Characterization of the NifA-RpoN Regulon in Rhizobium etli CFN42 in symbiosis using whole genome transcript analysis
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ABSTRACT: The NifA-RpoN complex is a master regulator of the nitrogen fixation genes in alpha-proteobacteria. Based on the complete Rhizobium etli genome sequence, we constructed the R. etli CFN42 oligonucleotide (70 mer) microarray, and utilized this tool to survey changes in gene expression in R. etli CFN42 wild type compared with NifA CFNX247 mutant strain in symbiosis with Phaseolus vulgaris. As expected, the genes associated with a NifA and RpoN binding sites were downregulated in the NifA mutant strain.
Project description:DNA microarray technology was used to survey changes in gene expression in R. etli CFN42 wild type compared with NifA CFNX247 mutant strain under microaerobic (free living) conditions. As expected, several genes associated with a NifA binding site were downregulated in the NifA mutant strain.
Project description:Dna microarray technology was used to survey changes in gene expression in R. etli CFN42 in biofilm formation In these organisms, two main phases, biofilm and planktonic, have been identified. In this work, using microarray assays, we evaluated global gene expression in biofilm and planktonic growth phases in rich medium, in the bacterium Rhizobium etli CFN42.
Project description:89 small non-coding RNAs (ncRNAs) were identified in the soil-dwelling alpha-proteobacterium Rhizobium etli by comparing an extensive compilation of ncRNA predictions to intergenic expression data of a whole-genome tiling array. The differential expression levels of some of these ncRNAs during free-living growth and during interaction with the eukaryotic host plant may indicate a role in adaptation to changing environmental conditions. In order to study expression in the free-living state, wild-type R. etli CFN42 was grown at 30ËC in acid minimal salts medium supplied with 10 mM NH4Cl and 10 mM succinate while monitoring the optical density (OD) of the culture. Samples were taken at OD600 = 0.3, 0.7 and 6 hours after reaching the maximum OD, representing early/late exponential and stationary phase, respectively. In order to study gene expression during host-associated growth, common bean plants (Phaseolus vulgaris cv. Limburgse vroege) were cultivated and inoculated as described previously. Nodules were harvested 2 and 3 weeks after inoculation and the bacteroids were purified by differential centrifugation.
Project description:Gene expression during stationary phase and symbiosis of R. etli CFN42 was compared to that of exponentially growing cells. This allowed us to better understand how R. etli adapts to a non-growing lifestyle, both the free-living and symbiotic state, as well as to determine to what extent this adaptation is similar in both states. R. etli CFN42 was grown at 30˚C in AMS medium supplied with 10 mM NH4Cl and 10 mM succinate while monitoring the optical density (OD) of the culture. Free-living samples were taken at OD600 = 0.3 and 6 hours after reaching the maximum OD, representing early exponential and stationary phase respectively. Bacteroid samples were obtained from nodules 3 weeks after inoculation of Common bean plants (Phaseolus vulgaris cv Limburgse vroege).
Project description:The impact on gene expression by the alarmone (p)ppGpp during growth and non-growth was determined by comparing the transcriptome of R. etli CFN42 wild type and rel mutant. This allowed us to better understand the pleiotropic stress phenotype of the rel mutant as well as identifying specific (p)ppGpp-dependent stress regulators. In order to study expression, R. etli CFN42 wild type and rel mutant was grown at 30˚C in acid minimal salts medium supplied with 10 mM NH4Cl and 10 mM succinate while monitoring the optical density (OD) of the culture. Samples were taken at OD600 = 0.3, 0.7 and 6 hours after reaching the maximum OD, representing early/late exponential and stationary phase, respectively.
Project description:The impact on gene expression by the alarmone (p)ppGpp during growth and non-growth was determined by comparing the transcriptome of R. etli CFN42 wild type and rel mutant. This allowed us to better understand the pleiotropic stress phenotype of the rel mutant as well as identifying specific (p)ppGpp-dependent stress regulators.
Project description:We report an small RNA sequencing (sRNA-seq) approach to identify host sRNAs involved in the nitrogen fixing symbiosis between Mesoamerican Phaseolus vulgaris and Rhizobium etli strains with different degrees in nodulation efficiency. This approach identified conserved and known microRNAs (miRNAs) differentially accumulated in Mesoamerican P. vulgaris roots in response to a highly efficient strain, to a less efficient one or to both strains.