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Abstract
Aspergillus nidulans has long-been used as a model organism to gain insights into the genetic basis of asexual and sexual developmental processes both in other members of the genus Aspergillus, and filamentous fungi in general. Paradigms have been established concerning the regulatory mechanisms of conidial development. However, recent studies have shown considerable genome divergence in the fungal kingdom, questioning the general applicability of findings from Aspergillus, and certain longstanding evolutionary theories have been questioned. The phylogenetic distribution of key regulatory elements of asexual reproduction in A. nidulans was investigated in a broad taxonomic range of fungi. This revealed that some proteins were well conserved in the Pezizomycotina (e.g. AbaA, FlbA, FluG, NsdD, MedA, and some velvet proteins), suggesting similar developmental roles. However, other elements (e.g. BrlA) had a more restricted distribution solely in the Eurotiomycetes, and it appears that the genetic control of sporulation seems to be more complex in the aspergilli than in some other taxonomic groups of the Pezizomycotina. The evolution of the velvet protein family is discussed based on the history of expansion and contraction events in the early divergent fungi. Heterologous expression of the A. nidulans abaA gene in Monascus ruber failed to induce development of complete conidiophores as seen in the aspergilli, but did result in increased conidial production. The absence of many components of the asexual developmental pathway from members of the Saccharomycotina supports the hypothesis that differences in the complexity of their spore formation is due in part to the increased diversity of the sporulation machinery evident in the Pezizomycotina. Investigations were also made into the evolution of sex and sexuality in the aspergilli. MAT loci were identified from the heterothallic Aspergillus (Emericella) heterothallicus and Aspergillus (Neosartorya) fennelliae and the homothallic Aspergillus pseudoglaucus (=Eurotium repens). A consistent architecture of the MAT locus was seen in these and other heterothallic aspergilli whereas much variation was seen in the arrangement of MAT loci in homothallic aspergilli. This suggested that it is most likely that the common ancestor of the aspergilli exhibited a heterothallic breeding system. Finally, the supposed prevalence of asexuality in the aspergilli was examined. Investigations were made using A. clavatus as a representative 'asexual' species. It was possible to induce a sexual cycle in A. clavatus given the correct MAT1-1 and MAT1-2 partners and environmental conditions, with recombination confirmed utilising molecular markers. This indicated that sexual reproduction might be possible in many supposedly asexual aspergilli and beyond, providing general insights into the nature of asexuality in fungi.
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Hong SB, Go SJ, Shin HD, Frisvad JC, Samson RA. Polyphasic taxonomy ofAspergillus fumigatusand related species. Mycologia 2017. [DOI: 10.1080/15572536.2006.11832738] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
| | - Seung-Joo Go
- Korean Agricultural Culture Collection, NIAB, Suwon, 441-707, Korea
| | - Hyeon-Dong Shin
- Division of Environmental Science and Ecological Engineering, College of Life and Environmental Science, Korea University, Seoul 136-701, Korea
| | - Jens C. Frisvad
- Center for Microbial Biotechnology, Biocentrum-DTU, Technical University of Denmark, Building 221, DK-2800, Kgs. Lyngby, Denmark
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Sekhohola LM, Isaacs ML, Cowan AK. Fungal colonization and enzyme-mediated metabolism of waste coal by Neosartorya fischeri strain ECCN 84. Biosci Biotechnol Biochem 2014; 78:1797-802. [PMID: 25273148 DOI: 10.1080/09168451.2014.930325] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Colonization and oxidative metabolism of South African low-rank discard coal by the fungal strain ECCN 84 previously isolated from a coal environment and identified as Neosartorya fischeri was investigated. Results show that waste coal supported fungal growth. Colonization of waste coal particles by N. fischeri ECCN 84 was associated with the formation of compact spherical pellets or sclerotia-like structures. Dissection of the pellets from liquid cultures revealed a nucleus of "engulfed" coal which when analyzed by energy dispersive X-ray spectroscopy showed a time-dependent decline in weight percentage of elemental carbon and an increase in elemental oxygen. Proliferation of peroxisomes in hyphae attached to coal particles and increased extracellular laccase activity occurred after addition of waste coal to cultures of N. fischeri ECCN 84. These results support a role for oxidative enzyme action in the biodegradation of coal and suggest that extracellular laccase is a key component in this process.
