| 1. |
- Hafner, Christoph, et al.
(författare)
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Investigations on sediment toxicity of German rivers applying a standardized bioassay battery
- 2015
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Ingår i: Environmental Science and Pollution Research. - : Springer Berlin/Heidelberg. - 0944-1344 .- 1614-7499. ; 22:21, s. 16358-16370
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Tidskriftsartikel (refereegranskat)abstract
- River sediments may contain a huge variety of environmental contaminants and play a key role in the ecological status of aquatic ecosystems. Contaminants adsorbed to sediments and suspended solids may contribute directly or after remobilization to an adverse ecological and chemical status of surface water. In this subproject of the joint research project DanTox, acetonic Soxhlet extracts from three German river sediments from the River Rhine (Altrip and Ehrenbreitstein with moderate contamination) and River Elbe (Veringkanal Hamburg heavily contaminated) were prepared and redissolved in dimethyl sulfoxide (DMSO). These extracts were analyzed with a standard bioassay battery with organisms from different trophic levels (bacteria, algae, Daphnia, fish) as well as in the Ames test and the umuC test for bacterial mutagenicity and genotoxicity according to the respective OECD and ISO guidelines. In total, 0.01 % (standard) up to 0.25 % (only fish embryo test) of the DMSO sediment extract was dosed to the test systems resulting in maximum sediment equivalent concentrations (SEQ) of 2 up to 50 g l(-1). The sediment of Veringkanal near Hamburg harbor was significantly more toxic in most tests compared to the sediment extracts from Altrip and Ehrenbreitstein from the River Rhine. The most toxic effect found for Veringkanal was in the algae test with an ErC50 (72 h) of 0.00226 g l(-1) SEQ. Ehrenbreitstein and Altrip samples were about factor 1,000 less toxic. In the Daphnia, Lemna, and acute fish toxicity tests, no toxicity at all was found at 2 g l(-1) SEQ. corresponding to 0.01 % DMSO. Only when increasing the DMSO concentration the fish embryo test showed a 22-fold higher toxicity for Veringkanal than for Ehrenbreitstein and Altrip samples, while the toxicity difference was less evident for the Daphnia test due to the overlaying solvent toxicity above 0.05 % dimethyl sulfoxide (DMSO). The higher toxicities observed with the Veringkanal sample are supported by the PAH and PCB concentrations analyzed in the sediments. The sediment extracts of Altrip andVeringkanal were mutagenic in the Ames tester strain TA98 with metabolic activation (S9mix). The findings allow a better ecotoxicological characterization of the sediments extensively analyzed in all subprojects of the DanTox project (e. g., Garcia-Kaeufer et al. Environ Sci Pollut Res. doi: 10.1007/s11356-014-3894-4, 2014; Schiwy et al. Environ Sci Pollut Res. doi: 10.1007/s11356-014-31850, 2014; Hollert and Keiter 2015). In the absence of agreed limit values for sediment extracts in standard tests, further data with unpolluted reference sediments are required for a quantitative risk assessment of the investigated polluted sediments.
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| 2. |
- Feiler, Ute, et al.
(författare)
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Inter-laboratory trial of a standardized sediment contact test with the aquatic plant Myriophyllum aquaticum (ISO 16191)
- 2014
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 33:3, s. 662-670
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Tidskriftsartikel (refereegranskat)abstract
- A whole-sediment toxicity test with Myriophyllum aquaticum has been developed by the German Federal Institute of Hydrology and standardized within the International Organization for Standardization (ISO; ISO 16191). An international ring-test was performed to evaluate the precision of the test method. Four sediments (artificial, natural) were tested. Test duration was 10 d, and test endpoint was inhibition of growth rate (r) based on fresh weight data. Eighteen of 21 laboratories met the validity criterion of r >= 0.09 d(-1) in the control. Results from 4 tests that did not conform to test-performance criteria were excluded from statistical evaluation. The inter-laboratory variability of growth rates (20.6%-25.0%) and inhibition (26.6%-39.9%) was comparable with the variability of other standardized bioassays. The mean test-internal variability of the controls was low (7% [control], 9.7% [solvent control]), yielding a high discriminatory power of the given test design (median minimum detectable differences [MDD] 13% to 15%). To ensure these MDDs, an additional validity criterion of CV <= 15% of the growth rate in the controls was recommended. As a positive control, 90 mg 3,5-dichlorophenol/kg sediment dry mass was tested. The range of the expected growth inhibition was proposed to be 35 +/- 15%. The ring test results demonstrated the reliability of the ISO 16191 toxicity test and its suitability as a tool to assess the toxicity of sediment and dredged material. Environ Toxicol Chem 2014;33:662-670. (c) 2013 SETAC
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| 3. |
- Garcia-Käufer, Manuel, et al.
