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  • SpringerLink  (27)
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  • 1
    Language: English
    In: Journal of Soils and Sediments, 2011, Vol.11(6), pp.1099-1114
    Description: Byline: Sabine Ulrike Gerbersdorf (1), Henner Hollert (2), Markus Brinkmann (2), Silke Wieprecht (1), Holger Schuttrumpf (3), Werner Manz (4) Keywords: Biofilm; Freshwater; Interdisciplinary approach; Management of sediments; Pollutants; Risk assessment Abstract: Purpose Freshwater sediments and their attached microbial communities (biofilms) are essential features of rivers and lakes, providing valuable ecosystem services such as nutrient recycling or self-purification which extend beyond the aquatic environment. Anthropogenic pollutants, whether from the industrial era or as a result of our contemporary lifestyles, can negatively affect these functions with hitherto unknown consequences on ecology, the economy and human health. Thus far, the singular view of the involved disciplines such as ecotoxicology, environmental microbiology, hydrology and geomorphology has prevented a deeper understanding of this emerging issue. Main features This paper discusses briefly the progressions and the state-of-the-art methods within the disciplines of concern related to contaminated sediments, ranging from ecotoxicological test systems, microbiological/molecular approaches to unravel changes of microbial ecosystems, up to the modelling of sediment transport and sorption/desorption of associated pollutants. The first bilateral research efforts on contaminated sediments include efforts to assess ecotoxicological sediment risk including sediment mobility (i.e. ecotoxicology and engineering), enhance bioremediation potential (i.e. microbiology and ecotoxicology) or to understand biostabilisation processes of sediments by microbial assemblages (i.e. microbiology and engineering). Conclusions and perspectives In freshwater habitats, acute, chronic and mechanism-specific toxic effects on organisms, shifts in composition, structure and functionality of benthic microbial communities, as well as the obstruction of important ecosystem services by continuously discharged and long-deposited pollutants, should be related to the in situ sediment dynamics. To achieve an improved understanding of the ecology of freshwater sediments and the impairment of their important ecosystem functions by human-derived pollutants, we suggest a "triad plus x" approach combining advanced methods of ecotoxicology, environmental microbiology and engineering science. Author Affiliation: (1) Department of Hydraulic Engineering and Water Resources Management, Institute of Hydraulic Engineering, University Stuttgart, Pfaffenwaldring 61, 70569, Stuttgart, Germany (2) Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringer Weg 1, 52074, Aachen, Germany (3) Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Mies-van-der-Rohe-Strasse 1, 52056, Aachen, Germany (4) Institute for Integrated Natural Sciences, University Koblenz--Landau, Universitatsstrasse 1, 56070, Koblenz, Germany Article History: Registration Date: 25/04/2011 Received Date: 20/11/2010 Accepted Date: 24/04/2011 Online Date: 11/05/2011 Article note: Responsible editor: Ian G. Droppo
    Keywords: Biofilm ; Freshwater ; Interdisciplinary approach ; Management of sediments ; Pollutants ; Risk assessment
    ISSN: 1439-0108
    E-ISSN: 1614-7480
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  • 2
    Language: English
    In: Environmental Science and Pollution Research, 2016, Vol.23(23), pp.24277-24288
    Description: Bacterial biofilms are most likely confronted with silver nanoparticles (Ag NPs) as a pollutant stressor in aquatic systems. In this study, biofilms of Aquabacterium citratiphilum were exposed for 20 h to 30 and 70 nm citrate stabilized Ag NPs in low-dose concentrations ranging from 600 to 2400 μg l −1 , and the Ag NP-mediated effects on descriptive, structural, and functional biofilm characteristics, including viability, protein content, architecture, and mechanical stability, were investigated. Viability, based on the bacterial cell membrane integrity of A. citratiphilum , as determined by epifluorescence microscopy, remained unaffected after Ag NP exposure. Moreover, in contrast to information in the current literature, protein contents of cells and extracellular polymeric substances (EPS) and biofilm architecture, including dry mass, thickness, and density, were not significantly impacted by exposure to Ag NPs. However, the biofilms themselves served as effective sinks for Ag NPs, exhibiting enrichment factors from 5 to 8. Biofilms showed a greater capacity to accumulate 30 nm sized Ag NPs than 70 nm Ag NPs. Furthermore, Ag NPs significantly threatened the mechanical stability of biofilms, as determined by a newly developed assay. For 30 nm Ag NPs, the mechanical stability of biofilms decreased as the Ag NP concentrations applied to them increased. In contrast, 70 nm Ag NPs produced a similar decrease in mechanical stability for each applied concentration. Overall, this finding demonstrates that exposure to Ag NPs triggers remarkable changes in biofilm adhesion and/or cohesiveness. Because of biofilm-mediated ecological services, this response raises environmental concerns regarding Ag NP release into freshwater systems, even in sublethal concentrations.