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Affiliation(s)
- Lerato Mary Sekhohola
- a Institute for Environmental Biotechnology (EBRU) , Rhodes University , Grahamstown , South Africa
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Soleiro C, Pena G, Cavaglieri L, Coelho I, Keller L, Dalcero A, Rosa C. Typing clinical and animal environment Aspergillus fumigatus
gliotoxin producer strains isolated from Brazil by PCR-RFLP markers. Lett Appl Microbiol 2013; 57:484-91. [DOI: 10.1111/lam.12136] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 07/12/2013] [Accepted: 07/18/2013] [Indexed: 11/25/2022]
Affiliation(s)
- C.A. Soleiro
- Departamento de Microbiologia e Imunología Veterinária; Universidade Federal Rural do Rio de Janeiro, Instituto de Veterinária; Seropédica Brazil
- Conselho Nacional de Pesquisas Científicas (CNPq); Belo Horizonte Brazil
| | - G.A. Pena
- Departamento de Microbiología e Inmunología; Facultad de Ciencias Exactas; Físico-Químicas y Naturales; Universidad Nacional de Río Cuarto; Río Cuarto Córdoba Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Buenos Aires Argentina
| | - L.R. Cavaglieri
- Departamento de Microbiología e Inmunología; Facultad de Ciencias Exactas; Físico-Químicas y Naturales; Universidad Nacional de Río Cuarto; Río Cuarto Córdoba Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Buenos Aires Argentina
| | - I. Coelho
- Departamento de Microbiologia e Imunología Veterinária; Universidade Federal Rural do Rio de Janeiro, Instituto de Veterinária; Seropédica Brazil
| | - L.M. Keller
- Departamento de Microbiologia e Imunología Veterinária; Universidade Federal Rural do Rio de Janeiro, Instituto de Veterinária; Seropédica Brazil
- Conselho Nacional de Pesquisas Científicas (CNPq); Belo Horizonte Brazil
| | - A.M. Dalcero
- Departamento de Microbiología e Inmunología; Facultad de Ciencias Exactas; Físico-Químicas y Naturales; Universidad Nacional de Río Cuarto; Río Cuarto Córdoba Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Buenos Aires Argentina
| | - C.A.R. Rosa
- Departamento de Microbiologia e Imunología Veterinária; Universidade Federal Rural do Rio de Janeiro, Instituto de Veterinária; Seropédica Brazil
- Conselho Nacional de Pesquisas Científicas (CNPq); Belo Horizonte Brazil
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Woudenberg JHC, De Gruyter J, Crous PW, Zwiers LH. Analysis of the mating-type loci of co-occurring and phylogenetically related species of Ascochyta and Phoma. MOLECULAR PLANT PATHOLOGY 2012; 13:350-62. [PMID: 22014305 PMCID: PMC6638728 DOI: 10.1111/j.1364-3703.2011.00751.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Ascochyta and Phoma are fungal genera containing several important plant pathogenic species. These genera are morphologically similar, and recent molecular studies performed to unravel their phylogeny have resulted in the establishment of several new genera within the newly erected Didymellaceae family. An analysis of the structure of fungal mating-type genes can contribute to a better understanding of the taxonomic relationships of these plant pathogens, and may shed some light on their evolution and on differences in sexual strategy and pathogenicity. We analysed the mating-type loci of phylogenetically closely related Ascochyta and Phoma species (Phoma clematidina, Didymella vitalbina, Didymella clematidis, Peyronellaea pinodes and Peyronellaea pinodella) that co-occur on the same hosts, either on Clematis or Pisum. The results confirm that the mating-type genes provide the information to distinguish between the homothallic Pey. pinodes (formerly Ascochyta pinodes) and the heterothallic Pey. pinodella (formerly Phoma pinodella), and indicate the close phylogenetic relationship between these two species that are part of the disease complex responsible for Ascochyta blight on pea. Furthermore, our analysis of the mating-type genes of the fungal species responsible for causing wilt of Clematis sp. revealed that the heterothallic D. vitalbina (Phoma anamorph) is more closely related to the homothallic D. clematidis (Ascochyta anamorph) than to the heterothallic P. clematidina. Finally, our results indicate that homothallism in D. clematidis resulted from a single crossover between MAT1-1 and MAT1-2 sequences of heterothallic ancestors, whereas a single crossover event followed by an inversion of a fused MAT1/2 locus resulted in homothallism in Pey. pinodes.
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Affiliation(s)
- Joyce H C Woudenberg
- CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT Utrecht, the Netherlands.
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Serrano R, Gusmão L, Amorim A, Araujo R. Rapid identification of Aspergillus fumigatus within the section Fumigati. BMC Microbiol 2011; 11:82. [PMID: 21510879 PMCID: PMC3102036 DOI: 10.1186/1471-2180-11-82] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 04/21/2011] [Indexed: 12/01/2022] Open
Abstract
Background New fungal species that are morphologically similar to Aspergillus fumigatus were recently described and included in section Fumigati. Misidentification of such fungal species, particularly of the human pathogens, Aspergillus lentulus, Neosartorya fischeri, Neosartorya hiratsukae, Neosartorya pseudofischeri and Neosartorya udagawae, has been increasingly reported by numerous clinical labs. Nevertheless, A. fumigatus still accounts for more than 90% of all invasive aspergillosis cases. The purpose of the present study was to develop a rapid method for the molecular identification of A. fumigatus to distinguish it from other species within the section Fumigati. Results A multiplex PCR was developed using prior information based on β-tubulin (βtub) and rodlet A (rodA) partial gene sequences. PCR amplification of βtub and rodA fragments resulted in a distinctive electrophoretic pattern in A. fumigatus and N. udagawae. The polymorphisms found in the smallest amplified sequence of βtub (153 bp) and rodA (103 bp) genes were then compared among and within species of this taxonomic section. βtub was able to differentiate among 13 individual species and two groups of species that included the pathogenic fungus A. lentulus. A more limited number of sequences were available for rodA; nevertheless, we were able to distinguish Aspergillus viridinutans, N. hiratsukae and N. udagawae. Conclusions The assay described in the present study proved to be specific and highly reproducible, representing a fast and economic way of targeting molecular identification of the relevant mould, A. fumigatus, in clinical laboratories.
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Affiliation(s)
- Rita Serrano
- IPATIMUP, Institute of Molecular Pathology and Immunology of University of Porto, Rua Dr, Roberto Frias s/n, 4200-465 Porto, Portugal
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Hong SB, Kim DH, Park IC, Choi YJ, Shin HD, Samson R. Re-identification of Aspergillus fumigatus sensu lato based on a new concept of species delimitation. J Microbiol 2010; 48:607-15. [PMID: 21046338 DOI: 10.1007/s12275-010-0084-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 05/24/2010] [Indexed: 11/27/2022]
Abstract
The species concept of Aspergillus fumigatus sensu stricto has recently been defined by polyphasic taxonomy. Based on the new concept of species delimitations, 146 worldwide strains of Aspergillus fumigatus sensu lato were re-identified. Of those 146 strains, 140 (95.8%) could be identified as A. fumigatus sensu stricto, 3 (2.1%) as A. lentulus, and the remaining 3 strains as A. viridinutans complex, Neosartorya udagawae, and N. cf. nishimurae. Of 98 clinical strains, only 1 from dolphin nostril was identified as A. lentulus and not A. fumigatus sensu stricto. Random amplification of polymorphic DNA-polymerase chain reaction (RAPD-PCR) with primers PELF and URP1F produced nearly the same band patterns among 136 strains of A. fumigatus sensu stricto while discriminated the species from its related species. We also discussed about identification of several atypical A. fumigatus strains from clinical environments.
