Project description:Hemicellulose, the second most abundant plant biomass fraction after cellulose, is widely viewed as a potential feedstock for the production of liquid fuels and other value-added materials. Degradation of hemicellulose by filamentous fungi requires production of many different enzymes, which are induced by biopolymers or its derivatives and regulated mainly at the transcriptional level through transcription factors (TFs). Neurospora crassa has been shown to express and secrete plant cell wall associated enzymes. To better understand genes specifically associated with degradation of hemicellulose, we identified 353 genes by transcriptome analysis of N. crassa wild type strain grown on beechwood xylan. Exposure to xylan induces 9 of the 19 predicted hemicellulase genes. The xylanolytic phenotype of strains with deletions in genes identified from the secretome and transcriptome analysis of wild type showed that none were essential for growth on beechwood xylan. The transcription factor XlnR/Xyr1 in Aspergillus and Trichoderma species is considered to be the major transcriptional regulator of genes encoding both cellulases and hemicellulases. We identified a xlnR/xyr1 homolog in N. crassa, NCU06971, termed xlr-1 (xylanase regulator 1). Deletion of xlr-1 in N. crassa abolishes the growth on xylan and xylose, but growth on cellulose was indistinguishable from wild type. To determine regulatory mechanisms associated with hemicellulose degradation, we explored the transcriptional regulon of XLR-1 under xylose and xylanolytic versus cellulolytic conditions. XLR-1 regulated only some predicted hemicellulase genes in N. crassa and was required for a full induction of several cellulase genes. Hemicellulase gene expression was induced by a combination of release from carbon catabolite repression (CCR) and induction. However, in N. crassa, xlr-1 is subject to non-CRE-1 mediated CCR. This systematic analysis provides the similarities and differences of hemicellulose degradation and regulation mechanisms used by N. crassa in comparison to other filamentous fungi. Four-condition experiments (minimal medium, xylan medium,xylose and Avicel medium) of mutant strain(xlr-1) compared to wild type strain; Cy3 and Cy5 dye swap

Project description:We investigated ecotoxicological effects and toxicogenomic responses in fathead minnows (Pimephales promelas) exposed to an environmentally-relevant concentration (0.83 mg/L) of the munitions compound cyclotrimethylenetrinitramine (RDX) in one year and multi-generational assays. In the one year assay, RDX effects were discerned by comparing breeding groups reared in control or RDX-exposure conditions for one year. RDX had no detectable effect on gonad-somatic index, or condition factor in females assayed at 1 day and at 1, 3, 6, 9, and 12 months, however the liver-somatic index was significantly increased versus controls only at the 12 month time point. RDX had no effect on live-prey capture rates at all time points assayed and no significant impacts on egg production, fertilization or hatch success in the 1-year exposure trial. Genomic analyses indicated that RDX exposure caused limited differential expression of transcripts within time points and no functional conservation of effects indicative of RDX exposure among time points for either brain or liver tissues in the one year exposure. In the multi-generational assay, the effects of acute (96h) exposure to RDX were compared in fish reared to the F2 generation in either control or RDX-exposure conditions. The RDX-reared fish were not observed to have appreciably enhanced RDX tolerance versus the control-reared fish. However, significant differences in gene expression were observed among the control and RDX-reared fish related to neuro-excitatory glutamate metabolism, sensory signaling and processes in neurological development. In total, our results indicate that exposure to an RDX concentration approximating maximum levels observed in the field (0.83 mg/L) caused limited impacts in fathead minnows in a one year exposure, however caused altered expression in genes involved in neural function in a multi-generational exposure. Adult fathead minnows were exposed to 0.83 mg/L (0.15 mg/L standard deviation) in experimental units including 2 male and 4 fish. Five replicate males were randomly sampled with replacement from each of 8 control and 8 RDX-exposed experimental units at 1d, 1mo, 3mo, 6mo, 9mo and 12mo sampling periods. Brain tissue was investigated for differential expression in response to RDX exposure. Data were analyzed in 3 separate investigations. First, the Reference vs Reference data were analysed to determine an empirical false positive detection rate. Next, in order to meet milestones set up by our upper management, we were forced to generate results prior to the end of the bioassay. Therefore, we investigated gene expression among Control and RDX-exposed fish in the 1 day - 6 month sampling periods. Investigation of gene expression among the control and RDX-exposed fish for the 9 month and 12 month time periods were investigated separately.