    Keywords: Aquabacterium citratiphilum ; biofilm ; Silver nanoparticles ; Toxicity ; Mechanical stability ; Nanoparticle enrichment
    ISSN: 0944-1344
    E-ISSN: 1614-7499
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  • 3
    Language: English
    In: Analytical and Bioanalytical Chemistry, 2008, Vol.390(8), pp.2009-2019
    Description: This study is a consequence of a distinct fish decline in the Danube river since the beginning of the 1990s. In contrast to the decline of fish population, former studies have repeatedly documented that the water quality along the Danube river is improving. However, the conclusion of a pilot study in 2002 was that a high hazard potential is associated with local sediments. The present study documents that sediment samples from the Danube river showed comparatively high aryl hydrocarbon receptor mediated activity in biotests, using the cell lines GPC.2D.Luc, H4IIE (DR-CALUX®) and RTL-W1. The combination of chemical analysis, fractionation techniques and different in vitro tests revealed that priority pollutants could not explain the main induction, even though the concentrations of priority polycyclic aromatic hydrocarbons (PAHs) were very high (maximum in the tributary Schwarzach, sum of 16 EPA PAHs 26 μg/g). In conclusion, this investigation shows that nonpriority pollutants mainly mediate the high induction rates. Nevertheless, owing to the effects of PAHs towards fish and the connection between dioxin-like activity and carcinogenicity, the link between contamination and the fish population decline cannot be ruled out.
    Keywords: Danube ; Fish decline ; Dioxin-like activity ; Aryl hydrocarbon receptor agonists ; Weight of evidence
    ISSN: 1618-2642
    E-ISSN: 1618-2650
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  • 4
    Language: English
    In: Environmental Science and Pollution Research, 2009, Vol.16(1), pp.54-64
    Description: Byline: Robert Kase (1), Peter D. Hansen (2), Birgit Fischer (2), Werner Manz (1), Peter Heininger (1), Georg Reifferscheid (1) Keywords: Endocrine disrupting compounds (EDC); Enzyme-linked receptor assay (ELRA); Hormonally active agents (HAA); pT-method; Salinity adaptation; Salinity tolerance Abstract: Background, aim, and scope The enzyme-linked receptor assay (ELRA) detects estrogenic and anti-estrogenic effects at the molecular level of receptor binding and is a useful tool for the integrative assessment of ecotoxicological potentials caused by hormonally active agents (HAA) and endocrine disrupting compounds (EDC). The main advantage of the ELRA is its high sample throughput and its robustness against cytotoxicity and microbial contamination. After a methodological adaptation to salinity of the ELRA, according to the first part of this study, which increased its salinity tolerance and sensitivity for 17-[beta]-estradiol, the optimised ELRA was used to investigate 13 native sediments characterised by different levels of salinity and chemical contamination. The applicability of the ELRA for routine analysis in environmental assessment was evaluated. Salinity is often a critical factor for bioassays in ecotoxicological sediment assessment. Therefore, salinity of the samples was additionally adjusted to different levels to characterise its influence on elution and binding processes of receptor-binding substances. Materials and methods The ELRA was carried out with the human estrogen receptor [alpha] (ER) in a 96-well microplate format using the experimental setup known from the competitive immunoassay based on ligand--protein interaction. It is an important improvement that a physiologically relevant receptor was used as a linking protein instead of an antibody. The microplates were coated with a 17-[beta]-estradiol-BSA conjugate, and dilution series of estradiol and of native sediment samples were added and incubated with the ER. After a washing step, a biotinylated mouse anti-ER antibody was added to each well. Receptor binding to estradiol, agonistic and antagonistic receptor binding, were determined by a streptavidin-POD-biotin complex with subsequent measurement of the peroxidase activity at the wavelength of 450 nm using a commercial ELISA multiplate reader. The sediment elutriates and pore water samples of sediments were tested in a dilution series to evaluate at which dilution step the receptor-binding potential ends. In the elution process (see Section 2.1 to 2.2), a method was developed to adjust the salinity to the levels of the reference testings, which offers an appropriate option to adjust the salinity in both directions. Statistical evaluation was made with a combination of the Mann--Whitney U test and the pT-method. Results This part of the study characterised the environmental factor 'salinity' for prospective applications of the ELRA. Using reference substances such as 17-[beta]-estradiol, the ELRA showed sigmoid concentration-effect relations over a broad range from 0.05 ug/l to 100 ug/l under physiological conditions. After methodological optimisation, both sensitivity and tolerance of the assay against salinity could be significantly raised, and the ELRA became applicable under salinity conditions up to concentrations of 20.5[per thousand]. The mean relative inter-test error (n=3) was around 11% with reference substances and below 5% for single sediments elutriates in three replicates each. For