Differential expression of Aspergillus genes as a result of disrupting maf1
Ontology highlight
ABSTRACT:
ORGANISM(S): Aspergillus flavus
PROVIDER: GSE861 | GEO | 2004/12/09
SECONDARY ACCESSION(S): PRJNA87877
REPOSITORIES: GEO
Similar Datasets
Project description:We identified a 14-3-3 homolog (maf1) in an EST library made under conditions conducive to aflatoxin biosynthesis. Disruption of this gene in A. flavus by site directed mutagenesis abolished aflatoxin production. The maf1 mutant was morphologically similar to wild type but had reduced conidiation and growth on some media. DNA expression analysis of the wild type and maf1 mutant revealed that the mutation affected the expression profile of a set of genes associated with aflatoxin production. Keywords = Aspergillus Keywords = aflatoxin Keywords = 14-3-3
2010-05-27 | E-GEOD-861 | biostudies-arrayexpress
Project description:Gene expression analysis of A. parasiticus grown under conditions conducive and nonconductive for aflatoxin production was evaluated using glass slide microarrays containing 765 ESTs. Aflatoxins (AF) produced by Aspergillus flavus and A. parasiticus are responsible for approximately $270M in losses annually in the corn, peanut, cotton, and tree nut industries of the United States. In an attempt to develop effective control procedures, research has focused on elucidating the pathway of aflatoxin biosynthesis with the goal of identifying potential targets for intervention. Research to date points to the involvement of complex and likely overlapping regulatory circuits. To better understand the regulation by nutritional and environmental factors, a targeted cDNA microarray consisting of genes associated with AF production was employed to investigate the influence of nitrogen source, carbon source, temperature, and pH on AF production. For each nutritional or environmental parameter examined, a condition conducive for aflatoxin production was compared with a condition that was non-conducive. Three replicate cultures for each condition were grown. Cultures were grown for 24 hours and harvested. AF production for each culture was quantified and tissues were stored separately at -80C. For array hybridization, tissue samples for each condition were pooled and RNA extracted using Trizol reagent. Keywords = aspergillus Keywords = aflatoxin Keywords = regulation Keywords = secondary metabolism
2010-06-10 | E-GEOD-1649 | biostudies-arrayexpress
Project description:Gene expression analysis of A. parasiticus grown under conditions conducive and nonconductive for aflatoxin production was evaluated using glass slide microarrays containing the 753 ESTs. A complex regulatory network governs the biosynthesis of aflatoxin. While several genes involved in aflatoxin production are known, their action alone cannot account for its regulation. Arrays of clones from an Aspergillus flavus cDNA library and glass slide microarrays of ESTs were screened to identify additional genes. An initial screen of the cDNA clone arrays lead to the identification of 753 unique ESTs. Many showed sequence similarity to known metabolic and regulatory genes; however, no function could be ascribed to over 50% of the ESTs. Gene expression analysis of Aspergillus parasiticus grown under conditions conducive and non-conductive for aflatoxin production was evaluated using glass slide microarrays containing the 753 ESTs. Twenty-four genes were more highly expressed during aflatoxin biosynthesis and 18 genes were more highly expressed prior to aflatoxin biosynthesis. No predicted function could be ascribed to 18 of the 24 genes whose elevated expression was associated with aflatoxin biosynthesis. Keywords = Aspergillus Keywords = aflatoxin Keywords: time-course
2003-01-15 | E-GEOD-204 | biostudies-arrayexpress
Project description:Gene expression analysis of A. parasiticus grown under conditions conducive and nonconductive for aflatoxin production was evaluated using glass slide microarrays containing 765 ESTs. Aflatoxins (AF) produced by Aspergillus flavus and A. parasiticus are responsible for approximately $270M in losses annually in the corn, peanut, cotton, and tree nut industries of the United States. In an attempt to develop effective control procedures, research has focused on elucidating the pathway of aflatoxin biosynthesis with the goal of identifying potential targets for intervention. Research to date points to the involvement of complex and likely overlapping regulatory circuits. To better understand the regulation by nutritional and environmental factors, a targeted cDNA microarray consisting of genes associated with AF production was employed to investigate the influence of nitrogen source, carbon source, temperature, and pH on AF production. For each nutritional or environmental parameter examined, a condition conducive for aflatoxin production was compared with a condition that was non-conducive. Three replicate cultures for each condition were grown. Cultures were grown for 24 hours and harvested. AF production for each culture was quantified and tissues were stored separately at -80C. For array hybridization, tissue samples for each condition were pooled and RNA extracted using Trizol reagent. Keywords = aspergillus Keywords = aflatoxin Keywords = regulation Keywords = secondary metabolism Keywords: other
