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Pal S, Chatterjee N, Das AK, McClements DJ, Dhar P. Sophorolipids: A comprehensive review on properties and applications. Adv Colloid Interface Sci 2023; 313:102856. [PMID: 36827914 DOI: 10.1016/j.cis.2023.102856] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 01/27/2023] [Accepted: 02/04/2023] [Indexed: 02/11/2023]
Abstract
Sophorolipids are surface-active glycolipids produced by several non-pathogenic yeast species and are widely used as biosurfactants in several industrial applications. Sophorolipids provide a plethora of benefits over chemically synthesized surfactants for certain applications like bioremediation, oil recovery, and pharmaceuticals. They are, for instance less toxic, more benign and environment friendly in nature, biodegradable, freely adsorb to different surfaces, self-assembly in hydrated solutions, robustness for industrial applications etc. These miraculous properties result in valuable physicochemical attributes such as low critical micelle concentrations (CMCs), reduced interfacial surface tension, and capacity to dissolve non-polar components. Moreover, they exhibit a diverse range of physicochemical, functional, and biological attributes due to their unique molecular composition and structure. In this article, we highlight the physico-chemical properties of sophorolipids, how these properties are exploited by the human community for extensive benefits and the conditions which lead to their unique tailor-made structures and how they entail their interfacial behavior. Besides, we discuss the advantages and disadvantages associated with the use of these sophorolipids. We also review their physiological and functional attributes, along with their potential commercial applications, in real-world scenario. Biosurfactants are compared to their man-made equivalents to show the variations in structure-property correlations and possible benefits. Those attempting to manufacture purported natural or green surfactant with innovative and valuable qualities can benefit from an understanding of biosurfactant features structured along the same principles. The uniqueness of this review article is the detailed physico-chemical study of the sophorolipid biosurfactant and how these properties helps in their usage and detailed explicit study of their applications in the current scenario and also covering their pros and cons.
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Affiliation(s)
- Srija Pal
- Laboratory of Food Science and Technology, Food and Nutrition Division, University of Calcutta, 20B Judges Court Road, Kolkata 700027, West Bengal, India
| | - Niloy Chatterjee
- Laboratory of Food Science and Technology, Food and Nutrition Division, University of Calcutta, 20B Judges Court Road, Kolkata 700027, West Bengal, India; Centre for Research in Nanoscience & Nanotechnology, University of Calcutta, JD 2, Sector III, Salt Lake City, Kolkata 700 098, West Bengal, India
| | - Arun K Das
- Eastern Regional Station, ICAR-IVRI, 37 Belgachia Road, Kolkata 700037, West Bengal, India
| | - David Julian McClements
- Department of Food Science, University of Massachusetts Amherst, Amherst, MA 01003, USA; Department of Food Science & Bioengineering, Zhejiang Gongshang University, 18 Xuezheng Street, Hangzhou, Zhejiang 310018, China
| | - Pubali Dhar
- Laboratory of Food Science and Technology, Food and Nutrition Division, University of Calcutta, 20B Judges Court Road, Kolkata 700027, West Bengal, India; Centre for Research in Nanoscience & Nanotechnology, University of Calcutta, JD 2, Sector III, Salt Lake City, Kolkata 700 098, West Bengal, India.
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What Is Candida Doing in My Food? A Review and Safety Alert on Its Use as Starter Cultures in Fermented Foods. Microorganisms 2022; 10:microorganisms10091855. [PMID: 36144457 PMCID: PMC9502980 DOI: 10.3390/microorganisms10091855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/02/2022] [Accepted: 09/07/2022] [Indexed: 12/02/2022] Open
Abstract
The use of yeasts as starter cultures was boosted with the emergence of large-scale fermentations in the 20th century. Since then, Saccharomyces cerevisiae has been the most common and widely used microorganism in the food industry. However, Candida species have also been used as an adjuvant in cheese production or as starters for coffee, cocoa, vegetable, meat, beer, and wine fermentations. A thorough screening of candidate Candida is sometimes performed to obtain the best performing strains to enhance specific features. Some commonly selected species include C. pulcherrima (teleomorph Metschnikowia pulcherrima) (wine), C. parapsilosis (teleomorph Monilia parapsilosis) (coffee), C. famata (teleomorph Debaryomyces hansenii) (cheese), and C. zeylanoides (teleomorph Kurtzmaniella zeylanoides) and C. norvegensis (teleomorph Pichia norvegensis) (cocoa). These species are associated with the production of key metabolites (food aroma formation) and different enzymes. However, safety-associated selection criteria are often neglected. It is widely known that some Candida species are opportunistic human pathogens, with important clinical relevance. Here, the physiology and metabolism of Candida species are addressed, initially emphasizing their clinical aspects and potential pathogenicity. Then, Candida species used in food fermentations and their functional roles are reported. We recommended that Candida not be used as food cultures if safety assessments are not performed. Some safety features are highlighted to help researchers choose methods and selection criteria.
