Whole genome sequence of Aspergillus flavus : strain NRRL 118543
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ABSTRACT:
PROVIDER: PRJNA402046 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR6047485.fastq.gz | Fastqsanger.gz |
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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: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
Project description:Aspergillus flavus is one of the major fungal molds that colonize peanut in the field and during storage. The impact to human and animal health and to economy in agriculture and commerce are significant since this mold produces the most potent natural toxins, aflatoxins, which are carcinogenic, mutagenic, immunosuppressive, and teratogenic. A strain of marine Bacillus megaterium isolated from the Yellow Sea of East China was evaluated for its effect to inhibit aflatoxin formation through down-regulating aflatoxin pathway gene expression in A. flavus as demonstrated by genechip analysis in liquid medium and peanuts. The results showed that aflatoxin accumulation in potato dextrose broth liquid medium and liquid minimal medium was almost totally (more than 98%) inhibited by B. megaterium. The expression of many of the aflatoxin biosynthetic genes in the fungus was confirmed to be turned down. Some of the target genes down-regulated by B. megaterium within the whole genome and within the aflatoxin pathway gene cluster (aflF, aflT, aflS, aflJ, aflL, aflX) were identified. These target genes could be used for controlling aflatoxin contamination in crops such as corn, cotton, and peanut. Importantly, the expression of the regulatory gene aflS was found to be significantly down-regulated.
2013-10-22 | GSE51469 | GEO
Project description:Aspergillus flavus strain:NRRL 3357 Genome sequencing
| PRJNA575750 | ENA
Project description:Aspergillus flavus strain:NRRL 21882 Genome sequencing and assembly
| PRJNA392584 | ENA
Project description:Aspergillus flavus is one of the major fungal molds that colonize peanut in the field and during storage. The impact to human and animal health and to economy in agriculture and commerce are significant since this mold produces the most potent natural toxins, aflatoxins, which are carcinogenic, mutagenic, immunosuppressive, and teratogenic. A strain of marine Bacillus megaterium isolated from the Yellow Sea of East China was evaluated for its effect to inhibit aflatoxin formation through down-regulating aflatoxin pathway gene expression in A. flavus as demonstrated by genechip analysis in liquid medium and peanuts. The results showed that aflatoxin accumulation in potato dextrose broth liquid medium and liquid minimal medium was almost totally (more than 98%) inhibited by B. megaterium. The expression of many of the aflatoxin biosynthetic genes in the fungus was confirmed to be turned down. Some of the target genes down-regulated by B. megaterium within the whole genome and within the aflatoxin pathway gene cluster (aflF, aflT, aflS, aflJ, aflL, aflX) were identified. These target genes could be used for controlling aflatoxin contamination in crops such as corn, cotton, and peanut. Importantly, the expression of the regulatory gene aflS was found to be significantly down-regulated. The effect of B. megaterium on aflatoxin biosynthesis and genes expression of pathogen was firstly tested in potato dextrose broth (PDB) and glucose minimal salts medium (MM). The cell suspension of B. megaterium (concentration in PDB and MM was finally adjusted to 108 CFU/ml) or sterile distilled water as a control was added into the 100 ml beaker flask containing 15 ml PDB or MM, respectively. Then 100 M-NM-<l of spore suspension (5 M-CM-^W 106 spores/ml) of A. flavus were added into each beaker flask. After 48 h of incubation at 28M-BM-0C at 200 rpm, mycelia were collected, fresh frozen with liquid nitrogen, ground to a fine powder in liquid nitrogen, and stored at -80M-BM-0C for further analysis. The effect of B. megaterium on aflatoxin biosynthesis and genes expression in the A. flavus fungal pathogen was also tested in two types of peanut kernels, UF 715133-1 and Jinhua 1012, respectively. Peanut kernels were wounded (6 mm diameter and approximately 3 mm deep) using a sterile borer and then 20 M-NM-<l of 1 M-CM-^W 108 CFU/ml cell suspension of B. megaterium was inoculated on wounded peanut kernels respectively. Sterile distilled water was also used for inoculation as control. Two hours after bacterial inoculation, 10 M-NM-<l A. flavus spore suspension was inoculated into each wound at a concentration of 106 spores/ml. The kernels were placed in artificial weather chamber to maintain high humidity (85%) and incubated at 28M-BM-0C for 7 days. Each treatment was replicated three times with 20 peanut kernels in each test. The mycelia on kernels were harvested at day 7 and fresh frozen immediately in liquid nitrogen, ground into powder, and stored at -80M-BM-0C for further analysis.