(författare)
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Genotoxic and teratogenic effect of freshwater sediment samples from the Rhine and Elbe River (Germany) in zebrafish embryo using a multi-endpoint testing strategy
- 2015
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Ingår i: Environmental Science and Pollution Research. - Heidelberg, Germany : Springer. - 0944-1344 .- 1614-7499. ; 22:21, s. 16341-16357
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Tidskriftsartikel (refereegranskat)abstract
- The embryotoxic potential of three model sediment samples with a distinct and well-characterized pollutant burden from the main German river basins Rhine and Elbe was investigated. The Fish Embryo Contact Test (FECT) in zebrafish (Danio rerio) was applied and submitted to further development to allow for a comprehensive risk assessment of such complex environmental samples. As particulate pollutants are constructive constituents of sediments, they underlay episodic source-sink dynamics, becoming available to benthic organisms. As bioavailability of xenobiotics is a crucial factor for ecotoxicological hazard, we focused on the direct particle-exposure pathway, evaluating through put-capable endpoints and considering toxicokinetics. Fish embryo and larvae were exposed toward reconstituted (freeze-dried) sediment samples on a microcosm-scale experimental approach. A range of different developmental embryonic stages were considered to gain knowledge of potential correlations with metabolic competence during the early embryogenesis. Morphological, physiological, and molecular endpoints were investigated to elucidate induced adverse effects, placing particular emphasis on genomic instability, assessed by the in vivo comet assay. Flow cytometry was used to investigate the extent of induced cell death, since cytotoxicity can lead to confounding effects. The implementation of relative toxicity indices further provides inter-comparability between samples and related studies. All of the investigated sediments represent a significant ecotoxicological hazard by disrupting embryogenesis in zebrafish. Beside the induction of acute toxicity, morphological and physiological embryotoxic effects could be identified in a concentration-response manner. Increased DNA strand break frequency was detected after sediment contact in characteristic non-monotonic dose–response behavior due to overlapping cytotoxic effects. The embryonic zebrafish toxicity model along with the in vivo comet assay and molecular biomarker analysis should prospectively be considered to assess the ecotoxicological potential of sediments allowing for a comprehensive hazard ranking. In order to elucidate mode of action, novel techniques such as flow cytometry have been adopted and proved to be valuable tools for advanced risk assessment and management.
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| 4. |
- 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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| 5. |
- Mannes, Marco, et al.
(författare)
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Complement and platelets : prothrombotic cell activation requires membrane attack complex-induced release of danger signals
- 2023
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Ingår i: Blood Advances. - : American Society of Hematology. - 2473-9529 .- 2473-9537. ; 7:20, s. 6367-6380
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Tidskriftsartikel (refereegranskat)abstract
- Complement activation in the diseases paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS) results in cytolysis and fatal thrombotic events, which are largely refractory to anticoagulation and/or antiplatelet therapy. Anticomplement therapy, however, efficiently prevents thrombotic events in PNH and aHUS, but the underlying mechanisms remain unresolved. We show that complement-mediated hemolysis in whole blood induces platelet activation similarly to activation by adenosine 5 '-diphosphate (ADP). Blockage of C3 or C5 abolished platelet activation. We found that human platelets failed to respond functionally to the anaphylatoxins C3a and C5a. Instead, complement activation did lead to prothrombotic cell activation in the whole blood when membrane attack complex (MAC)-mediated cytolysis occurred. Consequently, we demonstrate that ADP receptor antagonists efficiently inhibited platelet activation, although full complement activation, which causes hemolysis, occurred. By using an established model of mismatched erythrocyte transfusions in rats, we crossvalidated these findings in vivo using the complement inhibitor OmCI and cobra venom factor. Consumptive complement activation in this animal model only led to a thrombotic phenotype when MAC-mediated cytolysis occurred. In conclusion, complement activation only induces substantial prothrombotic cell activation if terminal pathway activation culminates in MAC-mediated release of intracellular ADP. These results explain why anticomplement therapy efficiently prevents thromboembolisms without interfering negatively with hemostasis.
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| 6. |
- Miehe, Georg, et al.
(författare)
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The Kobresia pygmaea ecosystem of the Tibetan highlands – Origin, functioning and degradation of the world's largest pastoral alpine ecosystem: Kobresia pastures of Tibet
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 648, s. 754-771
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Tidskriftsartikel (refereegranskat)abstract
- With 450,000 km2 Kobresia (syn. Carex) pygmaea dominated pastures in the eastern Tibetan highlands are the world's largest pastoral alpine ecosystem forming a durable turf cover at 3000–6000 m a.s.l. Kobresia's resilience and competitiveness is based on dwarf habit, predominantly below-ground allocation of photo assimilates, mixture of seed production and clonal growth, and high genetic diversity. Kobresia growth is co-limited by livestock-mediated nutrient withdrawal and, in the drier parts of the plateau, low rainfall during the short and cold growing season. Overstocking has caused pasture degradation and soil deterioration over most parts of the Tibetan highlands and is the basis for this man-made ecosystem. Natural autocyclic processes of turf destruction and soil erosion are initiated through polygonal turf cover cracking, and accelerated by soil-dwelling endemic small mammals in the absence of predators. The major consequences of vegetation cover deterioration include the release of large amounts of C, earlier diurnal formation of clouds, and decreased surface temperatures. These effects decrease the recovery potential of Kobresia pastures and make them more vulnerable to anthropogenic pressure and climate change. Traditional migratory rangeland management was sustainable over millennia, and possibly still offers the best strategy to conserve and possibly increase C stocks in the Kobresia turf.
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| 7. |
- Wayne, Greg, et al.
(författare)
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Principles of Systems Biology, No. 11
- 2016
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Ingår i: CELL SYSTEMS. - : CELL PRESS. - 2405-4712. ; 3:5, s. 406-410
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Tidskriftsartikel (refereegranskat)abstract
- This month: AI that learns patterns and facts, new protein-RNA and protein-protein relationships, engineering signaling and metabolism, and more variants of Cas9.
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