Project description:Investigation of mRNA expression (using HiSeq 2500) in response to treatment of Daphnia magna to pyriproxyfen, wetland water, or stormwater samples.
Project description:Mesocosms (600 L) were deployed at the Southern Ocean Time Series (SOTS) in Austral late summer during a high nutrient, low chlorophyll period. One mesocosm represented control, present-day conditions (high nutrients/low temperature/low pCO2/low Fe/low irradiance), while the other was amended to represent a projected 2100 scenario (low nutrients/high temperature/high pCO2/high Fe/high irradiance). Approximately 2 L were filtered from the mesocosms onto 5 µm filters at Days 0, 2, 4, and 7 of the incubation.
Project description:The synthetic microbial community used in this study was composed of the major functional guilds (cellulolytic fermenter, sulfate reducer, hydrogenotrophic methanogen and acetoclastic methanogen) that mediate the anaerobic conversion of cellulosic biomass to CH4 and CO2 in wetland soils. The choice of a facultative sulfate-reducing bacterium (Desulfovibrio vulgaris Hildenborough) introduced metabolic versatility and enabled investigations into the community response to sulfate intrusion. The growth status of these multi-species cultures was measured over a week by daily analysis of substrate consumption and product accumulation. The quad-cultures were analyzed with metaproteomics at the end of experiment to characterize the community structure and metabolic activities.
Project description:To unravel complex dynamics of environmental disturbance and microbial metabolic activities, we set up laboratory microcosms to investigate the effects of SO42- and O2 alone or in combination on microbial activities and interactions, as well as the resulting fate of carbon within wetland soil. We used proteogenomics to characterize the biochemical and physiological responses of microbial communities to individual perturbations and their combined effects. Stoichiometric models were employed to deconvolute carbon exchanges among the main functional guilds. These findings can contribute to the development of mechanistic models for predicting greenhouse gas emissions from wetland ecosystems under various climate change scenarios.
Project description:Purpose: Analyze changes in the transcriptome of Arabidopsis thaliana in response to sublethal concentrations of silver nanoparticles in order to gain insight into phytotoxicity caused by these nanomaterials. Methods: mRNA was extracted from non-treated and silver nanoparticle-treated 14-day old Arabidopsis thaliana seedlings using the RNAeasy extraction kit (Qiagen). RNA-seq libraries (3 rep/treatment and 3 reps/control) constructed with the TruSeq Stranded mRNA Sample Preparation kit (Illumina) were single-end sequenced (100-nt read length) on an Illumina HiSeq2500 system. Reads were mapped to the A. thaliana TAIR10 reference genome sequence and transcript levels were analyzed using the softare CLC Genomics Workbench (version 7.0.40, Qiagen). Results: Chronic exposure of A. thaliana plants to silver nanoparticles caused a change in abundance of transcripts involved in cell wall synhtesis and response to oxidative and biotic stress-related genes. Conclusions: While exposure to silver nanoparticle lead to gene expression changes, the reduction in chlorophyll concentration and carbon assimilation rate measured in exposed plants cannot be attributed to a shift in photosynthesis-related gene regulation.
Project description:Background: The uncontrolled and widespread use of (nano)silver compounds has led to the increased release of these compounds into the environment, raising concerns about their negative impact on ecosystems. Concomitantly, silver resistance determinants are widely spread among environmental and clinically relevant bacteria although the underlying mechanisms are not yet fully understood. Results: In this study, we show that Cupriavidus metallidurans is able to adapt to toxic silver concentrations and explicate the genetic circuit responsible for this adaptation. None of the known silver resistant determinants present in C. metallidurans are involved in the adapted response. Instead, increased silver resistance is achieved by the concerted action of a two-component system AgrR-AgrS, previously not associated with metal resistance, and two intrinsically disordered proteins PrsQ1 and PrsQ2. Both belong to an unique group of small, uncharacterized, extracellular proteins restricted to the genera Cupriavidus and Ralstonia. This system seems to be much more efficient as it gives C. metallidurans the ability to withstand much higher silver concentrations. The latter could be facilitated by the accumulation of silver ions and the formation of silver nanoparticles. Conclusions: Detailed knowledge and exploitation of this protein family could result in novel routes for metal nanoparticle formation and metal processing relevant for biotechnical and biomedical applications.
Project description:Silver nanoparticles cause toxicity in exposed organisms and are an environmental health concern. The mechanisms of silver nanoparticle toxicity, however, remain unclear. We examined the effects of exposure to silver in nano-, bulk- and ionic forms on zebrafish embryos (Danio rerio) using a Next Generation Sequencing approach in an Illumina platform (High-Throughput SuperSAGE). Significant alterations in gene expression were found for all treatments and many of the gene pathways affected, most notably those associated with oxidative phosphorylation and protein synthesis, overlapped strongly between the three treatments indicating similar mechanisms of toxicity for the three forms of silver studied. Changes in oxidative phosphorylation indicated a down-regulation of this pathway at 24h of exposure, but with a recovery at 48h. This finding was consistent with a dose-dependent decrease in oxygen consumption at 24h, but not at 48h, following exposure to silver ions. Overall, our data provide support for the hypothesis that the toxicity caused by silver nanoparticles is principally associated with bioavailable silver ions in exposed zebrafish embryos. These findings are important in the evaluation of the risk that silver particles may pose to exposed vertebrate organisms. mRNA profiles of whole zebrafish embryos at 24 and 48 hours post-fertilisation (hpf) exposed to silver in nano, bulk and ionic forms were generated by deep sequencing using HT-SuperSAGE (Illumina GA2).
Project description:The toxicity of silver and zinc oxide nanoparticles is hypothesised to be mediated by dissolved metal ions and cerium dioxide nanoparticles (CeO2 NPs) are hypothesised to induce toxicity specifically by oxidative stress dependant on their surface redox state. To test these hypotheses, RNAseq was applied to characterise the molecular responses of cells to metal nanoparticle and metal ion exposures. The human epithelial lung carcinoma cell line A549 was exposed to different CeO2 NPs with different surface charges, micron-sized and nano-sized silver particles and silver ions, micron-sized and nano-sized zinc oxide particles and zinc ions, or control conditions, for 1 hour, 6 hours and 24 hours. Concentrations were the lower of either EC20 or 128 micrograms/mL. Transcriptional responses were characterised by RNAseq transcriptomics using an Illumina HiSeq2500 .