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Trinks N, Reinhard S, Drobny M, Heilig L, Löffler J, Sauer M, Terpitz U. Subdiffraction-resolution fluorescence imaging of immunological synapse formation between NK cells and A. fumigatus by expansion microscopy. Commun Biol 2021; 4:1151. [PMID: 34608260 PMCID: PMC8490467 DOI: 10.1038/s42003-021-02669-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 09/13/2021] [Indexed: 11/17/2022] Open
Abstract
Expansion microscopy (ExM) enables super-resolution fluorescence imaging on standard microscopes by physical expansion of the sample. However, the investigation of interactions between different organisms such as mammalian and fungal cells by ExM remains challenging because different cell types require different expansion protocols to ensure identical, ideally isotropic expansion of both partners. Here, we introduce an ExM method that enables super-resolved visualization of the interaction between NK cells and Aspergillus fumigatus hyphae. 4-fold expansion in combination with confocal fluorescence imaging allows us to resolve details of cytoskeleton rearrangement as well as NK cells' lytic granules triggered by contact with an RFP-expressing A. fumigatus strain. In particular, subdiffraction-resolution images show polarized degranulation upon contact formation and the presence of LAMP1 surrounding perforin at the NK cell-surface post degranulation. Our data demonstrate that optimized ExM protocols enable the investigation of immunological synapse formation between two different species with so far unmatched spatial resolution.
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Affiliation(s)
- Nora Trinks
- Department of Biotechnology and Biophysics, Theodor-Boveri-Institute, Biocenter, Julius Maximilian University, Würzburg, Germany
| | - Sebastian Reinhard
- Department of Biotechnology and Biophysics, Theodor-Boveri-Institute, Biocenter, Julius Maximilian University, Würzburg, Germany
| | - Matthias Drobny
- Department of Internal Medicine II, WÜ4i, University Hospital Würzburg, Würzburg, Germany
| | - Linda Heilig
- Department of Internal Medicine II, WÜ4i, University Hospital Würzburg, Würzburg, Germany
| | - Jürgen Löffler
- Department of Internal Medicine II, WÜ4i, University Hospital Würzburg, Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Theodor-Boveri-Institute, Biocenter, Julius Maximilian University, Würzburg, Germany
| | - Ulrich Terpitz
- Department of Biotechnology and Biophysics, Theodor-Boveri-Institute, Biocenter, Julius Maximilian University, Würzburg, Germany.
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Wang J, Zhou H, Lu H, Du T, Luo Y, Wilson IBH, Jin C. Kexin-like endoprotease KexB is required for N-glycan processing, morphogenesis and virulence in Aspergillus fumigatus. Fungal Genet Biol 2015; 76:57-69. [PMID: 25687931 DOI: 10.1016/j.fgb.2015.02.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 02/05/2015] [Accepted: 02/06/2015] [Indexed: 11/18/2022]
Abstract
Kexin-like proteins belong to the subtilisin-like family of the proteinases that cleave secretory proproteins to their active forms. Several fungal kexin-like proteins have been investigated. The mutants lacking of kexin-like protein display strong phenotypes such as cell wall defect, abnormal polarity, and, in case of Candida albicans, diminished virulence. However, only several proteins have been confirmed as the substrates of kexin-like proteases in these fungal species. It still remains unclear how kexin-like proteins contribute to the morphogenesis in these fungal species. In this study, a kexB-null mutant of the human opportunistic fungal pathogen Aspergillus fumigatus was constructed and analyzed. The ΔkexB mutant showed retarded growth, temperature-sensitive cell wall defect, reduced conidia formation, and abnormal polarity. Biochemical analyses revealed that deletion of the kexB gene resulted in impaired N-glycan processing, activation of the MpkA-dependent cell wall integrity signaling pathway, and ER-stress. Results from in vivo assays demonstrated that the mutant exhibited an attenuated virulence in immunecompromised mice. Based on our results, the kexin-like endoprotease KexB was involved in the N-glycan processing, which provides a novel insight to understand how kexin-like protein affects the cell-wall modifying enzymes and therefore morphogenesis in fungi.
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Affiliation(s)
- Jingyang Wang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, China
| | - Hui Zhou
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Hua Lu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Ting Du
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuanming Luo
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Iain B H Wilson
- Department of Chemistry, University of Natural Resources and Life Sciences, Vienna A-1190, Austria
| | - Cheng Jin
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
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Wrede D, Taha M, Miranda AF, Kadali K, Stevenson T, Ball AS, Mouradov A. Co-cultivation of fungal and microalgal cells as an efficient system for harvesting microalgal cells, lipid production and wastewater treatment. PLoS One 2014; 9:e113497. [PMID: 25419574 PMCID: PMC4242625 DOI: 10.1371/journal.pone.0113497] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 10/24/2014] [Indexed: 11/18/2022] Open
Abstract
The challenges which the large scale microalgal industry is facing are associated with the high cost of key operations such as harvesting, nutrient supply and oil extraction. The high-energy input for harvesting makes current commercial microalgal biodiesel production economically unfeasible and can account for up to 50% of the total cost of biofuel production. Co-cultivation of fungal and microalgal cells is getting increasing attention because of high efficiency of bio-flocculation of microalgal cells with no requirement for added chemicals and low energy inputs. Moreover, some fungal and microalgal strains are well known for their exceptional ability to purify wastewater, generating biomass that represents a renewable and sustainable feedstock for biofuel production. We have screened the flocculation efficiency of the filamentous fungus A. fumigatus against 11 microalgae representing freshwater, marine, small (5 µm), large (over 300 µm), heterotrophic, photoautotrophic, motile and non-motile strains. Some of the strains are commercially used for biofuel production. Lipid production and composition were analysed in fungal-algal pellets grown on media containing alternative carbon, nitrogen and phosphorus sources contained in wheat straw and swine wastewater, respectively. Co-cultivation of algae and A. fumigatus cells showed additive and synergistic effects on biomass production, lipid yield and wastewater bioremediation efficiency. Analysis of fungal-algal pellet's fatty acids composition suggested that it can be tailored and optimised through co-cultivating different algae and fungi without the need for genetic modification.
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Affiliation(s)
- Digby Wrede
- Royal Melbourne Institute of Technology University, School of Applied Sciences, 3083 Bundoora, VIC, Australia
| | - Mohamed Taha
- Royal Melbourne Institute of Technology University, School of Applied Sciences, 3083 Bundoora, VIC, Australia
| | - Ana F. Miranda
- Royal Melbourne Institute of Technology University, School of Applied Sciences, 3083 Bundoora, VIC, Australia
| | - Krishna Kadali
- Royal Melbourne Institute of Technology University, School of Applied Sciences, 3083 Bundoora, VIC, Australia
| | - Trevor Stevenson
- Royal Melbourne Institute of Technology University, School of Applied Sciences, 3083 Bundoora, VIC, Australia
| | - Andrew S. Ball
- Royal Melbourne Institute of Technology University, School of Applied Sciences, 3083 Bundoora, VIC, Australia
| | - Aidyn Mouradov
- Royal Melbourne Institute of Technology University, School of Applied Sciences, 3083 Bundoora, VIC, Australia
- * E-mail:
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Amarsaikhan N, O’Dea EM, Tsoggerel A, Owegi H, Gillenwater J, Templeton SP. Isolate-dependent growth, virulence, and cell wall composition in the human pathogen Aspergillus fumigatus. PLoS One 2014; 9:e100430. [PMID: 24945802 PMCID: PMC4063936 DOI: 10.1371/journal.pone.0100430] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 05/27/2014] [Indexed: 01/01/2023] Open
Abstract
The ubiquitous fungal pathogen Aspergillus fumigatus is a mediator of allergic sensitization and invasive disease in susceptible individuals. The significant genetic and phenotypic variability between and among clinical and environmental isolates are important considerations in host-pathogen studies of A. fumigatus-mediated disease. We observed decreased radial growth, rate of germination, and ability to establish colony growth in a single environmental isolate of A. fumigatus, Af5517, when compared to other clinical and environmental isolates. Af5517 also exhibited increased hyphal diameter and cell wall β-glucan and chitin content, with chitin most significantly increased. Morbidity, mortality, lung fungal burden, and tissue pathology were decreased in neutropenic Af5517-infected mice when compared to the clinical isolate Af293. Our results support previous findings that suggest a correlation between in vitro growth rates and in vivo virulence, and we propose that changes in cell wall composition may contribute to this phenotype.
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Affiliation(s)
- Nansalmaa Amarsaikhan
- Department of Microbiology and Immunology, Indiana University School of Medicine – Terre Haute, Terre Haute, Indiana, United States of America
| | - Evan M. O’Dea
- Department of Microbiology and Immunology, Indiana University School of Medicine – Terre Haute, Terre Haute, Indiana, United States of America
| | - Angar Tsoggerel
- Department of Microbiology and Immunology, Indiana University School of Medicine – Terre Haute, Terre Haute, Indiana, United States of America
| | - Henry Owegi
- Department of Microbiology and Immunology, Indiana University School of Medicine – Terre Haute, Terre Haute, Indiana, United States of America
| | - Jordan Gillenwater
- Department of Microbiology and Immunology, Indiana University School of Medicine – Terre Haute, Terre Haute, Indiana, United States of America
| | - Steven P. Templeton
- Department of Microbiology and Immunology, Indiana University School of Medicine – Terre Haute, Terre Haute, Indiana, United States of America
- * E-mail:
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Yao LY, Zhu YX, Jiao RH, Lu YH, Tan RX. Enhanced production of fumigaclavine C by ultrasound stimulation in a two-stage culture of Aspergillus fumigatus CY018. Bioresour Technol 2014; 159:112-117. [PMID: 24632633 DOI: 10.1016/j.biortech.2014.02.072] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 02/17/2014] [Accepted: 02/19/2014] [Indexed: 06/03/2023]
Abstract
Stimulation by physical means including ultrasound is important to cell morphology and the product yield. In this work, the effect of ultrasound on the production of fumigaclavine C (FC), a conidiation-associated alkaloid with strong anti-inflammatory activity, was investigated in a newly developed two-stage culture of Aspergillus fumigatus CY018. The optimum ultrasonication conditions consisted of exposing cultures (at 12h of growth phase) to 10-min repeated irradiation (4 times) with a 24-h interval at the fixed power (500 W). Under this condition, FC production reached 118.09 mg/L, which was 89% higher than the control and much higher than previous reported values. Morphological analysis demonstrated that mycelia morphology from ultrasonication was in the form smaller and looser pellets as compared to that of the control. In addition, conidia that is closely related to FC biosynthesis were significantly increased after ultrasound stimulation, with 3 folds of that from the control.
