Project description:Drosophila melanogaster larvae and filamentous fungi both utilise organic material. Here they compete for resources. Filamentous fungi can defend themselves and their substrate from predation respectively competition by the production and excretion of secondary metabolites, including substances with antibiotic and insecticidal properties. To analyse the traits that enables D. melanogaster larvae to reduce the harmful effects of fungal secondary metabolites and to develop on fungal infested substrate we confronted larvae with a toxin-producing wild type of Aspergillus nidulans, with a toxin-production-impaired mutant strain of A. nidulans, and with sterigmatocystin, a highly toxic metabolite of A. nidulans. Early first instar larvae were transferred to breeding substrate inhabited by fungal colonies respectively inoculated with the purified mycotoxin or controls. After 3, 6, 12, and 24 hours of confrontation larvae were collected and samples prepared for whole transcriptome shotgun sequencing.
Project description:Investigation of whole genome gene expression level changes in Aspergillus nidulans AN1599 (PbcR) overexpression mutant, compared to the FGSC A4 wild-type strain. Overexpression of the Zn(II)2Cys6 –type transcription factor, AN1599.4 (PbcR, pimaradiene biosynthetic cluster regulator), activates a secondary metabolite gene cluster in Aspergillus nidulans. Activation of the pathway in Aspergillus nidulans lead to a production of ent-pimara-8(14),15-diene.
Project description:Using genetic engineering tools available for the model organism Aspergillus nidulans, we constructed two recombinant strains; one expressing the model polyketide Penicillium griseofulvum 6-methylsalicylic acid (6-MSA) polyketide synthase gene, and one expressing the 6-MSA gene and overexpressing the native phosphoketolase (phk) for increasing the pool of polyketide precursor levels. The physiology of the recombinant strains and a reference wild type were characterized on glucose, xylose, glycerol and ethanol medium in controlled bioreactors. Glucose was found to be the preferable carbon source for 6-MSA production and 6-MSA titers up to 455 mg/L were achieved. Our findings indicate that overexpression of phk does not directly improve 6-MSA production on glucose but if the lower glycolysis is lowered, it is possible to obtain quite high conversion yields of sugar to 6-MSA. Systems biology tools were employed for in-depth analysis of the metabolic processes. Transcriptome analysis of 6-MSA producing strains on glucose and xylose in the presence and absence of phk overexpression combined with flux and physiology data enabled us to propose a model of phk/6msas interaction describing two different responses influencing 6-MSA production. Four strains on two carbon sources
Project description:Using genetic engineering tools available for the model organism Aspergillus nidulans, we constructed two recombinant strains; one expressing the model polyketide Penicillium griseofulvum 6-methylsalicylic acid (6-MSA) polyketide synthase gene, and one expressing the 6-MSA gene and overexpressing the native phosphoketolase (phk) for increasing the pool of polyketide precursor levels. The physiology of the recombinant strains and a reference wild type were characterized on glucose, xylose, glycerol and ethanol medium in controlled bioreactors. Glucose was found to be the preferable carbon source for 6-MSA production and 6-MSA titers up to 455 mg/L were achieved. Our findings indicate that overexpression of phk does not directly improve 6-MSA production on glucose but if the lower glycolysis is lowered, it is possible to obtain quite high conversion yields of sugar to 6-MSA. Systems biology tools were employed for in-depth analysis of the metabolic processes. Transcriptome analysis of 6-MSA producing strains on glucose and xylose in the presence and absence of phk overexpression combined with flux and physiology data enabled us to propose a model of phk/6msas interaction describing two different responses influencing 6-MSA production.
Project description:The study aims essentially at the characterisation of suberin degradation mechanisms by Aspergillus nidulans, at a fundamental level. Suberin is an important protective barrier in plant, thus the study of its biodegradation significantly impacts on phytopatology. In addition, fungal suberin degrading enzymes might provide important insights to develop new waste management, bioremediation and biodeterioration prevention strategies.
Project description:Investigation of whole genome gene expression level changes in Aspergillus nidulans OE::rsmA compared to wild-type RDIT9.32 (veA). A twelve array study using total RNA recovered from six separate cultures of Aspergillus nidulans wild-type RDIT9.32 (veA) and six separate cultures of Aspergillus nidulans overexpressing rsmA (restorer of secondary metabolism A), using custom-designed, four-plex arrays. The experiment was divided into two runs. In the first run, three biological replicates each of Aspergillus nidulans wild-type RDIT9.32 (veA) and Aspergillus nidulans carrying a plasmid overexpressing rsmA under the control of the gpdA promoter were assayed. In the second run, three biological replicates each of Aspergillus nidulans wild-type RDIT9.32 (veA) and Aspergillus nidulans overexpressing rsmA at the native locus under the control of the gpdA promoter were assayed.
