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1.
J Fungi (Basel) ; 10(5)2024 May 13.
Article in English | MEDLINE | ID: mdl-38786704

ABSTRACT

Autophagy, a conserved cellular recycling process, plays a crucial role in maintaining homeostasis under stress conditions. It also regulates the development and virulence of numerous filamentous fungi. In this study, we investigated the specific function of ATG8, a reliable autophagic marker, in the opportunistic pathogen Aspergillus flavus. To investigate the role of atg8 in A. flavus, the deletion and complemented mutants of atg8 were generated according to the homologous recombination principle. Deletion of atg8 showed a significant decrease in conidiation, spore germination, and sclerotia formation compared to the WT and atg8C strains. Additionally, aflatoxin production was found severely impaired in the ∆atg8 mutant. The stress assays demonstrated that ATG8 was important for A. flavus response to oxidative stress. The fluorescence microscopy showed increased levels of reactive oxygen species in the ∆atg8 mutant cells, and the transcriptional result also indicated that genes related to the antioxidant system were significantly reduced in the ∆atg8 mutant. We further found that ATG8 participated in regulating the pathogenicity of A. flavus on crop seeds. These results revealed the biological role of ATG8 in A. flavus, which might provide a potential target for the control of A. flavus and AFB1 biosynthesis.

2.
Talanta ; 274: 126028, 2024 Jul 01.
Article in English | MEDLINE | ID: mdl-38599126

ABSTRACT

Mechanical forces play a crucial role in cellular processes, including ferroptosis, a form of regulated cell death associated with various diseases. However, the mechanical aspects of organelle lipid droplets (LDs) during ferroptosis are poorly understood. In this study, we designed and synthesized a fluorescent probe, TPE-V1, to enable real-time monitoring of LDs' viscosity using a dual-channel fluorescence-on model (red channel at 617 nm and NIR channel at 710 nm). The fluorescent imaging of using TPE-V1 was achieved due to the integrated mechanisms of the twisted intramolecular charge transfer (TICT) and aggregation-induced emission (AIE). Through dual-emission channel fluorescence imaging, we observed the enhanced mechanical energy of LDs triggering cellular mechanosensing, including ferroptosis and cell deformation. Theoretical calculations confirmed the probe's behavior, showing that high-viscosity media prevented the rotation processes and restored fluorescence quenching in low viscosity. These findings suggest that our TICT-TPE design strategy provides a practical approach to study LDs' mechanical properties during ferroptosis. This development enhances our understanding of the interplay between mechanical forces and LDs, contributing to the knowledge of ferroptotic cell death and potential therapeutic interventions targeting dysregulated cell death processes.


Subject(s)
Ferroptosis , Fluorescent Dyes , Lipid Droplets , Lipid Droplets/chemistry , Lipid Droplets/metabolism , Fluorescent Dyes/chemistry , Humans , Optical Imaging , Viscosity , Fluorescence
3.
J Hazard Mater ; 471: 134385, 2024 Jun 05.
Article in English | MEDLINE | ID: mdl-38678711

ABSTRACT

Nitric oxide (NO) is a signaling molecule with diverse roles in various organisms. However, its role in the opportunistic pathogen Aspergillus flavus remains unclear. This study investigates the potential of NO, mediated by metabolites from A. oryzae (AO), as an antifungal strategy against A. flavus. We demonstrated that AO metabolites effectively suppressed A. flavus asexual development, a critical stage in its lifecycle. Transcriptomic analysis revealed that AO metabolites induced NO synthesis genes, leading to increased intracellular NO levels. Reducing intracellular NO content rescued A. flavus spores from germination inhibition caused by AO metabolites. Furthermore, exogenous NO treatment and dysfunction of flavohemoglobin Fhb1, a key NO detoxification enzyme, significantly impaired A. flavus asexual development. RNA-sequencing and metabolomic analyses revealed significant metabolic disruptions within tricarboxylic acid (TCA) cycle upon AO treatment. NO treatment significantly reduced mitochondrial membrane potential (Δψm) and ATP generation. Additionally, aberrant metabolic flux within the TCA cycle was observed upon NO treatment. Further analysis revealed that NO induced S-nitrosylation of five key TCA cycle enzymes. Genetic analysis demonstrated that the S-nitrosylated Aconitase Acon and one subunit of succinate dehydrogenase Sdh2 played crucial roles in A. flavus development by regulating ATP production. This study highlights the potential of NO as a novel antifungal strategy to control A. flavus by compromising its mitochondrial function and energy metabolism.