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Affiliation(s)
- Seung-Beom Hong
- Korean Agricultural Culture Collection, National Agrobiodiversity Center, NAAS, RDA, Suwon 441-707, Republic of Korea.
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Alvarez-Pérez S, Blanco JL, Alba P, García ME. [Sexuality and pathogenicity in Aspergillus fumigatus: is there any relationship?]. Rev Iberoam Micol 2010; 27:1-5. [PMID: 20167523 DOI: 10.1016/j.riam.2009.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 11/18/2009] [Accepted: 11/30/2009] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Aspergillus fumigatus, like many other fungal species of clinical relevance, has been traditionally regarded as an asexual organism. However, in last few years several pieces of evidence question this such assumption, suggesting that the sexual state of A. fumigatus may still be undiscovered. These investigations have finally led to the recent discovery of a teleomorph stage of A. fumigatus, which has been named Neosartorya fumigata. AIMS To review the most important findings on A. fumigatus sexuality and discuss the possible implications of such findings on its pathogenicity. METHODS A bibliographic search was performed to find the main works that study the sexuality of fungal pathogens and, especially, of A. fumigatus. Moreover, data from our recent investigations in this field were also introduced to the discussion. RESULTS The existence of a teleomorph for A. fumigatus could have significant clinical repercussions, as sexual reproduction might produce offspring with increased virulence and/or resistance to antifungal agents. In this sense, the results of our investigations suggest the existence of an association between the MAT1-1 mating type and the invasiveness of A. fumigatus isolates. CONCLUSIONS The study of the sexual reproduction of the fungal pathogens and its possible relationship with virulence will continue to be a topic of interest during the next years, not only because of its basic interest, but also for the possible clinical repercussions.
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Affiliation(s)
- Sergio Alvarez-Pérez
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, España.
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Neosartorya udagawae (Aspergillus udagawae), an emerging agent of aspergillosis: how different is it from Aspergillus fumigatus? J Clin Microbiol 2009; 48:220-8. [PMID: 19889894 DOI: 10.1128/jcm.01556-09] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
A recent report on several cases of invasive aspergillosis caused by Neosartorya udagawae suggested distinctive patterns of disease progression between N. udagawae and Aspergillus fumigatus. This prompted us to characterize N. udagawae in comparison to A. fumigatus. Our findings showed that both species exist in two mating types at similar ratios and produce gliotoxin. However, the thermotolerance of the two species differs: while A. fumigatus is able to grow at 55 degrees C but not at 10 degrees C, N. udagawae is able to grow at 10 degrees C but fails to grow at >42 degrees C. Furthermore, compared to A. fumigatus, the conidia of N. udagawae require longer incubation periods to germinate at 37 degrees C and are more susceptible to neutrophil attack as well as hydrogen peroxide; N. udagawae is also less virulent in gp91(phox-/-) mice. These findings suggest that growth and susceptibility to the host response might account for the reduced virulence of N. udagawae and the subtle distinction in the progression of the disease caused by the two species.
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Ghebremedhin B, Bluemel A, Neumann KH, Koenig B, Koenig W. Peritonitis due to Neosartorya pseudofischeri in an elderly patient undergoing peritoneal dialysis successfully treated with voriconazole. J Med Microbiol 2009; 58:678-682. [PMID: 19369533 DOI: 10.1099/jmm.0.005785-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Aspergillus peritonitis is a rare life-threatening complication of peritoneal dialysis (PD). We report a case of symptomatic Neosartorya pseudofischeri peritonitis in a 60-year-old woman treated by continuous ambulatory peritoneal dialysis (CAPD) for 13 months, who performed peritoneal exchanges independently. This is believed to be the first published case of N. pseudofischeri in an elderly patient. Comprehensive treatment included early removal of the PD catheter and the use of voriconazole (200 mg Vfend twice daily) for a period of 5 weeks. This case supports the need for more effective prophylaxis and treatment of non-Candida fungal infections in CAPD patients. Our conclusions from this case and a review of the literature are that infection with this fungus can cause substantial morbidity and is best treated with prompt catheter removal, aggressive antifungal therapy with voriconazole or amphotericin B, and vigilant observation for complications. Our report describes for what is believed to be the first time the administration of voriconazole to treat a Neosartorya peritonitis case.
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Affiliation(s)
- B Ghebremedhin
- Clinical Microbiology, University Clinic, Magdeburg, Germany
| | - A Bluemel
- Division of Nephrology, University Clinic, Magdeburg, Germany
| | - K-H Neumann
- Division of Nephrology, University Clinic, Magdeburg, Germany
| | - B Koenig
- Clinical Microbiology, University Clinic, Magdeburg, Germany
| | - W Koenig
- Clinical Microbiology, University Clinic, Magdeburg, Germany
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Igbinigie EE, Aktins S, van Breugel Y, van Dyke S, Davies-Coleman MT, Rose PD. Fungal biodegradation of hard coal by a newly reported isolate,Neosartorya fischeri. Biotechnol J 2008; 3:1407-16. [DOI: 10.1002/biot.200800227] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Aspergillus section Fumigati: antifungal susceptibility patterns and sequence-based identification. Antimicrob Agents Chemother 2008; 52:1244-51. [PMID: 18212093 DOI: 10.1128/aac.00942-07] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
This study analyzed 28 Aspergillus strains belonging to the section Fumigati that were isolated from clinical samples in Spain. All isolates sporulated slowly and were unable to grow at 48 degrees C. Phylogenetic analysis based on sequencing of partial sequences of the beta-tubulin and rodlet A genes was used to classify the 28 strains into six different clades (Neosartorya hiratsukae, Neosartorya pseudofischeri, Aspergillus viridinutans, Aspergillus lentulus, Aspergillus fumigatiaffinis, and Aspergillus fumisynnematus). Antifungal susceptibility testing showed heterogeneous patterns and grouped the strains together by species. Most A. lentulus and A. fumigatiaffinis isolates showed high MICs of amphotericin B (geometric mean [GM] MICs, >or=4.5 microg/ml), itraconazole (GM MICs, >or=6 microg/ml), voriconazole (GM MICs, >or=3 microg/ml), and ravuconazole (GM MICs, >or=3 microg/ml); N pseudofischeri and A. viridinutans showed high MICs of itraconazole (GM MICs, >or=8 microg/ml), voriconazole (GM MICs, >or=3.33 microg/ml), and ravuconazole (GM MICs, >or=2 microg/ml); and N. hiratsukae and A. fumisynnematus were susceptible to all the antifungals tested. In conclusion, a number of different species whose morphological features resemble those of Aspergillus fumigatus could succeed in producing invasive infections in the susceptible host. In addition, some of them showed high MICs for most of the antifungals available for the treatment of patients infected with these organisms. The epidemiology and clinical relevance of these species should therefore be addressed.