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Robbins N, Cowen LE. Genomic Approaches to Antifungal Drug Target Identification and Validation. Annu Rev Microbiol 2022; 76:369-388. [PMID: 35650665 PMCID: PMC10727914 DOI: 10.1146/annurev-micro-041020-094524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The last several decades have witnessed a surge in drug-resistant fungal infections that pose a serious threat to human health. While there is a limited arsenal of drugs that can be used to treat systemic infections, scientific advances have provided renewed optimism for the discovery of novel antifungals. The development of chemical-genomic assays using Saccharomyces cerevisiae has provided powerful methods to identify the mechanism of action of molecules in a living cell. Advances in molecular biology techniques have enabled complementary assays to be developed in fungal pathogens, including Candida albicans and Cryptococcus neoformans. These approaches enable the identification of target genes for drug candidates, as well as genes involved in buffering drug target pathways. Here, we examine yeast chemical-genomic assays and highlight how such resources can be utilized to predict the mechanisms of action of compounds, to study virulence attributes of diverse fungal pathogens, and to bolster the antifungal pipeline.
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Affiliation(s)
- Nicole Robbins
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada;
| | - Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada;
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Fu C, Zhang X, Veri AO, Iyer KR, Lash E, Xue A, Yan H, Revie NM, Wong C, Lin ZY, Polvi EJ, Liston SD, VanderSluis B, Hou J, Yashiroda Y, Gingras AC, Boone C, O’Meara TR, O’Meara MJ, Noble S, Robbins N, Myers CL, Cowen LE. Leveraging machine learning essentiality predictions and chemogenomic interactions to identify antifungal targets. Nat Commun 2021; 12:6497. [PMID: 34764269 PMCID: PMC8586148 DOI: 10.1038/s41467-021-26850-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/22/2021] [Indexed: 02/08/2023] Open
Abstract
Fungal pathogens pose a global threat to human health, with Candida albicans among the leading killers. Systematic analysis of essential genes provides a powerful strategy to discover potential antifungal targets. Here, we build a machine learning model to generate genome-wide gene essentiality predictions for C. albicans and expand the largest functional genomics resource in this pathogen (the GRACE collection) by 866 genes. Using this model and chemogenomic analyses, we define the function of three uncharacterized essential genes with roles in kinetochore function, mitochondrial integrity, and translation, and identify the glutaminyl-tRNA synthetase Gln4 as the target of N-pyrimidinyl-β-thiophenylacrylamide (NP-BTA), an antifungal compound.
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Affiliation(s)
- Ci Fu
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Xiang Zhang
- grid.17635.360000000419368657Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Amanda O. Veri
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Kali R. Iyer
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Emma Lash
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Alice Xue
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Huijuan Yan
- grid.266102.10000 0001 2297 6811Department of Microbiology and Immunology, UCSF School of Medicine, San Francisco, CA 94143 USA
| | - Nicole M. Revie
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Cassandra Wong
- grid.250674.20000 0004 0626 6184Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
| | - Zhen-Yuan Lin
- grid.250674.20000 0004 0626 6184Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
| | - Elizabeth J. Polvi
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Sean D. Liston
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Benjamin VanderSluis
- grid.17635.360000000419368657Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Jing Hou
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada ,grid.17063.330000 0001 2157 2938Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1 Canada
| | - Yoko Yashiroda
- grid.509461.fRIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198 Japan
| | - Anne-Claude Gingras
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada ,grid.250674.20000 0004 0626 6184Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
| | - Charles Boone
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada ,grid.17063.330000 0001 2157 2938Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1 Canada ,grid.509461.fRIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198 Japan
| | - Teresa R. O’Meara
- grid.214458.e0000000086837370Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109 USA
| | - Matthew J. O’Meara
- grid.214458.e0000000086837370Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109 USA
| | - Suzanne Noble
- grid.266102.10000 0001 2297 6811Department of Microbiology and Immunology, UCSF School of Medicine, San Francisco, CA 94143 USA
| | - Nicole Robbins