sediment testings, the pore water and different salinity-adjusted elutriates of 13 sediments were used. A clear differentiation of the receptor-binding potential could be reached by application of the pT-method. Thereby, pT-values from one to six could be assigned to the sediments, and the deviation caused by the different salinity conditions was one pT-value. The mean standard deviation in the salinity adaptation procedure of the elutriates was below 5%. Discussion Although the ELRA has already been used for assessments of wastewater, sludge and soil, its applicability for samples to different salinity levels has not been investigated so far. Even if the ELRA is not as sensitive as the E-screen or the YES-assay, with regard to reference substances like 17-[beta]-estradiol, it is a very useful tool for pre-screening, because it is able to integrate both estrogenic as well as anti-estrogenic receptor-binding effects. According to the results of sediment testing, and given the integrative power to detect different directions of effects, the ELRA shows sufficient sensitivity and salinity tolerance to discriminate receptor-binding potentials in environmental samples. Conclusions The optimised ELRA assay is a fast, cost-effective, reliable and highly reproducible tool that can be used for high-throughput screening in a microplate format in detecting both estrogenic and anti-estrogenic effects. Additionally, the ELRA is robust against microbial contaminations, and is not susceptible towards cytotoxic interferences like the common cell-culture methods. The general applicability and sufficient sensitivity of the ELRA was shown in freshwater environments. Marine and brackish samples can be measured up to salinity levels of 20.5[per thousand]. Recommendations and perspectives In view of the proven sensitivity, functionality and the fastness of the ELRA, it is recommendable to standardise the test method. At the moment, no adequate in vitro test procedure exists which is standardised to DIN or ISO levels. The E-screen and the yeast estrogen/androgen screens (YES/YAS) sometimes underlie strong cytotoxic effects, as reported in the first part of this study. Further development of an ELRA assay using human androgen receptors appears to be very promising to gain information about androgenic and anti-androgenic effects, too. This would offer a possibility to use the ELRA as a fast and reliable pre-screening tool for the detection of endocrine potentials, thus minimising time and cost-expensive animal experiments. Author Affiliation: (1) German Federal Institute of Hydrology, Am Mainzer Tor 1, 56068, Koblenz, Germany (2) Department of Ecotoxicology, Technical University of Berlin, Franklinstrasse 29, 10587, Berlin, Germany Article History: Registration Date: 06/10/2008 Received Date: 13/12/2007 Accepted Date: 25/09/2008 Online Date: 15/11/2008 Article note: Responsible editor: Jan Schwarzbauer
    Keywords: Endocrine disrupting compounds (EDC) ; Enzyme-linked receptor assay (ELRA) ; Hormonally active agents (HAA) ; pT-method ; Salinity adaptation ; Salinity tolerance
    ISSN: 0944-1344
    E-ISSN: 1614-7499
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  • 5
    Language: English
    In: Journal of Soils and Sediments, 2009, Vol.9(3), pp.168-179
    Description: Byline: Steffen Keiter (1), Thomas Braunbeck (1), Susanne Heise (2), Stefan Pudenz (3), Werner Manz (4), Henner Hollert (1,5) Keywords: Classification; Ecological relevance; Fuzzy logic; Hazard assessment; Ranking Abstract: Background, aim, and scope Ecotoxicological risk assessment of sediments is usually based on a multitude of data obtained from tests with different endpoints. In the present study, a fuzzy logic-based model was developed in order to reduce the complexity of these data sets and to classify sediments on the basis of results from a battery of in vitro biotests. Materials and methods The membership functions were adapted to fit the specific sensitivity and variability of each biotest. For this end, data sets were categorized into three toxicity levels using the box plot and empirical methods. The variability of each biotest was determined to calculate the range of the gradual membership. In addition, the biotests selected were ranked according to the biological organisation level in order to consider the ecological relevance of the endpoints measured by selected over- or underestimation of the toxicity levels. In the next step of the fuzzy logic model, a rule-base was implemented using if...and...then decisions to arrive at a system of five quality classes. Results The results of the classification of sediments from the Rhine and Danube Rivers showed the highest correlation between the biotest results and the fuzzy logic alternative based on the empirical method (i.e. the classification of the data sets into toxicity levels). Discussion Many different classification systems based on biological test systems are depending on respective data sets therefore, they are difficult to compare with other locations. Furthermore, they don't consider the inherent variability of biotests and the ecological relevance of these test systems as well. In order to create a comprehensive risk assessment for sediments, mathematical models should be used which take uncertainties of biotest systems into account, since they are of particular importance for a reliable