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Hong SB, Shin HD, Hong J, Frisvad JC, Nielsen PV, Varga J, Samson RA. New taxa of Neosartorya and Aspergillus in Aspergillus section Fumigati. Antonie van Leeuwenhoek 2007; 93:87-98. [PMID: 17610141 PMCID: PMC2140094 DOI: 10.1007/s10482-007-9183-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 06/08/2007] [Indexed: 12/02/2022]
Abstract
Three new species of Neosartorya and one new Aspergillus of section Fumigati are proposed using a polyphasic approach based on morphology, extrolite production and partial β-tubulin, calmodulin, and actin gene sequences. The phylogenetic analyses using the three genes clearly show that the taxa grouped separately from the known species and confirmed the phenotypic differences. Neosartorya denticulata is characterized by its unique denticulate ascospores with a prominent equatorial furrow; N. assulata by well developed flaps on the convex surface of the ascospores which in addition have two distinct equatorial crests and N. galapagensis by a funiculose colony morphology, short and narrow conidiophores and ascospores with two wide equatorial crests with a microtuberculate convex surface. Aspergillus turcosus can be distinguished by velvety, gray turquoise colonies and short, loosely columnar conidial heads. The four new taxa also have unique extrolite profiles, which contain the mycotoxins gliotoxin and viriditoxin in N. denticulate; apolar compounds provisionally named NEPS in N. assulata and gregatins in N. galapagensis. A. turcosus produced kotanins. N.denticulata sp. nov., N. assulata sp. nov., N. galapagensis sp. nov., and A. turcosus sp. nov. are described and illustrated.
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Affiliation(s)
- Seung-Beom Hong
- Korean Agricultural Culture Collection, NIAB, Suwon, 441-707 South Korea
| | - Hyeon-Dong Shin
- Division of Environmental Science and Ecological Engineering, College of Life and Environmental Sciences, Korea University, Seoul, 136-701 South Korea
| | - Joonbae Hong
- Consumer Safety Center, Korea Consumer Agency, Seoul, 137-700 South Korea
| | - Jens C. Frisvad
- Center for Microbial Biotechnology, Biocentrum-DTU, Technical University of Denmark, Building 221, Kgs. Lyngby, 2800 Denmark
| | - Per V. Nielsen
- Center for Microbial Biotechnology, Biocentrum-DTU, Technical University of Denmark, Building 221, Kgs. Lyngby, 2800 Denmark
| | - János Varga
- CBS Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Robert A. Samson
- CBS Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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Rydholm C, Dyer PS, Lutzoni F. DNA sequence characterization and molecular evolution of MAT1 and MAT2 mating-type loci of the self-compatible ascomycete mold Neosartorya fischeri. EUKARYOTIC CELL 2007; 6:868-74. [PMID: 17384199 PMCID: PMC1899244 DOI: 10.1128/ec.00319-06] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Accepted: 03/19/2007] [Indexed: 11/20/2022]
Abstract
Degenerate PCR and chromosome-walking approaches were used to identify mating-type (MAT) genes and flanking regions from the homothallic (sexually self-fertile) euascomycete fungus Neosartorya fischeri, a close relative of the opportunistic human pathogen Aspergillus fumigatus. Both putative alpha- and high-mobility-group-domain MAT genes were found within the same genome, providing a functional explanation for self-fertility. However, unlike those in many homothallic euascomycetes (Pezizomycotina), the genes were not found adjacent to each other and were termed MAT1 and MAT2 to recognize the presence of distinct loci. Complete copies of putative APN1 (DNA lyase) and SLA2 (cytoskeleton assembly control) genes were found bordering the MAT1 locus. Partial copies of APN1 and SLA2 were also found bordering the MAT2 locus, but these copies bore the genetic hallmarks of pseudogenes. Genome comparisons revealed synteny over at least 23,300 bp between the N. fischeri MAT1 region and the A. fumigatus MAT locus region, but no such long-range conservation in the N. fischeri MAT2 region was evident. The sequence upstream of MAT2 contained numerous candidate transposase genes. These results demonstrate a novel means involving the segmental translocation of a chromosomal region by which the ability to undergo self-fertilization may be acquired. The results are also discussed in relation to their significance in indicating that heterothallism may be ancestral within the Aspergillus section Fumigati.
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Affiliation(s)
- C Rydholm
- Biology Department, Box 90338, Duke University, Durham, NC 27708, USA.
