Project description:Small organisms can be used as biomonitoring tools to assess chemicals in the environment. Chemical stressors are especially hard to assess and monitor when present as complex mixtures. Here, Daphnia magna were exposed for 24 hours to five different munitions constituents 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), trinitrobenzene (TNB), dinitrobenzene (DNB), or 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) as well as to 8 different munitions mixtures and ground water contaminated with munitions constituents. To better understand possible mixture effects, gene expression changes from all treatments were compared using high-density microarrays. While mixtures and ground water exposures had genes and gene functions in common with single chemical exposures, unique functions were also affected, which was consistent with the non-additivity of chemical effects in these mixtures. The study consisted of three different experiments: (1) exposure to a concentration corresponding to 70% of 1/10th of the LC50 value of six individual MCs (TNT, 2,4-DNT, 2,6-DNT, DNB, TNB, RDX) and a control; (2) exposure to eight different laboratory mixtures of the previously mentioned MCs. Different combinations of MCs including four mixtures (Mixtures 5, 6, 7 and 8) representative of field collected groundwater from LAAP (Louisiana Army Ammunition Plant) were created; and (3) exposure to MC-contaminated ground water field-collected from 3 different wells (85, 108, and 141) at the LAAP. All exposures were conducted for 24h.
Project description:We investigated a contaminant-degrading microbial community by sequencing total RNA (without rRNA depletion) from microcosms containing sediment from a hypoxic contaminated aquifer fed with isotopically labeled toluene.
Project description:A functional microarray targeting 24 genes involved in chlorinated solvent biodegradation pathways has been developed and used to monitor the gene expression in a contaminated site (site B) under ERD (enhanced reductive dechlorination) treatment. The microarray format provided by NimbleGen and used in this study is 12x135K. 4 M-BM-5g of labelled antisense mRNA from 3 groundwater samples were hybridized on the microarray. A 3-chip study was performed, each corresponding to hybridization with 4 M-BM-5g of labelled antisense mRNA retrieved from a monitoring well of a contaminated site (site B). Each probe (760nt) on the microarray was synthesized in eight replicates, and a total of 5,707 random probes was used to determine the background noise. Groundwater samples were collected from a contaminated site (site B) from three monitoring wells (P1, P2 and P3). P1: well located upstream to the contamination source. P2: well in the contamination source. P3 : well located downstream to the contamination source.
Project description:A functional microarray targeting 24 genes involved in chlorinated solvent biodegradation pathways has been developed and used to monitor the gene diversity present in four trichloroethylene (TCE) contaminated sites under ERD (enhanced reductive dechlorination) treatment. The microarray format provided by NimbleGen and used in this study is 12x135K. 2 µg of labelled gDNA from 30 groundwater samples were hybridized on the microarrays.
Project description:Flounder fish were exposed in mesocosms for seven months to a contaminated estuarine sediment made by mixing material from the Forth (high organics) and Tyne (high metals and tributyltin) estuaries (FT) or control sediment from the Ythan estuary (Y). Their gene expression profiles were compatred by cDNA microarrays.
Project description:We analyzed the transcriptional response of the actinomycete Rhodococcus aetherivorans I24 to biphenyl and polychlorinated biphenyls (PCBs). This species has not been extensively exposed to PCBs, as it was first isolated from a toluene contaminated aquifer, rather than a site contaminated with polychlorinated hydrocarbons. Using a microarray targeting 3524 genes, we assessed gene expression in minimal medium supplemented with various substrates (e.g. PCBs) and in both PCB-contaminated and non-contaminated sediment slurries. Relative to the reference condition (minimal medium supplemented with glucose), 408 genes were up-regulated in the various treatments. In medium and in sediment, PCBs elicited the up-regulation of a common set of 100 genes, including chaperones (groEL), a superoxide dismutase (sodA), alkyl hydroperoxide reductase protein C (ahpC), and a catalase/peroxidase (katG). Analysis of the R. aetherivorans I24 genome sequence identified orthologs of many of the genes in the canonical biphenyl pathway, but very few of these genes were up-regulated in response to PCBs or biphenyl. This study is one of the first which utilizes microarrays to assess the transcriptional response of a soil bacterium to a pollutant under conditions which more closely resemble the natural environment. Our results indicate that the transcriptional response of R. aetherivorans I24 to PCBs, in both medium and sediment, is primarily directed towards reducing oxidative stress, rather than catabolism. In addition, the identification of numerous genes expressed in contaminated soil specifically may have implications for the development of biosensors. Finally, comparative genomic and transcriptomic analyses suggest that the mere presence of orthologs of the required enzymes may not be sufficient to confer a vigorous biphenyl/PCB metabolism. RNA was isolated from cells incubated in the following: sediment from a PCB-contaminated industrial site, uncontaminated sediment from a comparable site, and defined media supplemented with glucose (3 g/L), glucose and biphenyl (3 g/L, 4.5 μM), or glucose and PCBs (3 g/L, 5 mg/L Aroclor 1254). In all cases, there were 3 biological replicates and 2 technical replicates (repeat hybridizations). A total of 3524 genes are represented on the arrays; of these, 41 and 176 are found on the plasmids pRA2 and pRA3, respectively. On average, there are 3 distinct 24nt probes per gene.