom : Springer. - 0890-6238 .- 1873-1708. ; 33, s. 224-232
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Tidskriftsartikel (refereegranskat)abstract
- Heterocyclic aromatic compounds (NSO-HET) have frequently been detected in the environment. Several studies have concluded that NSO-HET pose a threat to organisms in waters, sediments and soils. However, few publications are available assessing the ecotoxicology of NSO-HET. The present study aims toassess the embryo toxicity of heterocycles using Danio rerio. A combination of the Fish Embryo Toxicity Test and analytical quantification should aid to determine the hazard potential. Changes of the total concentrations due to sorption or volatility were quantified by GC/MS. Loss of compounds during the testwas observed primarily for volatile or hydrophobic NSO-HET. The LC50 calculated with nominal concentrations underestimates the toxicity by a factor up to 16 (2 h), demonstrating that a chemical analysis for comparing nominal and measured concentrations is essential for such investigations.
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