Project description:Transcriptional profiling of A. nidulans comparing starvation for 0 (reference), 12 and 24 h. The main objective was to identify genes specifically regulated during starvation by atmA and xprG. The results of the experiment were further validated by real-time PCR. Experimental procedure: Three A. nidulans strains were used in this study: WT, delta atmA and delta xprG. Strains were grown on minimal medium for 24 h (0 h starvation reference), then exposed to 12 and 24 h starvation. atmA: ATM, Ataxia-Telangiectasia mutated; Malavazi, I., Savoldi, M., Da Silva Ferreira, M. E., Soriani, F. M., Bonato, P. S., De Souza Goldman, M. H. and Goldman, G. H. (2007), Transcriptome analysis of the Aspergillus nidulans AtmA (ATM, Ataxia-Telangiectasia mutated) null mutant. Molecular Microbiology, 66: 74-99 (PMID 17880424). xprG: extracellular protease; Margaret E. Katz, Karen-Ann Gray, Brian F. Cheetham, (2006) The Aspergillus nidulans xprG (phoG) gene encodes a putative transcriptional activator involved in the response to nutrient limitation, Fungal Genetics and Biology, 43, 190-199 (PMID 16464624).
Project description:Investigation of whole genome gene expression level changes in Aspergillus nidulans AN1599 (PbcR) overexpression mutant, compared to the FGSC A4 wild-type strain. Overexpression of the Zn(II)2Cys6 M-bM-^@M-^Stype transcription factor, AN1599.4 (PbcR, pimaradiene biosynthetic cluster regulator), activates a secondary metabolite gene cluster in Aspergillus nidulans. Activation of the pathway in Aspergillus nidulans lead to a production of ent-pimara-8(14),15-diene. 12x135K array of two separate cultures of FGSC A4 and two separate cultures of oe:AN1599(PbcR) with three separate RNA extractions from each culture. Each 135K array measures expression level of 10,546 genes with 6 probes/transcript. In addition, the array format contains tiling probes for 36 longer transcripts. All probes are in duplicates, giving the total number of 137,562 probes per array.
Project description:David2008 - Genome-scale metabolic network of
Aspergillus nidulans (iHD666)
This model is described in the article:
Analysis of Aspergillus
nidulans metabolism at the genome-scale.
David H, Ozçelik IS, Hofmann G,
Nielsen J.
BMC Genomics 2008; 9: 163
Abstract:
BACKGROUND: Aspergillus nidulans is a member of a diverse
group of filamentous fungi, sharing many of the properties of
its close relatives with significance in the fields of
medicine, agriculture and industry. Furthermore, A. nidulans
has been a classical model organism for studies of development
biology and gene regulation, and thus it has become one of the
best-characterized filamentous fungi. It was the first
Aspergillus species to have its genome sequenced, and automated
gene prediction tools predicted 9,451 open reading frames
(ORFs) in the genome, of which less than 10% were assigned a
function. RESULTS: In this work, we have manually assigned
functions to 472 orphan genes in the metabolism of A. nidulans,
by using a pathway-driven approach and by employing comparative
genomics tools based on sequence similarity. The central
metabolism of A. nidulans, as well as biosynthetic pathways of
relevant secondary metabolites, was reconstructed based on
detailed metabolic reconstructions available for A. niger and
Saccharomyces cerevisiae, and information on the genetics,
biochemistry and physiology of A. nidulans. Thereby, it was
possible to identify metabolic functions without a gene
associated, and to look for candidate ORFs in the genome of A.
nidulans by comparing its sequence to sequences of
well-characterized genes in other species encoding the function
of interest. A classification system, based on defined
criteria, was developed for evaluating and selecting the ORFs
among the candidates, in an objective and systematic manner.
The functional assignments served as a basis to develop a
mathematical model, linking 666 genes (both previously and
newly annotated) to metabolic roles. The model was used to
simulate metabolic behavior and additionally to integrate,
analyze and interpret large-scale gene expression data
concerning a study on glucose repression, thereby providing a
means of upgrading the information content of experimental data
and getting further insight into this phenomenon in A.
nidulans. CONCLUSION: We demonstrate how pathway modeling of A.
nidulans can be used as an approach to improve the functional
annotation of the genome of this organism. Furthermore we show
how the metabolic model establishes functional links between
genes, enabling the upgrade of the information content of
transcriptome data.
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and identified by:
MODEL1507180016.
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Project description:Mining of fungal genomes uncovered their great potential for the production of novel secondary metabolites (SMs). However most of them stay silent under standard laboratory cultivation conditions. Co-cultivation of fungi with organism that occur in their natural habitat has shown to be trigger for the activation of such silent SM gene clusters. Recently, we showed that the cultivation of Aspergillus nidulans with the bacterium Streptomyces rapamycinicus leads to the activation of the orsellinic acid gene cluster. Hence we decided to study this interaction further to gain insight into the regulation of SM gene clusters and more specifically to study the chromatin remodelling network actuve upon co-cultivation of the two organisms. This study gives novel insight into the regulation of the orsellinic acid gene cluster and the interaction of the two organisms. To the best of our knowledge this is the first report of mapping the chromatin landscape of microbial interactions, making this study a role model for the analysis of similar systems.