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John E Linz - One of the best experts on this subject based on the ideXlab platform.
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the fungal bzip transcription factor atfb controls virulence associated processes in Aspergillus parasiticus
Toxins, 2017Co-Authors: Josephine Wee, Anindya Chanda, Ludmila V Roze, Sung Yong Hong, Devin M Day, John E LinzAbstract:Fungal basic leucine zipper (bZIP) transcription factors mediate responses to oxidative stress. The ability to regulate stress response pathways in Aspergillus spp. was postulated to be an important virulence-associated cellular process, because it helps establish infection in humans, plants, and animals. Previous studies have demonstrated that the fungal transcription factor AtfB encodes a protein that is associated with resistance to oxidative stress in asexual conidiospores, and AtfB binds to the promoters of several stress response genes. Here, we conducted a gene silencing of AtfB in Aspergillus parasiticus, a well-characterized fungal pathogen of plants, animals, and humans that produces the secondary metabolite and carcinogen aflatoxin, in order to determine the mechanisms by which AtfB contributes to virulence. We show that AtfB silencing results in a decrease in aflatoxin enzyme levels, the down-regulation of aflatoxin accumulation, and impaired conidiospore development in AtfB-silenced strains. This observation is supported by a decrease of AtfB protein levels, and the down-regulation of many genes in the aflatoxin cluster, as well as genes involved in secondary metabolism and conidiospore development. Global expression analysis (RNA Seq) demonstrated that AtfB functionally links oxidative stress response pathways to a broader and novel subset of target genes involved in cellular defense, as well as in actin and cytoskeleton arrangement/transport. Thus, AtfB regulates the genes involved in development, stress response, and secondary metabolism in A. parasiticus. We propose that the bZIP regulatory circuit controlled by AtfB provides a large number of excellent cellular targets to reduce fungal virulence. More importantly, understanding key players that are crucial to initiate the cellular response to oxidative stress will enable better control over its detrimental impacts on humans.
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Proteomic and Biochemical Evidence Support a Role for Transport Vesicles and Endosomes in Stress Response and Secondary Metabolism in Aspergillus parasiticus
Journal of Proteome Research, 2011Co-Authors: John E Linz, Anindya Chanda, Sung Yong Hong, Douglas Whitten, Curtis G. Wilkerson, Ludmila V RozeAbstract:Aflatoxin is among the most potent naturally occurring carcinogens known. Previous studies demonstrated that endosomes in the filamentous fungus Aspergillus parasiticus carry enzymes that catalyze the final two steps in aflatoxin synthesis, and these structures also play a role in aflatoxin storage and export. We hypothesized that endosomes house a complete and functional aflatoxin biosynthetic pathway. To address this hypothesis, we purified a cellular fraction containing endosomes, transport vesicles, and vacuoles (V fraction) from A. parasiticus grown under aflatoxin inducing and noninducing conditions. We also added (fed) aflatoxin pathway intermediates to V fraction to test the functional status of aflatoxin pathway enzymes. High throughput LC–MS/MS analysis of proteins in V fraction detected 8 aflatoxin enzymes with high reliability and 8 additional enzymes at lower reliability, suggesting that most aflatoxin pathway enzymes are present. Purified V fraction synthesized aflatoxin and addition of the ...
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Willow volatiles influence growth, development, and secondary metabolism in Aspergillus parasiticus
Applied Microbiology and Biotechnology, 2011Co-Authors: Ludmila V Roze, Randolph M Beaudry, Maris Laivenieks, Anna V Koptina, Daniel A. Jones, Albert V. Kanarsky, John E LinzAbstract:Aflatoxin is a mycotoxin and the most potent naturally occurring carcinogen in many animals. Aflatoxin contamination of food and feed crops causes a significant global burden on human and animal health. However, available methods to eliminate aflatoxin from food and feed are not fully effective. Our goal is to discover novel, efficient, and practical methods to control aflatoxin contamination in crops during storage. In the present study, we tested the effect of volatiles produced by willow ( Salix acutifolia and Salix babylonica ) and maple ( Acer saccharinum ) bark on fungal growth, development, and aflatoxin production by the fungus Aspergillus parasiticus , one economically important aflatoxin producer. S. acutifolia bark volatiles nearly eliminated aflatoxin accumulation (>90% reduction) by A. parasiticus grown on a minimal agar medium. The decrease in aflatoxin accumulation correlated with a twofold reduction in ver-1 (encodes a middle aflatoxin pathway enzyme) transcript level. Expression data also indicate that one histone H4 acetyltransferase, MYST3, may play a role in epigenetic control of aflatoxin gene transcription in response to volatile exposure. Volatiles derived from wood bark samples also increased fungal growth up to 20% and/or enhanced conidiospore development. Solid-phase microextraction–gas chromatographic–mass spectrometric analysis of bark samples identified sets of shared and unique volatile compounds that may mediate the observed regulatory effects on growth, development, and aflatoxin synthesis. This work provides an experimental basis for the use of willow industry by-products to control aflatoxin contamination in food and feed crops.