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Chad L. Myers
- grid.17635.360000000419368657Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Leah E. Cowen
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
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Mixão V, Saus E, Boekhout T, Gabaldón T. Extreme diversification driven by parallel events of massive loss of heterozygosity in the hybrid lineage of Candida albicans. Genetics 2021; 217:5995314. [PMID: 33724404 PMCID: PMC8045679 DOI: 10.1093/genetics/iyaa004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 11/03/2020] [Indexed: 01/23/2023] Open
Abstract
Candida albicans is the most commonly reported species causing candidiasis. The taxonomic classification of C. albicans and related lineages is controversial, with Candida africana (syn. C. albicans var. africana) and Candida stellatoidea (syn. C. albicans var. stellatoidea) being considered different species or C. albicans varieties depending on the authors. Moreover, recent genomic analyses have suggested a shared hybrid origin of C. albicans and C. africana, but the potential parental lineages remain unidentified. Although the genomes of C. albicans and C. africana have been extensively studied, the genome of C. stellatoidea has not been sequenced so far. In order to get a better understanding of the evolution of the C. albicans clade, and to assess whether C. stellatoidea could represent one of the unknown C. albicans parental lineages, we sequenced C. stellatoidea type strain (CBS 1905). This genome was compared to that of C. albicans and of the closely related lineage C. africana. Our results show that, similarly to C. africana, C. stellatoidea descends from the same hybrid ancestor as other C. albicans strains and that it has undergone a parallel massive loss of heterozygosity.
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Affiliation(s)
- Verónica Mixão
- Life Sciences Department, Barcelona Supercomputing Center (BSC), 08034 Barcelona, Spain.,Mechanisms of Disease Department, Institute for Research in Biomedicine (IRB), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain
| | - Ester Saus
- Life Sciences Department, Barcelona Supercomputing Center (BSC), 08034 Barcelona, Spain.,Mechanisms of Disease Department, Institute for Research in Biomedicine (IRB), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain
| | - Teun Boekhout
- Westerdijk Fungal Biodiversity Institute, 3584 CT Utrecht, The Netherlands.,Institute of Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
| | - Toni Gabaldón
- Life Sciences Department, Barcelona Supercomputing Center (BSC), 08034 Barcelona, Spain.,Mechanisms of Disease Department, Institute for Research in Biomedicine (IRB), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
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6
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Genomic evidence for a hybrid origin of the yeast opportunistic pathogen Candida albicans. BMC Biol 2020; 18:48. [PMID: 32375762 PMCID: PMC7204223 DOI: 10.1186/s12915-020-00776-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 03/31/2020] [Indexed: 12/25/2022] Open
Abstract
Background Opportunistic yeast pathogens of the genus Candida are an important medical problem. Candida albicans, the most prevalent Candida species, is a natural commensal of humans that can adopt a pathogenic behavior. This species is highly heterozygous and cannot undergo meiosis, adopting instead a parasexual cycle that increases genetic variability and potentially leads to advantages under stress conditions. However, the origin of C. albicans heterozygosity is unknown, and we hypothesize that it could result from ancestral hybridization. We tested this idea by analyzing available genomes of C. albicans isolates and comparing them to those of hybrid and non-hybrid strains of other Candida species. Results Our results show compelling evidence that C. albicans is an evolved hybrid. The genomic patterns observed in C. albicans are similar to those of other hybrids such as Candida orthopsilosis MCO456 and Candida inconspicua, suggesting that it also descends from a hybrid of two divergent lineages. Our analysis indicates that most of the divergence between haplotypes in C. albicans heterozygous blocks was already present in a putative heterozygous ancestor, with an estimated 2.8% divergence between homeologous chromosomes. The levels and patterns of ancestral heterozygosity found cannot be fully explained under the paradigm of vertical evolution and are not consistent with continuous gene flux arising from lineage-specific events of admixture. Conclusions Although the inferred level of sequence divergence between the putative parental lineages (2.8%) is not clearly beyond current species boundaries in Saccharomycotina, we show here that all analyzed C. albicans strains derive from a single hybrid ancestor and diverged by extensive loss of heterozygosity. This finding has important implications for our understanding of C. albicans evolution, including the loss of the sexual cycle, the origin of the association with humans, and the evolution of virulence traits.
