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:Microbial community analysis with DNA oligonucleotide microarrays targeting ribosomal RNA (rRNA) provides a highly parallel interrogation of nucleic acids isolated from environmental samples. High fidelity readout is essential for accurate interpretation of hybridisations. We describe the hybridisation of in vitro transcribed 16S rRNA from an uncontaminated and 2,4,6-trinitrotoluene contaminated soil to an oligonucleotide microarray containing group- and species-specific perfect match (PM) probes and their 2 corresponding mismatch (MM) probes. Thermal dissociation analysis was used to determine the specificity of each PM-MM probe set. Functional ANOVA often discriminated PM-MM probe sets when Td values (temperature at 50% probe-target dissociation) could not. Maximum discrimination for many PM and MM probes often occurred at temperatures greater than the Td. Comparison of signal intensities measured prior to dissociation analysis from hybridisations of the two soil samples revealed significant differences in domain-, group- and species-specific probes. Functional ANOVA showed significantly different dissociation curves for 11 PM probes when hybridisations from the two soil samples were compared, even though initial signal intensities for 3 of the 11 did not vary. This approach provides a highly parallel, multi-level analysis that incorporates MM probes and dissociation curves into high fidelity microarray analysis of complex environmental nucleic acid profiles. Keywords: Microbial diversity, thermal dissociation analysis