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a possible role for exocytosis in aflatoxin export in Aspergillus parasiticus
Eukaryotic Cell, 2010Co-Authors: Anindya Chanda, Ludmila V Roze, John E LinzAbstract:Filamentous fungi synthesize bioactive secondary metabolites with major human health and economic impacts. Little is known about the mechanisms that mediate the export of these metabolites to the cell exterior. Aspergillus parasiticus synthesizes aflatoxin, a secondary metabolite that is one of the most potent naturally occurring carcinogens known. We previously demonstrated that aflatoxin is synthesized and compartmentalized in specialized vesicles called aflatoxisomes and that these subcellular organelles also play a role in the export process. In the current study, we tested the hypothesis that aflatoxisomes fuse with the cytoplasmic membrane to facilitate the release of aflatoxin into the growth environment. Microscopic analysis of A. parasiticus grown under aflatoxin-inducing and non-aflatoxin-inducing conditions generated several lines of experimental evidence that supported the hypothesis. On the basis of the evidence, we propose that export of the mycotoxin aflatoxin in Aspergillus parasiticus occurs by exocytosis, and we present a model to illustrate this export mechanism.
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volatile profiling reveals intracellular metabolic changes in Aspergillus parasiticus vea regulates branched chain amino acid and ethanol metabolism
BMC Biochemistry, 2010Co-Authors: Ludmila V Roze, Anindya Chanda, Randolph M Beaudry, Maris Laivenieks, Katherine A Artymovich, Anna V Koptina, Deena Awad, Dina Valeeva, Arthur Daniel Jones, John E LinzAbstract:Background Filamentous fungi in the genus Aspergillus produce a variety of natural products, including aflatoxin, the most potent naturally occurring carcinogen known. Aflatoxin biosynthesis, one of the most highly characterized secondary metabolic pathways, offers a model system to study secondary metabolism in eukaryotes. To control or customize biosynthesis of natural products we must understand how secondary metabolism integrates into the overall cellular metabolic network. By applying a metabolomics approach we analyzed volatile compounds synthesized by Aspergillus parasiticus in an attempt to define the association of secondary metabolism with other metabolic and cellular processes.
Ludmila V Roze - One of the best experts on this subject based on the ideXlab platform.
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the fungal bzip transcription factor atfb controls virulence associated processes in Aspergillus parasiticus
Toxins, 2017Co-Authors: Josephine Wee, Anindya Chanda, Ludmila V Roze, Sung Yong Hong, Devin M Day, John E LinzAbstract:Fungal basic leucine zipper (bZIP) transcription factors mediate responses to oxidative stress. The ability to regulate stress response pathways in Aspergillus spp. was postulated to be an important virulence-associated cellular process, because it helps establish infection in humans, plants, and animals. Previous studies have demonstrated that the fungal transcription factor AtfB encodes a protein that is associated with resistance to oxidative stress in asexual conidiospores, and AtfB binds to the promoters of several stress response genes. Here, we conducted a gene silencing of AtfB in Aspergillus parasiticus, a well-characterized fungal pathogen of plants, animals, and humans that produces the secondary metabolite and carcinogen aflatoxin, in order to determine the mechanisms by which AtfB contributes to virulence. We show that AtfB silencing results in a decrease in aflatoxin enzyme levels, the down-regulation of aflatoxin accumulation, and impaired conidiospore development in AtfB-silenced strains. This observation is supported by a decrease of AtfB protein levels, and the down-regulation of many genes in the aflatoxin cluster, as well as genes involved in secondary metabolism and conidiospore development. Global expression analysis (RNA Seq) demonstrated that AtfB functionally links oxidative stress response pathways to a broader and novel subset of target genes involved in cellular defense, as well as in actin and cytoskeleton arrangement/transport. Thus, AtfB regulates the genes involved in development, stress response, and secondary metabolism in A. parasiticus. We propose that the bZIP regulatory circuit controlled by AtfB provides a large number of excellent cellular targets to reduce fungal virulence. More importantly, understanding key players that are crucial to initiate the cellular response to oxidative stress will enable better control over its detrimental impacts on humans.