Subject(s)
Aspergillus flavus , Citric Acid Cycle , Mitochondria , Nitric Oxide , Citric Acid Cycle/drug effects , Aspergillus flavus/metabolism , Aspergillus flavus/growth & development , Aspergillus flavus/drug effects , Nitric Oxide/metabolism , Mitochondria/drug effects , Mitochondria/metabolism , Antifungal Agents/pharmacology , Membrane Potential, Mitochondrial/drug effects , Spores, Fungal/drug effects , Spores, Fungal/growth & development , Fungal Proteins/metabolism , Fungal Proteins/genetics
4.
Mol Plant Pathol ; 24(9): 1139-1153, 2023 09.
Article in English | MEDLINE | ID: mdl-37278525

ABSTRACT

Striatin-interacting phosphatases and kinases (STRIPAKs) are evolutionarily conserved supramolecular complexes that control various important cellular processes such as signal transduction and development. However, the role of the STRIPAK complex in pathogenic fungi remains elusive. In this study, the components and function of the STRIPAK complex were investigated in Fusarium graminearum, an important plant-pathogenic fungus. The results obtained from bioinformatic analyses and the protein-protein interactome suggested that the fungal STRIPAK complex consisted of six proteins: Ham2, Ham3, Ham4, PP2Aa, Ppg1, and Mob3. Deletion mutations of individual components of the STRIPAK complex were created, and observed to cause a significant reduction in fungal vegetative growth and sexual development, and dramatically attenuae virulence, excluding the essential gene PP2Aa. Further results revealed that the STRIPAK complex interacted with the mitogen-activated protein kinase Mgv1, a key component in the cell wall integrity pathway, subsequently regulating the phosphorylation level and nuclear accumulation of Mgv1 to control the fungal stress response and virulence. Our results also suggested that the STRIPAK complex was interconnected with the target of rapamycin pathway through Tap42-PP2A cascade. Taken together, our findings revealed that the STRIPAK complex orchestrates cell wall integrity signalling to govern the fungal development and virulence of F. graminearum and highlighted the importance of the STRIPAK complex in fungal virulence.


Subject(s)
Fusarium , Signal Transduction , Virulence , Signal Transduction/genetics , Mitogen-Activated Protein Kinases/genetics , Mitogen-Activated Protein Kinases/metabolism , Cell Wall/metabolism , Fungal Proteins/genetics , Fungal Proteins/metabolism , Spores, Fungal/metabolism
6.
J Fungi (Basel) ; 9(2)2023 Feb 15.
Article in English | MEDLINE | ID: mdl-36836371

ABSTRACT

Root rot caused by Fusarium solani is one of the major postharvest diseases limiting sweet potato production. Here, antifungal activity and the action mode of perillaldehyde (PAE) against F. solani were investigated. A PAE concentration of 0.15 mL/L in air (mL/L air) markedly inhibited the mycelial growth, spore reproduction and spore viability of F. solani. A PAE vapor of 0.25 mL/L in air could control the F. solani development in sweet potatoes during storage for 9 days at 28 °C. Moreover, the results of a flow cytometer demonstrated that PAE drove an increase in cell membrane permeability, reduction of mitochondrial membrane potential (MMP) and accumulation of reactive oxygen species (ROS) in F. solani spores. Subsequently, a fluorescence microscopy assay demonstrated that PAE caused serious damage to the cell nuclei in F. solani by inducing chromatin condensation. Further, the spread plate method showed that the spore survival rate was negatively correlated with the level of ROS and nuclear damage, of which the results indicated that PAE-driven ROS accumulation plays a critical role in contributing to cell death in F. solani. In all, the results revealed a specific antifungal mechanism of PAE against F. solani, and suggest that PAE could be a useful fumigant for controlling the postharvest diseases of sweet potatoes.

