Aspergillus flavus
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ABSTRACT:
PROVIDER: PRJNA144055 | ENA |
REPOSITORIES: ENA
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Project description:To better understand the effect of temperature on mycotoxin biosynthesis, RNA-Seq technology was used to profile the Aspergillus flavus transcriptome under different temperature conditions. This approachallowed us to quantify transcript abundance for over 80% of fungal genes including 1,153 genes that were differentially expressed at 30°C and 37°C. Wleven of the 55 secondary metabolite clusters were up-regulated at the lower temperature, including aflatoxin biosynthesis genes, which were among the most highly up-expressed genes. On average, transcript abundance for the 30 aflatoxin biosynthesis genes was 3,300 times greater at 30°C as compared to 37°C. The results are consistent with the view that high temperature negatively affects aflatoxin production by turning down transcription of the two key transcriptional regulators, aflR and aflS. Subtle changes in the expression levels of aflS to aflR appear to control transcription activation of the aflatoxin cluster.
2011-06-16 | GSE30031 | 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:To better understand the effect of temperature on mycotoxin biosynthesis, RNA-Seq technology was used to profile the Aspergillus flavus transcriptome under different temperature conditions. This approachallowed us to quantify transcript abundance for over 80% of fungal genes including 1,153 genes that were differentially expressed at 30M-BM-0C and 37M-BM-0C. Wleven of the 55 secondary metabolite clusters were up-regulated at the lower temperature, including aflatoxin biosynthesis genes, which were among the most highly up-expressed genes. On average, transcript abundance for the 30 aflatoxin biosynthesis genes was 3,300 times greater at 30M-BM-0C as compared to 37M-BM-0C. The results are consistent with the view that high temperature negatively affects aflatoxin production by turning down transcription of the two key transcriptional regulators, aflR and aflS. Subtle changes in the expression levels of aflS to aflR appear to control transcription activation of the aflatoxin cluster. 2 samples examined: from the fungus grown at 30M-BM-0C and 37M-BM-0C
2011-06-16 | E-GEOD-30031 | biostudies-arrayexpress
Project description:Several are the inputs which are able to modulate mycotoxin synthesis. In particular, when a fungus receives an external stimulus reacts by activating, through a quite well-defined signal cascade, an evident switch in its lifestyle. This profound change is also due to the activation of global gene regulators and, in particular, of transcription factors able to switch on the mycotoxin gene clusters expression. Aflatoxins (AF) are harmful carcinogenic compounds produced mainly by Aspergillus flavus and A. parasiticus. AF are produced during the contamination of maize kernels into the field, even if their role in phyto-toxicity is not yet assessed. Nevertheless, AF biosynthesis is tightly regulated by host-derived signals. Recently, the nature of some of these signals have been elucidated. In particular, a role in susceptibility and resistance of maize to A. flavus contamination has been assigned to some plant oxylipins. These findings draw a scenario in which a complex interplay is under way between A. flavus and maize. For uncovering all the implications of this cross-talk we decide to follow a holistic approach. In particular, we designed experimental conditions aimed to mimic the different phases of A. flavus infection cycle on maize and then by performing a microarray analysis on the harvested mycelia. The microarray data set has been processed for performing the differential expression analysis of almost 14000 gene probes, the pathway analysis based on the gene ontology and inter pro annotations, the secondary metabolites cluster co-expression analysis and an identification of groups of co-expressed neighbor genes, possibly associated with production of secondary metabolites. Analysis of 12 microarrays monitoring gene expression of Aspergillus flavus over various growth conditions
2013-09-19 | E-GEOD-28163 | 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: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: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:Dimethyl sulfoxide (DSMO) is a simple molecule widely used because of its great solvating ability. Beyond its physico-chemical properties, it is also biologically active, including on fungal species. Aspergillus flavus is a saprophytic and famous pathogenic fungus able to produce Aflatoxin B1 (AFB1), a potent carcinogenic mycotoxin which may contaminate many food crops. The aim of this study was to characterize the effect of DMSO on A. flavus transcriptome profile using high-throughput RNA-sequencing assay.
2021-12-20 | GSE189211 | GEO
Project description:Aspergillus flavus is a common saprophyte and opportunistic pathogen producing aflatoxin (AF) and many other secondary metabolites. 5-Azacytidine (5-AC), a derivative of nucleoside cytidine, is widely used for studies in epigenetics and cancer biology as an inactivator of DNA methyltransferase and is also used for studying secondary metabolism in fungi. Our previous studies showed that 5-AC affects development and inhibits AF production in A. flavus, and that A. flavus lacks DNA methylation. How this common DNA methyltransferase inhibitor affects development and AF production is not clear. In this study, we applied an RNA-Seq approach to elucidate the mechanism of 5-ACM-bM-^@M-^Ys effect on A. flavus. In our current study, we identified 240 significantly differently expressed (Q-value<0.05) genes after 5-AC treatment, including two backbone genes in secondary metabolite clusters #27 and #35, which are involved in development or survival of sclerotia. With 5-AC treatment, about three quarters of the genes in the AF biosynthetic gene cluster in A. flavus were down-regulated to a certain degree. Strikingly, at least two genes aflI and aflLa, were completely inhibited. Interestingly, several genes involved in fungal development were down-regulated, especially veA, which is a gene that encodes protein bridges VelB and LaeA. This result supports the hypothesis that 5-AC affects development and AF production through weakening or even interrupting the connection between VelB and LaeA and then causing dysregulation of the expression pattern of genes involved in development and secondary metabolism. Our results improved the A. flavus genome annotation, provided a comprehensive view of the transcriptome of A. flavus responding to 5-AC and confirmed that fungal development and secondary metabolism are co-regulated. In additon, the RNA-Seq data of another sample treated with gallic acid was used to improve A. flavus genome annotation. mRNA of Aspergillus flavus cultured in three different culture media PDB, PDB+5-AC(5-Azacytidine),and PDB+GA(gallic acid) was subjected to sequence independently.
2013-06-15 | E-GEOD-40202 | biostudies-arrayexpress
Project description:Naturally occurring Antisense Transcripts (NATs) compose an emerging group of regulatory RNAs. These regulatory elements appear in all organisms examined, but little is known about global expression of NATs in fungi. Analysis of currently available EST sequences suggests that 352 cis NATs are present in Aspergillus flavus. An Affymetrix GeneChip® microarray containing probes for these cis NATs, as well as all predicted genes in A. flavus, allowed a whole genome expression analysis of these elements in response to two ecologically important temperatures for the fungus. RNA expression analysis showed that 32 NATs and 2709 genes were differentially expressed between 37°C, the optimum temperature for growth, and 28°C, the conducive temperature for the biosynthesis of aflatoxin (AF) and many other secondary metabolites. These NATs correspond to sense genes with diverse functions including transcription initiation, carbohydrate processing and binding, temperature sensitive morphogenesis, and secondary metabolism. This is the first report of a whole genome transcriptional analysis of NAT expression in a fungus and shows that although less than 10% of putative NATs are differentially expressed in response to temperature, some of the NAT-cis gene interactions are likely to be important. Keywords: temperature response
2009-03-25 | GSE12594 | GEO