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Proteomic and Biochemical Evidence Support a Role for Transport Vesicles and Endosomes in Stress Response and Secondary Metabolism in Aspergillus parasiticus
Journal of Proteome Research, 2011Co-Authors: John E Linz, Anindya Chanda, Sung Yong Hong, Douglas Whitten, Curtis G. Wilkerson, Ludmila V RozeAbstract:Aflatoxin is among the most potent naturally occurring carcinogens known. Previous studies demonstrated that endosomes in the filamentous fungus Aspergillus parasiticus carry enzymes that catalyze the final two steps in aflatoxin synthesis, and these structures also play a role in aflatoxin storage and export. We hypothesized that endosomes house a complete and functional aflatoxin biosynthetic pathway. To address this hypothesis, we purified a cellular fraction containing endosomes, transport vesicles, and vacuoles (V fraction) from A. parasiticus grown under aflatoxin inducing and noninducing conditions. We also added (fed) aflatoxin pathway intermediates to V fraction to test the functional status of aflatoxin pathway enzymes. High throughput LC–MS/MS analysis of proteins in V fraction detected 8 aflatoxin enzymes with high reliability and 8 additional enzymes at lower reliability, suggesting that most aflatoxin pathway enzymes are present. Purified V fraction synthesized aflatoxin and addition of the ...
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Willow volatiles influence growth, development, and secondary metabolism in Aspergillus parasiticus
Applied Microbiology and Biotechnology, 2011Co-Authors: Ludmila V Roze, Randolph M Beaudry, Maris Laivenieks, Anna V Koptina, Daniel A. Jones, Albert V. Kanarsky, John E LinzAbstract:Aflatoxin is a mycotoxin and the most potent naturally occurring carcinogen in many animals. Aflatoxin contamination of food and feed crops causes a significant global burden on human and animal health. However, available methods to eliminate aflatoxin from food and feed are not fully effective. Our goal is to discover novel, efficient, and practical methods to control aflatoxin contamination in crops during storage. In the present study, we tested the effect of volatiles produced by willow ( Salix acutifolia and Salix babylonica ) and maple ( Acer saccharinum ) bark on fungal growth, development, and aflatoxin production by the fungus Aspergillus parasiticus , one economically important aflatoxin producer. S. acutifolia bark volatiles nearly eliminated aflatoxin accumulation (>90% reduction) by A. parasiticus grown on a minimal agar medium. The decrease in aflatoxin accumulation correlated with a twofold reduction in ver-1 (encodes a middle aflatoxin pathway enzyme) transcript level. Expression data also indicate that one histone H4 acetyltransferase, MYST3, may play a role in epigenetic control of aflatoxin gene transcription in response to volatile exposure. Volatiles derived from wood bark samples also increased fungal growth up to 20% and/or enhanced conidiospore development. Solid-phase microextraction–gas chromatographic–mass spectrometric analysis of bark samples identified sets of shared and unique volatile compounds that may mediate the observed regulatory effects on growth, development, and aflatoxin synthesis. This work provides an experimental basis for the use of willow industry by-products to control aflatoxin contamination in food and feed crops.
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a possible role for exocytosis in aflatoxin export in Aspergillus parasiticus
Eukaryotic Cell, 2010Co-Authors: Anindya Chanda, Ludmila V Roze, John E LinzAbstract:Filamentous fungi synthesize bioactive secondary metabolites with major human health and economic impacts. Little is known about the mechanisms that mediate the export of these metabolites to the cell exterior. Aspergillus parasiticus synthesizes aflatoxin, a secondary metabolite that is one of the most potent naturally occurring carcinogens known. We previously demonstrated that aflatoxin is synthesized and compartmentalized in specialized vesicles called aflatoxisomes and that these subcellular organelles also play a role in the export process. In the current study, we tested the hypothesis that aflatoxisomes fuse with the cytoplasmic membrane to facilitate the release of aflatoxin into the growth environment. Microscopic analysis of A. parasiticus grown under aflatoxin-inducing and non-aflatoxin-inducing conditions generated several lines of experimental evidence that supported the hypothesis. On the basis of the evidence, we propose that export of the mycotoxin aflatoxin in Aspergillus parasiticus occurs by exocytosis, and we present a model to illustrate this export mechanism.