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Affiliation(s)
- Ling-Yun Yao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, PR China
| | - Yi-Xiang Zhu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, PR China
| | - Rui-Hua Jiao
- Institute of Functional Biomolecules, State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, PR China
| | - Yan-Hua Lu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, PR China.
| | - Ren-Xiang Tan
- Institute of Functional Biomolecules, State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, PR China.
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Papi M, Maiorana A, Bugli F, Torelli R, Posteraro B, Maulucci G, De Spirito M, Sanguinetti M. Detection of biofilm-grown Aspergillus fumigatus by means of atomic force spectroscopy: ultrastructural effects of alginate lyase. Microsc Microanal 2012; 18:1088-1094. [PMID: 23026204 DOI: 10.1017/s1431927612001067] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Aspergillus fumigatus has become a leading cause of fungal morbidity and mortality, especially in immunocompromised patients. This fungus is able to grow as a multicellular community and produce a hydrophobic extracellular matrix (ECM), mainly composed of galactomannan and α-1,3 glucans, to protect itself from host defenses and antimicrobial drugs. This matrix envelops the fungus hyphae, binding them into a contiguous sheath on the colony surface, forming a biofilm and increasing the fungal resistance to adverse environmental factors. Adherence to host cells and resistance to physical removal play a key role in fungal colonization and invasion of the host and in a wide range of infections. Here we show that, by using atomic force spectroscopy, it is possible to exploit the peculiar hydrophobicity of the biofilm components (i.e., cell walls, ECM) to detect the biofilm spread, its growth, and lysis on rough surfaces. By means of this approach, we demonstrate that alginate lyase, an enzyme known to reduce negatively charged alginate levels in microbial biofilms, reduces the biofilm adhesion forces suggesting a loss of ECM from the biofilm, which could be used to enhance pharmacological treatments.
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Affiliation(s)
- M Papi
- Istituto di Fisica, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma, Italy
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Ingham CJ, Schneeberger PM. Microcolony imaging of Aspergillus fumigatus treated with echinocandins reveals both fungistatic and fungicidal activities. PLoS One 2012; 7:e35478. [PMID: 22536390 PMCID: PMC3334906 DOI: 10.1371/journal.pone.0035478] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Accepted: 03/18/2012] [Indexed: 11/25/2022] Open
Abstract
Background The echinocandins are lipopeptides that can be employed as antifungal drugs that inhibit the synthesis of 1,3-β-glucans within the fungal cell wall. Anidulafungin and caspofungin are echinocandins used in the treatment of Candida infections and have activity against other fungi including Aspergillus fumigatus. The echinocandins are generally considered fungistatic against Aspergillus species. Methods Culture of A. fumigatus from conidia to microcolonies on a support of porous aluminium oxide (PAO), combined with fluorescence microscopy and scanning electron microscopy, was used to investigate the effects of anidulafungin and caspofungin. The PAO was an effective matrix for conidial germination and microcolony growth. Additionally, PAO supports could be moved between agar plates containing different concentrations of echinocandins to change dosage and to investigate the recovery of fungal microcolonies from these drugs. Culture on PAO combined with microscopy and image analysis permits quantitative studies on microcolony growth with the flexibility of adding or removing antifungal agents, dyes, fixatives or osmotic stresses during growth with minimal disturbance of fungal microcolonies. Significance Anidulafungin and caspofungin reduced but did not halt growth at the microcony level; additionally both drugs killed individual cells, particularly at concentrations around the MIC. Intact but not lysed cells showed rapid recovery when the drugs were removed. The classification of these drugs as either fungistatic or fungicidal is simplistic. Microcolony analysis on PAO appears to be a valuable tool to investigate the action of antifungal agents.
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Affiliation(s)
- Colin J Ingham
- Department of Medical Microbiology and Infection Control, Jeroen Bosch Hospital, 's-Hertogenbosch, The Netherlands.
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Xu XY, Shi Y, Zhang PP, Zhang F, Shen YY, Su X, Zhao BL. E-cadherin mediates adhesion and endocytosis of Aspergillus fumigatus blastospores in human epithelial cells. Chin Med J (Engl) 2012; 125:617-621. [PMID: 22490484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023] Open
Abstract
BACKGROUND Aspergillus fumigatus (A. fumigatus) is a ubiquitous saprophytic fungus responsible for the majority of invasive mold infections in patients undergoing chemotherapy, organ transplantation or with persistent neutropenia. This study aimed to determine the role of E-cadherin for adhesion and endocytosis of A. fumigatus blastospores in the human epithelial cell line A549. METHODS A. fumigatus blastospores were incubated with the total protein of A549 to investigate the binding of E-cadherin and blastospores followed by an affinity purification procedure. After establishing the adhesion model, the adhesion and endocytosis of A. fumigatus blastospores by A549 cells were evaluated by down-regulating E-cadherin of A549 cells using blocking antibody or small interfering RNA (siRNA). RESULTS E-cadherin was adhered to the surface of A. fumigatus blastospore. Adhesion and endocytosis of the blastospores were reduced by blocking or down-regulating E-cadherin in A549 cells. CONCLUSIONS E-cadherin is a receptor for adhesion and endocytosis of A. fumigatus blastospores in epithelial cells. This may open a new approach to treat this fungal infection.
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Affiliation(s)
- Xiao-yong Xu
- Department of Respiratory Medicine, Second Military Medical University/Nanjing General Hospital of Nanjing Military Command, People's Liberation Army, Nanjing, Jiangsu, China
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Mech F, Thywißen A, Guthke R, Brakhage AA, Figge MT. Automated image analysis of the host-pathogen interaction between phagocytes and Aspergillus fumigatus. PLoS One 2011; 6:e19591. [PMID: 21573171 PMCID: PMC3088683 DOI: 10.1371/journal.pone.0019591] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 04/01/2011] [Indexed: 11/20/2022] Open
Abstract
Aspergillus fumigatus is a ubiquitous airborne fungus and opportunistic human pathogen. In immunocompromised hosts, the fungus can cause life-threatening diseases like invasive pulmonary aspergillosis. Since the incidence of fungal systemic infections drastically increased over the last years, it is a major goal to investigate the pathobiology of A. fumigatus and in particular the interactions of A. fumigatus conidia with immune cells. Many of these studies include the activity of immune effector cells, in particular of macrophages, when they are confronted with conidia of A. fumigus wild-type and mutant strains. Here, we report the development of an automated analysis of confocal laser scanning microscopy images from macrophages coincubated with different A. fumigatus strains. At present, microscopy images are often analysed manually, including cell counting and determination of interrelations between cells, which is very time consuming and error-prone. Automation of this process overcomes these disadvantages and standardises the analysis, which is a prerequisite for further systems biological studies including mathematical modeling of the infection process. For this purpose, the cells in our experimental setup were differentially stained and monitored by confocal laser scanning microscopy. To perform the image analysis in an automatic fashion, we developed a ruleset that is generally applicable to phagocytosis assays and in the present case was processed by the software Definiens Developer XD. As a result of a complete image analysis we obtained features such as size, shape, number of cells and cell-cell contacts. The analysis reported here, reveals that different mutants of A. fumigatus have a major influence on the ability of macrophages to adhere and to phagocytose the respective conidia. In particular, we observe that the phagocytosis ratio and the aggregation behaviour of pksP mutant compared to wild-type conidia are both significantly increased.
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Affiliation(s)
- Franziska Mech
- Research Group Applied Systems Biology, Leibniz Institute for Natural Product Research and Infection Biology – Hans-Knöll-Institute (HKI), Jena, Germany
| | - Andreas Thywißen
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology – Hans-Knöll-Institute (HKI), Jena, Germany
- Friedrich Schiller University Jena, Jena, Germany
| | - Reinhard Guthke
- Research Group Systems Biology/Bioinformatics, Leibniz Institute for Natural Product Research and Infection Biology – Hans-Knöll-Institute (HKI), Jena, Germany
| | - Axel A. Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology – Hans-Knöll-Institute (HKI), Jena, Germany
- Friedrich Schiller University Jena, Jena, Germany
| | - Marc Thilo Figge
- Research Group Applied Systems Biology, Leibniz Institute for Natural Product Research and Infection Biology – Hans-Knöll-Institute (HKI), Jena, Germany
- Friedrich Schiller University Jena, Jena, Germany
- * E-mail:
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Wang JS, Hu XJ, Liu YG, Xie SB, Bao ZL. Biosorption of uranium (VI) by immobilized Aspergillus fumigatus beads. J Environ Radioact 2010; 101:504-508. [PMID: 20359793 DOI: 10.1016/j.jenvrad.2010.03.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 03/01/2010] [Accepted: 03/03/2010] [Indexed: 05/29/2023]
Abstract
Biosorption of uranium (VI) ions by immobilized Aspergillus fumigatus beads was investigated in a batch system. The influences of solution pH, biosorbent dose, U (VI) concentration, and contact time on U (VI) biosorption were studied. The results indicated that the adsorption capacity was strongly affected by the solution pH, the biosorbent dose and initial U (VI) concentration. Optimum biosorption was observed at pH 5.0, biosrobent dose (w/v) 2.5%, initial U (VI) concentration 60 mg L(-1). Biosorption equilibrium was established in 120 min. The adsorption process conformed to the Freunlich and Temkin isothermal adsorption models. The dynamic adsorption model conformed to pseudo-second order model.