2005-01-01 | GSE1649 | GEO
Project description:Gene expression analysis of A. parasiticus grown under conditions conducive and nonconductive for aflatoxin production was evaluated using glass slide microarrays containing the 753 ESTs. A complex regulatory network governs the biosynthesis of aflatoxin. While several genes involved in aflatoxin production are known, their action alone cannot account for its regulation. Arrays of clones from an Aspergillus flavus cDNA library and glass slide microarrays of ESTs were screened to identify additional genes. An initial screen of the cDNA clone arrays lead to the identification of 753 unique ESTs. Many showed sequence similarity to known metabolic and regulatory genes; however, no function could be ascribed to over 50% of the ESTs. Gene expression analysis of Aspergillus parasiticus grown under conditions conducive and non-conductive for aflatoxin production was evaluated using glass slide microarrays containing the 753 ESTs. Twenty-four genes were more highly expressed during aflatoxin biosynthesis and 18 genes were more highly expressed prior to aflatoxin biosynthesis. No predicted function could be ascribed to 18 of the 24 genes whose elevated expression was associated with aflatoxin biosynthesis. Keywords = Aspergillus Keywords = aflatoxin Keywords: time-course
2003-01-15 | GSE204 | GEO
Project description:Aspergillus flavus is a pathogen of corn, peanut, and other crops which produces carcinogenic mycotoxins known as aflatoxins. Previous studies have shown that drought stress results in exacerbated aflatoxin production. Drought-associated oxidative stress caused by reactive oxygen species (ROS) is suspected to contribute to increased aflatoxin production during infection. Here, the responses of field isolates of A. flavus with varying degrees of aflatoxin production capability to H2O2-derived oxidative stress were examined using iTRAQ proteomics. Three isolates: AF13 (highly toxigenic), NRRL3357 (moderately toxigenic), and K54A (atoxigenic), were cultures in aflatoxin conducive yeast extract-sucrose (YES) medium amended with 0, 10, or 20/25mM of H2O2. Identified differentially expressed proteins were used for functional prediction, cellular localization, and pathway analyses to identify molecular mechanisms involved in A. flavus oxidative stress responses relative to aflatoxin production capability. Correlative analyses with previously obtained transcriptome data for the same isolates under the same experimental conditions was also performed with a low degree of correlation (r = 0.1114) observed between the protein and transcript data suggesting possible post-transcriptional regulation of oxidative stress responses. The identified stress responsive mechanisms provide a basis of investigating novel approaches of enhancing host resistance against aflatoxin contamination.
2018-02-27 | PXD007164 | Pride
Project description:Diverse expression patterns for secondary metabolism gene clusters from Aspergillus flavus under different environmental conditions and in genetic mutants: Insights into regulation of cyclopiazonic acid along with aflatoxin Species of Aspergillus produce a diverse array of secondary metabolites, and recent genomic analysis predicts that these species have the capacity to synthesize many more compounds. It has been possible to infer the presence of 55 gene clusters associated with secondary metabolism in A. flavus. Presumably, secondary metabolites play important roles in the ecology of the producing species, but functions for most secondary metabolites remain unknown. Only three metabolic pathways have been associated with the predicted clusters in A. flavus. These include aflatoxin, cyclopiazonic acid (CPA), and aflatrem. To gain insight into the regulation of, and infer ecological significance for the 55 secondary metabolite gene clusters predicted in A. flavus, we examined their expression over 28 diverse conditions. Variables included culture media and temperature, fungal development, colonization of developing maize seeds, and misexpression of laeA, the global regulator of secondary metabolism. Hierarchical clustering analysis of expression profiles allowed us to categorize the gene clusters into four distinct clades. Gene clusters for the production of aflatoxins, CPA, and seven other unknown compound(s) were identified as belonging to one clade. To further explore the relationships found by gene expression analysis, aflatoxin and CPA production were quantified under five different cell culture environments known to be conducive or non-conducive for aflatoxin biosynthesis and during colonization of developing maize seeds. Results from these studies showed that secondary metabolism gene clusters have distinctive gene expression profiles. Aflatoxin and CPA were found to have unique regulation but similar enough that they would be expected to co-occur in commodities colonized with A. flavus.
