Similar Datasets
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.
2012-08-02 | E-GEOD-35122 | biostudies-arrayexpress
Project description:Sensory circuit activation can induce neurotransmitter respecification. To understand the consequences and mechanisms of this neuroplasticity we investigated the effects of olfactory system activation on transmitter expression in interneurons of the accessory olfactory bulb (AOB) during development. Frog larvae use olfactory-mediated kin recognition to distinguish siblings from non-siblings. Prolonged exposure to kin (sibling) or non-kin (non-sibling) odorants changed the number of neurons expressing dopamine or GABA compared to odorant deprivation (orphan condition). To identify signaling molecules mediating this behavior we performed mass spectrometry of kin-conditioned water samples. Vitellogenin-derived peptides, uniquely present in kin-conditioned samples of one genotype, were sufficient to elicit aversion behavior in non-kin larvae. RNA profiling identified AOB microRNAs (miRs) differentially regulated across conditions. Inhibition of miR-375 and miR-200b revealed that they regulate the dopaminergic and GABAergic phenotypes by targeting Pax6 and Bcl11b. Altering the ratio of dopamine/GABA AOB interneurons or locally introducing receptor blockers reversed kinship preference.
2017-09-01 | GSE78854 | GEO
Project description:The ecophysiology of complete ammonia oxidizing Nitrospira (CMX) and their widespread occurrence in groundwater suggests that CMX bacteria have a competitive advantage over ammonia-oxidizing bacteria (AOB) and archaea (AOA) in these environments. However, the relevance of their activity from the ecosystem-level process perspective has remained unclear. We investigated oligotrophic carbonate rock aquifers as a model system to assess the contribution of CMX, AOA and AOB to nitrification and to identify the environmental drivers of their niche differentiation at different levels of ammonium and oxygen. CMX accounted for up to 95% of the ammonia oxidizer communities. Nitrification rates were positively correlated to CMX clade A-associated phylotypes and AOB affiliated with Nitrosomonas ureae. Surprisingly, short-term incubations amended with the nitrification inhibitors allylthiourea and chlorate suggested that AOB contributed more than 90% to overall ammonia oxidation, while metaproteomics analysis confirmed an active role of CMX in both ammonia and nitrite oxidation. Ecophysiological niche differentiation of CMX clades A and B, AOA and AOB was linked to their requirements for ammonium, oxygen tolerance, and metabolic versatility. Our results demonstrate that despite numerical predominance of CMX, the first step of nitrification in oligotrophic groundwater is primarily governed by AOB. Higher growth yields at lower NH4+ turnover rates and energy derived from nitrite oxidation most likely enable CMX to maintain consistently high populations. Activity measurements combined with differential inhibition allowed a refined understanding of ammonia oxidizer coexistence, competition and cooperation beyond the insights from molecular data alone.
2023-10-24 | PXD039573 | Pride
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.
2012-08-03 | GSE35122 | GEO
Project description:The abundance of bacterial (AOB) and archaeal (AOA) ammonia oxidisers, assessed using quantitative PCR measurements of their respective a-subunit of the ammonia monooxygenase (amoA) genes, and ammonia oxidation rates were measured in four contrasting coastal sediments in the Western English Channel. Sediment was sampled bimonthly from July 2008 to May 2011, and measurements of ammonia oxidiser abundance and activity compared to a range of environmental variables including salinity, temperature, water column nutrients and sediment carbon and nitrogen content. Despite a higher abundance of AOA amoA genes within all sediments, and at all time-points, rates of ammonia oxidation correlated with AOB and not AOA amoA gene abundance. Other than ammonia oxidation rate, sediment particle size was the only variable that correlated with the spatial and temporal patterns of AOB amoA gene abundance, implying a preference of the AOB for larger sediment particles. This is possibly due to deeper oxygen penetration into the sandier sediments, increasing the area available for ammonia oxidation to occur, higher concentrations of inhibitory sulphide with pore waters of muddier sediments or a combination of both oxygen and sulphide concentrations. Similar to many other temporal studies of nitrification within estuarine and coastal sediments, decreases in AOB amoA gene abundance were evident during summer and autumn, with maximum abundance and ammonia oxidation rates occurring in winter and early spring. The lack of correlation between AOA amoA gene abundance and ammonium oxidation rate suggests an alternative role for amoA-carrying AOA within these sediments.
2013-08-24 | GSE50163 | GEO