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Abstract
Over the past decade, opportunistic fungal infectious diseases have increased in prevalence as the population of immunocompromised individuals escalated due to HIV/AIDS and immunosuppression associated with organ transplantation and cancer therapies. In the three predominant human pathogenic fungi (Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus), a unifying feature is that all three retained the machinery needed for sex, and yet all limit their access to sexual reproduction. While less well characterized, many of the other human pathogenic fungi also appear to have the ability to undergo sexual reproduction. Recent studies with engineered pairs of diploid strains of the model yeast Saccharomyces cerevisiae, one that is sexual and the other an obligate asexual, provide direct experimental validation of the benefits of both sexual and asexual reproduction. The obligate asexual strain had an advantage in response to constant environmental conditions whereas the sexual strain had a competitive edge under stressful conditions (Goddard et al., 2005; Grimberg and Zeyl, 2005). The human pathogenic fungi have gone to great lengths to maintain all of the machinery required for sex, including the mating-type locus and the pheromone response and cell fusion pathways. Yet these pathogens limit their access to sexual or parasexual reproduction in unique and specialized ways. Our hypothesis is that this has enabled the pathogenic fungi to proliferate in their environmental niche, but to also undergo genetic exchange via sexual reproduction in response to stressful conditions such as new environments, different host organisms, or changes in the human host such as antimicrobial therapy. Further study of the sexual nature of the human pathogenic fungi will illuminate how these unique microbes have evolved into successful pathogens in humans.
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Affiliation(s)
- Kirsten Nielsen
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Samson RA, Hong S, Peterson SW, Frisvad JC, Varga J. Polyphasic taxonomy of Aspergillus section Fumigati and its teleomorph Neosartorya. Stud Mycol 2007; 59:147-203. [PMID: 18490953 PMCID: PMC2275200 DOI: 10.3114/sim.2007.59.14] [Citation(s) in RCA: 182] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The taxonomy of Aspergillus section Fumigati with its teleomorph genus Neosartorya is revised. The species concept is based on phenotypic (morphology and extrolite profiles) and molecular (beta-tubulin and calmodulin gene sequences) characters in a polyphasic approach. Four new taxa are proposed: N. australensis N. ferenczii, N. papuaensis and N. warcupii. All newly described and accepted species are illustrated. The section consists of 33 taxa: 10 strictly anamorphic Aspergillus species and 23 Neosartorya species. Four other Neosartorya species described previously were not available for this monograph, and consequently are relegated to the category of doubtful species.
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Affiliation(s)
- R A Samson
- CBS Fungal Biodiversity Centre, Uppsalalaan 8, NL-3584 CT Utrecht, The Netherlands
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Yaguchi T, Horie Y, Tanaka R, Matsuzawa T, Ito J, Nishimura K. Molecular Phylogenetics of Multiple Genes on Aspergillus Section Fumigati Isolated from Clinical Specimens in Japan. ACTA ACUST UNITED AC 2007; 48:37-46. [PMID: 17287721 DOI: 10.3314/jjmm.48.37] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A phylogenetic study based on sequence analysis of the beta-tubulin, hydrophobin and calmodulin genes was performed in 19 strains of Aspergillus fumigatus and related species isolated from clinical specimens in Japan. Correlations between detailed morphology and phylogeny were examined. Species in the section Fumigati were divided into five clades: clade I, typical strains of A. fumigatus; clade II, species including A. lentulus and A. fumisynnematus; clade III, species including A. fumigatiaffinis and A. novofumigatus, clade IV, atypical strains of A. fumigatus including A. viridinutans; and clade V, species including A. brevipes, A. duricaulis and A. unilateralis. Most of the examined strains from clinical specimens in Japan clustered together in clade I and exhibit globose conidia with lobate-reticulate ornamentation. Other strains from clinical specimens were divided into two clades (clades II and IV). The strains in clades II and the six strains in clade IV exhibit conidia with microtuberculate ornamentation, while A. viridinutans-complex in clades IV and the strains in clade V have conidia with lobate-reticulate ornamentation. The six strains are clearly distinguished from A. viridinutans-complex and are considered to be related to Neosartorya udagawae. The maximal growth temperatures of clades I, II, IV and V were above 50 degrees C, 45 degrees C, 42 degrees C and 42 degrees C, respectively. These data are useful for classification of species within the Aspergillus section Fumigati.
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Affiliation(s)
- Takashi Yaguchi
- Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Japan
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Butler MI, Gray J, Goodwin TJD, Poulter RTM. The distribution and evolutionary history of the PRP8 intein. BMC Evol Biol 2006; 6:42. [PMID: 16737526 PMCID: PMC1508164 DOI: 10.1186/1471-2148-6-42] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Accepted: 05/31/2006] [Indexed: 12/31/2022] Open
Abstract
Background We recently described a mini-intein in the PRP8 gene of a strain of the basidiomycete Cryptococcus neoformans, an important fungal pathogen of humans. This was the second described intein in the nuclear genome of any eukaryote; the first nuclear encoded intein was found in the VMA gene of several saccharomycete yeasts. The evolution of eukaryote inteins is not well understood. In this report we describe additional PRP8 inteins (bringing the total of these to over 20). We compare and contrast the phylogenetic distribution and evolutionary history of the PRP8 intein and the saccharomycete VMA intein, in order to derive a broader understanding of eukaryote intein evolution. It has been suggested that eukaryote inteins undergo horizontal transfer and the present analysis explores this proposal. Results In total, 22 PRP8 inteins have been detected in species from three different orders of euascomycetes, including Aspergillus nidulans and Aspergillus fumigatus (Eurotiales), Paracoccidiodes brasiliensis, Uncinocarpus reesii and Histoplasma capsulatum (Onygales) and Botrytis cinerea (Helotiales). These inteins are all at the same site in the PRP8 sequence as the original Cryptococcus neoformans intein. Some of the PRP8 inteins contain apparently intact homing endonuclease domains and are thus potentially mobile, while some lack the region corresponding to the homing endonuclease and are thus mini-inteins. In contrast, no mini-inteins have been reported in the VMA gene of yeast. There are several examples of pairs of closely related species where one species carries the PRP8 intein while the intein is absent from the other species. Bio-informatic and phylogenetic analyses suggest that many of the ascomycete PRP8 homing endonucleases are active. This contrasts with the VMA homing endonucleases, most of which are inactive. Conclusion PRP8 inteins are widespread in the euascomycetes (Pezizomycota) and apparently their homing endonucleases are active. There is no evidence for horizontal transfer within the euascomycetes. This suggests that the intein is of ancient origin and has been vertically transmitted amongst the euascomycetes. It is possible that horizontal transfer has occurred between the euascomycetes and members of the basidiomycete genus Cryptococcus.