assessment. In the present investigation, the variability and ecological relevance of biotests were incorporated into a classification system based on fuzzy logic. Furthermore, since data from different sites and investigations were used to create membership functions of the fuzzy logic, this classification system has the potential to be independent of locations. Conclusions In conclusion, the present fuzzy logic classification model provides an opportunity to integrate expert knowledge as well as acute and mechanism-specific effects for the classification of sediments for an ecotoxicological risk assessment. Recommendations and perspectives In order to achieve a more comprehensive classification, further investigation is needed to incorporate results of chemical analyses and in situ parameters. Furthermore, more discussions are necessary with respect to the relative weight attributed to different ecological and chemical parameters in order to obtain a more precise assessment of sediments. Author Affiliation: (1) Department of Zoology, Aquatic Ecology and Toxicology Section, University of Heidelberg, Im Neuenheimer Feld 230, 69120, Heidelberg, Germany (2) Institut fur Biogefahrenstoffe und Umwelttoxikologie, Hamburg University of Applied Sciences (HAW), Lohbrugger Kirchstr. 65, Hamburg, 21033, Germany (3) Westlakes Scientific Consulting Ltd., Department of Environmental Science, Moor Row, Cumbria, CA24 3 LN, UK (4) German Federal Institute of Hydrology, Am Mainzer Tor 1, 56068, Koblenz, Germany (5) Institute for Environmental Research (Biology V), Department of Ecosystem Analysis, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany Article History: Registration Date: 04/05/2009 Received Date: 20/10/2008 Accepted Date: 27/03/2009 Online Date: 10/06/2009
    Keywords: Classification ; Ecological relevance ; Fuzzy logic ; Hazard assessment ; Ranking
    ISSN: 1439-0108
    E-ISSN: 1614-7480
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  • 6
    Language: English
    In: Journal of Soils and Sediments, 2009, Vol.9(6), pp.640-652
    Description: Byline: Sabine Ulrike Gerbersdorf (1,3), Robert Bittner (1), Helen Lubarsky (1), Werner Manz (2), David M. Paterson (1) Keywords: CSM; Extracellular polymeric substances (EPS); FISH; MagPI; Microbial engineering; Sediment erosion; Sediment stability Abstract: Purpose Sediment erosion and transport is a governing factor in the ecological and commercial health of aquatic ecosystems from the watershed to the sea. There is now a general consensus that biogenic mediation of submersed sediments contributes significantly to the resistance of the bed to physical forcing. This important ecosystem function has mainly been linked to microalgae ("ecosystem engineers") and their associated extracellular polymeric substances (EPS), yet little is known about the impact of bacterial assemblages and how their varying interactions with microalgae affect the overall biostabilization potential of the combined community. Materials and methods Natural assemblages of bacteria and diatoms--originating from sediment and water samples from the Eden Estuary (Scotland, UK)--were growing on noncohesive glass beads over 5 weeks. The adhesion and the stability of the biofilm was determined by magnetic particle induction (MagPI) and by Cohesive Strength Meter (CSM), respectively, and related to EPS (spectrophotometric determination of carbohydrates and proteins), bacterial cell numbers (flow cytometry), bacterial community (fluorescence in situ hybridization (FISH)), diatom biomass (spectrophotometric determination of chlorophyll a), and diatom assemblage composition (microscopy). Results and discussion The adhesive properties and stability of the biofilm were significantly enhanced over time as compared to controls. The diatoms profited from additional nutrients, while bacteria dominated in nutrient-limited cultures. Subsequent shifts in the microbial population at a species level resulted in varying patterns of EPS production which moderated the biostabilization capacity: Cultures with strong diatom development were less stable than cultures dominated by bacteria (MagPI: x8.5 and x10.8, CSM: x2.5 and x5.7, respectively). The data also suggested synergistic effects between proteins and carbohydrates, which enhanced adhesion and stability. Conclusions Bacteria populations under these conditions can be regarded as "ecosystem engineers" since their role in sediment stabilization is more important than previously recognized. Abiotic factors such as nutrients altered the interactions between bacteria and microalgae to influence the overall microbial stabilization potential ("engineering web") by affecting the quantity and quality of EPS. Data from MagPI and CSM correlated well (R .sup.2 = 0.82, P 〈 0.0001), and the new technique, MagPI, is to be recommended for studies on growing biofilms since it determines subtle changes in sediment/biofilm properties with high sensitivity. Recommendations and perspectives Further studies should examine the highly species-specific interactions between microalgae and bacteria and their effects on EPS secretion to impact stability as well as postentrainment of sediments under varying abiotic scenarios. Our growing understanding of the ecosystem functionality of "bioengineering" will have wider implications for water framework directive and sediment/pollutant management strategies. Author Affiliation: (1) Sediment Ecology Research Group, Gatty Marine Laboratory, University of St. Andrews, St. Andrews, KY16 8LB, Scotland, UK (2) Department of Biochemistry and Ecotoxicology, Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56068, Koblenz, Germany (3) Institute of Hydraulic Engineering, University of Stuttgart, Pfaffenwaldring 61, 70569, Stuttgart, Germany Article History: Registration Date: 09/09/2009 Received Date: 25/06/2009 Accepted Date: 07/09/2009 Online Date: 06/10/2009 Article note: Responsible editor: Klara Hilscherova