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Affiliation(s)
- Jing-song Wang
- School of Urban Construction, University of South China, 28 West Changsheng Road, Hengyang, Hunan 421001, PR China.
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Vanhee LME, Nelis HJ, Coenye T. Rapid detection and quantification of Aspergillus fumigatus in environmental air samples using solid-phase cytometry. Environ Sci Technol 2009; 43:3233-3239. [PMID: 19534140 DOI: 10.1021/es803435a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Aspergillus fumigatus is an ubiquitous fungus capable of causing severe infections such as aspergilloma, allergic bronchopulmonary aspergillosis, and invasive aspergillosis, especially in immunocompromised patients. Monitoring the number of Aspergillus fumigatus spores in the air is crucial for infection control. In the present study, a novel approach for the quantification of Aspergillus fumigatus, based on solid-phase cytometry (SPC) and immunofluorescent labeling, was developed. The sensitivity and specificity of the assay were confirmed by testing pure cultures. Paecilomyces variotii and Rhizopus stolonifer were codetected but could be excluded on the basis of morphology of the microcolonies. The SPC method has considerable advantages compared to the culture-based method, including its low detection limit (4 cells/m3), its speed (results are obtained within 24 h), and the straightforward microscopic identification of Aspergillus fumigatus. Additionally, comparison of results obtained with both methods demonstrated that they are equally accurate for the quantification of Aspergillus fumigatus in environmental air samples.
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Affiliation(s)
- Lies M E Vanhee
- Laboratory of Pharmaceutical Microbiology, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium
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Magnani T, Soriani FM, Martins VDP, Policarpo ACDF, Sorgi CA, Faccioli LH, Curti C, Uyemura SA. Silencing of mitochondrial alternative oxidase gene of Aspergillus fumigatus enhances reactive oxygen species production and killing of the fungus by macrophages. J Bioenerg Biomembr 2009; 40:631-6. [PMID: 19148712 DOI: 10.1007/s10863-008-9191-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Accepted: 11/24/2008] [Indexed: 01/27/2023]
Abstract
We previously demonstrated that conidia from Aspergillus fumigatus incubated with menadione and paraquat increases activity and expression of cyanide-insensitive alternative oxidase (AOX). Here, we employed the RNA silencing technique in A. fumigatus using the vector pALB1/aoxAf in order to down-regulate the aox gene. Positive transformants for aox gene silencing of A. fumigatus were more susceptible both to an imposed in vitro oxidative stress condition and to macrophages killing, suggesting that AOX is required for the A. fumigatus pathogenicity, mainly for the survival of the fungus conidia during host infection and resistance to reactive oxygen species generated by macrophages.
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Affiliation(s)
- Taisa Magnani
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. Café, s/n, 14040-903, Ribeirão Preto, SP, Brazil
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Mota Júnior AO, Malavazi I, Soriani FM, Heinekamp T, Jacobsen I, Brakhage AA, Savoldi M, Goldman MHS, da Silva Ferreira ME, Goldman GH. Molecular characterization of the Aspergillus fumigatus NCS-1 homologue, NcsA. Mol Genet Genomics 2008; 280:483-95. [PMID: 18830711 DOI: 10.1007/s00438-008-0381-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Accepted: 09/03/2008] [Indexed: 12/23/2022]
Abstract
Here, we characterize the Aspergillus fumigatus homologue ncsA Neuronal Calcium Sensor. We showed that ncsA is not an essential gene and ncsA growth was decreased in the presence of EGTA and SDS. Furthermore, the ncsA mutant is more resistant to calcium chloride. NcsA:mRFP localizes to the cytoplasm and its cellular localization is not affected by the cellular response to either calcium chloride or EGTA. The ncsA mutant strain is more sensitive to voriconazole, itraconazole, and amphotericin. Polar growth in the DeltancsA mutant was also considerably more affected by lovastatin than in the wild type strain. The Spitzenkörper can be visualized in both strains and although the vacuolar system does not seem to be very different, there is an increase in the staining intensity on the germling surface of the ncsA strain. NcsA promotes pmcA and pmcB expression and therefore there is a reduced expression of these ion pumps in the DeltancsA mutant background, and also of other genes involved in the response to calcium in A. fumigatus. The ncsA inactivation mutation is not causing loss of virulence in a low dose murine infection when compared to the corresponding wild type strain.
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Affiliation(s)
- André Oliveira Mota Júnior
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
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Cramer RA, Perfect BZ, Pinchai N, Park S, Perlin DS, Asfaw YG, Heitman J, Perfect JR, Steinbach WJ. Calcineurin target CrzA regulates conidial germination, hyphal growth, and pathogenesis of Aspergillus fumigatus. Eukaryot Cell 2008; 7:1085-97. [PMID: 18456861 PMCID: PMC2446674 DOI: 10.1128/ec.00086-08] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2008] [Accepted: 04/17/2008] [Indexed: 11/20/2022]
Abstract
The calcineurin pathway is a critical signal transduction pathway in fungi that mediates growth, morphology, stress responses, and pathogenicity. The importance of the calcineurin pathway in fungal physiology creates an opportunity for the development of new antifungal therapies that target this critical signaling pathway. In this study, we examined the role of the zinc finger transcription factor Crz1 homolog (CrzA) in the physiology and pathogenicity of the opportunistic human fungal pathogen Aspergillus fumigatus. Genetic replacement of the crzA locus in A. fumigatus resulted in a strain with significant defects in conidial germination, polarized hyphal growth, cell wall structure, and asexual development that are similar to but with differences from defects seen in the A. fumigatus DeltacnaA (calcineurin A) strain. Like the DeltacnaA strain, the DeltacrzA strain was incapable of causing disease in an experimental persistently neutropenic inhalational murine model of invasive pulmonary aspergillosis. Our results suggest that CrzA is an important downstream effector of calcineurin that controls morphology in A. fumigatus, but additional downstream effectors that mediate calcineurin signal transduction are likely present in this opportunistic fungal pathogen. In addition, the importance of CrzA to the production of disease is critical, and thus CrzA is an attractive fungus-specific antifungal target for the treatment of invasive aspergillosis.
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Affiliation(s)
- Robert A Cramer
- Duke University Medical Center, Box 3499, Pediatric Infectious Diseases, Durham, NC 27710, USA
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15
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Sun D, Ran X, Wang J. [Isolation and identification of a taxol-producing endophytic fungus from Podocarpus]. Wei Sheng Wu Xue Bao 2008; 48:589-595. [PMID: 18652289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
OBJECTIVE Endophytic fungi can produce beneficial active components during symbiosis with host plants. We isolated a taxol-producing endophytic fungus strain from Podocrapus. METHODS The anti-tumor activity of the endophytic funguswas detected by Methyl Thiazolyl Tetrazolium (MTT) method with Vero cells. The production of taxol by one fungus was confirmed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). This strain was classified by morphology together with similarity of internal transcribed spacer (ITS) sequence by Clustal W method. The deduced apoptosis of taxol produced from the strain was detected by fluorescent staining method with Vero cells. RESULTS A total of 155 endophytic fungi were isolated from the tissue of Podocrapus. The result showed that 28 strains inhibited the growth of Vero cell (inhibitory ratio > or = 10%), and 7 strains had high activity (inhibitory ratio > or = 70%). The taxol-producing ability of strain A2 was confirmed by TLC and HPLC. Therefore, we recognized strain A2 as an endophytic fungus capable of producing taxol from Podocrapus-1 and named it EPTP-1. Its output of taxol was 0.56 mg/L when growing in liquid potato dextrose medium. EPTP-1 was classified as Aspergillus fumigates. Taxol extracted from strain EPTP-1 resulted in significant apoptosis of Vero cells at concentration of 5.553 microg/L for 24h. The activity of anti-Vero growth by extracts from strain EPTP-1 was similar to that of the purchased standard taxol (P > 0.05). CONCLUSION The identified endophytic fungus, strain EPTP-1, can be a candidate for taxol production.
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Affiliation(s)
- Duanfang Sun
- Faculty of Animal Science, Guizhou University, Guiyang 550025, China.
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16
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Dague E, Delcorte A, Latgé JP, Dufrêne YF. Combined use of atomic force microscopy, X-ray photoelectron spectroscopy, and secondary ion mass spectrometry for cell surface analysis. Langmuir 2008; 24:2955-2959. [PMID: 18237224 DOI: 10.1021/la703741y] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Understanding the surface properties of microbial cells is a major challenge of current microbiological research and a key to efficiently exploit them in biotechnology. Here, we used three advanced surface analysis techniques with different sensitivity, probing depth, and lateral resolution, that is, in situ atomic force microscopy, X-ray photoelectron spectroscopy, and secondary ion mass spectrometry, to gain insight into the surface properties of the conidia of the human fungal pathogen Aspergillus fumigatus. We show that the native ultrastructure, surface protein and polysaccharide concentrations, and amino acid composition of three mutants affected in hydrophobin production are markedly different from those of the wild-type, thereby providing novel insight into the cell wall architecture of A. fumigatus. The results demonstrate the power of using multiple complementary techniques for probing microbial cell surfaces.
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Affiliation(s)
- Etienne Dague
- Unité de Chimie des Interfaces, Université Catholique de Louvain, Croix du Sud 2/18, B-1348 Louvain-la-Neuve, Belgium.