7.
Food Chem ; 408: 135213, 2023 May 15.
Article in English | MEDLINE | ID: mdl-36527924

ABSTRACT

Root rot caused by Fusarium solani is one of major postharvest diseases limiting sweet potato production. Antifungal effect and possible mode of action of cinnamaldehyde (CA) against F. solani were investigated. CA concentration of 0.075 g/L inhibited conidial viability of F. solani. CA vapor of 0.3 g/L in air completely controlled the F. solani development in sweet potatoes during storage for 10 days at 28 °C, and protected soluble sugar and starch in the flesh from depletion by the fungus. Further results demonstrated that CA induced reduction in mitochondrial membrane potential (Δψm), ROS accumulation, and cell apoptosis characterized by DNA fragmentation in F. solani. Moreover, CA facilitated decomposition of mitochondria-specific cardiolipin (CL) into its catabolites by the catalytic action of phospholipases. Altogether, the results revealed a specific antifungal mechanism of CA against F. solani, and suggest that CA holds promise as a preservative for postharvest preservation of sweet potato.


Subject(s)
Fusarium , Ipomoea batatas , Antifungal Agents/pharmacology , Ipomoea batatas/microbiology
8.
Chin Herb Med ; 14(2): 254-262, 2022 Apr.
Article in English | MEDLINE | ID: mdl-36117661

ABSTRACT

Objective: In this study, the aim was to investigate the inhibitory effect of 6,6'-bieckol on the migration and epithelial-mesenchymal transition (EMT) of non-small cell lung cancer (NSCLC) cells, and explore its potential molecular mechanisms. Methods: Cell migration was measured using a CCK8, wound healing, and transwell migration assay. Apoptosis was determined using an Annexin V/propidium iodide staining. Western blotting and immunofluorescence were used to examine the expression level of apoptosis-related proteins and EMT marker proteins. Results: The results showed that 6,6'-bieckol inhibited migration and induced apoptosis of NSCLC cells. Furthermore, 6,6'-bieckol had significantly up-regulated the E-cadherin and down-regulated Snail1 and Twist1 transcriptional levels. 6,6'-Bieckol might inhibit TGF-ß-induced EMT by down-regulating Snail1 and Twist1 and up-regulating E-cadherin in lung cancer cells. Conclusion: It is suggested that 6,6'-bieckol has the potential to be developed as a therapeutic candidate for lung cancer.

9.
Environ Microbiol ; 24(7): 2857-2881, 2022 07.
Article in English | MEDLINE | ID: mdl-35645150

ABSTRACT

Post-translational modifications (PTMs) are important for protein function and regulate multiple cellular processes and secondary metabolites (SMs) in fungi. Aspergillus species belong to a genus renown for an abundance of bioactive secondary metabolites, many important as toxins, pharmaceuticals and in industrial production. The genes required for secondary metabolites are typically co-localized in biosynthetic gene clusters (BGCs), which often localize in heterochromatic regions of genome and are 'turned off' under laboratory condition. Efforts have been made to 'turn on' these BGCs by genetic manipulation of histone modifications, which could convert the heterochromatic structure to euchromatin. Additionally, non-histone PTMs also play critical roles in the regulation of secondary metabolism. In this review, we collate the known roles of epigenetic and PTMs on Aspergillus SM production. We also summarize the proteomics approaches and bioinformatics tools for PTM identification and prediction and provide future perspectives on the emerging roles of PTM on regulation of SM biosynthesis in Aspergillus and other fungi.


Subject(s)
Aspergillus , Multigene Family , Aspergillus/genetics , Aspergillus/metabolism , Fungi/genetics , Protein Processing, Post-Translational , Secondary Metabolism/genetics
10.
J Biol Chem ; 298(7): 102120, 2022 07.
Article in English | MEDLINE | ID: mdl-35697069