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Affiliation(s)
- Margaret I Butler
- Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand
| | - Jeremy Gray
- Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand
| | - Timothy JD Goodwin
- Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand
| | - Russell TM Poulter
- Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand
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Rydholm C, Szakacs G, Lutzoni F. Low genetic variation and no detectable population structure in aspergillus fumigatus compared to closely related Neosartorya species. EUKARYOTIC CELL 2006; 5:650-7. [PMID: 16607012 PMCID: PMC1459663 DOI: 10.1128/ec.5.4.650-657.2006] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Accepted: 02/07/2006] [Indexed: 01/29/2023]
Abstract
Aspergillus fumigatus is an anamorphic euascomycete mold with a ubiquitous presence worldwide. Despite intensive work to understand its success as a pathogen infecting immunosuppressed patients, the population dynamics and recent evolutionary history of A. fumigatus remain understudied. We examined patterns of genetic variation at three intergenic loci for 70 natural isolates from Europe, North America, South America, Asia, Africa, and Australia. The same loci were used to analyze within-population genetic variation for 33 isolates obtained from five geographic locations. Neither data set detected evidence of population differentiation or found any association between the genetic and geographic distances among these isolates. No evidence for genetic differentiation within the two A. fumigatus mating types was detected. The genetic diversity of A. fumigatus, contrasted with that of its close teleomorphic relatives, Neosartorya fischeri and Neosartorya spinosa, is remarkably low.
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Affiliation(s)
- Carla Rydholm
- Biology Department, Duke University, Box 90338, Durham, NC 27708, USA.
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21
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Hong SB, Cho HS, Shin HD, Frisvad JC, Samson RA. Novel Neosartorya species isolated from soil in Korea. Int J Syst Evol Microbiol 2006; 56:477-486. [PMID: 16449461 DOI: 10.1099/ijs.0.63980-0] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phenotypic and genotypic characters of strains of Neosartorya spinosa and related taxa were analysed. N. spinosa, Neosartorya botucatensis and Neosartorya paulistensis had identical partial β-tubulin and calmodulin gene sequences and could not be differentiated on macro- and micro-morphological characteristics, including by scanning electron microscopy. Based on partial β-tubulin and calmodulin gene sequences and ascospore morphology, two separate groups are distinguished and are proposed as novel species. Neosartorya laciniosa sp. nov. has microtuberculate ascospores with two bent crests and two distinct equatorial rings of small projections. Neosartorya coreana sp. nov. has rugose to weak reticulate ascospores with two often bent crests, but without the equatorial rings of small projections. The type strain of N. laciniosa is CBS 117721T (=NRRL 35589T=KACC 41657T) and the type strain of N. coreana is CBS 117059T (=NRRL 35590T=KACC 41659T).
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Affiliation(s)
- Seung-Beom Hong
- Korean Agricultural Culture Collection, NIAB, Suwon 441-707, Korea
| | - Hye-Sun Cho
- Korean Agricultural Culture Collection, NIAB, Suwon 441-707, Korea
| | - Hyeon-Dong Shin
- Division of Environmental Science and Ecological Engineering, College of Life and Environmental Science, Korea University, Seoul 136-701, Korea
| | - Jens C Frisvad
- Center for Microbial Biotechnology, Biocentrum-DTU, Technical University of Denmark, Building 221, DK-2800 Kgs. Lyngby, Denmark
| | - Robert A Samson
- Centraalbureau voor Schimmelcultures, Utrecht, The Netherlands
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22
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Mellado E, Alcazar-Fuoli L, García-Effrón G, Alastruey-Izquierdo A, Cuenca-Estrella M, Rodríguez-Tudela JL. New resistance mechanisms to azole drugs in Aspergillus fumigatus and emergence of antifungal drugs-resistant A. fumigatus atypical strains. Med Mycol 2006; 44:S367-S371. [PMID: 30408931 DOI: 10.1080/13693780600902243] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Azole drug resistance in Aspergillus fumigatus is an uncommon but well-known phenomenon. The analysis of resistance mechanisms at molecular level has identified the bases for A. fumigatus azole resistance. To date, the most prevalent mechanism of azole resistance appears to be the modification of Cyp51, specifically mutations in cyp51A gene. These mutations have been associated with three different antifungal susceptibility profiles: (i) cross-resistance to itraconazole and posaconazole that has been associated with amino acid substitutions at glycine 54 (G54), (ii) elevated MICs to all azole drugs associated with amino acid substitutions at methionine M220, and (iii) cross-resistance to all azole drugs related to the presence of Cyp51A substitutions at leucine 98 for histidine (L98H) linked to a duplication in tandem of a 34 bp repeat in the cyp51A promoter region, which seem to be responsible for increased cyp51A gene expression. Another matter of concern is the increasing reports of isolation of genetic variants of A. fumigatus, originally misidentified as poorly sporulating strains of A. fumigauts, as a causative agents of invasive infection. Many of these isolates belonging to the Aspergillus section Fumigati have been found to be resistant in vitro to multiple antifungal drugs. Current data show that susceptibility profile of these variants could be predictable depending on the species. Resistance among clinical strains of filamentous fungi may become more common in the future associated with the spread of prophylaxis, pre-emptive treatments and specific therapies with antifungal agents.