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volatile profiling reveals intracellular metabolic changes in Aspergillus parasiticus vea regulates branched chain amino acid and ethanol metabolism
BMC Biochemistry, 2010Co-Authors: Ludmila V Roze, Anindya Chanda, Randolph M Beaudry, Maris Laivenieks, Katherine A Artymovich, Anna V Koptina, Deena Awad, Dina Valeeva, Arthur Daniel Jones, John E LinzAbstract:Background Filamentous fungi in the genus Aspergillus produce a variety of natural products, including aflatoxin, the most potent naturally occurring carcinogen known. Aflatoxin biosynthesis, one of the most highly characterized secondary metabolic pathways, offers a model system to study secondary metabolism in eukaryotes. To control or customize biosynthesis of natural products we must understand how secondary metabolism integrates into the overall cellular metabolic network. By applying a metabolomics approach we analyzed volatile compounds synthesized by Aspergillus parasiticus in an attempt to define the association of secondary metabolism with other metabolic and cellular processes.
Anindya Chanda - One of the best experts on this subject based on the ideXlab platform.
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the fungal bzip transcription factor atfb controls virulence associated processes in Aspergillus parasiticus
Toxins, 2017Co-Authors: Josephine Wee, Anindya Chanda, Ludmila V Roze, Sung Yong Hong, Devin M Day, John E LinzAbstract:Fungal basic leucine zipper (bZIP) transcription factors mediate responses to oxidative stress. The ability to regulate stress response pathways in Aspergillus spp. was postulated to be an important virulence-associated cellular process, because it helps establish infection in humans, plants, and animals. Previous studies have demonstrated that the fungal transcription factor AtfB encodes a protein that is associated with resistance to oxidative stress in asexual conidiospores, and AtfB binds to the promoters of several stress response genes. Here, we conducted a gene silencing of AtfB in Aspergillus parasiticus, a well-characterized fungal pathogen of plants, animals, and humans that produces the secondary metabolite and carcinogen aflatoxin, in order to determine the mechanisms by which AtfB contributes to virulence. We show that AtfB silencing results in a decrease in aflatoxin enzyme levels, the down-regulation of aflatoxin accumulation, and impaired conidiospore development in AtfB-silenced strains. This observation is supported by a decrease of AtfB protein levels, and the down-regulation of many genes in the aflatoxin cluster, as well as genes involved in secondary metabolism and conidiospore development. Global expression analysis (RNA Seq) demonstrated that AtfB functionally links oxidative stress response pathways to a broader and novel subset of target genes involved in cellular defense, as well as in actin and cytoskeleton arrangement/transport. Thus, AtfB regulates the genes involved in development, stress response, and secondary metabolism in A. parasiticus. We propose that the bZIP regulatory circuit controlled by AtfB provides a large number of excellent cellular targets to reduce fungal virulence. More importantly, understanding key players that are crucial to initiate the cellular response to oxidative stress will enable better control over its detrimental impacts on humans.
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citrate coated silver nanoparticles growth independently inhibit aflatoxin synthesis in Aspergillus parasiticus
Environmental Science & Technology, 2017Co-Authors: Chandrani Mitra, Phani M Gummadidala, Kamelia Afshinnia, Ruth C Merrifield, Mohammed Baalousha, Jamie R Lead, Anindya ChandaAbstract:Manufactured silver nanoparticles (Ag NPs) have long been used as antimicrobials. However, little is known about how these NPs affect fungal cell functions. While multiple previous studies reveal that Ag NPs inhibit secondary metabolite syntheses in several mycotoxin producing filamentous fungi, these effects are associated with growth repression and hence need sublethal to lethal NP doses, which besides stopping fungal growth, can potentially accumulate in the environment. Here we demonstrate that citrate-coated Ag NPs of size 20 nm, when applied at a selected nonlethal dose, can result in a >2 fold inhibition of biosynthesis of the carcinogenic mycotoxin and secondary metabolite, aflatoxin B1 in the filamentous fungus and an important plant pathogen, Aspergillus parasiticus, without inhibiting fungal growth. We also show that the observed inhibition was not due to Ag ions, but was specifically associated with the mycelial uptake of Ag NPs. The NP exposure resulted in a significant decrease in transcript...
