ABSTRACT: Transcriptional responses in Enchytraeus albidus (Oligochaeta): comparison between cadmium and zinc exposure and linkage to reproduction effects
Project description:Metal ecotoxicity on soil organisms, e.g. in Enchytraeids (also known as potworms), has been addressed mainly by assessing effects on survival and reproduction but very little is known about the molecular underlying mechanisms of responses. The main purpose of the present study was to assess and compare the transcriptional responses of Enchytraeus albidus to an essential (zinc) and a non-essential metal (cadmium). Exposure was performed to two concentrations of known effect on reproduction (EC50, EC90) at three time periods (2, 4 and 8 days). Results showed that transcriptional responses were influenced by exposure duration but, independently of that, the mechanisms of response to Cd and Zn were consistently different. Both metals affected pathways related with the regulation of gene expression, calcium homeostasis and cellular respiration. Mechanisms of toxicity that were exclusively associated with Cd exposures were the inhibition of DNA repair and the impairment of ubiquitin-mediated proteolysis. The microarray for E. albidus was a useful tool to detect molecular pathways affected by metal exposures. Transcriptional responses strongly correlated with known mechanisms of Cd and Zn responses in other organisms, suggesting cross-species conserved mechanisms of action. It should be highlighted that we could not only retrieve mechanistic information, but also that genes responded within 2-8 days of exposure. This represents an additional advantage of using such molecular endpoints as a complement to the traditional, more time-consuming endpoints. Gene expression in E.albidus was measured at 2, 4, and 8 days after exposure to Cadmium and Zinc at 2 concentrations of effect on reprocduction (EC50 and EC90). Three biological replicates per exposure treatment in each time point and 4 biological replicates of control conditions 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. Gene expression in E.albidus was measured 4 days after exposure to Copper, Nickel, Cadmium and Zinc at 2 concentrations of effect on reprocduction (EC50 and EC90). Three biological replicates per exposure condition and 6 biological replicates of control conditions were used.
Project description:Metal ecotoxicity on soil organisms, e.g. in Enchytraeids (also known as potworms), has been addressed mainly by assessing effects on survival and reproduction but very little is known about the molecular underlying mechanisms of responses. The main purpose of the present study was to assess and compare the transcriptional responses of Enchytraeus albidus to an essential (zinc) and a non-essential metal (cadmium). Exposure was performed to two concentrations of known effect on reproduction (EC50, EC90) at three time periods (2, 4 and 8 days). Results showed that transcriptional responses were influenced by exposure duration but, independently of that, the mechanisms of response to Cd and Zn were consistently different. Both metals affected pathways related with the regulation of gene expression, calcium homeostasis and cellular respiration. Mechanisms of toxicity that were exclusively associated with Cd exposures were the inhibition of DNA repair and the impairment of ubiquitin-mediated proteolysis. The microarray for E. albidus was a useful tool to detect molecular pathways affected by metal exposures. Transcriptional responses strongly correlated with known mechanisms of Cd and Zn responses in other organisms, suggesting cross-species conserved mechanisms of action. It should be highlighted that we could not only retrieve mechanistic information, but also that genes responded within 2-8 days of exposure. This represents an additional advantage of using such molecular endpoints as a complement to the traditional, more time-consuming endpoints.
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:Effect of Cu-Nanoparticles versus Cu-salt in Enchytraeus albidus (Oligochaeta): differential gene expression through microarray analysis