    Keywords: CSM ; Extracellular polymeric substances (EPS) ; FISH ; MagPI ; Microbial engineering ; Sediment erosion ; Sediment stability
    ISSN: 1439-0108
    E-ISSN: 1614-7480
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  • 7
    Language: English
    In: Environmental Science and Pollution Research, 2008, Vol.15(1), pp.75-83
    Description: Byline: Robert Kase (1), Peter-D. Hansen (2), Birgit Fischer (2), Werner Manz (1), Peter Heininger (1), Georg Reifferscheid (1) Keywords: Anti-estrogenic substances; aquatic environment; endocrine disrupting chemicals (EDC); Enzyme-Linked Receptor Assay (ELRA); E-Screen; estrogenicity; salinity tolerance; Yeast Estrogen Screen (YES) Abstract: Goal, Scope and Background Exogenic endocrine-active substances are also called 'Endocrine Disrupting Chemicals' (EDC). They imitate or hinder the function of natural endogenic hormones or disturb the synthesis or the metabolism of hormones or of hormone receptors. The Enzyme-Linked Receptor Assay (ELRA) can detect estrogenic and anti-estrogenic effects at the level of receptor binding and is a useful tool for the integrative detection of contaminant effects. Although the test system has been used repeatedly in sediment assessments, the questions have remained concerning how it responds to variations in the physico-chemical matrix. For some bioassays, the salinity of the sample is a critical factor. This is especially relevant when testing wastewater samples or when sediment-associated samples in the tidal reaches of rivers are tested. Sediments in the tidal reaches of rivers change their salinity several times a day. Against this background, it would be beneficial to have a test procedure of known salinity tolerance. On account of this, the salinity tolerance of the ELRA was tested, assessed with reference substances at several salinity levels, and compared with the E-Screen method and a Yeast Estrogen Screen (YES), which are also frequently applied in environmental testing. The aim of this paper was to explore when the salinity limits within these test procedures are applicable. The trials should reveal the working range to be expected, characterize the salinity-dependent variations in sensitivity of the test, and provide options for methodological adjustments to improve the stability against increased salinity. Methods The ELRA was carried out with the human Estrogen Receptor [alpha]. (ER) using the same principle like a competitive immunoassay based on ligand-protein interaction. However, an essential difference is the use of a physiologically relevant receptor instead of an antibody as a linking protein. The ELRA measures the competition of sample estrogens and anti-estrogens against estradiol supplied as a BSA-coating conjugate for the binding site of dissolved ER. Estradiol or xeno-estrogen binding is quantified by a biotynilated anti-ER antibody and the subsequent measurement of peroxidase activity by a streptavidin-POD-biotin complex. The E-Screen was performed with the human breast cancer cell line MCF-7, which expresses the estrogen receptor constitutively. Cell proliferation depends on binding of estrogens or xeno-estrogens with the receptor. After incubation, estrogen-dependent cell growth was measured by sulforhodamin B staining. The YES was performed with a recombinant yeast strain, transfected with a receptor and a reporter plasmid bearing the estrogen receptor and a vitellogenin gene fused with the reporter gene lacZ. Estrogen or xeno-estrogen-dependent gene induction was measured indirectly by LacZ activity. The salinity levels were simulated in varying concentrations with NaCl from 0 to 40[per thousand] or Artificial Sea Water (ASW) from 0 to 32[per thousand]. Results The study characterized the factor 'salinity' for the prospective application fields of the ELRA. With reference substances such as 17-[beta]-estradiol, the ELRA showed classical sigmoidal concentration-effect relations in a range from 0.05 to 100 ug/l under physiological conditions. After a methodological adjustment to compensate decreasing receptor-binding affinity of estrogens and xeno-estrogens at higher salinity levels. the ELRA became applicable under salinity conditions up to concentrations of 20.5[per thousand]. In tests, the ELRA reached under the influence of salinity a mean limit of detection of 0.062 [beta]g/l 17-[beta]-estradiol. The mean relative inter-test error was around 11%. Above concentrations of 20.5[per thousand] there is a risk of false negative assessment. Compared with the E-Screen method using the MCF7 cell line and the yeast estrogen test system (YES), the ELRA shows a lower sensitivity to 17-[beta]-estradiol. In the E-Screen, the cell proliferation was strongly reduced by sodium chloride induced cytotoxicity. In comparison with the