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7
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Hennig S, Wenzel M, Haas C, Hoffmann A, Weber J, Rödel G, Ostermann K. New approaches in bioprocess-control: Consortium guidance by synthetic cell-cell communication based on fungal pheromones. Eng Life Sci 2018; 18:387-400. [PMID: 32624919 DOI: 10.1002/elsc.201700181] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 02/08/2018] [Accepted: 03/13/2018] [Indexed: 01/02/2023] Open
Abstract
Bioconversions in industrial processes are currently dominated by single-strain approaches. With the growing complexity of tasks to be carried out, microbial consortia become increasingly advantageous and eventually may outperform single-strain fermentations. Consortium approaches benefit from the combined metabolic capabilities of highly specialized strains and species, and the inherent division of labor reduces the metabolic burden for each strain while increasing product yields and reaction specificities. However, consortium-based designs still suffer from a lack of available tools to control the behavior and performance of the individual subpopulations and of the entire consortium. Here, we propose to implement novel control elements for microbial consortia based on artificial cell-cell communication via fungal mating pheromones. Coupling to the desired output is mediated by pheromone-responsive gene expression, thereby creating pheromone-dependent communication channels between different subpopulations of the consortia. We highlight the benefits of artificial communication to specifically target individual subpopulations of microbial consortia and to control e.g. their metabolic profile or proliferation rate in a predefined and customized manner. Due to the steadily increasing knowledge of sexual cycles of industrially relevant fungi, a growing number of strains and species can be integrated into pheromone-controlled sensor-actor systems, exploiting their unique metabolic properties for microbial consortia approaches.
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Affiliation(s)
- Stefan Hennig
- Institute of Genetics Technische Universität Dresden Dresden Germany
| | - Mandy Wenzel
- Institute of Genetics Technische Universität Dresden Dresden Germany
| | - Christiane Haas
- Institute of Natural Materials Technology Technische Universität Dresden Dresden Germany
| | - Andreas Hoffmann
- Institute of Natural Materials Technology Technische Universität Dresden Dresden Germany
| | - Jost Weber
- Institute of Natural Materials Technology Technische Universität Dresden Dresden Germany.,Evolva Biotec A/S Lersø Parkallé 42 Copenhagen Denmark
| | - Gerhard Rödel
- Institute of Genetics Technische Universität Dresden Dresden Germany
| | - Kai Ostermann
- Institute of Genetics Technische Universität Dresden Dresden Germany
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Defosse TA, Le Govic Y, Courdavault V, Clastre M, Vandeputte P, Chabasse D, Bouchara JP, Giglioli-Guivarc'h N, Papon N. [Yeasts from the CTG clade (Candida clade): Biology, impact in human health, and biotechnological applications]. J Mycol Med 2018; 28:257-268. [PMID: 29545121 DOI: 10.1016/j.mycmed.2018.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/05/2018] [Accepted: 02/12/2018] [Indexed: 11/29/2022]
Abstract
Among the subdivision of Saccharomycotina (ascomycetes budding yeasts), the CTG clade (formerly the Candida clade) includes species that display a particular genetic code. In these yeasts, the CTG codon is predominantly translated as a serine instead of a leucine residue. It is now well-known that some CTG clade species have a major impact on human and its activities. Some of them are recognized as opportunistic agents of fungal infections termed candidiasis. In addition, another series of species belonging to the CTG clade draws the attention of some research groups because they exhibit a strong potential in various areas of biotechnology such as biological control, bioremediation, but also in the production of valuable biocompounds (biofuel, vitamins, sweeteners, industrial enzymes). Here we provide an overview of recent advances concerning the biology, clinical relevance, and currently tested biotechnological applications of species of the CTG clade. Future directions for scientific research on these particular yeasts are also discussed.
