Project description:Nitrogen fixation is a highly energy-demanding process and highly regulated at multiple levels. The two major signals that regulate nitrogen fixation in most diazotrophs are oxygen and ammonia. In order to study the complex regulated mechanism and to highlight the complete nitrogen fixing system in genome level, here we present the transcriptional profiles of the nitrogen fixation genes of P.stutzeri A1501 in different growth conditions with a genome-wide DNA microarray. In this study, the three samples of "P.stutzeri A1501 treated with 0.1mM ammonia and 0.5% Oxygen tension","P.stutzeri A1501 treated with 0.1mM ammonia and 0.5% Oxygen tension-2" and "P.stutzeri A1501 treated with 0.1mM ammonia and 0.5% Oxygen tension-3" were three repeat experiments, while, the other three samples of "P.stutzeri A1501 treated with 20mM ammonia and 0.5% Oxygen tension-1", "P.stutzeri A1501 treated with 20mM ammonia and 0.5% Oxygen tension-2" and "P.stutzeri A1501 treated with 20mM ammonia and 0.5% Oxygen tension-3" were three repeat experiments. The gene expressions under these two growth phases were compared to investigate which genes' expression were effected by different ammonia concentrations. Keywords: nitrogen fixation, nitrogen repression
Project description:The Baltic Sea is one of the largest brackish water bodies in the world. Redoxclines that form between oxic and anoxic layers in the deepest sub-basins are a semi-permanent character of the pelagic Baltic Sea. The microbially mediated nitrogen removal processes in these redoxclines have been recognized as important ecosystem service that removes large proportion of the nitrogen load originating from the drainage basin. However, nitrification, which links mineralization of organic nitrogen and nitrogen removal processes, has remained poorly understood. To gain better understanding of the nitrogen cycling in the Baltic Sea, we analyzed the assemblage of ammonia oxidizing bacteria and archaea in the central Baltic Sea using functional gene microarrays and measured the biogeochemical properties along with potential nitrification rates. Overall, the ammonia oxidizer communities in the Baltic Sea redoxcline were very evenly distributed. However, the communities were clearly different between the eastern and western Gotland Basin and the correlations between different components of the ammonia oxidizer assemblages and environmental variables suggest ecological basis for the community composition. The more even community ammonia oxidizer composition in the eastern Gotland Basin may be related to the constantly oscillating redoxcline that does not allow domination of single archetype. The oscillating redoxcline also creates long depth range of optimal nitrification conditions. The rate measurements suggest that nitrification in the central Baltic Sea is able to produce all nitrate required by denitrification occurring below the nitrification zone.
2013-08-24 | GSE50164 | GEO
Project description:Nitrogen removal from contaminated water bodies
Project description:A whole genome DNA microarray was used to undertake a global transcriptional analysis of nitrogen fixation and ammonium repression in Pseudomonas stutzeri A1501. The aim of this study was to identify the genes that are up-regulated under nitrogen fixation conditions and rapidly down-regulated as soon as 10 min after ammonia shock. The expression changed genes may be the candidate genes for the ammonia signal transmission or be involved in the nitrogen regulatory mechanism.
Project description:Transcriptional profiling of the yeast Lachancea kluyveri when grown on minimal media with different compounds added as the sole nitrogen source. Cells grown on uracil, uridine, dihydrouracil and ammonia were profiled using cells grown on proline as the reference.
Project description:A whole genome DNA microarray was used to undertake a global transcriptional analysis of nitrogen fixation and ammonium repression in Pseudomonas stutzeri A1501. The aim of this study was to identify the genes that are up-regulated under nitrogen fixation conditions and rapidly down-regulated as soon as 10 min after ammonia shock. The expression changed genes may be the candidate genes for the ammonia signal transmission or be involved in the nitrogen regulatory mechanism. First, P. stutzeri A1501 was treated with 0.1 mM ammonia and 0.5% Oxygen tension until the nitrogenase activity was detectable. Then the cells were sudden shifted from the nitrogen fixation conditions to the ammonia repression conditions by addition of 20 mM ammonia for 10min. Subsequently, the bacterium was collected and began the RNA extraction process. Thus, we compare the expression profilings in these two conditions in order to identify the candidate genes.
Project description:Fission yeast cells undergo meiosis and sporulation under conditions of nutritional stress, most frequently nitrogen starvation. This is a complex developmental process, which results in the formation of four spores that are highly resistant to environmental stress. We have carried out time course experiments with diploid fission yeast cells undergoing meiosis and sporulation. In this experiment we have used wild type diploids, and induced meiosis by removal of nitrogen from the medium. As a reference we used a pool consisting of equal amount of RNA from all time points of the experiments. This experiment is part of a series, with accession numbers E-SNGR-2 to E-SNGR-7.
Project description:The Baltic Sea is one of the largest brackish water bodies in the world. Redoxclines that form between oxic and anoxic layers in the deepest sub-basins are a semi-permanent character of the pelagic Baltic Sea. The microbially mediated nitrogen removal processes in these redoxclines have been recognized as important ecosystem service that removes large proportion of the nitrogen load originating from the drainage basin. However, nitrification, which links mineralization of organic nitrogen and nitrogen removal processes, has remained poorly understood. To gain better understanding of the nitrogen cycling in the Baltic Sea, we analyzed the assemblage of ammonia oxidizing bacteria and archaea in the central Baltic Sea using functional gene microarrays and measured the biogeochemical properties along with potential nitrification rates. Overall, the ammonia oxidizer communities in the Baltic Sea redoxcline were very evenly distributed. However, the communities were clearly different between the eastern and western Gotland Basin and the correlations between different components of the ammonia oxidizer assemblages and environmental variables suggest ecological basis for the community composition. The more even community ammonia oxidizer composition in the eastern Gotland Basin may be related to the constantly oscillating redoxcline that does not allow domination of single archetype. The oscillating redoxcline also creates long depth range of optimal nitrification conditions. The rate measurements suggest that nitrification in the central Baltic Sea is able to produce all nitrate required by denitrification occurring below the nitrification zone. Two color array (Cy3 and Cy5): the universal standard 20-mer oligo is printed to the slide with a 70-mer oligo (an archetype). Environmental DNA sequences (fluoresced with Cy3) within 15% of the 70-mer conjugated to a 20-mer oligo (fluoresced with Cy5) complementary to the universal standard will bind to the oligo probes on the array. Signal is the ratio of Cy3 to Cy5. Three replicate probes were printed for each archetype. Two replicate arrays were run on duplicate targets.