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17
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Abstract
Traditionally, cell surface properties have been difficult to study at the subcellular level, especially on hydrated, live cells. Here, we demonstrate the ability of chemical force microscopy to map the hydrophobicity of single live cells with nanoscale resolution. After validating the technique on reference surfaces with known chemistry, we probe the local hydrophobic character of two medically important microorganisms, Aspergillus fumigatus and Mycobacterium bovis, in relation with function. Applicable to a wide variety of cells, the chemically sensitive imaging method presented here provides new opportunities for studying the nanoscale surface properties of live cells and for understanding their roles in mediating cellular events.
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Affiliation(s)
- Etienne Dague
- Unité de Chimie des Interfaces, Université Catholique de Louvain, Croix du Sud 2/18, B-1348 Louvain-la-Neuve, Belgium
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18
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Abstract
We used real-time atomic force microscopy with a temperature-controlled stage (37 degrees C) to probe the structural and physicochemical dynamics of single Aspergillus fumigatus conidia during germination. Nanoscale topographic images of dormant spores revealed the presence of a layer of rodlets made of hydrophobins, in agreement with earlier electron microscopy observations. Within the 3-h germination period, progressive disruption of the rodlet layer was observed, revealing hydrophilic inner cell wall structures. Using adhesion force mapping with hydrophobic tips, these ultrastructural changes were shown to correlate with major differences in cell surface hydrophobicity. That is, the rodlet surface was uniformly hydrophobic due to the presence of hydrophobins, whereas the cell wall material appearing upon germination was purely hydrophilic. This study illustrates the potential of real-time atomic force microscopy imaging and force spectroscopy for tracking cell-surface dynamics.
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Affiliation(s)
- Etienne Dague
- Unité de Chimie des Interfaces, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
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19
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Sugui JA, Pardo J, Chang YC, Müllbacher A, Zarember KA, Galvez EM, Brinster L, Zerfas P, Gallin JI, Simon MM, Kwon-Chung KJ. Role of laeA in the Regulation of alb1, gliP, Conidial Morphology, and Virulence in Aspergillus fumigatus. Eukaryot Cell 2007; 6:1552-61. [PMID: 17630330 PMCID: PMC2043373 DOI: 10.1128/ec.00140-07] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The alb1 (pksP) gene has been reported as a virulence factor controlling the pigmentation and morphology of conidia in Aspergillus fumigatus. A recent report suggested that laeA regulates alb1 expression and conidial morphology but not pigmentation in the A. fumigatus strain AF293. laeA has also been reported to regulate the synthesis of secondary metabolites, such as gliotoxin. We compared the role of laeA in the regulation of conidial morphology and the expression of alb1 and gliP in strains B-5233 and AF293, which differ in colony morphology and nutritional requirements. Deletion of laeA did not affect conidial morphology or pigmentation in these strains, suggesting that laeA is not involved in alb1 regulation during conidial morphogenesis. Deletion of laeA, however, caused down-regulation of alb1 during mycelial growth in a liquid medium. Transcription of gliP, involved in the synthesis of gliotoxin, was drastically reduced in B-5233laeADelta, and the gliotoxin level found in the culture filtrates was 20% of wild-type concentrations. While up-regulation of gliP in AF293 was comparable to that in B-5233, the relative mRNA level in AF293laeADelta was about fourfold lower than that in B-5233laeADelta. Strain B-5233laeADelta caused slower onset of fatal infection in mice relative to that with B-5233. Histopathology of sections from lungs of infected mice corroborated the survival data. Culture filtrates from B-5233laeADelta caused reduced death in thymoma cells and were less inhibitory to a respiratory burst of neutrophils than culture filtrates from B-5233. Our results suggest that while laeA is not involved in the regulation of alb1 function in conidial morphology, it regulates the synthesis of gliotoxin and the virulence of A. fumigatus.
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Affiliation(s)
- Janyce A Sugui
- Laboratory of Clinical Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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20
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Zarember KA, Sugui JA, Chang YC, Kwon-Chung KJ, Gallin JI. Human polymorphonuclear leukocytes inhibit Aspergillus fumigatus conidial growth by lactoferrin-mediated iron depletion. J Immunol 2007; 178:6367-73. [PMID: 17475866 DOI: 10.4049/jimmunol.178.10.6367] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Aspergillus fumigatus, a common mold, rarely infects humans, except during prolonged neutropenia or in cases of chronic granulomatous disease (CGD), a primary immunodeficiency caused by mutations in the NADPH oxidase that normally produces fungicidal reactive oxygen species. Filamentous hyphae of Aspergillus are killed by normal, but not CGD polymorphonuclear leukocytes (PMN); however, the few studies on PMN-mediated host defenses against infectious conidia (spores) of this organism have yielded conflicting results, some showing that PMN do not inhibit conidial growth, with others showing that they do, most likely using reactive oxygen species. Given that CGD patients are exposed daily to hundreds of viable A. fumigatus conidia, yet considerable numbers of them survive years without infection, we reasoned that PMN use ROS-independent mechanisms to combat Aspergillus. We show that human PMN from both normal controls and CGD patients are equipotent at arresting the growth of Aspergillus conidia in vitro, indicating the presence of a reactive oxygen species-independent factor(s). Cell-free supernatants of degranulated normal and CGD neutrophils both suppressed fungal growth and were found to be rich in lactoferrin, an abundant PMN secondary granule protein. Purified iron-poor lactoferrin at concentrations occurring in PMN supernatants (and reported in human mucosal secretions in vivo) decreased fungal growth, whereas saturation of lactoferrin or PMN supernatants with iron, or testing in the presence of excess iron in the form of ferritin, completely abolished activity against conidia. These results demonstrate that PMN lactoferrin sequestration of iron is important for host defense against Aspergillus.
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Affiliation(s)
- Kol A Zarember
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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21
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Abstract
The opportunistic human pathogen Aspergillus fumigatus produces a large quantity of asexual spores (conidia), which are the primary agent causing invasive aspergillosis in immunocompromised patients. We investigated the mechanisms controlling asexual sporulation (conidiation) in A. fumigatus via examining functions of four key regulators, GpaA (Galpha), AfFlbA (RGS), AfFluG, and AfBrlA, previously studied in Aspergillus nidulans. Expression analyses of gpaA, AfflbA, AffluG, AfbrlA, and AfwetA throughout the life cycle of A. fumigatus revealed that, while transcripts of AfflbA and AffluG accumulate constantly, the latter two downstream developmental regulators are specifically expressed during conidiation. Both loss-of-function AfflbA and dominant activating GpaA(Q204L) mutations resulted in reduced conidiation with increased hyphal proliferation, indicating that GpaA signaling activates vegetative growth while inhibiting conidiation. As GpaA is the primary target of AfFlbA, the dominant interfering GpaA(G203R) mutation suppressed reduced conidiation caused by loss of AfflbA function. These results corroborate the hypothesis that functions of G proteins and RGSs are conserved in aspergilli. We then examined functions of the two major developmental activators AfFluG and AfBrlA. While deletion of AfbrlA eliminated conidiation completely, null mutation of AffluG did not cause severe alterations in A. fumigatus sporulation in air-exposed culture, implying that, whereas the two aspergilli may have a common key downstream developmental activator, upstream mechanisms activating brlA may be distinct. Finally, both AffluG and AfflbA mutants showed reduced conidiation and delayed expression of AfbrlA in synchronized developmental induction, indicating that these upstream regulators contribute to the proper progression of conidiation.
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Affiliation(s)
- Jae-Hyung Mah
- Department of Food Microbiology and Toxicology and Food Research Institute, University of Wisconsin, Madison, Madison, WI 53706, USA
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22
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García ME, Caballero J, Blanco I, Cruzado M, Costas E, Blanco JL. Cambios en la actividad elastasa y la capacidad colonizadora de Aspergillus fumigatus tras inoculaciones sucesivas en ratones. Rev Iberoam Micol 2006; 23:221-3. [PMID: 17388646 DOI: 10.1016/s1130-1406(06)70048-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In a previous work we demonstrated a clear link between elastase activity and pathogenicity using what we have named the Elastase Activity Index (EAI). In the present study we have evaluated the possible variability of this index as a consequence of successive inoculations in mice. Two strains of Aspergillus fumigatus isolated from the environment without elastase activity were used. These strains were inoculated into successive batches of ten mice. Our results showed that with each inoculation there was an increase in the number of mice on each batch from which the strain could be isolated and an increase in the number of strains with an EAI>1. This study suggests that A. fumigatus could adapt to the environment in which it is developed, increasing its pathogenic capabilities from host to host.
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Affiliation(s)
- Marta E García
- Departamento Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain
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23
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Abstract
INTRODUCTION Aspergillosis colonisation in cystic fibrosis (CF), usually due to Aspergillus fumigatus (AF), classically presents as allergic bronchopulmonary aspergillosis. However, aspergillus infection can produce a range of manifestations: from minor colonization to an invasive infection. CASE REPORT A 14-year-old CF patient, chronically colonized with Staphylococcus aureus and Pseudomonas aeruginosa, presented with acute right-sided chest pain, a moderate fever and no modification of the sputum. The chest X-ray showed a 5 cm round opacity. Laboratory parameters were WBC 24,500 G/l, CRP 27 mg/l, Total IgE 1527 UI/l, Specific Aspergillus fumigatus IgE 31 UI/l. Bronchoscopy revealed external compression of the middle lobe bronchus with mucopurulent secretions coming from apical segment of the lower lobe. Bronchoalveolar lavage revealed the presence of pseudomonas aeruginosa 103 CFA/ml, staph aureus 107 CFA/ml and one colony of AF. Chest CT scan showed a large necrotic mass with an air-fluid level located in the apical segment of the right lower lobe. Initial therapy with itraconazole and corticosteroid was replaced by voriconazole, caspofungin, metronidazole and linezolide. Treatment was well tolerated and after 8 weeks the chest X-ray appearances had returned to normal. CONCLUSIONS The possible diagnoses and therapeutic options are discussed. Conventional antifungal treatment with amphotericin B is limited by nephrotoxicity. These newer antifungal agents appear to be effective and well-tolerated.