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Affiliation(s)
- T A Defosse
- Groupe d'étude des interactions Hôte-Pathogène (EA 3142), SFR interactions cellulaires et applications thérapeutiques, université d'Angers, 49933 Angers, France; EA 2106, université de Tours, biomolécules et biotechnologies végétales, Tours, France
| | - Y Le Govic
- Groupe d'étude des interactions Hôte-Pathogène (EA 3142), SFR interactions cellulaires et applications thérapeutiques, université d'Angers, 49933 Angers, France; Laboratoire de parasitologie - mycologie, centre hospitalier universitaire d'Angers, Angers, France
| | - V Courdavault
- EA 2106, université de Tours, biomolécules et biotechnologies végétales, Tours, France
| | - M Clastre
- EA 2106, université de Tours, biomolécules et biotechnologies végétales, Tours, France
| | - P Vandeputte
- Groupe d'étude des interactions Hôte-Pathogène (EA 3142), SFR interactions cellulaires et applications thérapeutiques, université d'Angers, 49933 Angers, France; Laboratoire de parasitologie - mycologie, centre hospitalier universitaire d'Angers, Angers, France
| | - D Chabasse
- Groupe d'étude des interactions Hôte-Pathogène (EA 3142), SFR interactions cellulaires et applications thérapeutiques, université d'Angers, 49933 Angers, France; Laboratoire de parasitologie - mycologie, centre hospitalier universitaire d'Angers, Angers, France
| | - J-P Bouchara
- Groupe d'étude des interactions Hôte-Pathogène (EA 3142), SFR interactions cellulaires et applications thérapeutiques, université d'Angers, 49933 Angers, France; Laboratoire de parasitologie - mycologie, centre hospitalier universitaire d'Angers, Angers, France
| | - N Giglioli-Guivarc'h
- EA 2106, université de Tours, biomolécules et biotechnologies végétales, Tours, France
| | - N Papon
- Groupe d'étude des interactions Hôte-Pathogène (EA 3142), SFR interactions cellulaires et applications thérapeutiques, université d'Angers, 49933 Angers, France.
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Parasex Generates Phenotypic Diversity de Novo and Impacts Drug Resistance and Virulence in Candida albicans. Genetics 2017; 207:1195-1211. [PMID: 28912344 DOI: 10.1534/genetics.117.300295] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 09/05/2017] [Indexed: 01/06/2023] Open
Abstract
Candida albicans is a diploid fungus that is a frequent cause of mucosal and systemic infections in humans. This species exhibits an unusual parasexual cycle in which mating produces tetraploid cells that undergo a nonmeiotic program of concerted chromosome loss to return to a diploid or aneuploid state. In this work, we used a multipronged approach to examine the capacity of parasex to generate diversity in C. albicans First, we compared the phenotypic properties of 32 genotyped progeny and observed wide-ranging differences in fitness, filamentation, biofilm formation, and virulence. Strikingly, one parasexual isolate displayed increased virulence relative to parental strains using a Galleria mellonella model of infection, establishing that parasex has the potential to enhance pathogenic traits. Next, we examined parasexual progeny derived from homothallic, same-sex mating events, and reveal that parasex can generate diversity de novo from identical parental strains. Finally, we generated pools of parasexual progeny and examined resistance of these pools to environmental stresses. Parasexual progeny were generally less fit than control strains across most test conditions, but showed an increased ability to grow in the presence of the antifungal drug fluconazole (FL). FL-resistant progeny were aneuploid isolates, often being diploid strains trisomic for both Chr3 and Chr6. Passaging of these aneuploid strains frequently led to loss of the supernumerary chromosomes and a concomitant decrease in drug resistance. These experiments establish that parasex generates extensive phenotypic diversity de novo, and that this process has important consequences for both virulence and drug resistance in C. albicans populations.
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Abstract
This article provides an overview of sexual reproduction in the ascomycetes, a phylum of fungi that is named after the specialized sacs or "asci" that hold the sexual spores. They have therefore also been referred to as the Sac Fungi due to these characteristic structures that typically contain four to eight ascospores. Ascomycetes are morphologically diverse and include single-celled yeasts, filamentous fungi, and more complex cup fungi. The sexual cycles of many species, including those of the model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe and the filamentous saprobes Neurospora crassa, Aspergillus nidulans, and Podospora anserina, have been examined in depth. In addition, sexual or parasexual cycles have been uncovered in important human pathogens such as Candida albicans and Aspergillus fumigatus, as well as in plant pathogens such as Fusarium graminearum and Cochliobolus heterostrophus. We summarize what is known about sexual fecundity in ascomycetes, examine how structural changes at the mating-type locus dictate sexual behavior, and discuss recent studies that reveal that pheromone signaling pathways can be repurposed to serve cellular roles unrelated to sex.
