Publications by authors named "Jens C Otte"

14 Publications

  • Page 1 of 1

Moving persistence assessments into the 21st century: A role for weight-of-evidence and overall persistence.

Integr Environ Assess Manag 2021 Nov 3. Epub 2021 Nov 3.

TotalEnergies Marketing & Services, Paris la Défense, France.

Assessing the persistence of chemicals in the environment is a key element in existing regulatory frameworks to protect human health and ecosystems. Persistence in the environment depends on many fate processes, including abiotic and biotic transformations and physical partitioning, which depend on substances' physicochemical properties and environmental conditions. A main challenge in persistence assessment is that existing frameworks rely on simplistic and reductionist evaluation schemes that may lead substances to be falsely assessed as persistent or the other way around-to be falsely assessed as nonpersistent. Those evaluation schemes typically assess persistence against degradation half-lives determined in single-compartment simulation tests or against degradation levels measured in stringent screening tests. Most of the available test methods, however, do not apply to all types of substances, especially substances that are poorly soluble, complex in composition, highly sorptive, or volatile. In addition, the currently applied half-life criteria are derived mainly from a few legacy persistent organic pollutants, which do not represent the large diversity of substances entering the environment. Persistence assessment would undoubtedly benefit from the development of more flexible and holistic evaluation schemes including new concepts and methods. A weight-of-evidence (WoE) approach incorporating multiple influencing factors is needed to account for chemical fate and transformation in the whole environment so as to assess overall persistence. The present paper's aim is to begin to develop an integrated assessment framework that combines multimedia approaches to organize and interpret data using a clear WoE approach to allow for a more consistent, transparent, and thorough assessment of persistence. Integr Environ Assess Manag 2021;00:1-20. © 2021 ExxonMobil Biomedical Sciences, Inc. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
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http://dx.doi.org/10.1002/ieam.4548DOI Listing
November 2021

Pax6 organizes the anterior eye segment by guiding two distinct neural crest waves.

PLoS Genet 2020 06 17;16(6):e1008774. Epub 2020 Jun 17.

Institute of Biological and Chemical Systems - Biological Information Processing, Karlsruhe Institute of Technology, Karlsruhe, Germany.

Cranial neural crest (NC) contributes to the developing vertebrate eye. By multidimensional, quantitative imaging, we traced the origin of the ocular NC cells to two distinct NC populations that differ in the maintenance of sox10 expression, Wnt signalling, origin, route, mode and destination of migration. The first NC population migrates to the proximal and the second NC cell group populates the distal (anterior) part of the eye. By analysing zebrafish pax6a/b compound mutants presenting anterior segment dysgenesis, we demonstrate that Pax6a/b guide the two NC populations to distinct proximodistal locations. We further provide evidence that the lens whose formation is pax6a/b-dependent and lens-derived TGFβ signals contribute to the building of the anterior segment. Taken together, our results reveal multiple roles of Pax6a/b in the control of NC cells during development of the anterior segment.
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http://dx.doi.org/10.1371/journal.pgen.1008774DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7323998PMC
June 2020

EmbryoMiner: A new framework for interactive knowledge discovery in large-scale cell tracking data of developing embryos.

PLoS Comput Biol 2018 04 19;14(4):e1006128. Epub 2018 Apr 19.

Institute for Automation and Applied Informatics, Karlsruhe Institute of Technology, Karlsruhe, Germany.

State-of-the-art light-sheet and confocal microscopes allow recording of entire embryos in 3D and over time (3D+t) for many hours. Fluorescently labeled structures can be segmented and tracked automatically in these terabyte-scale 3D+t images, resulting in thousands of cell migration trajectories that provide detailed insights to large-scale tissue reorganization at the cellular level. Here we present EmbryoMiner, a new interactive open-source framework suitable for in-depth analyses and comparisons of entire embryos, including an extensive set of trajectory features. Starting at the whole-embryo level, the framework can be used to iteratively focus on a region of interest within the embryo, to investigate and test specific trajectory-based hypotheses and to extract quantitative features from the isolated trajectories. Thus, the new framework provides a valuable new way to quantitatively compare corresponding anatomical regions in different embryos that were manually selected based on biological prior knowledge. As a proof of concept, we analyzed 3D+t light-sheet microscopy images of zebrafish embryos, showcasing potential user applications that can be performed using the new framework.
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http://dx.doi.org/10.1371/journal.pcbi.1006128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5929571PMC
April 2018

Intrinsic Xenobiotic Metabolizing Enzyme Activities in Early Life Stages of Zebrafish (Danio rerio).