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Affiliation(s)
- E Mellado
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III. Majadahonda, Madrid, Spain
| | - L Alcazar-Fuoli
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III. Majadahonda, Madrid, Spain
| | - G García-Effrón
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III. Majadahonda, Madrid, Spain
| | - A Alastruey-Izquierdo
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III. Majadahonda, Madrid, Spain
| | - M Cuenca-Estrella
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III. Majadahonda, Madrid, Spain
| | - J L Rodríguez-Tudela
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III. Majadahonda, Madrid, Spain
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Wortman JR, Fedorova N, Crabtree J, Joardar V, Maiti R, Haas BJ, Amedeo P, Lee E, Angiuoli SV, Jiang B, Anderson MJ, Denning DW, White OR, Nierman WC. Whole genome comparison of theA. fumigatusfamily. Med Mycol 2006; 44:S3-S7. [DOI: 10.1080/13693780600835799] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Abstract
Aspergillus spp. have been the subject of numerous epidemiological studies. The most useful typing techniques are DNA based methods including the random amplified polymorphic DNA technique, microsatellite length polymorphisms, restriction fragment length polymorphism (RFLP) analysis using retrotransposon-like sequences as probes, and multilocus sequence typing. The results of typing clinical isolates indicate that most of the invasive aspergillosis (IA) patients were infected by a single strain. Genetic analysis could not discriminate between clinical and environmental isolates of Aspergillus. fumigatus, indicating that every strain present in the environment is a potential pathogen if it encounters the appropriate host. The source of infection can also be monitored by typing. Typing studies led to the discovery of a new pathogenic species, A. lentulus, and to the identification of several species not known previously to be pathogenic. Typing studies revealed the existence of two genetically isolated groups within a global A. fumigatus population. Aspergillus fumigatus was found to be the first example of a true cosmopolitan fungus. Additionally, the results obtained in several studies support the premise that recombination played an important role in A. fumigatus populations. The discovery of functional mating type genes in A. fumigatus indicates that past or recent sexual processes could be responsible for the observed recombining population structure.
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Affiliation(s)
- János Varga
- Department of Microbiology, Faculty of Sciences, University of Szeged, Szeged, Hungary
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25
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Balajee SA, Gribskov JL, Hanley E, Nickle D, Marr KA. Aspergillus lentulus sp. nov., a new sibling species of A. fumigatus. EUKARYOTIC CELL 2005; 4:625-32. [PMID: 15755924 PMCID: PMC1087803 DOI: 10.1128/ec.4.3.625-632.2005] [Citation(s) in RCA: 280] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In a prior study, we identified seven clinical isolates of an Aspergillus sp. that were slow to sporulate in multiple media and demonstrated decreased in vitro susceptibilities to multiple antifungals, including amphotericin B, itraconazole, voriconazole, and caspofungin. These isolates were initially considered to be variants of Aspergillus fumigatus because of differences in mitochondrial cytochrome b sequences and unique randomly amplified polymorphic DNA PCR patterns (S. A. Balajee, M. Weaver, A. Imhof, J. Gribskov, and K. A. Marr, Antimicrob. Agents Chemother. 48: 1197-1203, 2004). The present study was performed to clarify the taxonomic status of these organisms by phylogenetic analyses based on multilocus sequence typing of five genes (the beta-tubulin gene, the rodlet A gene, the salt-responsive gene, the mitochondrial cytochrome b gene, and the internal transcribed spacer regions). Results revealed that four of the seven variant isolates clustered together in a clade very distant from A. fumigatus and distinct from other members of the A. fumigatus group. This new clade, consisting of four members, was monophyletic with strong bootstrap support when the protein-encoding regions were analyzed, indicating a new species status under the phylogenetic species concept. Phenotype studies revealed that the variant isolate has smaller conidial heads with diminutive vesicles compared to A. fumigatus and is not able to survive at 48 degrees C. Our findings suggest the presence of a previously unrecognized, potentially drug-resistant Aspergillus species that we designate A. lentulus.
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Affiliation(s)
- S Arunmozhi Balajee
- Program in Infectious Diseases, Fred Hutchinson Cancer Research Center, University of Washington, Seattle, WA 98109, USA
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26
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Paoletti M, Rydholm C, Schwier EU, Anderson MJ, Szakacs G, Lutzoni F, Debeaupuis JP, Latgé JP, Denning DW, Dyer PS. Evidence for sexuality in the opportunistic fungal pathogen Aspergillus fumigatus. Curr Biol 2005; 15:1242-8. [PMID: 16005299 DOI: 10.1016/j.cub.2005.05.045] [Citation(s) in RCA: 211] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Revised: 05/13/2005] [Accepted: 05/16/2005] [Indexed: 10/25/2022]
Abstract
Aspergillus fumigatus is a medically important opportunistic pathogen and a major cause of respiratory allergy. The species has long been considered an asexual organism. However, genome analysis has revealed the presence of genes associated with sexual reproduction, including a MAT-2 high-mobility group mating-type gene and genes for pheromone production and detection (Galagan et al., personal communication; Nierman et al., personal communication). We now demonstrate that A. fumigatus has other key characteristics of a sexual species. We reveal the existence of isolates containing a complementary MAT-1 alpha box mating-type gene and show that the MAT locus has an idiomorph structure characteristic of heterothallic (obligate sexual outbreeding) fungi. Analysis of 290 worldwide clinical and environmental isolates with a multiplex-PCR assay revealed the presence of MAT1-1 and MAT1-2 genotypes in similar proportions (43% and 57%, respectively). Further population genetic analyses provided evidence of recombination across a global sampling and within North American and European subpopulations. We also show that mating-type, pheromone-precursor, and pheromone-receptor genes are expressed during mycelial growth. These results indicate that A. fumigatus has a recent evolutionary history of sexual recombination and might have the potential for sexual reproduction. The possible presence of a sexual cycle is highly significant for the population biology and disease management of the species.