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Proteomic and Biochemical Evidence Support a Role for Transport Vesicles and Endosomes in Stress Response and Secondary Metabolism in Aspergillus parasiticus
Journal of Proteome Research, 2011Co-Authors: John E Linz, Anindya Chanda, Sung Yong Hong, Douglas Whitten, Curtis G. Wilkerson, Ludmila V RozeAbstract:Aflatoxin is among the most potent naturally occurring carcinogens known. Previous studies demonstrated that endosomes in the filamentous fungus Aspergillus parasiticus carry enzymes that catalyze the final two steps in aflatoxin synthesis, and these structures also play a role in aflatoxin storage and export. We hypothesized that endosomes house a complete and functional aflatoxin biosynthetic pathway. To address this hypothesis, we purified a cellular fraction containing endosomes, transport vesicles, and vacuoles (V fraction) from A. parasiticus grown under aflatoxin inducing and noninducing conditions. We also added (fed) aflatoxin pathway intermediates to V fraction to test the functional status of aflatoxin pathway enzymes. High throughput LC–MS/MS analysis of proteins in V fraction detected 8 aflatoxin enzymes with high reliability and 8 additional enzymes at lower reliability, suggesting that most aflatoxin pathway enzymes are present. Purified V fraction synthesized aflatoxin and addition of the ...
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a possible role for exocytosis in aflatoxin export in Aspergillus parasiticus
Eukaryotic Cell, 2010Co-Authors: Anindya Chanda, Ludmila V Roze, John E LinzAbstract:Filamentous fungi synthesize bioactive secondary metabolites with major human health and economic impacts. Little is known about the mechanisms that mediate the export of these metabolites to the cell exterior. Aspergillus parasiticus synthesizes aflatoxin, a secondary metabolite that is one of the most potent naturally occurring carcinogens known. We previously demonstrated that aflatoxin is synthesized and compartmentalized in specialized vesicles called aflatoxisomes and that these subcellular organelles also play a role in the export process. In the current study, we tested the hypothesis that aflatoxisomes fuse with the cytoplasmic membrane to facilitate the release of aflatoxin into the growth environment. Microscopic analysis of A. parasiticus grown under aflatoxin-inducing and non-aflatoxin-inducing conditions generated several lines of experimental evidence that supported the hypothesis. On the basis of the evidence, we propose that export of the mycotoxin aflatoxin in Aspergillus parasiticus occurs by exocytosis, and we present a model to illustrate this export mechanism.
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volatile profiling reveals intracellular metabolic changes in Aspergillus parasiticus vea regulates branched chain amino acid and ethanol metabolism
BMC Biochemistry, 2010Co-Authors: Ludmila V Roze, Anindya Chanda, Randolph M Beaudry, Maris Laivenieks, Katherine A Artymovich, Anna V Koptina, Deena Awad, Dina Valeeva, Arthur Daniel Jones, John E LinzAbstract:Background Filamentous fungi in the genus Aspergillus produce a variety of natural products, including aflatoxin, the most potent naturally occurring carcinogen known. Aflatoxin biosynthesis, one of the most highly characterized secondary metabolic pathways, offers a model system to study secondary metabolism in eukaryotes. To control or customize biosynthesis of natural products we must understand how secondary metabolism integrates into the overall cellular metabolic network. By applying a metabolomics approach we analyzed volatile compounds synthesized by Aspergillus parasiticus in an attempt to define the association of secondary metabolism with other metabolic and cellular processes.
Randolph M Beaudry - One of the best experts on this subject based on the ideXlab platform.