Toxicol Sci 2017 09;159(1):86-93

Experimental Toxicology and Ecology, BASF SE, 67056 Ludwigshafen, Germany.

Early life stages of zebrafish (Danio rerio, zf) are gaining attention as an alternative invivo test system for drug discovery, early developmental toxicity screenings and chemical testing in ecotoxicological and toxicological testing strategies. Previous studies have demonstrated transcriptional evidence for xenobiotic metabolizing enzymes (XME) during early zf development. However, elaborate experiments on XME activities during development are incomplete. In this work, the intrinsic activities of representative phase I and II XME were monitored by transformation of putative zf model substrates analyzed using photometry and high pressure liquid chromatography techniques. Six different defined stages of zf development (between 2.5 h postfertilization (hpf) to 120 hpf) were investigated by preparing a subcellular fraction from whole organism homogenates. We demonstrated that zf embryos as early as 2.5 hpf possess intrinsic metabolic activities for esterase, Aldh, Gst, and Cyp1a above the methodological detection limit. The activities of the enzymes Cyp3a and Nat were measurable during later stages in development. Activities represent dynamic patterns during development. The role of XME activities revealed in this work is relevant for the assessing toxicity in this test system and therefore contributes to a valuable characterization of zf embryos as an alternative testing organism in toxicology.
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http://dx.doi.org/10.1093/toxsci/kfx116DOI Listing
September 2017

Fishing for contaminants: identification of three mechanism specific transcriptome signatures using Danio rerio embryos.

Environ Sci Pollut Res Int 2018 Feb 8;25(5):4023-4036. Epub 2017 Apr 8.

Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany.

In ecotoxicology, transcriptomics is an effective way to detect gene expression changes in response to environmental pollutants. Such changes can be used to identify contaminants or contaminant classes and can be applied as early warning signals for pollution. To do so, it is important to distinguish contaminant-specific transcriptomic changes from genetic alterations due to general stress. Here we present a first step in the identification of contaminant class-specific transcriptome signatures. Embryos of zebrafish (Danio rerio) were exposed to three substances (methylmercury, chlorpyrifos and Aroclor 1254, each from 24 to 48 hpf exposed) representing sediment typical contaminant classes. We analyzed the altered transcriptome to detect discriminative genes significantly regulated in reaction to the three applied contaminants. By comparison of the results of the three contaminants, we identified transcriptome signatures and biologically important pathways (using Cytoscape/ClueGO software) that react significantly to the contaminant classes. This approach increases the chance of finding genes that play an important role in contaminant class-specific pathways rather than more general processes.
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http://dx.doi.org/10.1007/s11356-017-8977-6DOI Listing
February 2018

Fold-change threshold screening: a robust algorithm to unmask hidden gene expression patterns in noisy aggregated transcriptome data.

Environ Sci Pollut Res Int 2015 Nov 17;22(21):16384-92. Epub 2015 Jul 17.

Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany.

Transcriptomics is often used to investigate changes in an organism's genetic response to environmental contamination. Data noise can mask the effects of contaminants making it difficult to detect responding genes. Because the number of genes which are found differentially expressed in transcriptome data is often very large, algorithms are needed to reduce the number down to a few robust discriminative genes. We present an algorithm for aggregated analysis of transcriptome data which uses multiple fold-change thresholds (threshold screening) and p values from Bayesian generalized linear model in order to assess the robustness of a gene as a potential indicator for the treatments tested. The algorithm provides a robustness indicator (ROBI) as well as a significance profile, which can be used to assess the statistical significance of a given gene for different fold-change thresholds. Using ROBI, eight discriminative genes were identified from an exemplary dataset (Danio rerio FET treated with chlorpyrifos, methylmercury, and PCB) which could be potential indicators for a given substance. Significance profiles uncovered genetic effects and revealed appropriate fold-change thresholds for single genes or gene clusters. Fold-change threshold screening is a powerful tool for dimensionality reduction and feature selection in transcriptome data, as it effectively reduces the number of detected genes suitable for environmental monitoring. In addition, it is able to unmask patterns in altered genetic expression hidden by data noise and reduces the chance of type II errors, e.g., in environmental screening.
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http://dx.doi.org/10.1007/s11356-015-5019-0DOI Listing
November 2015

An ensemble-averaged, cell density-based digital model of zebrafish embryo development derived from light-sheet microscopy data with single-cell resolution.

Sci Rep 2015 Feb 25;5:8601. Epub 2015 Feb 25.

