Project description:We used microarrays to detail Arabidopsis gene expression in response to paraquat, a herbicide that acts as a terminal oxidant of photosystem I that in the light leads to the enhanced generation of superoxide and hydrogen peroxide inside plastids. Within a few hours after paraquat treatment changes in nuclear gene expression occur. Distinct sets of genes were activated that were different from those induced by another reactive oxygen species, singlet oxygen. Keywords: Time course
Project description:Green plants are more robust to hydrogen peroxide (H2O2) stress and contain high endogeneous H2O2 levels which is generated during photorespiration and photosynthesis. Therefore, exgeneous H2O2 application mostly impose oxidative stress. To reduce endogenous H2O2 background, we adopted a strategy which is to grow Arabidopsis seedlings in the dark to eliminate light-induced H2O2 production, thus to reduce the endogenous H2O2 level. Exogenous H2O2 was then applied to induce transcriptome changes. Global gene expression is studied and compared between samples collected under 7d dark, 7d H2O2 treatment under dark and 7d light conditions.
Project description:rs04-10_oxydative--stress - time course h2o2 treatment - Effect of an hydrogen peroxide treatment on gene regulation in arabidopsis cells - Arabidopsis cells (5 days after subculturing) were cultured at 21degreeC, 8 h photoperiod under agitation. H2O2 2.5 uM was added to cells 5 days after subculturing and 2 hours after the beginning of the light period. Treated and control cells were collected 15 min, 1 h, 5 h and 12 h after treatment. Keywords: treated vs untreated comparison
Project description:In this experiment we tested the transcriptome of transgenic Arabidopsis seedlings (5-day-old) constitutively expressing the zinc-finger protein Zat12 (At5g59820) under the control of the 35S-CaMV promoter (Zat12). The transcriptome of these seedlings was compared to that of wild type seedlings grown under the same conditions (WT) and to that of wild type seedlings grown under the same conditions and subjected to a hydrogen peroxide stress (WT+H2O2). Hydrogen peroxide treatment was performed by applying 20 mM hydrogen peroxide for 1 hour. In parallel to these experiments transgenic plants expressing Zat12 were subjected to a similar hydrogen peroxide stress (Zat12+H2O2). All treatments were performed with similar size and age seedlings grown in liquid culture (MS) and sampled at the same time as described by Davletova et al., 2005. Experimenter name = Ron Mittler Experimenter phone = 1-775-784-1384 Experimenter fax = 1-775-784-1650 Experimenter department = Dept. of Biochemistry Experimenter institute = University of Nevada Experimenter address = MS200 Experimenter address = Reno Experimenter address = Nevada Experimenter zip/postal_code = 89557 Experimenter country = USA Keywords: genetic_modification_design; stimulus_or_stress_design
Project description:In plants, reactive oxygen species and, more particularly, hydrogen peroxide (H2O2) play a dual role as toxic by-products of normal cell metabolism and as regulatory molecules in stress perception and signal transduction. Peroxisomal catalases are an important sink for photorespiratory H2O2. Using ATH1 Affymetrix microarrays, expression profiles were compared between control and catalase-deficient Arabidopsis (Arabidopsis thaliana) plants. Reduced catalase levels already provoked differences in nuclear gene expression under ambient growth conditions, and these effects were amplified by high light exposure in a sun simulator for 3 and 8 h. This genome-wide expression analysis allowed us to reveal the expression characteristics of complete pathways and functional categories during H2O2 stress. In total, 349 transcripts were significantly up-regulated by high light in catalase-deficient plants and 88 were down-regulated. From this data set, H2O2 was inferred to play a key role in the transcriptional up-regulation of small heat shock proteins during high light stress. In addition, several transcription factors and candidate regulatory genes involved in H2O2 transcriptional gene networks were identified. Comparisons with other publicly available transcriptome data sets of abiotically stressed Arabidopsis revealed an important intersection with H2O2-deregulated genes, positioning elevated H2O2 levels as an important signal within abiotic stress-induced gene expression. Finally, analysis of transcriptional changes in a combination of a genetic (catalase deficiency) and an environmental (high light) perturbation identified a transcriptional cluster that was strongly and rapidly induced by high light in control plants, but impaired in catalase-deficient plants. This cluster comprises the complete known anthocyanin regulatory and biosynthetic pathway, together with genes of hitherto unknown function.
Project description:We identified a small zinc finger protein, MBS, as a new mediator of singlet oxygen responses in Chlamydomonas and Arabidopsis. MBS is required for induction of singlet oxygen-dependent gene expression and, upon oxidative stress, accumulates in distinct granules in the cytosol of Arabidopsis cells. First, we recorded changes in light stress-regulated gene expression profiles after genetically perturbing MBS function by isolating mutants for the two MBS genes (MBS1 and MBS2) and by overexpression of MBS1 in Arabidopsis thaliana. Then, these light stress-related gene expression profiles were analyzed with respect to genes specifically responding to singlet oxygen and hydrogen peroxide/superoxide. The results indicated that MBS inactivation leads to an impaired response to singlet oxygen signaling under light stress.
Project description:Green plants are more robust to hydrogen peroxide (H2O2) stress and contain high endogeneous H2O2 levels which is generated during photorespiration and photosynthesis. Therefore, exgeneous H2O2 application mostly impose oxidative stress. To reduce endogenous H2O2 background, we adopted a strategy which is to grow Arabidopsis seedlings in the dark to eliminate light-induced H2O2 production, thus to reduce the endogenous H2O2 level. Exogenous H2O2 was then applied to induce transcriptome changes. Global gene expression is studied and compared between samples collected under 7d dark, 7d H2O2 treatment under dark and 7d light conditions. We cultured seedlings in the dark to reduce endogenous H2O2. Three conditions were used for transcriptome profiling: dark grown (dark); dark grown with exogenous H2O2 treatment (H2O2); and light grown (light). Three types of conditions were used for Arabidopsis seedling culture: dark, dark with 5 mM H2O2 treatment and light. Each condition was performed with two biological replicates. The seedlings were harvested at 7 days old.
Project description:We used microarrays to detail Arabidopsis gene expression in response to paraquat, a herbicide that acts as a terminal oxidant of photosystem I that in the light leads to the enhanced generation of superoxide and hydrogen peroxide inside plastids. Within a few hours after paraquat treatment changes in nuclear gene expression occur. Distinct sets of genes were activated that were different from those induced by another reactive oxygen species, singlet oxygen. Experiment Overall Design: Arabidopsis thaliana rosette leaves were harvested 1, 2, and 4 h after spraying either with a solution of 20 microM paraquat (methyl viologen, Sigma) in 0.1% Tween or with Tween alone for RNA extraction and hybridization on Affymetrix ATH1 microarrays. Plants were grown on soil for 3 weeks under continuous light at 90 mmol. m-2 . s-1. For each sample, the rosette leaves of five to six 3-week-old plants (before they start bolting) were collected for RNA extraction. Total RNAs from two separate biological experiments were pooled for the preparation of cDNA and the subsequent synthesis of biotin-labeled complementary RNA as recommended by Affymetrix.