E-Screen, the salinity tolerance of the YES and YAS methods is significantly higher. Discussion Despite adaption, total salinity tolerance could not be achieved with the ELRA. Freshwater samples were generally appraisable. Higher salinity levels above 20.5[per thousand] would tend towards false negative results. The low inter-test error of 11% makes the ELRA suitable for the detection of estrogenic and anti-estrogenic potentials of single substances, substance mixtures, and of environmental samples. Conclusions The ELRA is very fast and reproducible, it can be used for high-throughput screening in a microplate format at low cost, it is robust to microbial contamination, and is less susceptible to cytotoxic interferences than cell culture methods. Recommendations and Perspectives In their established form, the YES and the E-Screen methods are not applicable for liquid phase testing at higher salinity conditions. The salinity-adapted test version of the ELRA described here shows a broader working range for samples. Native water samples of more or less brackish origin or high-salinity effluent samples are testable. Results of tests with sediment associated samples of different salinity will be subject of a forthcoming publication. Author Affiliation: (1) German Federal Institute of Hydrology, Am Mainzer Tor 1, 56068, Koblenz, Germany (2) Department of Ecotoxicology, Technical University of Berlin, Franklinstrasse 29, 10587, Berlin, Germany Article History: Registration Date: 04/06/2007 Received Date: 07/08/2006 Accepted Date: 13/06/2007 Online Date: 13/06/2007 Article note: ESS-Submission Editor: Dr. Jan Schwarzbauer (schwarzbauer@lek.rwth-aachen.de)
    Keywords: Anti-estrogenic substances ; aquatic environment ; endocrine disrupting chemicals (EDC) ; Enzyme-Linked Receptor Assay (ELRA) ; E-Screen ; estrogenicity ; salinity tolerance ; Yeast Estrogen Screen (YES)
    ISSN: 0944-1344
    E-ISSN: 1614-7499
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  • 8
    Language: English
    In: Journal of Soils and Sediments, 2003, Vol.3(3), pp.188-196
    Description: River sediments are natural habitats of complex bacterial and fungal communities and therefore play a decisive role in the mineralization process of organic matter in freshwater systems. By means of comparative temporal and spatial analyses of microbial communities, the in situ impact of anthropogenically generated pollutants on these biofilm associations can be assessed and discriminated from seasonal variations.The aim was the adaptation of hybridization with fluorescently labelled rRNA-targeted oligonucleotides (FISH) for the in situ characterization of the structural and functional diversity of native microbial communities in complex lotic sediments. The impact of qualitatively and quantitatively different water pollutants on the microbial diversity, metabolic potential, and relative abundance of characteristic bacterial groups was assessed by oligonucleotide probes on different phylogenetic levels. In particular, sulfate reducing bacteria (SRB) were investigated to evaluate their potential applicability as microbial biomonitors in sediments.Sediment samples from the German lowland rivers Elbe and Oder were investigated over 12 months with regard to physico-chemical parameters and the composition of the attached microbial communities. Mechanical treatment including ultrasonification and sagitation under aerobic conditions combined with the use of pyrophosphate ensured the equal dispersion of fixed microbial cells within the sediment samples. The optimized whole-sediment FISH-technique was combined with an improved cell extraction procedure and applied, due to the specific grain size fraction distribution, at the different sampling sites.Up to 85.6% of the total bacterial cell counts as determined by DAPI (4’, 6-diamidino-2-phenylindole) staining could be successfully monitored by the eubacterial oligonucleotide probe set EUB338, EUB338-II and EUB338-III, simultaneously indicating a high proportion of Eubacteria and the high metabolic potential of the bacterial community. Desulfobacteriaceae could be detected by the specific probe SRB385Db in various relative percentages ranging from 2.4 to 16.0% of the total bacterial cell counts. The total number of bacteria and the metabolic potential of sediment related bacteria were barely affected by the different pollution pattern of the sampling sites.The pre-treatment step as conducted by cell extraction as well as the FISH hybridization procedure was successfully optimized to the specific conditions present within freshwater sediments. Beside seasonal variations, particularly occurring at hydrologically influenced sites, sampling sites with different pol lution levels could be successfully distinguished by the relative abundance of Desulfobacteriaceae used as microbial indicator organisms.The integration of ongoing insights into pollution induced changes of natural bacterial consortia should result in a system of ecotoxicological classes representing the different ecological status of riverine systems. Physiological directed methods like Community Level Physiological Profiling (CLPP) or Pollution Induced Community Tolerance (PICT), and structural techniques as FISH or microarrays should be used to investigate the influence of harmful substances on the biodiversity in natural microbial sediment communities.