2010-03-11 | GSE15435 | GEO
Project description:Aflatoxins are toxic and carcinogenic secondary metabolites produced by the fungi Aspergillus flavus and A. parasiticus. In order to better understand the molecular mechanisms that regulate aflatoxin production, the biosynthesis of the toxin in A. flavus and A. parasticus grown in yeast extract sucrose media supplemented with 50 mM tryptophan (Trp) were examined. A. flavus grown in the presence of 50 mM tryptophan was found to have significantly reduced aflatoxin B1 and B2 biosynthesis, while A. parasiticus cultures had significantly increased B1 and G1 biosynthesis. Microarray analysis of RNA extracted from fungi grown under these conditions revealed seventy seven genes that are expressed significantly different between A. flavus and A. parasiticus, including the aflatoxin biosynthetic genes aflD (nor-1), aflE (norA), and aflO (omtB). It is clear that the regulatory mechanisms of aflatoxin biosynthesis in response to Trp in A. flavus and A. parasiticus are different. These candidate genes may serve as regulatory factors of aflatoxin biosynthesis. Keywords: Aflatoxin, Aspergillus, flavus, Amnio Acids, Tryptophan
2007-06-07 | GSE6182 | GEO
Project description:The molecular mechanisms underlying aflatoxin production have been well-studied in strains of the fungus Aspergillus flavus (A. flavus) under artificial conditions. However, aflatoxin biosynthesis has rarely been studied in natural isolates of A. flavus strains. In the present study, tandem mass tag (TMT) labeling and high-performance liquid chromatography (HPLC) coupled with tandem-mass spectrometry analysiswere used for proteomic quantification in natural isolates of high- and low-aflatoxin-yield A. flavus strains.
2022-02-17 | PXD027517 | Pride
Project description:Aflatoxins are carcinogenic fungal secondary metabolites. Levels of aflatoxins in agricultural commodities are stringently regulated by many countries. A cluster of genes is responsible for aflatoxin biosynthesis by Aspergillus flavus and other closely related species. Expression of the clustered aflatoxin genes is governed by a complex network of regulatory mechanisms. To better understand the molecular events that are associated with aflatoxin production, transcription profiling by microarray analyses which compared three independent aflatoxigenic A. flavus strains to individual isogenic progenies that no longer produced aflatoxins after serial transfers was carried out. Twenty-two significantly differentially expressed features were identified. After physical mapping using the A. oryzae genome sequence as the reference, the number of unique genes was reduced to 16. Compared to the parental strains, changes in the aflatoxin gene expression levels in the progenies were not significant, which suggests that the inability to produce aflatoxins is not caused by decreased expression. The only gene showing higher expression levels in the progenies is homologous to glutathione S-transferease genes. Overexpression of this gene, named hcc, at six- to nine-fold in an aflatoxigenic A. flavus did not cause discernible changes in colony morphology or aflatoxin production. Loss of aflatoxin production after serial transfers may not result from a single event but caused by multiple factors. Keywords: Compartiave hybridization toxigenic and atoxigenic lines of Aspergillus Aspergillus flavus NRRL 29459, NRRL 29474, and NRRL 29490 are aflatoxigenic strains originated from soil collection in a peanut field (Terrell Co., Georgia, USA). Strains 459B-20-2, 474A-20, and 499A-20 were nonaflatoxigenic isolates obtained after 20 serial transfers of the parental strains on potato dextrose agar slants (Horn and Dorner 2002). Comparsions in each experiment consisted of one aflatoxigenic parental strain and one nonaflatoxigenic progeny, compared after 48- or 72-hr growth. Each comparison was repeated with duplicate dye-flip.
2010-05-26 | E-GEOD-8185 | biostudies-arrayexpress