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Affiliation(s)
- A-S Bonnel
- CRCM, Département de Pédiatrie, Centre Hospitalier Général Gustave Flaubert, Le Havre, France
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24
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Steinbach WJ, Cramer RA, Perfect BZ, Asfaw YG, Sauer TC, Najvar LK, Kirkpatrick WR, Patterson TF, Benjamin DK, Heitman J, Perfect JR. Calcineurin controls growth, morphology, and pathogenicity in Aspergillus fumigatus. Eukaryot Cell 2006; 5:1091-103. [PMID: 16835453 PMCID: PMC1489296 DOI: 10.1128/ec.00139-06] [Citation(s) in RCA: 228] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Calcineurin is implicated in a myriad of human diseases as well as homeostasis and virulence in several major human pathogenic microorganisms. The fungus Aspergillus fumigatus is a leading cause of infectious death in the rapidly expanding immunocompromised patient population. Current antifungal treatments for invasive aspergillosis are often ineffective, and novel therapeutic approaches are urgently needed. We demonstrate that a mutant of A. fumigatus lacking the calcineurin A (cnaA) catalytic subunit exhibited defective hyphal morphology related to apical extension and polarized growth, which resulted in drastically decreased filamentation. The delta cnaA mutant lacked the extensive lattice of invading hyphae seen with the wild-type and complemented strains. Sporulation was also affected in the delta cnaA mutant, including morphological conidial defects with the absence of surface rodlets and the added presence of disjunctors creating long conidial chains. Infection with the delta cnaA mutant in several distinct animal models with different types of immunosuppression and inoculum delivery led to a profound attenuation of pathogenicity compared to infection with the wild-type and complemented strains. Lung tissue from animals infected with the delta cnaA mutant showed a complete absence of hyphae, in contrast to tissue from animals infected with the wild-type and complemented strains. Quantitative fungal burden and pulmonary infarct scoring confirmed these findings. Our results support the clinical observation that substantially decreasing fungal growth can prevent disease establishment and decrease mortality. Our findings reveal that calcineurin appears to play a globally conserved role in the virulence of several pathogenic fungi and yet plays specialized roles in each and can be an excellent target for therapeutic intervention.
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Affiliation(s)
- William J Steinbach
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Box 3499, Duke University Medical Center, Durham, North Carolina 27710, USA.
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25
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Gersuk GM, Underhill DM, Zhu L, Marr KA. Dectin-1 and TLRs permit macrophages to distinguish between different Aspergillus fumigatus cellular states. J Immunol 2006; 176:3717-24. [PMID: 16517740 DOI: 10.4049/jimmunol.176.6.3717] [Citation(s) in RCA: 259] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Aspergillus fumigatus is a common cause of invasive and allergic pulmonary disease. Resting conidia of the filamentous fungus are constantly inhaled, but cause infection only after initiating hyphal growth. In this study, we have explored whether macrophages can distinguish between resting spores and the maturing, potentially invasive form of the fungus. Although macrophages bind and ingest A. fumigatus resting conidia efficiently, there is little inflammatory response; NF-kappabeta is not activated, inflammatory cytokines are not induced, and reactive oxygen species are not produced. However, maturing A. fumigatus conidia and germ tubes stimulate NF-kappabeta, secretion of proinflammatory cytokines and production of reactive oxygen by human monocyte-derived macrophages and murine macrophages from multiple anatomical sites. These responses are in part mediated by dectin-1, which binds cell wall beta-glucan that is not present on the surface of dormant conidia, but is present after cellular swelling and loss of the hydrophobic proteinaceous cell wall. Dectin-1 binding to germ tubes augments, but is not required for, TLR2-mediated inflammatory cytokine secretion. Dectin-1 recognition of germ tubes also stimulates TNF-alpha production in the absence of both TLR2 and MyD88 signaling. These data demonstrate one mechanism by which the pulmonary inflammatory response is tailored toward metabolically active cells, thereby avoiding unnecessary tissue damage with frequent inhalation of ubiquitous spores.
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Affiliation(s)
- Geoffrey M Gersuk
- Fred Hutchinson Cancer Research Center, University of Washington, 1100 Fairview Avenue North, Seattle, WA 98109, USA
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26
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Krappmann S, Sasse C, Braus GH. Gene targeting in Aspergillus fumigatus by homologous recombination is facilitated in a nonhomologous end- joining-deficient genetic background. Eukaryot Cell 2006; 5:212-5. [PMID: 16400185 PMCID: PMC1360265 DOI: 10.1128/ec.5.1.212-215.2006] [Citation(s) in RCA: 226] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The akuA gene encoding the Ku70 component of the nonhomologous end-joining machinery was deleted in the opportunistic pathogen Aspergillus fumigatus. No obvious phenotype could be assessed for the corresponding mutant strain but relative frequencies of homologous recombination were increased as deduced from targeting the laccase-encoding abr2 gene.
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Affiliation(s)
- Sven Krappmann
- Institute of Microbiology & Genetics, Department of Molecular Microbiology and Genetics, Grisebachstr. 8, D-37077 Göttingen, Germany.
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27
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Fortwendel JR, Zhao W, Bhabhra R, Park S, Perlin DS, Askew DS, Rhodes JC. A fungus-specific ras homolog contributes to the hyphal growth and virulence of Aspergillus fumigatus. Eukaryot Cell 2006; 4:1982-9. [PMID: 16339716 PMCID: PMC1317486 DOI: 10.1128/ec.4.12.1982-1989.2005] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The Ras family of GTPase proteins has been shown to control morphogenesis in many organisms, including several species of pathogenic fungi. In a previous study, we identified a gene encoding a fungus-specific Ras subfamily homolog, rasB, in Aspergillus fumigatus. Here we report that deletion of A. fumigatus rasB caused decreased germination and growth rates on solid media but had no effect on total biomass accumulation after 24 h of growth in liquid culture. The DeltarasB mutant had an irregular hyphal morphology characterized by increased branching. Expression of rasBDelta113-135, a mutant transgene lacking the conserved rasB internal amino acid insertion, did not complement the deletion phenotype of delayed growth and germination rates and abnormal hyphal morphology. Virulence of the rasB deletion strain was diminished; mice infected with this strain exhibited approximately 65% survival compared to approximately 10% with wild-type and reconstituted strains. These data support the hypothesis that rasB homologs, which are highly conserved among fungi that undergo hyphal growth, control signaling modules important to the directional growth of fungal hyphae.
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MESH Headings
- Alleles
- Amino Acid Sequence
- Animals
- Aspergillosis/microbiology
- Aspergillosis/mortality
- Aspergillosis/pathology
- Aspergillus fumigatus/cytology
- Aspergillus fumigatus/genetics
- Aspergillus fumigatus/growth & development
- Aspergillus fumigatus/pathogenicity
- Biomass
- Cell Culture Techniques
- Chromosome Mapping
- Chromosomes, Fungal
- Disease Models, Animal
- Gene Deletion
- Gene Expression Regulation, Fungal
- Genes, Dominant
- Genes, Fungal
- Genes, ras
- Genome, Fungal
- Hyphae/cytology
- Hyphae/growth & development
- Image Processing, Computer-Assisted
- Mice
- Mice, Inbred Strains
- Molecular Sequence Data
- Sequence Homology, Amino Acid
- Survival Analysis
- Time Factors
- Transgenes
- Virulence
- ras Proteins/chemistry
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Affiliation(s)
- Jarrod R Fortwendel
- Department of Pathology and Laboratory Medicine, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267-0529, USA
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28
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da Silva Ferreira ME, Kress MRVZ, Savoldi M, Goldman MHS, Härtl A, Heinekamp T, Brakhage AA, Goldman GH. The akuB(KU80) mutant deficient for nonhomologous end joining is a powerful tool for analyzing pathogenicity in Aspergillus fumigatus. Eukaryot Cell 2006; 5:207-11. [PMID: 16400184 PMCID: PMC1360264 DOI: 10.1128/ec.5.1.207-211.2006] [Citation(s) in RCA: 324] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Accepted: 11/07/2005] [Indexed: 11/20/2022]
Abstract
To increase the frequency of homologous recombination, we inactivated the KU80 homologue in Aspergillus fumigatus (named akuB(KU80)). Homologous integration reached about 80% for both calcineurin A (calA) and polyketide synthase pksP (alb1) genes in the akuB(KU80) mutant to 3 and 5%, respectively, when using a wild-type A. fumigatus strain. Deletion of akuB(KU80) had no influence on pathogenicity in a low-dose murine infection model.