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Willow volatiles influence growth, development, and secondary metabolism in Aspergillus parasiticus
Applied Microbiology and Biotechnology, 2011Co-Authors: Ludmila V Roze, Randolph M Beaudry, Maris Laivenieks, Anna V Koptina, Daniel A. Jones, Albert V. Kanarsky, John E LinzAbstract:Aflatoxin is a mycotoxin and the most potent naturally occurring carcinogen in many animals. Aflatoxin contamination of food and feed crops causes a significant global burden on human and animal health. However, available methods to eliminate aflatoxin from food and feed are not fully effective. Our goal is to discover novel, efficient, and practical methods to control aflatoxin contamination in crops during storage. In the present study, we tested the effect of volatiles produced by willow ( Salix acutifolia and Salix babylonica ) and maple ( Acer saccharinum ) bark on fungal growth, development, and aflatoxin production by the fungus Aspergillus parasiticus , one economically important aflatoxin producer. S. acutifolia bark volatiles nearly eliminated aflatoxin accumulation (>90% reduction) by A. parasiticus grown on a minimal agar medium. The decrease in aflatoxin accumulation correlated with a twofold reduction in ver-1 (encodes a middle aflatoxin pathway enzyme) transcript level. Expression data also indicate that one histone H4 acetyltransferase, MYST3, may play a role in epigenetic control of aflatoxin gene transcription in response to volatile exposure. Volatiles derived from wood bark samples also increased fungal growth up to 20% and/or enhanced conidiospore development. Solid-phase microextraction–gas chromatographic–mass spectrometric analysis of bark samples identified sets of shared and unique volatile compounds that may mediate the observed regulatory effects on growth, development, and aflatoxin synthesis. This work provides an experimental basis for the use of willow industry by-products to control aflatoxin contamination in food and feed crops.
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volatile profiling reveals intracellular metabolic changes in Aspergillus parasiticus vea regulates branched chain amino acid and ethanol metabolism
BMC Biochemistry, 2010Co-Authors: Ludmila V Roze, Anindya Chanda, Randolph M Beaudry, Maris Laivenieks, Katherine A Artymovich, Anna V Koptina, Deena Awad, Dina Valeeva, Arthur Daniel Jones, John E LinzAbstract:Background Filamentous fungi in the genus Aspergillus produce a variety of natural products, including aflatoxin, the most potent naturally occurring carcinogen known. Aflatoxin biosynthesis, one of the most highly characterized secondary metabolic pathways, offers a model system to study secondary metabolism in eukaryotes. To control or customize biosynthesis of natural products we must understand how secondary metabolism integrates into the overall cellular metabolic network. By applying a metabolomics approach we analyzed volatile compounds synthesized by Aspergillus parasiticus in an attempt to define the association of secondary metabolism with other metabolic and cellular processes.
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volatile profiling reveals intracellular metabolic changes in Aspergillus parasiticus vea regulates branched chain amino acid and ethanol metabolism
BMC Biochemistry, 2010Co-Authors: Ludmila V Roze, Anindya Chanda, Randolph M Beaudry, Maris Laivenieks, Katherine A Artymovich, Anna V Koptina, Deena Awad, Dina Valeeva, Arthur Daniel Jones, John E LinzAbstract:Filamentous fungi in the genus Aspergillus produce a variety of natural products, including aflatoxin, the most potent naturally occurring carcinogen known. Aflatoxin biosynthesis, one of the most highly characterized secondary metabolic pathways, offers a model system to study secondary metabolism in eukaryotes. To control or customize biosynthesis of natural products we must understand how secondary metabolism integrates into the overall cellular metabolic network. By applying a metabolomics approach we analyzed volatile compounds synthesized by Aspergillus parasiticus in an attempt to define the association of secondary metabolism with other metabolic and cellular processes. Volatile compounds were examined using solid phase microextraction - gas chromatography/mass spectrometry. In the wild type strain Aspergillus parasiticus SU-1, the largest group of volatiles included compounds derived from catabolism of branched chain amino acids (leucine, isoleucine, and valine); we also identified alcohols, esters, aldehydes, and lipid-derived volatiles. The number and quantity of the volatiles produced depended on media composition, time of incubation, and light-dark status. A block in aflatoxin biosynthesis or disruption of the global regulator veA affected the volatile profile. In addition to its multiple functions in secondary metabolism and development, VeA negatively regulated catabolism of branched chain amino acids and synthesis of ethanol at the transcriptional level thus playing a role in controlling carbon flow within the cell. Finally, we demonstrated that volatiles generated by a veA disruption mutant are part of the complex regulatory machinery that mediates the effects of VeA on asexual conidiation and sclerotia formation. 1) Volatile profiling provides a rapid, effective, and powerful approach to identify changes in intracellular metabolic networks in filamentous fungi. 2) VeA coordinates the biosynthesis of secondary metabolites with catabolism of branched chain amino acids, alcohol biosynthesis, and β-oxidation of fatty acids. 3) Intracellular chemical development in A. parasiticus is linked to morphological development. 4) Understanding carbon flow through secondary metabolic pathways and catabolism of branched chain amino acids is essential for controlling and customizing production of natural products.