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11
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Cutaneous, Subcutaneous and Systemic Mycology. VETERINARY MYCOLOGY 2015. [PMCID: PMC7122059 DOI: 10.1007/978-81-322-2280-4_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The first description of dermatophytosis was recorded by Celsus, a Roman encyclopaedist who described a suppurative infection of scalp (‘porrigo’ or ‘kerion of Celsus’) in De Re Medicina (30 A.D.). Throughout the middle ages, several descriptions of dermatophytosis were produced where it is described as ‘tinea’. The keratin-destroying moths which made circular holes in the woollen garments are known as Tinea. Due to similarity in the structure of circular lesion of dermatophytosis on the smooth skin with the circular hole made by moth, Cassius Felix introduced the term ‘tinea’ to describe the lesions. In 1806, Alibert used the term ‘favus’ to describe the honey-like exudate in some scalp infections. However, the fungal aetiology of tinea was first detected by Robert Remak, a Polish physician who first observed the presence of hyphae in the crusts of favus. This detection is also a landmark in medical history because this is the first description of a microbe causing a human disease. He himself did not publish his work, but he permitted the reference of his observations in a dissertation by Xavier Hube in 1837. Remak gave all the credits of his discovery to his mentor Schoenlein who first published the fungal etiological report of favus in 1839. He observed the infectious nature of the favus by autoinoculation into his own hands and also successfully isolated the fungus later (1945) and named Achorion schoenleinii (Trichophyton schoenleinii) in honour of his mentor. In 1844, Gruby described the etiologic agent of tinea endothrix, later became known as Trichophyton tonsurans. The genus Trichophyton was created and described by Malmsten (1845) with its representative species T. tonsurans. Charles Robin identified T. mentagrophytes in 1847 and T. equinum was identified by Matruchot and Dassonville in 1898. Raymond Jacques Adrien Sabouraud (France) first compiled the description of Trichophyton in his book (Les Teignes) in 1910 which was based on his observation in artificial culture. The sexual state of dermatophyte was described by Nannizzi (1927). Emmons (1934) first reported the classification of dermatophytes based on vegetative structures and conidia. Gentles (1958) established the successful treatment of tinea capitis with griseofulvin.
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12
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Liang SH, Cheng JH, Deng FS, Tsai PA, Lin CH. A novel function for Hog1 stress-activated protein kinase in controlling white-opaque switching and mating in Candida albicans. EUKARYOTIC CELL 2014; 13:1557-66. [PMID: 25344054 PMCID: PMC4248679 DOI: 10.1128/ec.00235-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 10/17/2014] [Indexed: 11/20/2022]
Abstract
Candida albicans is a commensal in heathy people but has the potential to become an opportunistic pathogen and is responsible for half of all clinical infections in immunocompromised patients. Central to understanding C. albicans behavior is the white-opaque phenotypic switch, in which cells can undergo an epigenetic transition between the white state and the opaque state. The phenotypic switch regulates multiple properties, including biofilm formation, virulence, mating, and fungus-host interactions. Switching between the white and opaque states is associated with many external stimuli, such as oxidative stress, pH, and N-acetylglucosamine, and is directly regulated by the Wor1 transcriptional circuit. The Hog1 stress-activated protein kinase (SAPK) pathway is recognized as the main pathway for adapting to environmental stress in C. albicans. In this work, we first show that loss of the HOG1 gene in A: / A: and α/α cells, but not A: /α cells, results in 100% white-to-opaque switching when cells are grown on synthetic medium, indicating that switching is repressed by the A1: /α2 heterodimer that represses WOR1 gene expression. Indeed, switching in the hog1Δ strain was dependent on the presence of WOR1, as a hog1Δ wor1Δ strain did not show switching to the opaque state. Deletion of PBS2 and SSK2 also resulted in C. albicans cells switching from white to opaque with 100% efficiency, indicating that the entire Hog1 SAPK pathway is involved in regulating this unique phenotypic transition. Interestingly, all Hog1 pathway mutants also caused defects in shmoo formation and mating efficiencies. Overall, this work reveals a novel role for the Hog1 SAPK pathway in regulating white-opaque switching and sexual behavior in C. albicans.
