Project description:The physiological and transcriptional response of Nitrosomonas europaea biofilms to phenol and toluene was examined and compared to suspended cells. Biofilms were grown in Drip Flow Biofilm Reactors under continuous flow conditions of growth medium containing ammonia as growth substrate. The responses of N. europaea biofilms to the aromatic hydrocarbons phenol and toluene were determined during short-term (3 h) additions of each compound to the biofilms. Ammonia oxidation in the biofilms was inhibited 50% by 60 uM phenol and 100 uM toluene. These concentrations were chosen for microarray analysis of phenol- and toluene-exposed N. europaea biofilms. Liquid batch cultures of exponentially growing N. europaea cells were harvested alongside the biofilms to determine differential gene expression between attached and suspended growth of N. europaea. Four sample groups of N. europaea cells were used in this study, with biological triplicates of each group. Groups were: Control (untreated) biofilms, phenol-exposed biofilms, toluene-exposed biofilms, and exponentially growing suspended cells. Biofilms were grown in Drip Flow Biofilm Reactors containing 4 independent growth channels and subject to 2 hour inhibition tests. During each experiment, 2 biofilm channels served as control with no inhibitor present and the other 2 biofilm channels were exposed to either 60 uM phenol or 100 uM toluene. Nitrite production was monitored throughout the experiment, and the given concentrations of phenol and toluene resulted in 50% inhibition of ammonia oxidation by the biofilms. Suspended cells were grown in batch reactors. Three 4-plex NimbleGen microarray chips were used, and each chip contained one sample from each experimental group. QC of samples was determined by spectrophotometric methods and using Agilent bioanalyzer traces to determine purity and integrity of RNA and cDNA. A sample tracking report was used to verify the correct hybridization of each sample to the intended array.

Project description:Investigation of the whole genome gene expression level changes relative to exponential phase growth in Nitrosomonas europaea ATCC19718 after 12 hours ammonia starvation, 144 hours ammonia starvation, and 20 minutes following ammonia addition to starved cells. The ammonia monooxygenase of chemolithotrophic ammonia oxidizing bacteria (AOB) catalyzes the first step in ammonia oxidation by converting ammonia to hydroxylamine. The monooxygenase of Nitrosomonas europaea is encoded by two nearly identical operon copies (amoCAB1,2). Several AOB, including N. europaea, also posess a divergent monocistronic copy of amoC (amoC3) of unknown function. Previous work suggested a possible functional role for amoC3 in N. europaea during recovery from extended ammonia starvation as part of the σE- stress response regulon during the recovery of N. europaea from extended ammonia starvation, thus indicating its importance during the exit of cells from starvation. We here used global transcription analysis to show that expression of amoC3 is part of a general post-starvation cellular response system in N. europaea. We also found that amoC3 is required for efficient exit from prolonged ammonia starvation, as deleting this gene impaired growth at elevated temperatures and recovery following starvation under high oxygen tensions. Deletion of the σ32 global stress response regulator demonstrated that the heat shock regulon also plays a significant role in mediating the recovery of N. europaea from starvation. These findings provide the first described phenotype associated with the divergent AmoC3 subunit which appears to function as a stress responsive subunit capable of maintaining ammonia oxidation activity under stress conditions. A twelve chip study using total RNA recovered from four timepoints for each of three biological replicates of wild-type cultures of Nitrosomonas europaea ATCC 19718. Total RNA was obtained from each biological culture replicate during exponential growth, following 12 hours ammonia starvation, 144 hours ammonia starvations, and 20 minutes following ammonia addition to starved cells.