1] Institute of Applied Physics, Karlsruhe Institute of Technology, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany [2] Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Post Office Box 3640, 76021 Karlsruhe, Germany [3] European Zebrafish Resource Centre, Karlsruhe Institute of Technology, Post Office Box 3640, 76021 Karlsruhe, Germany [4] Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.

A new era in developmental biology has been ushered in by recent advances in the quantitative imaging of all-cell morphogenesis in living organisms. Here we have developed a light-sheet fluorescence microscopy-based framework with single-cell resolution for identification and characterization of subtle phenotypical changes of millimeter-sized organisms. Such a comparative study requires analyses of entire ensembles to be able to distinguish sample-to-sample variations from definitive phenotypical changes. We present a kinetic digital model of zebrafish embryos up to 16 h of development. The model is based on the precise overlay and averaging of data taken on multiple individuals and describes the cell density and its migration direction at every point in time. Quantitative metrics for multi-sample comparative studies have been introduced to analyze developmental variations within the ensemble. The digital model may serve as a canvas on which the behavior of cellular subpopulations can be studied. As an example, we have investigated cellular rearrangements during germ layer formation at the onset of gastrulation. A comparison of the one-eyed pinhead (oep) mutant with the digital model of the wild-type embryo reveals its abnormal development at the onset of gastrulation, many hours before changes are obvious to the eye.
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http://dx.doi.org/10.1038/srep08601DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5390106PMC
February 2015

Impacts of different exposure scenarios on transcript abundances in Danio rerio embryos when investigating the toxicological burden of riverine sediments.

PLoS One 2014 4;9(9):e106523. Epub 2014 Sep 4.

Department of Ecosystem Analysis, Institute for Environmental Research, Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany; School of Environment, Nanjing University, Nanjing, China; Key Laboratory of Yangtze River Environment of Education Ministry of China, College of Environmental Science and Engineering, Tongji University, Shanghai, China; College of Resources and Environmental Science, Chongqing University, Chongqing, China.

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 as confirmed 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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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0106523PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4154683PMC
May 2015

Fast segmentation of stained nuclei in terabyte-scale, time resolved 3D microscopy image stacks.

PLoS One 2014 27;9(2):e90036. Epub 2014 Feb 27.

Institute for Applied Computer Science (IAI), Karlsruhe Institute of Technology, Karlsruhe, Germany.

Automated analysis of multi-dimensional microscopy images has become an integral part of modern research in life science. Most available algorithms that provide sufficient segmentation quality, however, are infeasible for a large amount of data due to their high complexity. In this contribution we present a fast parallelized segmentation method that is especially suited for the extraction of stained nuclei from microscopy images, e.g., of developing zebrafish embryos. The idea is to transform the input image based on gradient and normal directions in the proximity of detected seed points such that it can be handled by straightforward global thresholding like Otsu's method. We evaluate the quality of the obtained segmentation results on a set of real and simulated benchmark images in 2D and 3D and show the algorithm's superior performance compared to other state-of-the-art algorithms. We achieve an up to ten-fold decrease in processing times, allowing us to process large data sets while still providing reasonable segmentation results.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0090036PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3937404PMC
October 2014

Contribution of priority PAHs and POPs to Ah receptor-mediated activities in sediment samples from the River Elbe Estuary, Germany.

PLoS One 2013 11;8(10):e75596. Epub 2013 Oct 11.

KIT - Karlsruhe Institute of Technology, Institute of Toxicology and Genetics, Karlsruhe, Germany.

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, particularly the 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 priority PAHs revealed that sediments were moderately contaminated at all of the sites in the Elbe River Estuary (<0.02-0.906 µg/g dw). Sediments contained relatively small concentrations of dioxin equivalents (Bio-TEQ) with concentrations ranging from 15.5 to 322 pg/g dw, which were significantly correlated with dioxin equivalents calculated based on toxicity reference values and concentrations of PAH. The concentration of Bio-TEQ at the reference site exceeded 200,000 pg/g dw. In a potency 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 as sediments has rarely been reported.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0075596PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3795708PMC
July 2014

A combined DNA-microarray and mechanism-specific toxicity approach with zebrafish embryos to investigate the pollution of river sediments.

Reprod Toxicol 2012 Apr 2;33(2):245-53. Epub 2012 Feb 2.

Aquatic Ecology and Toxicology Group, COS-Center for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany.

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 the ecotoxicity 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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http://dx.doi.org/10.1016/j.reprotox.2012.01.005DOI Listing
April 2012

Toxicity, dioxin-like activities, and endocrine effects of DDT metabolites--DDA, DDMU, DDMS, and DDCN.