    Keywords: Cell extraction ; Desulfobacteriaceae ; Elbe ; Fluorescence hybridization ; lotic sediments ; microbial communities ; Oder ; river sediments ; sediment biofilms ; sulfate-reducing ; bacteria (SRB) ; Water Framework Directive
    ISSN: 1439-0108
    E-ISSN: 1614-7480
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  • 9
    Language: English
    In: Journal of Soils and Sediments, 2007, Vol.7(6), pp.377-387
    Description: Goals, Scope and Background While water quality strongly improved over decades in the Rhine River, sediments still reflect elapsed contaminations of organic pollutants and heavy metals. In comparing genotoxic effects induced by both sediment extracts and whole sediments, a ratio of bioavailable toxicity and total extractable toxicity is obtained. Since contaminated sites whose contaminants are toxic and as well bioavailable present an elevated risk to the ecosystem, such ratios may be used as a warning signal to identify sites of primary concern. Methods Accordingly, two different exposure scenarios were compared to reveal the genotoxic potential of 18 sediment samples derived from 9 sample sites along the River Rhine. For assessment of effects on genome integrity, DNA fragmentation was measured using the comet assay with primary cells isolated from zebrafish embryos previously exposed to either organic sediment extracts or freeze-dried sediments at sublethal concentrations. Additionally, chemical data were used to determine responsible pollutants and correlate them with biological effects. Results Whereas 17 out of 18 sediment extracts caused significant DNA damage to the embryo cells, only 4 native sediments showed a genotoxic potential. Thus, under field-like exposure conditions, a major part of potentially genotoxic compounds seem to remain particle-bound and ineffective, as shown for whole sediment exposure. Conversely, the organic extracts seem to contain enriched concentrations even of hardly soluble substances. Hence, organic extracts may be used as a screening tool to address potentially polluted sites, even though the relevance of these results for the field situation may be questionable. Investigations on native sediments determined few sites with bioavailable and therefore ecologically most relevant genotoxic sediment compounds. Discussion However, these results may underestimate the total hazard potential of sample sites with hardly bioavailable substances. Chemical data revealed a variety of anthropogenic pollutants, ranging from PAHs to heavy metals. Nevertheless, chemical data on the measured priority pollutants did not fully explain the pollution pattern of the bioassays but clearly determined substances of concern (e.g., HCB, heavy metals) in particular sample sites. Conclusions There is a striking advantage in assessing the genotoxicity by means of different exposure scenarios that focus on either bioavailable or extractable fractions, as the combination of the results allows obtaining information on specific properties of the genotoxicants and their bioavailability. An additional correlation with chemical data should be required to identify priority pollutants, as long as the responsible contaminant is known a priori. As many studies revealed inherent failures of such a correlation, an effect-driven analysis of pollutants is recommended as a promising tool to identify even non-priority pollutants by means of their ecotoxicological effectiveness. ; Includes references ; p. 377-387.