Project description:Production, usage and disposal of the munitions constituent (MC) cyclotrimethylenetrinitramine (RDX) has led to environmental releases on military facilities. The chemical attributes of RDX are conducive for leaching to surface water which may put aquatic organisms at risk of exposure. Because RDX has been observed to cause aberrant neuromuscular effects across a wide range of animal phyla, we assessed the effects of RDX on central nervous system (CNS) function in the representative aquatic ecotoxicological model species, fathead minnow (Pimephales promelas). A brain-tissue based cDNA library enriched for transcripts differentially expressed in response to RDX exposure was developed for fathead minnow and was transitioned to custom cDNA-based microarrays. All 4,128 cDNAs were sequenced, quality filtered and assembled yielding 3,018 unique sequences and 945 significant blastx matches (E ≤ 10-5). Bioassays were conducted exposing fathead minnows to RDX at 0.625, 1.25, 2.5, 5, 10 mg/L or an acetone-spike control for 10d. Overt toxicity of RDX in fathead minnow occurred only at the highest exposure concentration resulting in 50% mortality. Conversely, Bayesian analysis of microarray data indicated significant changes in transcript expression in fathead minnow brain tissue at RDX concentrations as low as 0.625 mg/L. In total, 154 microarray targets representing 44 unique transcript identities were differentially expressed in RDX exposures, the majority of which were validated by RT-qPCR. Investigation of molecular pathways, gene ontology and individual gene functions indicated that RDX exposures affected metabolic processes involved in: oxygen transport, neurological function, calcium binding / signaling, energy metabolism, cell cycle / cell proliferation, oxidative stress and ubiquitination. In total, our study indicated that RDX exposure affected molecular processes critical to CNS function in fathead minnow. 10 Day RDX Exposure, Brain Tissue Investigation: Sub-adult fathead minnows were exposed to RDX in a 10d dose-series experiment (0.625, 1.25, 2.5, 5.0, or 10 mg/L RDX) which included an acetone-spike control (1% acetone). Each experimental treatment included 8 replicate fish (48 total fish) and endpoints included mortality, total weight and neurotoxicogenomics. The 1.25mg/L dose was not included in the microarray experiment. Please see attached PDF file for detailed 'Balanced, Interwoven Loop Design'.