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Affiliation(s)
- Márcia Eliana da Silva Ferreira
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Departamento de Ciências Farmacêuticas, Universidade de São Paulo, Av. do Café S/N, CEP 14040-903, Ribeirão Preto, São Paulo, Brazil
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29
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Rambach G, Hagleitner M, Mohsenipour I, Lass-Flörl C, Maier H, Würzner R, Dierich MP, Speth C. Antifungal activity of the local complement system in cerebral aspergillosis. Microbes Infect 2005; 7:1285-95. [PMID: 16027023 DOI: 10.1016/j.micinf.2005.04.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Revised: 03/30/2005] [Accepted: 04/22/2005] [Indexed: 10/25/2022]
Abstract
Dissemination of aspergillosis into the central nervous system is associated with nearly 100% mortality. To study the reasons for the antifungal immune failure we analyzed the efficacy of cerebral complement to combat the fungus Aspergillus. Incubation of Aspergillus in non-inflammatory cerebrospinal fluid (CSF) revealed that complement levels were sufficient to obtain a deposition on the surface, but opsonization was much weaker than in serum. Consequently complement deposition from normal CSF on fungal surface stimulated a very low phagocytic activity of microglia, granulocytes, monocytes and macrophages compared to stimulation by conidia opsonized in serum. Similarly, opsonization of Aspergillus by CSF was not sufficient to induce an oxidative burst in infiltrating granulocytes, whereas conidia opsonized in serum induced a clear respiratory signal. Thus, granulocytes were capable of considerably reducing the viability of serum-opsonized Aspergillus conidia, but not of conidia opsonized in CSF. The limited efficacy of antifungal attack by cerebral complement can be partly compensated by enhanced synthesis, leading to elevated complement concentrations in CSF derived from a patient with cerebral aspergillosis. This inflammatory CSF was able to induce (i) a higher complement deposition on the Aspergillus surface than non-inflammatory CSF, (ii) an accumulation of complement activation products and (iii) an increase in phagocytic and killing activity of infiltrating granulocytes. However, levels and efficacy of the serum-derived complement were not reached. These data indicate that low local complement synthesis and activation may represent a central reason for the insufficient antifungal defense in the brain and the high mortality rate of cerebral aspergillosis.
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Affiliation(s)
- Günter Rambach
- Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, and Ludwig-Boltzmann-Institute for AIDS Research, Fritz-Pregl-Str. 3, 6020 Innsbruck, Austria
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Maerker C, Rohde M, Brakhage AA, Brock M. Methylcitrate synthase from Aspergillus fumigatus. Propionyl-CoA affects polyketide synthesis, growth and morphology of conidia. FEBS J 2005; 272:3615-30. [PMID: 16008561 DOI: 10.1111/j.1742-4658.2005.04784.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Methylcitrate synthase is a key enzyme of the methylcitrate cycle and required for fungal propionate degradation. Propionate not only serves as a carbon source, but also acts as a food preservative (E280-283) and possesses a negative effect on polyketide synthesis. To investigate propionate metabolism from the opportunistic human pathogenic fungus Aspergillus fumigatus, methylcitrate synthase was purified to homogeneity and characterized. The purified enzyme displayed both, citrate and methylcitrate synthase activity and showed similar characteristics to the corresponding enzyme from Aspergillus nidulans. The coding region of the A. fumigatus enzyme was identified and a deletion strain was constructed for phenotypic analysis. The deletion resulted in an inability to grow on propionate as the sole carbon source. A strong reduction of growth rate and spore colour formation on media containing both, glucose and propionate was observed, which was coincident with an accumulation of propionyl-CoA. Similarly, the use of valine, isoleucine and methionine as nitrogen sources, which yield propionyl-CoA upon degradation, inhibited growth and polyketide production. These effects are due to a direct inhibition of the pyruvate dehydrogenase complex and blockage of polyketide synthesis by propionyl-CoA. The surface of conidia was studied by electron scanning microscopy and revealed a correlation between spore colour and ornamentation of the conidial surface. In addition, a methylcitrate synthase deletion led to an attenuation of virulence, when tested in an insect infection model and attenuation was even more pronounced, when whitish conidia from glucose/propionate medium were applied. Therefore, an impact of methylcitrate synthase in the infection process is discussed.
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Abstract
Omphalitis associated with aspergillosis was diagnosed in four cases of commercial turkey poults ranging in age from 3 to 9 days old. In two cases, the mycotic agent present in the yolk sac was isolated and identified as Aspergillus fumigatus. In the other two cases, the fungi were identified as Aspergillus sp. on the basis of morphologic characteristics of the fungi in tissue sections. The fungi present were further confirmed to be of the genus Aspergillus by immunohistochemistry. Omphalitis by A. fumigatus infection has not been documented before.
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Affiliation(s)
- P L Cortes
- California Animal Health and Food Safety Laboratory System, Fresno Branch, University of California, Davis, 2789 South Orange Avenue, Fresno, CA 93725, USA
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Mouyna I, Henry C, Doering TL, Latgé JP. Gene silencing with RNA interference in the human pathogenic fungus Aspergillus fumigatus. FEMS Microbiol Lett 2004; 237:317-24. [PMID: 15321679 DOI: 10.1016/j.femsle.2004.06.048] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Revised: 06/18/2004] [Accepted: 06/29/2004] [Indexed: 10/26/2022] Open
Abstract
Aspergillus fumigatus is an opportunistic pathogenic fungus which causes fatal invasive aspergillosis among immunocompromised patients. To obtain a better understanding of the key elements involved in A. fumigatus virulence and to identify possible drug targets, it is necessary to be able to generate gene-deletion strains. Unfortunately, the molecular techniques available do not include a rapid method to disrupt and identify essential genes. RNA interference, a process in which the presence of double-stranded RNA homologous to a gene of interest results in specific degradation of the corresponding message, has been successfully tested on A. fumigatus. We have shown that expression of double stranded RNA corresponding to portions of the ALB1/PKSP and FKS1 genes results in reduced mRNA levels for those genes, with phenotypic consequences similar to that of gene disruption. The two genes could also be subjected to simultaneous interference through expression of chimeric double-stranded RNA. Use of RNA interference in Aspergillus will allow easier examination of the phenotypic consequences of reducing expression of a gene of interest, especially for essential genes.
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Affiliation(s)
- Isabelle Mouyna
- Institut Pasteur, Unité des Aspergillus, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France.
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Fortwendel JR, Panepinto JC, Seitz AE, Askew DS, Rhodes JC. Aspergillus fumigatus rasA and rasB regulate the timing and morphology of asexual development. Fungal Genet Biol 2004; 41:129-39. [PMID: 14732259 DOI: 10.1016/j.fgb.2003.10.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Expression of rasA plays an important role in conidial germination in Aspergillus nidulans. Conidial germination is required to initiate both infection and asexual development in the opportunistic pathogen Aspergillus fumigatus. Therefore, we sought to determine the requirements for Ras proteins in conidial germination and asexual development of A. fumigatus. A second homolog, rasB, has been identified that characterizes a new subclass of Ras genes. Dominant active (DA) and dominant negative (DN) mutations of each gene were introduced into protoplasts as transgenes. DArasA expression led to reduced conidiation, malformed conidiophores, and altered mitotic progression, whereas expression of DNrasA caused a significant reduction in the rate of conidial germination. In contrast, expression of DNrasB slightly delayed the initiation of germination and caused the development of conidiophores in submerged culture. DArasB expression led to reduced conidiation. RasA and RasB appear to play different, but overlapping, roles in the vegetative growth and asexual development of A. fumigatus.
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Affiliation(s)
- Jarrod R Fortwendel
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH 45267-0529, USA
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Moore CW, McKoy J, Del Valle R, Armstrong D, Bernard EM, Katz N, Gordon RE. Fungal cell wall septation and cytokinesis are inhibited by bleomycins. Antimicrob Agents Chemother 2004; 47:3281-9. [PMID: 14506042 PMCID: PMC201140 DOI: 10.1128/aac.47.10.3281-3289.2003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When the essential and distinctive cell walls of either pathogenic or nonpathogenic fungi break, cytoplasmic membranes rupture and fungi die. This fungicidal activity was discovered previously on nonproliferating Saccharomyces cerevisiae cells treated briefly with the oxidative tool and anticancer drug family of bleomycins. The present studies investigated effects of bleomycin on growing fungal organisms. These included the medically important Aspergillus fumigatus and Cryptococcus neoformans, as well as the emerging human pathogen and fungal model, S. cerevisiae. Bleomycin had its highest potency against A. fumigatus. Scanning electron microscopy and thin-section transmission electron microscopy were used to study morphological growth characteristics. Killing and growth inhibition were also measured. Long, thin, and segmented hyphae were observed when A. fumigatus was grown without bleomycin but were never observed when the mold was grown with the drug. Bleomycin arrested conidial germination, hyphal development, and the progression and completion of cell wall septation. Similarly, the drug inhibited the construction of yeast cell wall septa, preventing cytokinesis and progression in the cell division cycle of S. cerevisiae. Even when cytoplasms of mother and daughter cells separated, septation and cell division did not necessarily occur. Bizarre cell configurations, abnormally thickened cell walls at mother-daughter necks, abnormal polarized growth, large undivided cells, fragmented cells, and empty cell ghosts were also produced. This is the first report of a fungicidal agent that arrests fungal growth and development, septum formation, and cytokinesis and that also preferentially localizes to cell walls and alters isolated cell walls as well as intact cell walls on nongrowing cells.
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Affiliation(s)
- Carol W Moore
- Department of Microbiology and Immunology, City University of New York Medical School and Sophie Davis School of Biomedical Education, New York, New York 10031, USA.
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Abstract
A rapid method based on solid phase cytometry (SPC) for the detection of Aspergillus fumigatus hyphae is described. With an enzymatic "viability" staining procedure, fungal hyphae can be detected non-specifically within the hour. By combining this procedure with an immunofluorescence labelling, a distinction between Aspergillus spp. and other clinically important fungi is possible, except for Penicillium spp. due to cross-reactivity. To differentiate both genera, microcolonies are generated by incubation at 45 degrees C prior to viability staining. The latter approach in conjunction with immunofluorescence labelling allows a quasi-specific detection of A. fumigatus hyphae and has shown its applicability to samples of bronchoalveolar lavage liquid (BAL).
