ACC Synthase (ACS) is the key regulatory enzyme in the ethylene biosynthesis in plants. It catalyzes the conversion of s-adenosylmethionine (SAM) to 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene. Arabidopsis has nine ACS genes. The goal of the project is to inactivate each gene by insertional mutagenesis and amiRNA technology and eventually construct a null ACS mutant. We have been recently able to achieve this goal. Furthermore, we wanted to know how inactivation of individual ACS genes affects global gene expression.
A combinatorial interplay among the 1-aminocyclopropane-1-carboxylate isoforms regulates ethylene biosynthesis in Arabidopsis thaliana.
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View SamplesApproximately 2.5 mg dry Col-0 seedlings were surface sterilized and stratified for 2 days at 4degreesC in liquid media containing 1.5% sucrose (w/v) before being transferred to light with constant shaking at 100 rpm on an orbital shaker. After 7 days, the seedling clusters were subjected to the treatments for 1 hr followed by total RNA isolation using the RNAqueous kit (Ambion). Each treatment was performed in triplicate or quadruplicate. All labeling (Enzo) and hybridization (Affymetrix) procedures were performed as directed by the manufacturers. Raw probe intensities output by the Affymetrix MAS software were processed using the RMA algorithm to obtain an expression measure for each gene on each array.
Identification of inhibitors of auxin transcriptional activation by means of chemical genetics in Arabidopsis.
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View SamplesSalicylic acid (SA) is a critical molecule mediating plant innate immunity with an important role limiting the growth and reproduction of the virulent powdery mildew (PM) Golovinomyces orontii on Arabidopsis thaliana. To investigate this later phase of the PM interaction, and the role played by SA, we performed replicated global expression profiling for wild type and SA biosynthetic mutant ics1 Arabidopsis from 0 to 7 days post infection. We found that ICS1-impacted genes comprise 3.8% of profiled genes with known molecular markers of Arabidopsis defense ranked very highly by the multivariate empirical Bayes statistic (T2 statistic ((Tai and Speed, 2006)). Functional analyses of T2-selected genes identified statistically significant PM-impacted processes including photosynthesis, cell wall modification, and alkaloid metabolism that are ICS1-independent. ICS1-impacted processes include redox, vacuolar transport/secretion, and signaling. Our data also supports a role for ICS1 (SA) in iron and calcium homeostasis and identifies components of SA crosstalk with other phytohormones. Through our analysis, 39 novel PMimpacted transcriptional regulators were identified. Insertion mutants in one of these regulators, PUX2, results in significantly reduced reproduction of the powdery mildew in a cell death independent manner. Though little is known about PUX2, PUX1 acts as a negative regulator of Arabidopsis CDC48 (Rancour et al., 2004; Park et al., 2007), an essential AAA-ATPase chaperone that mediates diverse cellular activities including homotypic fusion of ER and Golgi membranes, ER-associated protein degradation, cell cycle progression, and apoptosis. Future work will elucidate the functional role of the novel regulator PUX2 in PM resistance.
Temporal global expression data reveal known and novel salicylate-impacted processes and regulators mediating powdery mildew growth and reproduction on Arabidopsis.
Age, Specimen part
View SamplesThe effect of benzene exposure on peripheral blood mononuclear cell (PBMC) gene expression was examined in a population of shoe-factory workers with well-characterized occupational exposures to benzene.
Changes in the peripheral blood transcriptome associated with occupational benzene exposure identified by cross-comparison on two microarray platforms.
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Cellulose-Derived Oligomers Act as Damage-Associated Molecular Patterns and Trigger Defense-Like Responses.