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Affiliation(s)
- Mathieu Paoletti
- School of Biology, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
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27
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Pringle A, Baker DM, Platt JL, Wares JP, Latgé JP, Taylor JW. CRYPTIC SPECIATION IN THE COSMOPOLITAN AND CLONAL HUMAN PATHOGENIC FUNGUS ASPERGILLUS FUMIGATUS. Evolution 2005. [DOI: 10.1111/j.0014-3820.2005.tb01059.x] [Citation(s) in RCA: 208] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Katz ME, Dougall AM, Weeks K, Cheetham BF. Multiple genetically distinct groups revealed among clinical isolates identified as atypical Aspergillus fumigatus. J Clin Microbiol 2005; 43:551-5. [PMID: 15695644 PMCID: PMC548029 DOI: 10.1128/jcm.43.2.551-555.2005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To investigate whether genetic variants of A. fumigatus are found among clinical isolates, four isolates that were originally identified as poorly sporulating strains of Aspergillus fumigatus were subjected to molecular analysis. DNA sequence analysis of the alkaline protease genes of these isolates showed that each is genetically distinct and each shows substantial variation (7 to 11%) from the A. fumigatus nucleotide sequence. Subsequent morphological examination suggested that all of the isolates could be classified as Aspergillus viridinutans. To clarify the taxonomic status of these four clinical isolates and of two previously identified as atypical A. fumigatus isolates, partial beta-tubulin and 18S rRNA gene sequences were determined. Each of the six atypical strains had a unique beta-tubulin sequence, whereas the sequences of three standard isolates of A. fumigatus, which were included as controls, were identical to the published A. fumigatus beta-tubulin sequence. The very low level of DNA sequence variation detected in standard isolates of A. fumigatus compared with other isolates from members of Aspergillus section Fumigati suggests that it may be a relatively recently evolved species. The 18S rRNA gene of two of the atypical isolates differed from that of A. fumigatus at a single nucleotide position. Phylogenetic analyses do not support the classification of all of these isolates as A. viridinutans. Thus, some of these isolates represent new species which are potential opportunistic pathogens.
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Affiliation(s)
- Margaret E Katz
- Department of Molecular and Cellular Biology, University of New England, Armidale, NSW 2351, Australia.
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29
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Pringle A, Baker DM, Platt JL, Wares JP, Latgé JP, Taylor JW. CRYPTIC SPECIATION IN THE COSMOPOLITAN AND CLONAL HUMAN PATHOGENIC FUNGUS ASPERGILLUS FUMIGATUS. Evolution 2005. [DOI: 10.1554/04-241.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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30
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Dyer PS, Paoletti M. Reproduction inAspergillus fumigatus: sexuality in a supposedly asexual species? Med Mycol 2005; 43 Suppl 1:S7-14. [PMID: 16110786 DOI: 10.1080/13693780400029015] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Aspergillus fumigatus has long been considered to reproduce only by asexual means. However, accumulating evidence suggest that a sexual stage for A. fumigatus may yet be identified. We describe results from published and ongoing studies involving population genetic analyses, genome analysis, studies of mating-type gene presence and distribution, expression of sex-related genes, and taxonomic work which support the assertion that A. fumigatus has the potential to reproduce by sexual means. The consequences of sexual reproduction for the population biology and disease management of the species are discussed. The possible mechanisms of evolution of asexuality are then considered. It is proposed that asexual species may arise in one step by mutation or loss of a key gene(s), and/or there may be a 'slow decline' in sexual fertility within the species as a whole. Thus, it is argued that species should not be considered simply as sexual or asexual, but rather as individual isolates being present on a continuum of sexual fertility, with the implications for understanding sexuality/asexuality in A. fumigatus discussed.
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Affiliation(s)
- P S Dyer
- School of Biology, University of Nottingham, Nottingham, UK.
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31
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Varga J. Mating type gene homologues in Aspergillus fumigatus. MICROBIOLOGY (READING, ENGLAND) 2003; 149:816-819. [PMID: 12686624 DOI: 10.1099/mic.0.c0113-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- János Varga
- Department of Microbiology, Faculty of Sciences, University of Szeged, P. O. Box 533, H-6701 Szeged, Hungary
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Varga J, Tóth B, Rigó K, Debets F, Kozakiewicz Z. Genetic variability within the Aspergillus viridinutans species. Folia Microbiol (Praha) 2000; 45:423-8. [PMID: 11347269 DOI: 10.1007/bf02817615] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The intraspecific variability of the Aspergillus viridinutans species was examined using various techniques including morphological examinations, carbon-source-utilization tests, restriction-enzyme analysis of the mitochondrial and nuclear DNA, and sequence analysis of part of the beta-tubulin gene. Although the genetic distances between the isolates were higher than between, e.g., A. fumigatus and Neosartorya fischeri, most A. viridinutans isolates, together with N. aureola and N. udagawae strains, were found to belong to a single cluster based on sequence data. Strain FRR 1266, which was earlier classified as a highly divergent A. fumigatus isolate, was found to belong to the A. viridinutans species. The ochratoxin A producing A. viridinutans strain IMI 306135 was most closely related to an asexual isolate. These two latter strains were more closely related to A. fumigatus and N. fischeri than to any A. viridinutans strains, and possibly represent a new species in the Aspergillus section Fumigati. The dendrogram based on carbon source utilization data and results of restriction analysis of the mitochondrial and nuclear DNA of the strains supported most of the evolutionary relationships observed on the basis of sequence data. The results indicate that the presence or absence of nodding conidial heads is not an unequivocal morphological character for the identification of species within the Aspergillus section Fumigati.
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Affiliation(s)
- J Varga
- Department of Microbiology, Faculty of Sciences, University of Szeged, 6701 Szeged, Hungary.
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