ABSTRACT

Aflatoxins are a series of highly toxic and carcinogenic secondary metabolites that are synthesized by Aspergillus species. The degradation of aflatoxin enzymes is an important regulatory mechanism which modulates mycotoxin producing. The retromer complex is responsible for the retrograde transport of specific biomolecules and the vacuolar fusion in the intracellular transport. Late endosomal-associated GTPase (Rab7) has been shown to be a downstream effector protein of the retromer complex. A deficiency in the retromer complex or Rab7 results in several cellular trafficking problems in yeast and humans, like protein abnormal accumulation. However, whether retromer dysfunction is involved in aflatoxin synthesis remains unclear. Here, we report that the core retromer complex, which comprises three vacuolar protein sorting-associated proteins (AflVps26-AflVps29-AflVps35), is essential for the development of dormant and resistant fungal forms such as conidia (asexual reproductive spore) and sclerotia (hardened fungal mycelium), as well as aflatoxin production and pathogenicity, in Aspergillus flavus. In particular, we show the AflVps26-AflVps29-AflVps35 complex is negatively correlated with aflatoxin exportation. Structural simulation, site-specific mutagenesis, and coimmunoprecipitation experiments showed that interactions among AflVps26, AflVps29, and AflVps35 played crucial roles in the retromer complex executing its core functions. We further found an intrinsic connection between AflRab7 and the retromer involved in vesicle-vacuole fusion, which in turn affected the accumulation of aflatoxin synthesis-associated enzymes, suggesting that they work together to regulate the production of toxins. Overall, these results provide mechanistic insights that contribute to our understanding of the regulatory role of the core retromer complex in aflatoxin metabolism.


Subject(s)
Aflatoxins , Aspergillus flavus , Aflatoxins/metabolism , Aspergillus/metabolism , Aspergillus flavus/genetics , Fungal Proteins/genetics , Fungal Proteins/metabolism , Humans , Secondary Metabolism , Spores, Fungal
11.
Appl Environ Microbiol ; 88(12): e0024422, 2022 06 28.
Article in English | MEDLINE | ID: mdl-35638847

ABSTRACT

Heterotrimeric G-proteins play crucial roles in growth, asexual development, and pathogenicity of fungi. The regulator of G-protein signaling (RGS) proteins function as negative regulators of the G proteins to control the activities of GTPase in Gα subunits. In this study, we functionally characterized the six RGS proteins (i.e., RgsA, RgsB, RgsC, RgsD, RgsE, and FlbA) in the pathogenic fungus Aspergillus flavus. All the aforementioned RGS proteins were also found to be functionally different in conidiation, aflatoxin (AF) biosynthesis, and pathogenicity in A. flavus. Apart from FlbA, all other RGS proteins play a negative role in regulating both the synthesis of cyclic AMP (cAMP) and the activation of protein kinase A (PKA). Additionally, we also found that although RgsA and RgsE play a negative role in regulating the FadA-cAMP/PKA pathway, they function distinctly in aflatoxin biosynthesis. Similarly, RgsC is important for aflatoxin biosynthesis by negatively regulating the GanA-cAMP/PKA pathway. PkaA, which is the cAMP-dependent protein kinase catalytic subunit, also showed crucial influences on A. flavus phenotypes. Overall, our results demonstrated that RGS proteins play multiple roles in the development, pathogenicity, and AF biosynthesis in A. flavus through the regulation of Gα subunits and cAMP-PKA signals. IMPORTANCE RGS proteins, as crucial regulators of the G protein signaling pathway, are widely distributed in fungi, while little is known about their roles in Aspergillus flavus development and aflatoxin. In this study, we identified six RGS proteins in A. flavus and revealed that these proteins have important functions in the regulation of conidia, sclerotia, and aflatoxin formation. Our findings provide evidence that the RGS proteins function upstream of cAMP-PKA signaling by interacting with the Gα subunits (GanA and FadA). This study provides valuable information for controlling the contamination of A. flavus and mycotoxins produced by this fungus in pre- and postharvest of agricultural crops.


Subject(s)
Aflatoxins , RGS Proteins , Aspergillus flavus/genetics , Aspergillus flavus/metabolism , Cyclic AMP/metabolism , Cyclic AMP-Dependent Protein Kinases/genetics , Cyclic AMP-Dependent Protein Kinases/metabolism , Fungal Proteins/metabolism , GTP-Binding Proteins/metabolism , RGS Proteins/genetics , RGS Proteins/metabolism , Signal Transduction/genetics , Spores, Fungal
12.
Antioxidants (Basel) ; 11(2)2022 Jan 18.
Article in English | MEDLINE | ID: mdl-35204061