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Affiliation(s)
- Muriel M De Vos
- Laboratory for Pharmaceutical Microbiology, University of Ghent, Harelbekestraat 72, B-9000 Ghent, Belgium
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Romero B, Turner G, Olivas I, Laborda F, De Lucas JR. The Aspergillus nidulans alcA promoter drives tightly regulated conditional gene expression in Aspergillus fumigatus permitting validation of essential genes in this human pathogen. Fungal Genet Biol 2003; 40:103-14. [PMID: 14516763 DOI: 10.1016/s1087-1845(03)00090-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aspergillus fumigatus causes invasive aspergillosis, a mycosis that is usually fatal in immunocompromised patients. Functional genomics in this fungus will aid the discovery of novel antifungal drugs to treat invasive aspergillosis. However, there is still a need for appropriate molecular genetic tools to facilitate such functional studies. Here, we describe the use of a conditional gene expression system allowing the identification of novel therapeutic targets through validation of essential genes in A. fumigatus. This system is based on the capacity of the Aspergillus nidulans alcA promoter (alcA(p)) to tightly regulate gene expression in this fungus. Conditionally regulated gene expression in A. fumigatus was demonstrated by transcriptional and phenotypic analyses of strains expressing a nuclear migration gene with a terminal phenotype, the A. fumigatus nudC gene, under control of this promoter. This conditional expression system, the first one described in A. fumigatus, will also be useful for investigating the function of essential genes by altering the threonine/glucose ratio in the growth medium.
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MESH Headings
- Alcohol Dehydrogenase/genetics
- Aspergillus fumigatus/cytology
- Aspergillus fumigatus/genetics
- Aspergillus fumigatus/growth & development
- Aspergillus fumigatus/metabolism
- Aspergillus nidulans/genetics
- Blotting, Northern
- Blotting, Southern
- Cloning, Molecular
- DNA, Fungal/chemistry
- DNA, Fungal/genetics
- DNA, Fungal/isolation & purification
- Gene Expression Regulation, Fungal
- Genes, Essential
- Genes, Fungal
- Molecular Sequence Data
- Promoter Regions, Genetic
- RNA, Messenger/analysis
- Recombination, Genetic
- Threonine/metabolism
- Transcription, Genetic
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Affiliation(s)
- Beatriz Romero
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Campus Universitario, Universidad de Alcalá, Ctra Madrid-Barcelona Km 33, E-28871 Alcalá de Henares, Madrid, Spain
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Leitao EA, Bittencourt VCB, Haido RMT, Valente AP, Peter-Katalinic J, Letzel M, de Souza LM, Barreto-Bergter E. Beta-galactofuranose-containing O-linked oligosaccharides present in the cell wall peptidogalactomannan of Aspergillus fumigatus contain immunodominant epitopes. Glycobiology 2003; 13:681-92. [PMID: 12851285 DOI: 10.1093/glycob/cwg089] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
O-linked oligosaccharide groups ranging from di- to hexasaccharide were beta-eliminated by mild alkaline treatment under reducting conditions from the peptidogalactomannan of Aspergillus fumigatus mycelial cell wall. The resulting reduced oligosaccharides, which were the minor components of the peptidogalactomannan fraction, were fractionated to homogeneity by successive gel filtration and high-performance liquid chromatography. Their primary structures were determined based on a combination of techniques including gas chromatography, ESI-QTOF-MS, 1H COSY and TOCSY, and 1H-13C HMQC NMR spectroscopy and methylation analysis, to be: alpha-Glcp-(1 --> 6)-Man-ol, beta-Galf-(1 --> 6)-alpha-Manp-(1 --> 6)-Man-ol, beta-Galf-(1 --> 5)-beta-Galf-(1 --> 6)-alpha-Manp-(1 --> 6)-Man-ol and beta-Galf-(1 --> 5)-[beta-Galf-(1 --> 5]3-beta-Galf-(1 --> 6)-Man-ol. The beta-Galf containing oligosaccharides have not been previously described as fungal O-linked oligosaccharides. The peptidogalactomannan is antigenic and was recognized by human sera of patients with aspergillosis when probed by ELISA, but de-O-glycosylation rendered a 50% decrease in its reactivity. Furthermore, when tested in a hapten inhibition test, the isolated oligosaccharide alditols were able to block, on a dose-response basis, recognition between human sera and the intact peptidogalactomannan. The immunodominant epitopes were present in the tetra- and hexasaccharide, which contain a beta-Galf-(1 --> 5)-beta-Galf terminal group. These results suggest that the O-glycosidically linked oligosaccharide chains, despite being the less abundant carbohydrate component of the A. fumigatus peptidogalactomannan, may account for a significant part of its antigenicity, other than the known activity associated with the galactomannan component.
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Affiliation(s)
- Eduardo A Leitao
- Instituto de Microbiologia Professor Paulo de Góes, CCS Universidade Federal do Rio de Janeiro, 21944-970, Rio de Janeiro, RJ, Brasil
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Mousavi SAA, Robson GD. Entry into the stationary phase is associated with a rapid loss of viability and an apoptotic-like phenotype in the opportunistic pathogen Aspergillus fumigatus. Fungal Genet Biol 2003; 39:221-9. [PMID: 12892635 DOI: 10.1016/s1087-1845(03)00047-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
When the opportunistic pathogen Aspergillus fumigatus entered the stationary phase, there was a rapid loss in cell viability which was associated with the appearance of markers characteristic of apoptosis, namely annexin V-FITC binding to the cytoplasmic membrane, demonstrating exposure of phosphatidylserine to the outer leaflet of the membrane; and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) staining of the nuclei, indicating DNA fragmentation. This was followed later by a loss of membrane integrity as revealed by propidium iodide staining. The development of the apoptotic phenotype was blocked when the protein synthesis inhibitor cycloheximide was added to the culture 1h prior to the onset of the stationary phase, demonstrating active participation of the cell. In addition, intracellular activity against substrates specific for caspase-1 and -8 also increased on stationary phase entry and the development of the apoptotic phenotype was blocked when the cell permeant caspase inhibitor Z-FAD-fmk was present in the medium. Cell death in A. fumigatus during the stationary phase therefore appears to share similarities to apoptotic cell death in higher eukaryotes and to be dependent on a caspase-like activity.
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Affiliation(s)
- S Amin A Mousavi
- School of Biological Sciences, 1.800 Stopford Building, University of Manchester, M13 9PT Manchester, UK
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Yang W, Hartwieg EA, Fang A, Demain AL. Effects of carboxymethylcellulose and carboxypolymethylene on morphology of Aspergillus fumigatus NRRL 2346 and fumagillin production. Curr Microbiol 2003; 46:24-7. [PMID: 12432459 DOI: 10.1007/s00284-002-3711-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Aspergillus fumigatus NRRL 2346 is the producer of fumagillin, an antitumor antibiotic that inhibits angiogenesis. This strain is very difficult to grow reproducibly in shake flasks owing to an extreme form of pellet growth and extensive wall growth. The effects of carboxymethylcellulose (CMC) and carboxypolymethylene (Carbopol) on growth and fumagillin production by A. fumigatus were investigated. By adding the polymers to the fermentation medium, the growth form of the mold was changed from a single large glob to small reproducible pellets, and wall growth was diminished to a minimum. Carbopol, at a lower concentration, was more effective than CMC in improving both morphology and production. Small pellets were produced which favored fumagillin biosynthesis. 1.5% (wt/vol) CMC and 0.3% (wt/vol) Carbopol were found to be the optimum concentrations; higher levels increased viscosity to an unacceptable level.
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Affiliation(s)
- Wen Yang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
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40
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Momany M, Taylor I. Landmarks in the early duplication cycles of Aspergillus fumigatus and Aspergillus nidulans: polarity, germ tube emergence and septation. Microbiology (Reading) 2000; 146 Pt 12:3279-3284. [PMID: 11101686 DOI: 10.1099/00221287-146-12-3279] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
When the spores of filamentous fungi break dormancy, nuclear division is accompanied by a series of ordered morphological events including the switch from isotropic to polar growth, the emergence of a second germ tube from the conidium and septation. Correlation of these morphological events with nuclear number allows them to serve as duplication cycle landmarks. Early duplication cycle landmarks have been characterized in Aspergillus nidulans, but not in other filamentous fungi. To learn more about duplication cycle control in filamentous fungi, a study was undertaken to compare the timing of landmarks in Aspergillus fumigatus and A. nidulans. Nuclear duplication took approximately 45 min in A. fumigatus, with mitosis occupying roughly 5% of this period. Under the same conditions, nuclear duplication in A. nidulans took approximately 60 min, with mitosis occupying roughly 4% of this period. In A. fumigatus the isotropic to polar switch preceded the first mitosis in 22% of cells, while in A. nidulans the isotropic to polar switch did not occur until after the first mitosis. In both A. fumigatus and A. nidulans the earliest emergence of a second germ tube from the conidium occurred after the third mitotic division. However, by the fifth mitosis only 19% of A. fumigatus conidia had a second germ tube, compared to 98% of A. nidulans conidia. In both A. fumigatus and A. nidulans, formation of the first septum occurred after the fourth mitotic division. In all experiments a few cells lagged behind the others in nuclear number. In this delayed group, it was common to see landmark events at an earlier mitotic division. Differences in nuclear number when identical landmarks occur in A. fumigatus versus A. nidulans, and uncoupling of mitotic division and landmarks in delayed cells suggest that nuclear division and morphogenesis lie in parallel pathways, perhaps coordinated by checkpoints.
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Affiliation(s)
- Michelle Momany
- Department of Botany, University of Georgia, Athens, GA 30602 7271, USA1
| | - Ian Taylor
- Department of Botany, University of Georgia, Athens, GA 30602 7271, USA1
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Abstract
The Aspergillus fumigatus group splits into the anamorphic A. fumigatus series and the teleomorphic Neosartorya fischeri series. The species A. fumigatus Fresenius is the most common species within the A. fumigatus series. Forty-seven clinical isolates out of the A. fumigatus group were obtained from patients with diseases such as localized and invasive aspergilloses or allergic disorders due to Aspergillus and were mainly isolated from respiratory secretions. Isolates were studied concerning macro- and micromorphological parameters. All isolates were shown to be isolates of the species A. fumigatus Fresenius. In general, the macro- and micromorphological variability between the different isolates was low. Four isolates (DSM 10661, DSM 10662, DSM 10705, DSM 11069) showed significant differences towards the type strain A. fumigatus Fresenius ATCC 1022; one of these isolates was highly atypical (DSM 10705).