Project description:Pulmonary exposure to high doses of nanoparticles (NP) leads to well characterized lung toxicity in addition to long-term NP retention. However, pulmonary NP accumulation and toxicity following low dose exposures are not well described. In the present study we sought to: (1) investigate particle retention in mouse lungs following intratracheal instillation of varying doses of nano-sized titanium dioxide (nano-TiO2) and (2) determine the effects of long-term particle accumulation on pulmonary systems. Female C57BL/6 mice were exposed to rutile nano-TiO2 (primary size of 20.6 nm and surface area of 107.7 m2/g) via single intratracheal instillations of 18, 54 and 162 M-BM-5g/mouse and sampled 1, 3 and 28 days post-exposure. The deposition of nano-TiO2 in the lungs was assessed using Nanoscale Hyperspectral Microscope. DNA microarrays, pathway-specific real-time RT-PCR (qPCR) and gene-specific qPCR arrays, and tissue protein analyses were employed to characterize pulmonary responses. Hyperspectral mapping showed dose-dependent retention of nano-TiO2 in the lungs up to 28 days post-exposure time. Retention did not correlate with the extent of inflammatory neutrophil influx into the lungs. DNA microarray analysis showed altered expression of approximately 3000 genes across all treatment groups (M-BM-11.3 fold; p<0.1). Several inflammatory mediators changed in a dose- and time-dependent manner at both the mRNA and protein levels. Although the low dose exposure failed to induce observable inflammation, significant changes in the expression of genes and proteins associated with inflammation were observed. Moreover, diminished (or absent) neutrophil influx in the low and medium dose groups was correlated with negative regulation of genes associated with ion homeostasis and muscle regulation. Gene expression changes for several inflammatory mediators have previously been noted in mice exposed to the same nano-TiO2 via inhalation. Our results suggest that retention of nano-TiO2 in the absence of inflammation and effective clearance can perturb calcium and ion homeostasis, and affect smooth muscle activities over time. This experiment consists of three different dosages of TiO2, e.g., low (18 ug), medium (54 ug) and high (162 ug), and one control. There are 3 time points for each treatment and control group, e.g., day 1, day 3 and day 28. Each dose or time point has 5-6 biological replicates. There are total 65 samples (arrays)

Project description:An estimated 1% or less of the nanoparticles (NPs) deposited in lungs translocate to systemic circulation and enter other organs; however this estimation may not be accurate considering the low sensitivity of the existing in vivo NP detection methods. Moreover, the biological outcomes of such low levels of translocation are not elucidated. The objectives of the present study were to employ a Nano-scale Hyperspectral Microscope to spatially observe and spectrally profile NPs in tissues, and characterize the effects of NPs in blood, liver and heart following pulmonary deposition and subsequent translocation from lungs. Adult female C57BL/6 mice were exposed via intratracheal instillation to 18 and 162 µg per mouse of industrially relevant non-doped titanium dioxide nanoparticles (nano-TiO2). Using the Nano-scale Hyperspectral Microscope translocation to heart and liver was confirmed at both doses and to blood at the highest dose at 24 hours post-exposure time-point. The analysis of biological effects using DNA microarrays, RT-qPCR and ELISA revealed activation of complement cascade and inflammatory process in heart and specific activation of complement factor 3 in blood, potentially suggestive of activation of early innate immune response essential for particle opsonisation and clearance. The liver showed subtle response with changes in the expression of few genes associated with acute phase genes. This study establishes a direct link between particle translocation and systemic effects. An estimated 1% or less of the nanoparticles (NPs) deposited in lungs translocate to systemic circulation and enter other organs; however this estimation may not be accurate considering the low sensitivity of the existing in vivo NP detection methods. Moreover, the biological outcomes of such low levels of translocation are not elucidated. The objectives of the present study were to employ a Nano-scale Hyperspectral Microscope to spatially observe and spectrally profile NPs in tissues, and characterize the effects of NPs in blood, liver and heart following pulmonary deposition and subsequent translocation from lungs. Adult female C57BL/6 mice were exposed via intratracheal instillation to 18 and 162 µg per mouse of industrially relevant non-doped titanium dioxide nanoparticles (nano-TiO2). Using the Nano-scale Hyperspectral Microscope translocation to heart and liver was confirmed at both doses and to blood at the highest dose at 24 hours post-exposure time-point. The analysis of biological effects using DNA microarrays, RT-qPCR and ELISA revealed activation of complement cascade and inflammatory process in heart and specific activation of complement factor 3 in blood, potentially suggestive of activation of early innate immune response essential for particle opsonisation and clearance. The liver showed subtle response with changes in the expression of few genes associated with acute phase genes. This study establishes a direct link between particle translocation and systemic effects. This experiment consists of one dose of nano-TiO2 (162 ug) and one control. There are 2 time points for each treatment and control group, e.g., day 1 and day 28. Each dose or time point has 5-6 biological replicates. There are total 22 samples (arrays)

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Combined effects of ZnO and TiO2 nanoparticles on functional gene expression of Nitrosomonas europaea

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