Specimen part, Treatment, Time
View SamplesTo elucidate host processes and components required for the sustained growth and reproduction of the obligate biotrophic fungus Golovinomyces orontii on Arabidopsis thaliana, laser microdissection was used to isolate cells at the site of infection at 5 days postinfection for downstream global Arabidopsis expression profiling. Site-specific profiling increased sensitivity dramatically, allowing us to identify specific host processes, process components, and their putative regulators hidden in previous whole-leaf global expression analyses. For example, 67 transcription factors exhibited altered expression at the powdery mildew (PM) infection site, with subsets of these playing known or inferred roles in photosynthesis, cold/dehydration responses, defense, auxin signaling, and the cell cycle. Using integrated informatics analyses, we constructed putative regulatory networks for a subset of these processes and provided strong support for host cell cycle modulation at the PM infection site. Further experimentation revealed induced host endoreduplication occurred exclusively at the infection site and led us to identify MYB3R4 as a transcriptional regulator of this process. Induced endoreduplication was abrogated in myb3r4 mutants, and G. orontii growth and reproduction were reduced. This suggests that, by increasing gene copy number, localized endoreduplication serves as a mechanism to meet the enhanced metabolic demands imposed by the fungus, which acquires all its nutrients from the plant host.
Laser microdissection of Arabidopsis cells at the powdery mildew infection site reveals site-specific processes and regulators.
Age, Specimen part
View SamplesPlants can perceive the presence of pathogens at the cell surface and plant damage-derived molecules via recognition of conserved microbial molecules, named pathogen- or microbe-associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs). Well-studied examples of PAMPs are chito-oligomers, breakdown products of fungal cell walls and insect exoskeletons. Pectin-derived oligogalacturonides (OGs) are well-characterized DAMPs. Both PAMPs nd DAMPs are capable of activating plant immunity, generating changes in gene expression that lead to increased production of defense compounds and proteins; thus, equipping the plant cell to defend itself.
Cellulose-Derived Oligomers Act as Damage-Associated Molecular Patterns and Trigger Defense-Like Responses.
Specimen part, Treatment, Time
View SamplesPlants can perceive the presence of pathogens at the cell surface and plant damage-derived molecules via recognition of conserved microbial molecules, named pathogen- or microbe-associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs). Well-studied examples of PAMPs are chito-oligomers, breakdown products of fungal cell walls and insect exoskeletons. Pectin-derived oligogalacturonides (OGs) are well-characterized DAMPs. Both PAMPs nd DAMPs are capable of activating plant immunity, generating changes in gene expression that lead to increased production of defense compounds and proteins; thus, equipping the plant cell to defend itself.
Cellulose-Derived Oligomers Act as Damage-Associated Molecular Patterns and Trigger Defense-Like Responses.
Specimen part, Treatment, Time
View SamplesWe used transcriptional profiling to monitor gene expression of whole olfactory bulbs at daily intervals from embryonic day 11 through birth, generating a compendium of gene expression encompassing the major developmental events of this tissue.
No associated publication
Specimen part
View SamplesThe essential process of dosage compensation equalizes X-chromosome gene expression between C. elegans XO males and XX hermaphrodites through a dosage compensation complex (DCC) that resembles condensin. The DCC binds to both X chromosomes of hermaphrodites to repress transcription by half. Here we show that post-translational modification by the SUMO conjugation pathway is essential for sex-specific assembly of the DCC onto X. Depletion of the SUMO peptide in vivo severely disrupts binding of particular DCC subunits and causes changes in X-linked gene expression similar to those caused by disrupting genes encoding DCC subunits. Three DCC subunits are themselves SUMOylated, and depletion of SUMO preferentially reduces their binding to X, suggesting that SUMOylation of DCC subunits is essential for robust association with X. DCC SUMOylation is triggered by the signal that initiates DCC assembly onto X. The initial step of assembly--binding of X-targeting factors to recruitment sites on X (rex sites)--is independent of SUMOylation, but robust binding of the complete complex requires SUMOylation. SUMOylated DCC subunits are enriched at rex sites, and SUMOylation enhances interactions between X-targeting factors and condensin subunits that facilitate DCC binding beyond the low level achieved without SUMOylation. DCC subunits also participate in condensin complexes essential for chromosome segregation, but their SUMOylation occurs only in the context of the DCC. Our results reinforce a newly emerging theme in which multiple proteins of a complex are SUMOylated in response to a specific stimulus, leading to accelerated complex formation and enhanced function.
SUMOylation is essential for sex-specific assembly and function of the Caenorhabditis elegans dosage compensation complex on X chromosomes.
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