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Aspergillus volatiles regulate aflatoxin synthesis and asexual sporulation in Aspergillus parasiticus
Applied and Environmental Microbiology, 2007Co-Authors: Ludmila V Roze, Randolph M Beaudry, Ana M Calvo, Anna E Arthur, John E LinzAbstract:Aspergillus parasiticus is one primary source of aflatoxin contamination in economically important crops. To prevent the potential health and economic impacts of aflatoxin contamination, our goal is to develop practical strategies to reduce aflatoxin synthesis on susceptible crops. One focus is to identify biological and environmental factors that regulate aflatoxin synthesis and to manipulate these factors to control aflatoxin biosynthesis in the field or during crop storage. In the current study, we analyzed the effects of Aspergillus volatiles on growth, development, aflatoxin biosynthesis, and promoter activity in the filamentous fungus A. parasiticus. When colonies of Aspergillus nidulans and A. parasiticus were incubated in the same growth chamber, we observed a significant reduction in aflatoxin synthesis and asexual sporulation by A. parasiticus. Analysis of the headspace gases demonstrated that A. nidulans produced much larger quantities of 2-buten-1-ol (CA) and 2-ethyl-1-hexanol (EH) than A. parasiticus. In its pure form, EH inhibited growth and increased aflatoxin accumulation in A. parasiticus at all doses tested; EH also stimulated aflatoxin transcript accumulation. In contrast, CA exerted dose-dependent up-regulatory or down-regulatory effects on aflatoxin accumulation, conidiation, and aflatoxin transcript accumulation. Experiments with reporter strains carrying nor-1 promoter deletions and mutations suggested that the differential effects of CA were mediated through separate regulatory regions in the nor-1 promoter. The potential efficacy of CA as a tool for analysis of transcriptional regulation of aflatoxin biosynthesis is discussed. We also identify a novel, rapid, and reliable method to assess norsolorinic acid accumulation in solid culture using a Chroma Meter CR-300 apparatus.
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ethylene inhibits aflatoxin biosynthesis in Aspergillus parasiticus grown on peanuts
Food Microbiology, 2007Co-Authors: A Gunterus, L V Roze, Randolph M Beaudry, John E LinzAbstract:The filamentous fungi Aspergillus parasiticus and Aspergillus flavus synthesize aflatoxins when they grow on a variety of susceptible food and feed crops. These mycotoxins are among the most carcinogenic naturally occurring compounds known and they pose significant health risks to humans and animals. We previously demonstrated that ethylene and CO2 act alone and together to reduce aflatoxin synthesis by A. parasiticus grown on laboratory media. To demonstrate the potential efficacy of treatment of stored seeds and grains with these gases, we tested ethylene and CO2 for ability to inhibit aflatoxin accumulation on Georgia Green peanuts stored for up to 5 days. We demonstrated an inverse relationship between A. parasiticus spore inoculum size and the level of toxin accumulation. We showed that ethylene inhibits aflatoxin synthesis in a dose-dependent manner on peanuts; CO2 also inhibits aflatoxin synthesis over a narrow dose range. Treatments had no discernable effect on mold growth. These observations support further exploration of this technology to reduce aflatoxin contamination of susceptible crops in the field and during storage.
Maris Laivenieks - One of the best experts on this subject based on the ideXlab platform.