ABSTRACT

Vulvovaginal candidiasis (VVC) is one of the most frequent diseases induced by Candida albicans (C. albicans) during pregnancy, which results in enormous pain to women and their partners in daily life. Perillaldehyde (PAE), a natural monoterpenoid, has significant anti-microbial, anti-inflammatory and anti-oxidation effects. Reactive oxygen species (ROS) are key factors for the host to resist the invasion of fungi. However, excess ROS can cause additional damage independent of the pathogen itself, and the mechanism of ROS in VVC has not been investigated. In this murine study, we revealed that C. albicans infection increased the expression of NADPH oxidase 2 (NOX2) and the content of malonaldehyde (MDA). C. albicans inhibited the activity of antioxidant enzymes in the vagina, including superoxide dismutase (SOD), Catalase (CAT), glutathione peroxidase (GSH-PX) and heme oxygenase (HO-1), which were returned to normal levels after treatment with PAE. Furthermore, PAE inhibited the activities of Keap1 and promoted Nrf2 transfer from cytoplasm to nucleus, which were mediated by excessive accumulation of ROS in the VVC mice. In this study, we also indicated that PAE inhibited the apoptosis of vagina cells via Caspase 9- Caspase 7-PARP pathway and prevented the release of IL-1ꞵ in VVC mice. In summary, this study revealed that the treatment of VVC in mice with PAE might be mediated by inhibition of ROS, and established the therapeutic potential of PAE as an antifungal agent for the treatment of VVC.

13.
Environ Microbiol ; 24(3): 1590-1607, 2022 03.
Article in English | MEDLINE | ID: mdl-35194912

ABSTRACT

Aspergillus flavus is an opportunistic fungal pathogen that colonizes agriculture crops with aflatoxin contamination. We found that Perillaldehyde (PAE) effectively inhibited A. flavus viability and aflatoxin production by inducing excess reactive oxygen species (ROS). Transcriptome analysis indicated that the Gα protein FadA was significantly induced by PAE. Functional characterization of FadA showed it is important for asexual development and aflatoxin biosynthesis by regulation of cAMP-PKA signalling. The ΔfadA mutant was more sensitive to PAE, while ΔpdeL and ΔpdeH mutants can tolerate excess PAE compared to wild-type A. flavus. Further RNA-sequence analysis showed that fadA was important for expression of genes involved in oxidation-reduction and cellular metabolism. The flow cytometry and fluorescence microscopy demonstrated that ΔfadA accumulated more concentration of ROS in cells, and the transcriptome data indicated that genes involved in ROS scavenging were downregulated in ΔfadA mutant. We further found that FadA participated in regulating response to extracellular environmental stresses by increasing phosphorylation levels of MAPK Kinase Slt2 and Hog1. Overall, our results indicated that FadA signalling engages in mycotoxin production and A. flavus resistance to antimicrobial PAE, which provide valuable information for controlling this fungus and AF biosynthesis in pre- and postharvest of agricultural crops.


Subject(s)
Aflatoxins , Anti-Infective Agents , Anti-Infective Agents/metabolism , Aspergillus flavus/metabolism , Crops, Agricultural/metabolism , Fungal Proteins/genetics , Fungal Proteins/metabolism , Gene Expression Regulation, Fungal , Monoterpenes , Reactive Oxygen Species/metabolism
14.
Food Chem ; 382: 132312, 2022 Jul 15.
Article in English | MEDLINE | ID: mdl-35158267

ABSTRACT

Spice essential oils (SEOs) are commonly used in food flavoring and are considered an effective food preservative. It has a broad range of applications and promising development prospects. As a natural food additive, SEOs' antimicrobial effects have been widely studied and utilized towards food preservation. Many SEOs have exhibited significant antimicrobial activities against food-borne pathogenic and food spoilage microorganisms. We reviewed the antibacterial and antifungal properties of SEOs, the active components, their corresponding mechanisms of actions, as well as their application in the food industry, providing a theoretical basis for SEOs' further development and application as natural preservatives.


