Project description:Toxicity of river sediments are assessed using whole sediment toxicity tests with benthic organisms. The challenge, however, is the differentiation between multiple effects caused by complex contaminant mixtures and the unspecific toxicity endpoints such as survival, growth or reproduction. Moreover, natural sediment properties, such as grain size distribution and organic carbon content, can influence the test parameters by masking pollutant toxicity. The use of gene expression profiling facilitates the identification of transcriptional changes at the molecular level that are specific to the bioavailable fraction of pollutants. The nematode Caenorhabditis elegans is ideally suited for these purposes, as (i) it can be exposed to whole sediments, and (ii) its genome is fully sequenced and widely annotated. In this pilot study we exposed C. elegans for 48 h to three sediments varying in degree of contamination with e.g. heavy metals and organic pollutants. Following the exposure period, gene expression was profiled using a whole genome DNA-microarray approach. Whole genome DNA microarray experiments were performed using a common reference design to identify differentially expressed genes in nematodes exposed to one of three river sediments of differing pollution level. Each sample consists of the 5 “biological replicates”.
Project description:Toxicity of river sediments are assessed using whole sediment toxicity tests with benthic organisms. The challenge, however, is the differentiation between multiple effects caused by complex contaminant mixtures and the unspecific toxicity endpoints such as survival, growth or reproduction. Moreover, natural sediment properties, such as grain size distribution and organic carbon content, can influence the test parameters by masking pollutant toxicity. The use of gene expression profiling facilitates the identification of transcriptional changes at the molecular level that are specific to the bioavailable fraction of pollutants. The nematode Caenorhabditis elegans is ideally suited for these purposes, as (i) it can be exposed to whole sediments, and (ii) its genome is fully sequenced and widely annotated. In this pilot study we exposed C. elegans for 48 h to three sediments varying in degree of contamination with e.g. heavy metals and organic pollutants. Following the exposure period, gene expression was profiled using a whole genome DNA-microarray approach.
Project description:Gas hydrates, also known as clathrates, are cages of ice-like water crystals encasing gas molecules such as methane (CH4). Despite the global importance of gas hydrates, their microbiomes remain mysterious. Microbial cells are physically associated with hydrates, and the taxonomy of these hydrate-associated microbiomes is distinct from non-hydrate-bearing sites. Global 16S rRNA gene surveys show that members of sub-clade JS-1 of the uncultivated bacterial candidate phylum Atribacteria are the dominant taxa in gas hydrates. The Atribacteria phylogeny is highly diverse, suggesting the potential for wide functional variation and niche specialization. Here, we examined the distribution, phylogeny, and metabolic potential of uncultivated Atribacteria in cold, salty, and high-pressure sediments beneath Hydrate Ridge, off the coast of Oregon, USA, using a combination of 16S rRNA gene amplicon, metagenomic, and metaproteomic analysis. Methods were developed to extract bacterial cellular protein from these sediments, as outlined below. Sample Description Three sediments samples were collected from beneath Hydrate Ridge, off the coast of Oregon, USA. Sediments were cored at ODP site 1244 (44°35.1784´N; 125°7.1902´W; 895 m water depth) on the eastern flank of Hydrate Ridge ~3 km northeast of the southern summit on ODP Leg 204 in 2002 and stored at -80°C at the IODP Gulf Coast Repository. E10H5 sediment is from 68.5 meters below sediment surface interface C1H2 sediment is from 2 meters below sediment surface interface. C3H4 sediment is from 21 meters below sediment surface interface.
Project description: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. Microarray analysis revealed several classes of significantly regulated genes which could to a considerably extend 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. Microarray analysis were performed with early life stages of zebrafish exposed to 2 sediment extracts from the Upper part of the River Rhine, Germany. The expression profile as then compared to the expression pattern of model toxicants, such as, 4-chloroaniline, Cadmium, DDT, TCDD, and Valproic acid (Gene Expression Omnibus Series GSE9357). Additionally, combining mechanism-specific bioassays as well as chemical analysis of the sediments to the gene expression data has contributed to a more comprehensive view on the hazard potential of the sediments.
Project description:To study the responses of microbial communities to short-term nitrogen addition and warming,here we examine microbial communities in mangrove sediments subjected to a 4-months experimental simulation of eutrophication with 185 g m-2 year-1 nitrogen addition (N), 3oC warming (W) and nitrogen addition*warming interaction (NW).
Project description:Compared to freshwater ecosystems, the health status of estuarine waters remains little studied despite their importance for many species. They also represent a zone of interest for Human settlements that make them the final sink of pollution in both the water column and sediment. Once in sediments, pollutants could represent a threat to benthic as well as pelagic estuarine species through resuspension events. In the Seine estuary, the copepod Eurytemora affinis has been previously presented as a relevant species to assess resuspended sediment contamination through the use of fitness-related effects at the individual level. The aim of the present study was to use E. affinis copepods to assess estuarine sediment-derived elutriates toxicity using both a molecular (i.e. transcriptomics) and a behavioral approach. Two sites along the Seine estuary were sampled. They were both under anthropic pressures from the industrial-port activities or wastewater treatment plants (i.e. Tancarville) or agricultural pressure from freshwater affluent (i.e. Fatouville). The analysis of sediments used to prepare elutriates reveals that both sites have close contamination profiles. The transcriptomic analysis reveals that exposure to both sites triggers the dysregulation of genes involved in biological function as defense response, immunity, ecdysone pathway or neurotoxicity. This analysis also reveals a higher count of dysregulated genes in the Fatouville site compared to the Tancarville despite their close contamination profile. These results emphasize the sensitivity of this molecular approach to assess environmental matrix toxicity with E. affinis. The analysis of the swimming behavior of E. affinis did not highlight significant effects after both sites elutriate exposure. However, our strategy to assess E. affinis swimming behavior (i.e the combination of the DanioVision observation chamber and the EthoVision analysis software) allows the discrimination of basal swimming behavior in this species. Thus, it represents a promising standardized tool to assess copepods swimming behavior in ecotoxicological studies.
Project description:The zebrafish embryo has repeatedly proved to be a useful model for the analysis of effects by environmental toxicants. This 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 freeze-dried whole sediment samples and their corresponding organic extracts in parallel. To this end, altered gene expression was compared to data from established bioassays as well as to results from chemical analysis. Microarray analysis revealed several classes of significantly regulated genes which could to a considerable extent 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. Additionally, different gene expression was shown to be less influenced by the sampling site than by the method of exposure, which could be attributed to differential bioavailability of contaminants. Microarray analyses were performed with early life stages of zebrafish exposed to sediment extracts or freeze-dried sediment from three sampling sites (Ehingen, Lauchert, Sigmaringen) along the Upper part of the Danube River, Germany. The expression profiles were compared within the sampling sites, between the exposure scheme and to the expression pattern of model toxicants, such as 4-chloroaniline, Cadmium, DDT, TCDD, and Valproic acid (Gene Expression Omnibus Series GSE9357). Additionally, mechanism-specific bioassays and chemical analysis of the sediments have been combined and compared to the present gene expression data.