Environ Sci Pollut Res Int 2012 Feb 27;19(2):403-15. Epub 2011 Jul 27.

Aquatic Ecology and Toxicology, COS-Center for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany.

Background, Aim, And Scope: 2,2-bis(chlorophenyl)-1,1,1-trichloroethane (DDT) metabolites, other than those routinely measured [i.e., 2,2-bis(chlorophenyl)-1,1-dichloroethylene (DDE) and 2,2-bis(chlorophenyl)-1,1-dichloroethane (DDD)], have recently been detected in elevated concentrations not only in the surface water of Teltow Canal, Berlin, but also in sediment samples from Elbe tributaries (e.g., Mulde and Havel/Spree). This was paralleled by recent reports that multiple other metabolites could emerge from the degradation of parent DDT by naturally occurring organisms or by interaction with some heavy metals. Nevertheless, only very few data on the biological activities of these metabolites are available to date. The objective of this communication is to evaluate, for the first time, the cytotoxicity, dioxin-like activity, and estrogenicity of the least-studied DDT metabolites.

Methods: Four DDT metabolites, p,p'-2,2-bis(chlorophenyl)-1-chloroethylene (DDMU), p,p'-2,2-bis(chlorophenyl)-1-chloroethane (DDMS), p,p'-2,2-bis(4-ch1oropheny1)acetonitrile (DDCN), and p,p'-2,2-bis(chlorophenyl)acetic acid (DDA), were selected based on their presence in environmental samples in Germany such as in sediments from the Mulde River and Teltow Canal. O,p'-DDT was used as reference in all assays. Cytotoxicity was measured by neutral red retention with the permanent cell line RTG-2 of rainbow trout (Oncorhynchus mykiss). Dioxin-like activity was determined using the 7-ethoxyresorufin-O-deetylase assay. The estrogenic potential was tested in a dot blot/RNAse protection-assay with primary hepatocytes from male rainbow trout (O. mykiss) and in a yeast estrogen screen (YES) assay.

Results: All DDT metabolites tested revealed a clear dose-response relationship for cytotoxicity in RTG-2 cells, but no dioxin-like activities with RTL-W1 cells. The dot blot/RNAse protection-assay demonstrated that the highest non-toxic concentrations of these DDT metabolites (50 μM) had vitellogenin-induction potentials comparable to the positive control (1 nM 17β-estradiol). The estrogenic activities could be ranked as o,p'-DDT > p,p'-DDMS > p,p'-DDMU > p,p'-DDCN. In contrast, p,p'-DDA showed a moderate anti-estrogenic effect. In the YES assay, besides the reference o,p'-DDT, p,p'-DDMS and p,p'-DDMU displayed dose-dependent estrogenic potentials, whereas p,p'-DDCN and p,p'-DDA did not show any estrogenic potential.

Discussion: The reference toxicant o,p'-DDT displayed a similar spectrum of estrogenic activities similar to 17β-estradiol, however, with a lower potency. Both p,p'-DDMS and p,p'-DDMU were also shown to have dose-dependent estrogenic potentials, which were much lower than the reference o,p'-DDT, in both the vitellogenin and YES bioassays. Interestingly, p,p'-DDA did not show estrogenic activity but rather displayed a tendency towards anti-estrogenic activity by inhibiting the estrogenic effect of 17β-estradiol. The results also showed that the p,p'-metabolites DDMU, DDMS, DDCN, and DDA do not show any dioxin-like activities in RTL-W1 cells, thus resembling the major DDT metabolites DDD and DDE.

Conclusions: All the DDT metabolites tested did not exhibit dioxin-like activities in RTL-W1 cells, but show cytotoxic and estrogenic activities. Based on the results of the in vitro assays used in our study and on the reported concentrations of DDT metabolites in contaminated sediments, such substances could, in the future, pose interference with the normal reproductive and endocrine functions in various organisms exposed to these chemicals. Consequently, there is an urgent need to examine more comprehensively the risk of environmental concentrations of the investigated DDT metabolites using in vivo studies. However, this should be paralleled also by periodic evaluation and monitoring of the current levels of the DDT metabolites in environmental matrices.

Recommendations And Perspectives: Our results clearly point out the need to integrate the potential ecotoxicological risks associated with the "neglected" p,p'-DDT metabolites. For instance, these DDT metabolites should be integrated into sediment risk assessment initiatives in contaminated areas. One major challenge would be the identification of baseline data for such risk assessment. Further studies are also warranted to determine possible additive, synergistic, or antagonistic effects that may interfere with the fundamental cytotoxicity and endocrine activities of these metabolites. For a more conclusive assessment of the spectrum of DDT metabolites, additional bioassays are needed to identify potential anti-estrogenic, androgenic, and/or anti-androgenic effects.
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http://dx.doi.org/10.1007/s11356-011-0570-9DOI Listing
February 2012

Spatio-temporal development of CYP1 activity in early life-stages of zebrafish (Danio rerio).