Subject(s)
Anti-Infective Agents , Oils, Volatile , Anti-Bacterial Agents/pharmacology , Anti-Infective Agents/pharmacology , Food Industry , Food Preservatives/pharmacology , Oils, Volatile/pharmacology , Spices
15.
Crit Rev Food Sci Nutr ; 62(23): 6328-6340, 2022.
Article in English | MEDLINE | ID: mdl-33749409

ABSTRACT

Monoterpene Perillaldehyde (PAE) is a major component of the essential oil extracted from perilla plants (Perilla frutescens), which has been used as a leafy vegetable and a medicinal agent. PAE has gained a lot of attention in recent years because of its antifungal and other microbial activities and, human health benefits. PAE has also been used as food additives, perfume ingredients, and traditional medicine concoctions. Biological analyses of PAE have revealed that it has good antioxidant activities and can serve as organic fruit and food preservative. Animal studies indicated potent anticancer, anti-depressant, and anti-inflammatory effects of PAE. Also, PAE is certified "generally recognized as safe" (GRAS) and not mutagenic. However, moderation during usage is advisable, as minor adverse effects are associated with a very high dosage. Despite the newly reported findings, its properties have not been thoroughly summarized and reviewed. Also, clinical trials and official large-scale field applications of PAE in the agricultural sectors are yet to be reported. In this review, updated PAE research progress was provided, focusing on its antifungal and other antimicrobial properties and the mechanisms behind it, phytochemical profile, pharmacological effects, and safety concerns.HighlightsIsolation and recovery techniques of PAE from perilla plants have been developed and improved in recent years.PAE is a potential anti-oxidant and antifungal agent that can be widely used in the food industry.PAE can be developed into drug ingredients for pharmaceutical industries due to its anti-inflammatory, anti-cancer and anti-depressant activities.PAE can be safely used in human when low and moderate dosage is used.


Subject(s)
Perilla , Animals , Anti-Inflammatory Agents/pharmacology , Antifungal Agents/pharmacology , Humans , Monoterpenes , Perilla/chemistry
16.
ACS Appl Mater Interfaces ; 14(2): 3385-3394, 2022 Jan 19.
Article in English | MEDLINE | ID: mdl-34932328

ABSTRACT

Chiral nanomaterials have drawn extensive attention on account of numerous application prospects in optoelectronics, asymmetric catalysis, chiral recognition, and three-dimensional (3D) display. Thereinto, chiral perovskite has been a hotspot due to brilliant optoelectronic properties, but some problems limit the development, including low quantum yield, low chiral intensity, and the lack of facile regulation. To overcome these issues, an effective ligand exchange strategy, i.e. the interface modification has been proposed for chiral perovskite nanocrystals (PNCs). With the surface modification of CsPbBr3 PNCs with chiral organic ammonium in methyl acetate in the typical purification process, excellent circular dichroism (CD) signals were obtained and defects were eliminated, leading to an increase in the photoluminescence quantum yield (PLQY) from 50% to nearly 100%. The CD signal can be regulated through a ligand exchange strategy in the longitudinal dimension, the chiral intensity, and the transverse dimension, the wavelength range. Here, the proper addition of R-α-PEAI into the R-α-PEABr-capped CsPbBr3 PNCs can produce a superstrong CD signal with the highest anisotropy factor (g-factor) of 0.0026 in the visible region among reported chiral colloidal PNCs. Simultaneously, the luminescence emission can be tuned from the green to red region with boosted PLQY through the approach. The density functional theory (DFT) calculation result supports that chirality comes from the hybridization between the energy level of a perovskite structure and that of chiral organic molecules. These properties can be used in the structural engineering of high-performance chiral optical materials, spin-polarized light-emitting devices, and polarized optoelectronic devices.

17.
G3 (Bethesda) ; 11(8)2021 08 07.
Article in English | MEDLINE | ID: mdl-34849826

ABSTRACT

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.


Subject(s)
Aflatoxins , Aspergillus flavus , Aspergillus flavus/genetics , Chromosomes , Genome, Fungal , Humans , Sequence Analysis, DNA
18.
Microb Biotechnol ; 14(2): 628-642, 2021 03.
Article in English | MEDLINE | ID: mdl-33159717

ABSTRACT

As a pathogenic fungus, Aspergillus flavus can produce carcinogenic aflatoxins (AFs), which poses a great threat to crops and animals. Msb2, the signalling mucin protein, is a part of mitogen-activated protein kinase (MAPK) pathway which contributes to a range of physiological processes. In this study, the roles of membrane mucin Msb2 were explored in A. flavus by the application of gene disruption. The deletion of msb2 gene (Δmsb2) caused defects in vegetative growth, sporulation and sclerotia formation when compared to WT and complement strain (Δmsb2C ) in A. flavus. Using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) analysis, it was found that deletion of msb2 down-regulated aflatoxin B1 (AFB1 ) synthesis and decreased the infection capacity of A. flavus. Consistently, Msb2 responds to cell wall stress and osmotic stress by positively regulating the phosphorylation of MAP kinase. Notably, Δmsb2 mutant exhibited cell wall defect, and it was more sensitive to inhibitor caspofungin when compared to WT and Δmsb2C . Taking together, these results revealed that Msb2 plays key roles in morphological development process, stresses adaptation, secondary metabolism and pathogenicity in fungus A. flavus.