    Keywords: Bioavailability ; comet assay ; Danio rerio ; genotoxicity ; sediment ; zebrafish
    ISSN: 1439-0108
    E-ISSN: 1614-7480
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  • 10
    Language: English
    In: Journal of Soils and Sediments, 2004, Vol.4(2), pp.84-94
    Description: Improved quality of surface waters and sediments requires advanced strategies for ecotoxicological assessment. Whilst at least in Germany assessment strategies on the basis of chemical analysis and acute toxicity data dominated the last decades, the development of more specific biological endpoints and biomarkers in ecotoxicology is required in order to arrive at a good ecological potential and good chemical status of surface waters in the European river basins until the year 2015, as required by the European Water Framework Directive. Since sediments have for long been known to function both as a sink and as a source of pollutants in aquatic systems, and since part of the particle-associated substances have frequently been demonstrated to cause mutagenic and carcinogenic effects in aquatic organisms, particularly in fish, there is, among other requirements, an urgent need to develop, standardize and implement integrated vertebrate-based test systems addressing genotoxicity into recent sediment investigation strategies. Thus, the present study was designed to compare the suitability of two commonly used test systems, the comet assay and the Ames test, for the evaluation of the ecotoxicological burden of surface and core sediment samples from the river Rhine. In order to determine the importance of inherent enzymatic activities, two permanent fish cell lines with different biotransformation capacities, RTL-W1 and RTG-2, were compared with respect to their capability of detecting genotoxic effects in 18 surface and core sediment samples from 9 locations along the River Rhine in the comet assay with and without exogenous bioactivation. For further comparison, as a prokaryotic mutagenicity assay, theSalmonella plate incorporation assay (Ames test) with the test strains TA98 and TA 100 with and without exogenous metabolic activation was used. Whereas all sediment extracts induced genotoxic effects in the comet assay with RTL-W1 cells, only 12 out of 18 sediment extracts revealed significant genotoxicity in the tests with the less biotransformation-competent RTG-2 cells. Exogenous bioactivation by addition of ß-naphthoflavone /phenobarbital-induced S9 from rat liver resulted in both reduction or increase of genotoxicity in samples from different sites, however, without consistent reaction patterns. In general, the responses of RTL-W1 cells indicated higher biotransformation capacity than in RTG-2 cells without S9 complementation. In Ames tests using TA98 with S9, 16 out of 18 extracts induced significant mutagenicity with induction factors up to 4. Compared to TA98, the strain TA100 proved less sensitive, with maximum induction factors of 1.3, indicating the potential presence of substances inducing frarneshift mutations, which can only be detected in the strain TA98. Chemical analyses revealed particularly high levels of hexachlorbenzene (up to 860 µg/kg) and priority PAHs (up to 4.8 mg/kg); so far, however, no correlation could be found between compounds analyzed and the corresponding biotests. Results document that both comet assay and Ames test are capable of detecting xenobiotic interaction with DNA in consequence of exposure to complex environmental samples. Whereas the alkaline version of the comet assay detects a broad range of interactions with the DNA, however without information about their eventual importance, the Ames test only reveals established mutations, but fails to detect transient (reparable) DNA alterations. However, even transient primary changes in the DNA structure might result in carcinogenic processes and, eventually, in implications at the population level. As a consequence, for hazard assessment purposes, a combination of both assays is required to avoid false negatives in genotoxicity evaluation. Poor correlation between data obtained by chemical analysis and results in bioassays is indicative of our limited understanding of the sources of genotoxicity. In fact, numerous studies combining chemical and biological approaches for hazard assessment of complex environmental mixtures indicate that priority pollutant concentrations are a poor indicator of toxicity. If compared to the cell line RTG-2, RTL-W1 proved more effective in detecting genotoxicity in surface sediment samples and, thus, indicated the importance of bioactivation of at least part of the compounds in superficial layers of sediments. Results further document that the common assumption may be wrong that, in comparison to deeper strata, surface layers carry a lower toxic burden in consequence of the current decrease in water pollution. This might at least in part be due to remobilization of more heavily polluted sediments from deeper layers during severe flood events followed by re-sedimentation in flood plains or upstream weirs, where they might cover less polluted younger sediment layers. For a comprehensive assessment of genotoxicity in surface and core sediments, a combination of eukaryotic (comet assay) and prokaryotic assays (Ames test) with and without exogenous bioactivation is recommended. Since studies with organic sediments extracts simulate a worst-case scenario and fail to take into account bioavailability, there is broad consensus that whole-sediment exposure protocols represent the most realistic scenarios. Whereas more realistic solid phase exposure has frequently been applied in both microbial and invertebrate acute toxicity testing, there is an urgent need to develop corresponding whole sediment fish-based genotoxicity tests.[PUBLICATION ]
    Keywords: Ames test ; bioassay battery ; comet assay ; fish cell line ; genotoxicity ; mutagenicity ; river Rhine ; RTG-2 ; RTL-W1 ; sediments
    ISSN: 1439-0108
    E-ISSN: 1614-7480
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