Project description:Transcriptomic study of A. ferrooxidans was explored either during aerobic growth with sulfur as an electron source and oxygen as final electron acceptor or in anaerobic conditions with ferric iron as the final electron receptor. Differential RNA levels were related to changes in cellular functions that were used to develop a preliminary model for A. ferrooxidans electron transport during dissimilatory ferric iron reduction.
Project description:Iron is an essential nutrient for bacterial growth but poorly bioavailable. To scavenge ferric iron present in their environment, bacteria synthesize and secrete siderophores, small compounds with a high affinity for iron. Pyochelin (PCH) is one of the two siderophores produced by the opportunistic pathogen Pseudomonas aeruginosa. Once having captured a ferric iron, PCH-Fe is imported back into bacteria first by the outer membrane transporter FptA and afterwards by the inner membrane permease FptX. Here using molecular biology, 55Fe uptake assays and LC-MS/MS quantification of PCH in the different bacterial cell fractions, we show that (i) PCH (probably under its PCH-Fe form) is able to rich bacterial periplasm and cytoplasm when both FptA and FptX are expressed, and (ii) that PchHI (a heterodimeric ABC transporter) plays a role in the translocation of siderophore-free iron siderophore-free iron across the inner membrane into the cytoplasm. Consequently, probably the first fraction of PCH-Fe internalized by FptA may be transported further by FptX in the bacterial cytoplasm to activate the transcriptional regulator PchR, regulating the transcription of all genes of the PCH pathway. The further fractions of PCH-Fe transported by FptA may dissociate in the bacterial periplasm by an unknown mechanism, with the siderophore-free iron being transported into the cytoplasm by PchHI.
Project description:The ability of Microlunatus phosphovorus to accumulate large amounts of polyphosphate (Poly-P) plays an important role in removing soluble phosphorus from wastewater. Our analyses indicate that Microlunatus phosphovorus accumulates Poly-P under aerobic conditions but releases phosphorus under anaerobic conditions. To determine the mechanisms underlying Poly-P metabolism, we compared transcriptional profiles under aerobic and anaerobic conditions. Significant differences were detected in the expression levels of genes associated with Poly-P metabolism between aerobic and anaerobic conditions. These findings enhance our understanding of phosphate metabolism in a major bacterial species involved in wastewater phosphorus reduction.
Project description:We performed small RNA-seq (sRNA-seq) study of Arabidopsis shoots under iron-sufficient (+Fe), iron deficient (-Fe) and iron resupply (Fe resupply) conditions to investigate and identify sRNAs whose expression is regulated by iron deficiency.
Project description:An iron chelate, ferric nitrilotriacetate (Fe-NTA), induces oxidative renal tubular damage that subsequently leads to renal cell carcinoma in rodents. Here we used gene expression microarrays to find target oncogenes in this model. Network analysis of the gene expression microarray data revealed the involvement of beta-catenin pathway in the induced cancers. Experiment Overall Design: Carcinogenesis protocol was performed using specific pathogen-free male Wistar rats or male F1 hybrid rats between Fischer344 and Brown-Norway strains. A total of 10 microarrays (Rat Genome 230 2.0; 31,999 genes; Affymetrix Inc., Santa Clara, CA) were used for the screening purpose; two for each group of untreated control, Fe-NTA treatment for 1 week, Fe-NTA treatment for 3 weeks, Fe-NTA-induced RCCs with neither peritoneal invasion nor metastasis and Fe-NTA-induced RCCs with pulmonarymetastasis.
Project description:Transcriptional profile of whole roots of wild-type and pye-1 mutants exposed to 24 hours -Fe were generated Global population increases and climate change underscore the need for better comprehension of how plants acquire and process nutrients such as iron. A systems biology approach was taken to elucidate novel regulatory mechanisms involved in plant responses to iron deficiency (-Fe). Using cell-type specific transcriptional profiling we identified a pericycle-specific iron deficiency response, and a previously uncharacterized transcription factor, POPEYE (PYE), that plays an important role in this response. Functional analysis of PYE suggests that it positively regulates growth and development under iron deficient conditions. ChIP-on-chip analysis and transcriptional profiling reveal that PYE helps maintain iron homeostasis by directly and indirectly regulating the expression of ferric reductases, metal ion transporters, iron storage proteins, and other key iron homeostasis genes. In addition to PYE, we also identified a second protein BRUTUS (BTS), which appears to negatively regulate the response to iron deficiency. BTS is a unique putative E3 ligase protein, with metal ion binding and DNA binding domains. PYE and BTS are tightly co-regulated and physically interact with PYE paralogs, one of which is thought to positively regulate expression of genes involved in iron homeostasis. We propose that iron content is sensed within the pericycle where PYE, perhaps in conjunction with BTS and other regulatory proteins, is then activated to control a regulatory network involved in maintaining proper iron distribution in plants. Keywords: Expression analysis To determine how loss of PYE expression affects the transcriptional profile of whole roots, pye-1 mutants and wild-type seeds were germinated under standard growth conditions then transferred to standard media (control, MS media) or iron deficient media (-Fe, 0.3mM Ferrozine in MS media containing no ferrous sulfate). After 24 hours of exposure to +Fe or -Fe whole roots were collected and analyzed.
Project description:The transcriptome approach was used to characterize the global change (2 Fe concentrations) in Synechocystis gene expression in response to continuous iron starvation, compared to standard medium (17 microM). For iron depletion, exponentially growing cells were washed in Fe-free medium, and grown for 48 hrs under standard conditions in liquid medium cotaining either 1 mM or 2 mM of ferric ammonium citrate. Then, cells were washed, and resuspended in Fe-free medium (Fe contaminations 0.5 microM) and grown for another 48 hrs period. For each concentration point, total RNA were isolated from stressed and unstressed cells, reverse-transcribed, differentially labelled (dye swapped), hybridized together (stressed versus unstressed samples) and analyzed with DNA glass microarrays (two slides per each concentration point) (Custom-commercial array : IntelliGeneTM CyanoCHIP version 2.0, TAKARA). To identify differentially expressed genes, the median of the normalized ratio of Cy5/Cy3 intensity was calculated for each spot of the replicated dye-swap. The results of the analysis were carefully examined to exclude the dye effect between the 2 Cy-swapped arrays. Keywords: stress responses
Project description:Transcriptional profiling of rice genes analyzing the effect of knockdown of OsHRZ1 and OsHRZ2 in HRZ2i lines. NT and HRZ2i lines 1, 2 and 3 (2i-1, 2i-2 and 2i-3, respectively) were treated under iron sufficiency for 7 days (+Fe 7d) or under iron deficiency for 1 day (-Fe 1d) or 7 days (-Fe 7d) in hydroponic culture. Comparison between NT and HRZ2i lines at +Fe 7d, -Fe 1d and -Fe 7d. Biological replicates: 2-3 NT replicates, 3 HRZ2i replicates (one each for 2i-1, 2i-2 and 2i-3) for each treatment.
Project description:Transcriptional profiling of R. sphaeroides Δirr under iron limitation (-Fe) compared to control R. sphaeroides Δirr under normal growth conditions (+Fe).