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Affiliation(s)
- A Schmidt
- Institute for Microbiology and Virology, University Witten/Herdecke, Germany
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Abstract
Sixty-one isolates and collection strains of Aspergillus fumigatus were compared for their phenotypic (morphological features and isoenzyme profiles) and genotypic (restriction enzyme-generated mitochondrial DNA and ribosomal DNA profiles and random amplified polymorphic DNA patterns) features. The examined strains exhibited highly variable colony morphologies and growth rates at different temperatures, but their micromorphologies and conidial diameters were characteristic of the species. Of the isoenzymes studied, the beta-arylesterase and phosphatase patterns were the most divergent, and the 61 strains could be classified into seven groups. The glucose 6-phosphate dehydrogenase and catalase isoenzyme patterns displayed only a limited variability, while the profiles of superoxide dismutase, lactate dehydrogenase, and glutamate dehydrogenase were highly conserved. The HaeIII-generated mitochondrial DNA patterns and SmaI-digested repetitive DNA and ribosomal DNA hybridization patterns of almost all strains were also invariable. The level of variation was much higher when random amplified polymorphic DNA analysis was applied. Although the patterns of the strains were very similar with most of the primers, the application of some primers made it possible to cluster the A. fumigatus isolates into several groups. The results indicate that the random amplified polymorphic DNA technique could be used more efficiently than isoenzyme analysis for typing A. fumigatus isolates. A good correlation was found between the dendrograms obtained from the isoenzyme and random amplified polymorphic DNA data, but the isoenzyme and amplified DNA patterns did not correlate with the pathogenicity, pigment production, or geographical origin of the strains. One "A. fumigatus" strain (strain FRR 1266) exhibited unique isoenzyme, mitochondrial DNA, ribosomal DNA, and random amplified polymorphic DNA patterns; it is proposed that this strain represents a new species of the section Fumigati.
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Affiliation(s)
- E Rinyu
- Department of Microbiology, Attila-József University, Szeged, Hungary
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Roilides E, Uhlig K, Venzon D, Pizzo PA, Walsh TJ. Enhancement of oxidative response and damage caused by human neutrophils to Aspergillus fumigatus hyphae by granulocyte colony-stimulating factor and gamma interferon. Infect Immun 1993; 61:1185-93. [PMID: 7681040 PMCID: PMC281347 DOI: 10.1128/iai.61.4.1185-1193.1993] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Invasive aspergillosis is a serious fungal infection caused by the proliferation and invasion of Aspergillus hyphae in tissue. Neutrophils (PMNs) are the most important line of defense against Aspergillus hyphae. To investigate the role of granulocyte colony-stimulating factor (G-CSF) and gamma interferon (IFN-gamma) against Aspergillus fumigatus, we studied the effects of the two cytokines on the oxidative burst and the capacity of normal human PMNs to damage hyphae of the organism. G-CSF enhanced PMN oxidative burst measured as superoxide anion (O2-) production in response to N-formylmethionyl leucyl phenylalanine, serum opsonized hyphae, and nonopsonized hyphae by 75, 37, and 24%, respectively, compared with control PMNs (P < 0.015). IFN-gamma also induced increases of 52, 71, and 96%, respectively, in response to the same stimuli (P < 0.006). In addition, the capacity of PMNs to damage hyphae as measured by the 3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MMT) colorimetric metabolic assay was significantly enhanced by G-CSF and IFN-gamma (P < 0.01 and < 0.05, respectively). The enhancement was achieved irrespective of serum opsonization of the hyphae, suggesting upregulatory actions of the two cytokines on signal pathways specific for opsonized and nonopsonized hyphae. The combination of the two cytokines exhibited an additive effect at the higher concentrations compared with the effects of the cytokines alone (P < 0.05). Pretreatment of PMNs with protein synthesis inhibitors showed that IFN-gamma activates PMN function through transcriptional regulation, whereas the effect of G-CSF does not require new proteins. These in vitro effects suggest modulatory roles for G-CSF and IFN-gamma in the host defense against Aspergillus hyphae irrespective of serum opsonization and a potential utility of the cytokines as adjuncts for the prevention and possible treatment of invasive aspergillosis.
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Affiliation(s)
- E Roilides
- Infectious Diseases Section, National Cancer Institute, Bethesda, Maryland 20892
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McGuire TW, Bullock JD, Bullock JD, Elder BL, Funkhouser JW. Fungal endophthalmitis. An experimental study with a review of 17 human ocular cases. Arch Ophthalmol 1991; 109:1289-96. [PMID: 1929959 DOI: 10.1001/archopht.1991.01080090115034] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Pseudallescheria boydii is an opportunistic fungus that is histologically indistinguishable from Aspergillus fumigatus. Pseudallescheria boydii has been reported to cause endophthalmitis, orbital cellulitis, and corneal ulceration and is, thus, important to the ophthalmologist. A clinical review of 17 patients with P boydii ophthalmic infections is presented. In addition, animal models of endophthalmitides caused by A fumigatus and P boydii were created and compared. Dutch-Belted rabbits used for the experimental models were immunosuppressed with methylprednisolone acetate (Depomedrol). Exogenous and endogenous models of P boydii endophthalmitis were created in immunocompetent and immunosuppressed animals. An exogenous model of A fumigatus endophthalmitis was created in immunocompetent and immunosuppressed animals for comparison. The clinical and histopathologic features of A fumigatus and P boydii endophthalmitis are indistinguishable in the immunocompetent and immunosuppressed exogenously infected rabbits. Endogenous P boydii endophthalmitis has a similar fundus appearance to that caused by Nocardia asteroides.
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Affiliation(s)
- T W McGuire
- Wright State University School of Medicine, Dayton, OH
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Abstract
Complement activation by Aspergillus fumigatus may play a crucial role in stimulating binding and killing of this organism by phagocytes. We examined the amount and type of C3 deposited on resting conidia, swollen conidia, and hyphae of A. fumigatus after incubation in pooled human serum. All three life forms of A. fumigatus were potent activators of the complement cascade, with deposition on the organisms of similar amounts of C3 per unit of surface area. The rate of deposition was slowest for resting conidia, although maximal deposition was still achieved within 40 min. The roles of the alternative and classical pathways were assessed by use of serum chelated with magnesium EGTA [magnesium ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] and with an alternative pathway reconstituted from the six purified alternative-pathway proteins. Complement activation by resting conidia was mediated by the alternative pathway. In contrast, there was a progressive dependence on the classical pathway as the fungal particles matured into swollen conidia and then hyphae. Treatment with hydroxylamine, which disrupts ester linkages, removed 89 to 95% of the C3 bound to all three forms of A. fumigatus. This released C3 contained a mixture of C3b and iC3b, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. These data demonstrate that although all three forms of A. fumigatus are potent activators of the complement system, the transition from resting conidia to swollen conidia to hyphae results in progressive changes in the manner in which the fungal particles interact with the complement system. The lack of participation of the classical pathway in complement activation by resting conidia may have important implications regarding their ability to effectively stimulate phagocytes.
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Affiliation(s)
- T R Kozel
- Department of Microbiology, University of Nevada-Reno
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Body BA, Schwartzman JD, Brown H, Gröschel DH. Possible confusion of Aspergillus fumigatus and Pneumocystis carinii. Eur J Clin Microbiol 1987; 6:603-4. [PMID: 2449349 DOI: 10.1007/bf02014265] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Staib F. Pleural fluid as nutrient substratum for Aspergillus fumigatus and A. flavus. Submerged growth in pleural fluid and extracellular proteolysis in pleural fluid agar. A preliminary report. Zentralbl Bakteriol Mikrobiol Hyg A 1985; 260:543-9. [PMID: 3938910 DOI: 10.1016/s0176-6724(85)80070-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Pleural fluid in liquid and agar form from a patient with adenocarcinoma of the lung was used as a nutrient medium for culturing Aspergillus fumigatus and A, flavus. The extracellular proteolytic activity of both strains could be demonstrated after an incubation period of 5 d at 37 degrees C by the agar block method using pleural fluid agar (protein content ca. 0.1-0.5% and initial pH values of 7.0 and 5.0) and protein staining with naphthalene black. In the undiluted pleural fluid, after stationary culture at 37 degrees C for 8 days, compact white granule-like colonies of a size of ca. 0.5-1.0 mm were found near the surface of the liquid and as sediment. Microscopically, these colonies consisted of radially arranged septate hyphae, similar in size and form to those seen in invasive aspergillosis.
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Marsella R, Mercantini R, Stefanini A, Volterra L. An atypical isolate of Aspergillus fumigatus from a man affected with a pulmonary disease. Mykosen 1983; 26:201-6. [PMID: 6346091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Staib F. Extracellular proteolytic activity of Aspergillus fumigatus strains with septum-like structures in their phialides in serum-albumin agar--preliminary report. Zentralbl Bakteriol Mikrobiol Hyg A Med Mikrobiol Infekt Parasitol 1982; 252:279-85. [PMID: 6750988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Rajendran C, Staib F. Studies on Aspergillus fumigatus from the human lungs. Zentralbl Bakteriol Mikrobiol Hyg A Med Mikrobiol Infekt Parasitol 1982; 252:132-41. [PMID: 6750981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
On the basis of cultural, morphological and developmental studies of the two Aspergillus isolates from the lungs of an aspergillosis patient, the taxonomic status of Aspergillus phialiseptus is discussed. The elimination of the name A. phialiseptus is proposed as the isolates were found by the authors to belong to A. fumigatus.
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