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Willow volatiles influence growth, development, and secondary metabolism in Aspergillus parasiticus
Applied Microbiology and Biotechnology, 2011Co-Authors: Ludmila V Roze, Randolph M Beaudry, Maris Laivenieks, Anna V Koptina, Daniel A. Jones, Albert V. Kanarsky, John E LinzAbstract:Aflatoxin is a mycotoxin and the most potent naturally occurring carcinogen in many animals. Aflatoxin contamination of food and feed crops causes a significant global burden on human and animal health. However, available methods to eliminate aflatoxin from food and feed are not fully effective. Our goal is to discover novel, efficient, and practical methods to control aflatoxin contamination in crops during storage. In the present study, we tested the effect of volatiles produced by willow ( Salix acutifolia and Salix babylonica ) and maple ( Acer saccharinum ) bark on fungal growth, development, and aflatoxin production by the fungus Aspergillus parasiticus , one economically important aflatoxin producer. S. acutifolia bark volatiles nearly eliminated aflatoxin accumulation (>90% reduction) by A. parasiticus grown on a minimal agar medium. The decrease in aflatoxin accumulation correlated with a twofold reduction in ver-1 (encodes a middle aflatoxin pathway enzyme) transcript level. Expression data also indicate that one histone H4 acetyltransferase, MYST3, may play a role in epigenetic control of aflatoxin gene transcription in response to volatile exposure. Volatiles derived from wood bark samples also increased fungal growth up to 20% and/or enhanced conidiospore development. Solid-phase microextraction–gas chromatographic–mass spectrometric analysis of bark samples identified sets of shared and unique volatile compounds that may mediate the observed regulatory effects on growth, development, and aflatoxin synthesis. This work provides an experimental basis for the use of willow industry by-products to control aflatoxin contamination in food and feed crops.
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volatile profiling reveals intracellular metabolic changes in Aspergillus parasiticus vea regulates branched chain amino acid and ethanol metabolism
BMC Biochemistry, 2010Co-Authors: Ludmila V Roze, Anindya Chanda, Randolph M Beaudry, Maris Laivenieks, Katherine A Artymovich, Anna V Koptina, Deena Awad, Dina Valeeva, Arthur Daniel Jones, John E LinzAbstract:Background Filamentous fungi in the genus Aspergillus produce a variety of natural products, including aflatoxin, the most potent naturally occurring carcinogen known. Aflatoxin biosynthesis, one of the most highly characterized secondary metabolic pathways, offers a model system to study secondary metabolism in eukaryotes. To control or customize biosynthesis of natural products we must understand how secondary metabolism integrates into the overall cellular metabolic network. By applying a metabolomics approach we analyzed volatile compounds synthesized by Aspergillus parasiticus in an attempt to define the association of secondary metabolism with other metabolic and cellular processes.
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volatile profiling reveals intracellular metabolic changes in Aspergillus parasiticus vea regulates branched chain amino acid and ethanol metabolism
BMC Biochemistry, 2010Co-Authors: Ludmila V Roze, Anindya Chanda, Randolph M Beaudry, Maris Laivenieks, Katherine A Artymovich, Anna V Koptina, Deena Awad, Dina Valeeva, Arthur Daniel Jones, John E LinzAbstract:Filamentous fungi in the genus Aspergillus produce a variety of natural products, including aflatoxin, the most potent naturally occurring carcinogen known. Aflatoxin biosynthesis, one of the most highly characterized secondary metabolic pathways, offers a model system to study secondary metabolism in eukaryotes. To control or customize biosynthesis of natural products we must understand how secondary metabolism integrates into the overall cellular metabolic network. By applying a metabolomics approach we analyzed volatile compounds synthesized by Aspergillus parasiticus in an attempt to define the association of secondary metabolism with other metabolic and cellular processes. Volatile compounds were examined using solid phase microextraction - gas chromatography/mass spectrometry. In the wild type strain Aspergillus parasiticus SU-1, the largest group of volatiles included compounds derived from catabolism of branched chain amino acids (leucine, isoleucine, and valine); we also identified alcohols, esters, aldehydes, and lipid-derived volatiles. The number and quantity of the volatiles produced depended on media composition, time of incubation, and light-dark status. A block in aflatoxin biosynthesis or disruption of the global regulator veA affected the volatile profile. In addition to its multiple functions in secondary metabolism and development, VeA negatively regulated catabolism of branched chain amino acids and synthesis of ethanol at the transcriptional level thus playing a role in controlling carbon flow within the cell. Finally, we demonstrated that volatiles generated by a veA disruption mutant are part of the complex regulatory machinery that mediates the effects of VeA on asexual conidiation and sclerotia formation. 1) Volatile profiling provides a rapid, effective, and powerful approach to identify changes in intracellular metabolic networks in filamentous fungi. 2) VeA coordinates the biosynthesis of secondary metabolites with catabolism of branched chain amino acids, alcohol biosynthesis, and β-oxidation of fatty acids. 3) Intracellular chemical development in A. parasiticus is linked to morphological development. 4) Understanding carbon flow through secondary metabolic pathways and catabolism of branched chain amino acids is essential for controlling and customizing production of natural products.