Project description:Munitions constituents (MCs) including hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT), and TNT derivatives are recognized to elicit aberrant neuromuscular responses in many species. The onset of seizures resulting in death was observed in the avian model Northern bobwhite after oral dosing with RDX beginning at 8 mg/kg/day in subacute (14 days) exposures, whereas affective doses of the TNT derivative, 2,6-dinitrotoluene (2,6-DNT), caused gastrointestinal impacts, lethargy, and emaciation in subacute and subchronic (60 days) exposures. To assess and contrast the potential neurotoxicogenomic effects of these MCs, a Northern bobwhite microarray was developed consisting of 4119 complementary DNA (cDNA) features enriched for differentially-expressed brain transcripts from exposures to RDX and 2,6-DNT. RDX affected hundreds of genes in brain tissue, whereas 2,6-DNT affected few (M-bM-^IM-$ 17), indicating that 2,6-DNT exposure had relatively little impact on the brain in comparison to RDX. Birds exhibiting RDX-induced seizures accumulated over 20M-CM-^W more RDX in brain tissues in comparison to non-seizing birds even within a common dose. In parallel, expression patterns were unrelated among seizing and non-seizing birds exposed to equivalent RDX doses. In birds experiencing seizures, genes related to neuronal electrophysiology and signal transduction were significantly affected. Comparative toxicology revealed strong similarity in acute exposure effects between RDX and the organochlorine insecticide dichlorodiphenyltrichloroethane (DDT) regarding both molecular mechanisms and putative mode of action. In a manner similar to DDT, we hypothesize that RDX elicits seizures by inhibition of neuronal cell repolarization postaction potential leading to heightened neuronal excitability and seizures facilitated by multiple molecular mechanisms. Female Northern Bobwhite 14 Day 2,6-DNT Exposure, Brain Tissue Investigation (Low Laser Intensity Scan): Juvenile female Northern bobwhite (12 weeks of age) were dosed with 2,6-DNT by daily gavage (0, 50, 100, 190, or 350 mg/kg/day). Each treatment group included seven birds (at least three of each sex per treatment). Microarray experiments were conducted using an interwoven-loop design using Cyanine-3 (Cy3) and A647. This experiment investigated the effects of the 14-day 2,6-DNT exposure in females including controls, 60, and 100 mg/kg/day treatments, each including 3 biological replicates. To broaden signal detection, each microarray was scanned at high and low laser power to resolve low-intensity spots and reduce signal saturation, respectively (Skibbe et al., 2006). This dataset represents the Low Intensity Scan.

Project description:Munitions constituents (MCs) including hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT), and TNT derivatives are recognized to elicit aberrant neuromuscular responses in many species. The onset of seizures resulting in death was observed in the avian model Northern bobwhite after oral dosing with RDX beginning at 8 mg/kg/day in subacute (14 days) exposures, whereas affective doses of the TNT derivative, 2,6-dinitrotoluene (2,6-DNT), caused gastrointestinal impacts, lethargy, and emaciation in subacute and subchronic (60 days) exposures. To assess and contrast the potential neurotoxicogenomic effects of these MCs, a Northern bobwhite microarray was developed consisting of 4119 complementary DNA (cDNA) features enriched for differentially-expressed brain transcripts from exposures to RDX and 2,6-DNT. RDX affected hundreds of genes in brain tissue, whereas 2,6-DNT affected few (M-bM-^IM-$ 17), indicating that 2,6-DNT exposure had relatively little impact on the brain in comparison to RDX. Birds exhibiting RDX-induced seizures accumulated over 20M-CM-^W more RDX in brain tissues in comparison to non-seizing birds even within a common dose. In parallel, expression patterns were unrelated among seizing and non-seizing birds exposed to equivalent RDX doses. In birds experiencing seizures, genes related to neuronal electrophysiology and signal transduction were significantly affected. Comparative toxicology revealed strong similarity in acute exposure effects between RDX and the organochlorine insecticide dichlorodiphenyltrichloroethane (DDT) regarding both molecular mechanisms and putative mode of action. In a manner similar to DDT, we hypothesize that RDX elicits seizures by inhibition of neuronal cell repolarization postaction potential leading to heightened neuronal excitability and seizures facilitated by multiple molecular mechanisms. Female Northern Bobwhite 14 Day 2,6-DNT Exposure, Brain Tissue Investigation (High Laser Intensity Scan): Juvenile female Northern bobwhite (12 weeks of age) were dosed with 2,6-DNT by daily gavage (0, 50, 100, 190, or 350 mg/kg/day). Each treatment group included seven birds (at least three of each sex per treatment). Microarray experiments were conducted using an interwoven-loop design using Cyanine-3 (Cy3) and A647. This experiment investigated the effects of the 14-day 2,6-DNT exposure in females including controls, 60, and 100 mg/kg/day treatments, each including 3 biological replicates. To broaden signal detection, each microarray was scanned at high and low laser power to resolve low-intensity spots and reduce signal saturation, respectively (Skibbe et al., 2006). This dataset represents the High Intensity Scan.

Dataset Information

Neurospora crassa wild-type cells (WT, FGSC 2489) undergoing a time-course treatment with staurosporine

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