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Affiliation(s)
- Shen-Huan Liang
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Jen-Hua Cheng
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Fu-Sheng Deng
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Pei-An Tsai
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Ching-Hsuan Lin
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
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13
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Kahar P, Tanaka S. A xylose-fermenting yeast hybridized by intergeneric fusion between Saccharomyces cerevisiae and Candida intermediamutants for ethanol production. ACTA ACUST UNITED AC 2014. [DOI: 10.1186/s40508-014-0017-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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14
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Bennett RJ, Forche A, Berman J. Rapid mechanisms for generating genome diversity: whole ploidy shifts, aneuploidy, and loss of heterozygosity. Cold Spring Harb Perspect Med 2014; 4:cshperspect.a019604. [PMID: 25081629 DOI: 10.1101/cshperspect.a019604] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Human fungal pathogens can exist in a variety of ploidy states, including euploid and aneuploid forms. Ploidy change has a major impact on phenotypic properties, including the regulation of interactions with the human host. In addition, the rapid emergence of drug-resistant isolates is often associated with the formation of specific supernumerary chromosomes. Pathogens such as Candida albicans and Cryptococcus neoformans appear particularly well adapted for propagation in multiple ploidy states with novel pathways driving ploidy variation. In both species, heterozygous cells also readily undergo loss of heterozygosity (LOH), leading to additional phenotypic changes such as altered drug resistance. Here, we examine the sexual and parasexual cycles that drive ploidy variation in human fungal pathogens and discuss ploidy and LOH events with respect to their far-reaching roles in fungal adaptation and pathogenesis.
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Affiliation(s)
- Richard J Bennett
- Department of Molecular Microbiology and Immunology, Brown University, Providence, Rhode Island 02912
| | - Anja Forche
- Department of Biology, Bowdoin College, Brunswick, Maine 04011
| | - Judith Berman
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455 Department of Molecular Microbiology and Biotechnology, George Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
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Czaika V, Nenoff P, Glöckner A, Fegeler W, Becker K, Schmalreck AF. Epidemiology and changes in patient-related factors from 1997 to 2009 in clinical yeast isolates related to dermatology, gynaecology, and paediatrics. Int J Microbiol 2013; 2013:703905. [PMID: 24391669 PMCID: PMC3874336 DOI: 10.1155/2013/703905] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Revised: 06/30/2013] [Accepted: 07/01/2013] [Indexed: 12/20/2022] Open
Abstract
From 1997 to 2009, 1,862 dermatology, gynaecology, and paediatrics (DGP) associated clinical yeast isolates were analysed for species occurrence, specimen origin and type, (multi-) resistance pattern, and testing period. The top seven of the isolated DGP-associated species remained the same as compared to total medical wards, with Candida albicans (45%) as most frequent pathogen. However, the DGP wards and DGP ICUs showed species-specific profiles; that is, the species distribution is clinic-specific similar and however differs in their percentage from ward to ward. By applying the "one fungus one name" principle, respectively, the appropriate current taxonomic species denominations, it has been shown that no trend to emerging species from 1998 to 2008 could be detected. In particular the frequently isolated non-Candida albicans species isolated in the DGP departments have already been detected in or before 1997. As yeasts are part of the cutaneous microbiota and play an important role as opportunistic pathogens for superficial infections, proper identification of the isolates according to the new nomenclature deems to be essential for specific and calculated antifungal therapy for yeast-like DGP-related infectious agents.
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Affiliation(s)
- Viktor Czaika
- Klinik für Dermatologie, Venerologie und Allergologie, Campus Benjamin Franklin, Charité-Universitätsmedizin Berlin, Hindenburgdamm 30, 12203 Berlin, Germany
| | - Pietro Nenoff
- Laboratorium für medizinische Mikrobiologie, Straße des Friedens 8, 04579 Mölbis, Germany
| | - Andreas Glöckner
- BDH-Klinik Greifswald GmbH, Karl-Liebknecht-Ring 26a, 17491 Greifswald, Germany
| | - Wolfgang Fegeler
- Institute of Medical Microbiology, Domagkstraße 10, 48149 Münster, Germany
| | - Karsten Becker
- Institute of Medical Microbiology, Domagkstraße 10, 48149 Münster, Germany
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16
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Abstract
Candida species exhibit a variety of ploidy states and modes of sexual reproduction. Most species possess the requisite genes for sexual reproduction, recombination, and meiosis, yet only a few have been reported to undergo a complete sexual cycle including mating and sporulation. Candida albicans, the most studied Candida species and a prevalent human fungal pathogen, completes its sexual cycle via a parasexual process of concerted chromosome loss rather than a conventional meiosis. In this study, we examine ploidy changes in Candida tropicalis, a closely related species to C. albicans that was recently revealed to undergo sexual mating. C. tropicalis diploid cells mate to form tetraploid cells, and we show that these can be induced to undergo chromosome loss to regenerate diploid forms by growth on sorbose medium. The diploid products are themselves mating competent, thereby establishing a parasexual cycle in this species for the first time. Extended incubation (>120 generations) of C. tropicalis tetraploid cells under rich culture conditions also resulted in instability of the tetraploid form and a gradual reduction in ploidy back to the diploid state. The fitness levels of C. tropicalis diploid and tetraploid cells were compared, and diploid cells exhibited increased fitness relative to tetraploid cells in vitro, despite diploid and tetraploid cells having similar doubling times. Collectively, these experiments demonstrate distinct pathways by which a parasexual cycle can occur in C. tropicalis and indicate that nonmeiotic mechanisms drive ploidy changes in this prevalent human pathogen.
