Project description:Despite the increased utilization of nanoparticles, the behavior and effect in the environment is largely unknown and few resources are available for health and environmental effect studies. Enchytraeids are extensively used in studies of soil ecotoxicology and recently, a cDNA microarray for Enchytraeus albidus was developed, allowing also toxicogenomic studies in this species. These organisms are ecologically relevant small worms that indirectly contribute to the regulation and degradation of organic matter. In this study we compared the gene expression profiles of E. albidus when exposed to copper-salt (CuCl2) and copper nanoparticles (Cu-NP) spiked soil. The worms were exposed for 48 hours in soil to a range of concentrations. Microarray hybridizations revealed different response patterns between copper-salt and copper nanoparticles exposed organisms, these differences are mainly related with transcripts involved in the energy metabolism of the organisms. Despite unknown gene function in the data-set there are indications that Cu-salt and Cu-NP exposure induced specific gene level responses.
Project description:Despite the increased utilization of nanoparticles, the behavior and effect in the environment is largely unknown and few resources are available for health and environmental effect studies. Enchytraeids are extensively used in studies of soil ecotoxicology and recently, a cDNA microarray for Enchytraeus albidus was developed, allowing also toxicogenomic studies in this species. These organisms are ecologically relevant small worms that indirectly contribute to the regulation and degradation of organic matter. In this study we compared the gene expression profiles of E. albidus when exposed to copper-salt (CuCl2) and copper nanoparticles (Cu-NP) spiked soil. The worms were exposed for 48 hours in soil to a range of concentrations. Microarray hybridizations revealed different response patterns between copper-salt and copper nanoparticles exposed organisms, these differences are mainly related with transcripts involved in the energy metabolism of the organisms. Despite unknown gene function in the data-set there are indications that Cu-salt and Cu-NP exposure induced specific gene level responses. Fluorescently labelled cDNA, from enchytraeids exposed during 2 days to control soil (from Hygum site in Denmark) and to the different exposure conditions (Cy5), was synthesized for microarray analysis and hybridizations were performed. After scanning, spots were identified and ratios quantified using the QuantArray (Packard Biochip Technologies). Statistical analysis of the microarrays was performed using limmaGUI package (1.18.0) (Smyth, 2005) in the R (2.8.0) software environment (http://www.R-project.org/). After being submitted to local background subtraction, microarrays were normalized using global loess method. To statistically evaluate the differential gene expression between the different conditions, a gene-per-gene linear model (limma – linear model for microarray analysis) and empirical Bayes methods were applied. The results were then corrected for multiple testing using the Benjamini-Hochberg’s method (adjusted p<0.05 was considered significant) (Benjamini and Hochberg, 1995).
Project description:Due to its antimicrobial activity, silver nanoparticles (Ag-NPs) are among the most used NPs worldwide, yet little information is available regarding their effects, particularly in soil dwelling organisms. Enchytraeids (Oligochaeta) are important members of the soil fauna which actively contribute to the acceleration of organic matter decomposition and nutrient recycling processes. Hence, for hazard and risk assessment it is important to provide toxicity data for these organisms and to understand more in regard to the mode of action of Ag-NPs within organism. To study this we conducted toxicity experiments using the OECD standard guideline, testing Ag-NPs and AgNO3, having assessed survival, reproduction and differential gene expression. Population toxicity responses were assessed showing higher toxicity for the AgNO3. In an attempt to understand the mode of action we performed transcription profiling using the microarray. Gene expression profile of Enchytraeus albidus was analysed after 2 days of exposure to 100 and 200 mg/kg of two silver forms (nanoparticles and salt_silver nitrate) in OECD soil. Three biological replicates per test treatment and control (clean OECD soil) were used.
Project description:Metals, including copper (Cu) and nickel (Ni) are among the most common contaminants in soils in Europe. Although their effects are relatively well known regarding survival and reproduction of soil invertebrates, their modes of action in these organisms are still poorly studied. Enchytraeus albidus has been used in soil ecotoxicology for many years, and more recently has a gene library and an oligonucleotide microarray for this species which allowed gene expression studies. This has potentiated the means to study further in depth the mechanisms of response to stressors. The main aim of this study is to understand the mechanisms of response of E. albidus to Cu and Ni. For that we have 1) assessed and compared the transcriptomic profile of E. albidus in response to Cu and Ni and 2) compared the Cu, Ni, Cd and Zn transcriptomic profiles. For the microarray hybridizations, E. albidus were exposed to the reproduction effect concentrations EC50 and EC90 of Cu and Ni during 4 days. Results indicate that Cu and Ni have to some extent, similar mechanisms of toxicity and that have already been identified in other species, indicating cross-species conserved mechanisms. Based on hierarchical clustering, it was possible to observe a clear separation of Cd treatments from all other metals. This separation strongly correlates with the available information regarding the toxicokinetics of the tested metals, in which Ni shows properties similar to essential metals.
Project description:Transcriptional responses in Enchytraeus albidus (Oligochaeta): comparison between cadmium and zinc exposure and linkage to reproduction effects