2013-10-22 | E-GEOD-51469 | biostudies-arrayexpress
Project description:RNA-seq was used to compare differential gene expressions for Aspergillus flavus wild type strain and ASPES transcription factor deletion strains.The goals of this study are to explore the aflatoxin regulation pathway in A. flavus.
2018-12-25 | GSE107025 | GEO
Project description:Aspergillus flavus and A. parasiticus are two of the most important aflatoxin-producing species that contaminate agricultural commodities worldwide. Both species are heterothallic and undergo sexual reproduction in laboratory crosses. Here, we examine the possibility of interspecific matings between A. flavus and A. parasiticus. These species can be distinguished morphologically and genetically, as well as by their mycotoxin profiles. Aspergillus flavus produces both B aflatoxins and cyclopiazonic acid (CPA), B aflatoxins or CPA alone, or neither mycotoxin; Aspergillus parasiticus produces B and G aflatoxins or the aflatoxin precursor O-methylsterigmatocystin, but not CPA. Only four out of forty-five attempted interspecific crosses between compatible mating types of A. flavus and A. parasiticus were fertile and produced viable ascospores. Single ascospore strains from each cross were isolated and were shown to be recombinant hybrids using multilocus genotyping and array comparative genome hybridization. Conidia of parents and their hybrid progeny were haploid and predominantly monokaryons and dikaryons based on flow cytometry. Multilocus phylogenetic inference showed that experimental hybrid progeny were grouped with naturally occurring A. flavus L strain and A. parasiticus. Higher total aflatoxin concentrations in some F1 progeny strains compared to midpoint parent aflatoxin levels indicate synergism in aflatoxin production; moreover, three progeny strains synthesized G aflatoxins that were not produced by the parents, and there was evidence of putative allopolyploidization in one strain. These results suggest that hybridization is an important diversifying force resulting in the genesis of novel toxin profiles in these agriculturally important species.
2015-10-01 | GSE61981 | GEO
Project description:Linking cell reproduction and survival is a key task of all life forms. All fungi in the genus Aspergillus reproduce by forming asexual spores called conidia, of which formation is governed by the central regulatory circuit, BrlA->AbaA->WetA. Here, we report that WetA is a key multi-functional regulator that bridged spore differentiation, long-term survival, and chemical development in Aspergillus flavus.
2017-06-04 | GSE95711 | GEO
Project description:Aspergillus flavus is an opportunistic pathogen of crops, including peanuts and maize, and is the second leading cause of aspergillosis in immunocompromised patients. A. flavus is also a major producer of the mycotoxin, aflatoxin, a potent carcinogen, which results in significant crop losses annually. The A. flavus isolate NRRL 3357 was originally isolated from peanut and has been used as a model organism for understanding the regulation and production of secondary metabolites, such as aflatoxin. A draft genome of NRRL 3357 was previously constructed, enabling the development of molecular tools and for understanding population biology of this particular species. Here, we describe an updated, near complete, telomere-to-telomere assembly and re-annotation of the eight chromosomes of A. flavus NRRL 3357 genome, accomplished via long-read PacBio and Oxford Nanopore technologies combined with Illumina short-read sequencing. A total of 13,715 protein-coding genes were predicted. Using RNA-seq data, a significant improvement was achieved in predicted 5' and 3' untranslated regions, which were incorporated into the new gene models.
| S-EPMC8496237 | biostudies-literature