Aquat Toxicol 2010 Oct 13;100(1):38-50. Epub 2010 Jul 13.

Aquatic Ecology & Toxicology, Department of Zoology, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany.

Endpoints of planar halogenated aromatic hydrocarbon (pHAH) and polycyclic aromatic hydrocarbon (PAH) toxicity are mediated via activation of the aryl hydrocarbon receptor (AhR) followed by activation of the so called "AhR-battery" of genes including the cytochrome P450 1 (CYP1) isoforms. The aim of this study was to develop a method to identify CYP1 activity in early life-stages of zebrafish (Danio rerio) in order to elucidate the spatio-temporal pattern of basal and induced CYP1 activities. Preliminary experiments with the fish embryo toxicity test (FET) were carried out to determine toxic effect thresholds of the AhR agonist β-naphthoflavone. To assess basal and β-naphthoflavone-induced CYP1 activity during early life-stages of zebrafish, the commonly used 7-ethoxyresorufin-O-deethylase (EROD) assay was developed further for use in confocal laser scanning microscopy (CLSM) and spectrometry. Following exposure to selected cytochrome P450 inducers, zebrafish embryos were dechorionated, anaesthetized and inspected in vivo under the CLSM. Alternatively, embryos were homogenized, and EROD activity was measured using classical spectrometry in vitro. CLSM of CYP-induced fluorescence allowed for the in vivo detection of CYP1 enzyme activity down to the cellular level as early as in the gastrulation stage. Basal and induced CYP1 activity was detected at all time points examined from 8h post-fertilization to early adulthood and showed a highly dynamic spatio-temporal pattern throughout zebrafish development. Basal and induced EROD activity was prominent in tissues of the cardiovascular system, the urinary tract, the digestive system, and parts of the brain as well as in the central portion of the eye and the otic vesicle during distinct stages of development. The differentiation between constitutive and induced spatio-temporal patterns of CYP1 activity even as early as the gastrula stage provide further insights into the endogenous role of CYP1 activity.
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http://dx.doi.org/10.1016/j.aquatox.2010.07.006DOI Listing
October 2010

A bioassay approach to determine the dioxin-like activity in sediment extracts from the Danube River: ethoxyresorufin-O-deethylase induction in gill filaments and liver of three-spined sticklebacks (Gasterosteus aculeatus L.).

Environ Int 2008 Nov 20;34(8):1176-84. Epub 2008 Jun 20.

Department of Environmental Toxicology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.

Sediment samples from the upper Danube River in Germany have previously been characterized as ecotoxicologically hazardous and contaminants in these sediments may contribute to the observed decline of fish populations in this river section. For the investigation of sediment toxicity there is a need for development, standardization and implementation of in vivo test systems using vertebrates. Therefore, the main objective of this study was to apply and evaluate a recently established fish gill EROD assay as a biomarker in sediment toxicity assessment by using extracts of well characterised sediment samples from the upper Danube River. This to our knowledge is the first application of this novel assay to sediment extracts. Sediments from four different sites along the upper Danube River were Soxhlet-extracted with acetone and dissolved in DMSO. Three-spined sticklebacks (Gasterosteus aculeatus L.) were exposed for 48 h to various concentrations of the extracts, to the positive control beta-naphthoflavone or to the solvent. Measurements of EROD activity in gill filaments and liver microsomes followed the exposure. Concentration-dependent induction of EROD in both gill and liver was found for all sediment extracts. The highest EROD-inducing potency was determined for extracts of sediments from the sites "Opfinger See" and "Sigmaringen" and the EROD activities in gill and liver correlated well. The results from the gill and liver assays were in accordance with in vitro results of previous investigations. The EROD activities measured in the present study corresponded with the concentrations of PAHs, PCBs and PCDD/Fs in the sediment samples derived in a previous study. The sticklebacks in this study were in the reproductive phase and a stronger EROD induction was obtained in the females than in the males. Implementation of the EROD assay in testing of sediment extracts gave highly reliable results which make this assay an ecotoxicologically relevant method for assessment of contamination with Ah receptor agonists in sediments.
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http://dx.doi.org/10.1016/j.envint.2008.05.004DOI Listing
November 2008
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