Aspergillus flavus
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ABSTRACT:
PROVIDER: PRJNA730642 | ENA |
REPOSITORIES: ENA
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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: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: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:Purpose: Aflatoxin B1 is the most toxic and carcinogenic compound in nature produced by Aspergillus fungi. In our study, we applied RNA-seq to compare the transcriptomic profiles of Aspergillus flavus strains in the presence and absence of medicinal plant Zanthoxylum bungeanum. Methods: mRNA profiles of Aspergillus flavus supplemented with 250 µg/ml of methanolic extract fraction (treated samples) or DMSO (control samples) were generated in triplicate, by an Illumina platform using paired-end 150 bp sequencing strategy. Clean paired-end reads were mapped to the reference genome of A. flavus NRRL3357. Gene expression quantification was calculated by FPKM (Fragments Per Kilobase of transcript sequence per Millions base pairs sequenced). The differentially expressed genes (DGEs) between the control and test samples were analyzed using the DESeq2 R package. Results: RNA-seq produced 24.5–32.1 million clean paired-end reads (150 bp read length) per sample and most of them (83–91%) were uniquely mapped to the reference genome of A. flavus NRRL3357. Eighty-two percent of genes displayed FPKM value ≥1 and were thus classified as expressed genes. Ninety-six percent of the expressed genes were expressed both in the control and test groups whereas 2.3% and 1.8% of the genes were expressed only in the control or test group, respectively. With the combination of FPKM fold change ≥2 and adjusted p-value <0.05, we found in total 950 DEG’s. Among them, 515 genes were downregulated and 435 genes were upregulated. We used FungiFun software to analyze the functions of the DEGs based on FunCat pathways and categories. About half of the DEG’s had a relevant annotation in the FunCat database, and 60–70% of the annotated DEG’s were found to be enriched in specific functional pathways. Conclusions: we showed that simple organic extracts from Z. bungeanum inhibit both the growth and aflatoxin production by Aspergillus flavus. The repression of AF pathway is mediated by global regulators instead of pathway specific regulators AflR or AflS. Consistently, the expression of Velvet complex, a prominent regulator of fungal secondary metabolism and development, was substantially reduced. Natural compound extracts from Z. bungeanum have potential to facilitate the development of safe and economical control strategies that shutdown aflatoxin production in aflatoxigenic Aspergillus species.
2022-04-10 | GSE179477 | 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