| 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. |
- Hadzhiev, Yavor, et al.
(författare)
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Hedgehog signaling patterns the outgrowth of unpaired skeletal appendages in zebrafish
- 2007
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Ingår i: BMC Developmental Biology. - 1471-213X. ; 7, s. 75-
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundLittle is known about the control of the development of vertebrate unpaired appendages such as the caudal fin, one of the key morphological specializations of fishes. Recent analysis of lamprey and dogshark median fins suggests the co-option of some molecular mechanisms between paired and median in Chondrichthyes. However, the extent to which the molecular mechanisms patterning paired and median fins are shared remains unknown.ResultsHere we provide molecular description of the initial ontogeny of the median fins in zebrafish and present several independent lines of evidence that Sonic hedgehog signaling emanating from the embryonic midline is essential for establishment and outgrowth of the caudal fin primordium. However, gene expression analysis shows that the primordium of the adult caudal fin does not harbor a Sonic hedgehog-expressing domain equivalent to the Shh secreting zone of polarizing activity (ZPA) of paired appendages.ConclusionOur results suggest that Hedgehog proteins can regulate skeletal appendage outgrowth independent of a ZPA and demonstrates an unexpected mechanism for mediating Shh signals in a median fin primordium. The median fins evolved before paired fins in early craniates, thus the patterning of the median fins may be an ancestral mechanism that controls the outgrowth of skeletogenic appendages in vertebrates.
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| 3. |
- Hausen, Jonas, et al.
(författare)
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Fishing for contaminants : identification of three mechanism specific transcriptome signatures using Danio rerio embryos
- 2018
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 25:5, s. 4023-4036
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Tidskriftsartikel (refereegranskat)abstract
- 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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| 4. |
- Hollert, Henner, et al.
(författare)
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Eine Weight-of-Evidence-Studie zur Bewertung der Sedimentbelastung und des Fischrückgangs in der Oberen Donau [Assessing sediments and fish health using a weight-of-evidence approach : in search for the causes of fish decline in the Danube river]
- 2009
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Ingår i: Umweltwissenschaften und Schadstoff-Forschung. - Berlin : Springer. - 0934-3504 .- 1865-5084. ; 21:3, s. 260-263
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Tidskriftsartikel (refereegranskat)abstract
- Background and aim Despite intensive and continuous stocking and improvement of water quality since the 1970s, fish populations, especially those of the grayling (Thymallus thymallus), have declined over the last two decades in the upper Danube River (Germany). In order to assess 1) possible links between molecular/biochemical responses and ecologically relevant effects, and 2) if ecotoxicological effects might be related to the decline in fish catches in the upper Danube river, sediment samples and fish were collected at different locations and analyzed using a weight-of-evidence (WOE) approach with several lines of evidence. The objective of the presentation is to introduce the conceptual framework and to review results of the ongoing study. As previously addressed by Chapman and Hollert (2006) a variety of lines of evidence can be used in WOE studies. Briefly, 1) a comprehensive battery of acute and mechanism-specific bioassays was used to characterize the ecotoxicological hazard potential. 2) Histopathological investigations and the micronucleus assay with erythrocytes were applied, analyzing in situ parameters. 3) Diversity and abundance of benthic macroinvertebrates and fish as well as 4) persistent organic pollutants, endocrine disrupting substances, limnochemical parameters and the concentration of heavy metals were recorded. To identify organic contaminants a spotential causes of sediment toxicity assays, 5) effect directed analysis was applied. © 2009 Springer-Verlag.
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| 5. |
- 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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| 6. |
- 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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