Subject(s)
Aflatoxins , Aspergillus flavus , Aflatoxin B1 , Animals , Aspergillus flavus/genetics , Fungal Proteins/genetics , Mucins , Virulence
19.
Int J Mol Sci ; 21(19)2020 Sep 23.
Article in English | MEDLINE | ID: mdl-32977505

ABSTRACT

Aflatoxins (AFs) have always been regarded as the most effective carcinogens, posing a great threat to agriculture, food safety, and human health. Aspergillus flavus is the major producer of aflatoxin contamination in crops. The prevention and control of A. flavus and aflatoxin continues to be a global problem. In this study, we demonstrated that the cell-free culture filtrate of Aspergillus oryzae and a non-aflatoxigenic A. flavus can effectively inhibit the production of AFB1 and the growth and reproduction of A. flavus, indicating that both of the non-aflatoxigenic Aspergillus strains secrete inhibitory compounds. Further transcriptome sequencing was performed to analyze the inhibitory mechanism of A. flavus treated with fermenting cultures, and the results revealed that genes involved in the AF biosynthesis pathway and other biosynthetic gene clusters were significantly downregulated, which might be caused by the reduced expression of specific regulators, such as AflS, FarB, and MtfA. The WGCNA results further revealed that genes involved in the TCA cycle and glycolysis were potentially involved in aflatoxin biosynthesis. Our comparative transcriptomics also revealed that two conidia transcriptional factors, brlA and abaA, were found to be significantly downregulated, which might lead to the downregulation of conidiation-specific genes, such as the conidial hydrophobins genes rodA and rodB. In summary, our research provides new insights for the molecular mechanism of controlling AF synthesis to control the proliferation of A. flavus and AF pollution.


Subject(s)
Aflatoxins , Aspergillus flavus/physiology , Gene Expression Regulation, Fungal , RNA-Seq , Spores, Fungal , Transcriptome , Aflatoxins/biosynthesis , Aflatoxins/genetics , Glycine max/microbiology , Spores, Fungal/genetics , Spores, Fungal/metabolism
20.
Biochem Pharmacol ; 180: 114201, 2020 10.
Article in English | MEDLINE | ID: mdl-32822688

ABSTRACT

Perillaldehyde (PAE), a natural monoterpenoid agent extracted from Perilla frutescence, PAE has been reported to present various physiological capabilities, such as anti-inflammation, anti-oxidative and anti-fungal. In this study, we show that PAE exhibits strong antifungal activity against Candida albicans (C. albicans). C. albicans, a fungal pathogen with high incidence of antifungal resistance in clinical settings, is the major cause of oropharyngeal candidiasis (OPC). OPC is characterized by inflammatory immunological responses to fungal infections. Our in vitro results show PAE inhibited several virulence attributes of C. albicans including biofilm formation, yeast-to-hyphal transition and secreted aspartic proteinases (SAPs) gene expression. Using an experimental murine model of OPC, we found that PAE inhibited NLRP3 inflammasome assembly, reduced the excessive accumulation of ROS and prevented the p65 transfer in nuclear; processes all leading to reduced inflammation burden in the host. Together, this supports use PAE as a promising new agent to improve OPC.


Subject(s)
Antifungal Agents/therapeutic use , Candida albicans/drug effects , Candidiasis, Oral/drug therapy , Monoterpenes/therapeutic use , Pharyngeal Diseases/drug therapy , Animals , Antifungal Agents/pharmacology , Candida albicans/physiology , Candidiasis, Oral/pathology , Dose-Response Relationship, Drug , Mice , Mice, Inbred C57BL , Monoterpenes/pharmacology , Pharyngeal Diseases/microbiology , Pharyngeal Diseases/pathology , Random Allocation
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