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17
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Haag KL, Sheikh-Jabbari E, Ben-Ami F, Ebert D. Microsatellite and single-nucleotide polymorphisms indicate recurrent transitions to asexuality in a microsporidian parasite. J Evol Biol 2013; 26:1117-28. [PMID: 23530861 DOI: 10.1111/jeb.12125] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Accepted: 01/07/2013] [Indexed: 01/10/2023]
Abstract
Assessing the mode of reproduction of microparasites remains a difficult task because direct evidence for sexual processes is often absent and the biological covariates of sex and asex are poorly known. Species with geographically divergent modes of reproduction offer the possibility to explore some of these covariates, for example, the influence of life-history traits, mode of transmission and life-cycle complexity. Here, we present a phylogeographical study of a microsporidian parasite, which allows us to relate population genetic structure and mode of reproduction to its geographically diverged life histories. We show that in microsporidians from the genus Hamiltosporidium, that use the cladoceran Daphnia as host, an epidemic population structure has evolved, most probably since the last Ice Age. We partially sequenced three housekeeping genes (alpha tubulin, beta tubulin and hsp70) and genotyped seven microsatellite loci in 51 Hamiltosporidium isolates sampled within Europe and the Middle East. We found two phylogenetically related asexual parasite lines, one each from Fennoscandia and Israel, which share the unique ability of being transmitted both vertically and horizontally from Daphnia to Daphnia. The sexual forms cannot transmit horizontally among Daphnia, but presumably have a complex life cycle with a second host species. In spite of the similarities between the two asexual lineages, a clustering analysis based on microsatellite polymorphisms shows that asexual Fennoscandian parasites do not share ancestry with any other Hamiltosporidium that we have sampled. Moreover, allele sequence divergence at the hsp70 locus is twice as large in Fennoscandian than in Israeli parasites. Our results indicate that asexual reproduction evolved twice independently, first in Fennoscandian and more recently in the Israeli parasites. We conclude that the independent origin of asexuality in these two populations is associated with the altered parasite mode of transmission and the underlying dynamics of host populations.
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Affiliation(s)
- K L Haag
- Zoological Institute, University of Basel, Basel, Switzerland
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18
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Porman AM, Hirakawa MP, Jones SK, Wang N, Bennett RJ. MTL-independent phenotypic switching in Candida tropicalis and a dual role for Wor1 in regulating switching and filamentation. PLoS Genet 2013; 9:e1003369. [PMID: 23555286 PMCID: PMC3605238 DOI: 10.1371/journal.pgen.1003369] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 01/22/2013] [Indexed: 01/09/2023] Open
Abstract
Phenotypic switching allows for rapid transitions between alternative cell states and is important in pathogenic fungi for colonization and infection of different host niches. In Candida albicans, the white-opaque phenotypic switch plays a central role in regulating the program of sexual mating as well as interactions with the mammalian host. White-opaque switching is controlled by genes encoded at the MTL (mating-type-like) locus that ensures that only a or α cells can switch from the white state to the mating-competent opaque state, while a/α cells are refractory to switching. Here, we show that the related pathogen C. tropicalis undergoes white-opaque switching in all three cell types (a, α, and a/α), and thus switching is independent of MTL control. We also demonstrate that C. tropicalis white cells are themselves mating-competent, albeit at a lower efficiency than opaque cells. Transcriptional profiling of C. tropicalis white and opaque cells reveals significant overlap between switch-regulated genes in MTL homozygous and MTL heterozygous cells, although twice as many genes are white-opaque regulated in a/α cells as in a cells. In C. albicans, the transcription factor Wor1 is the master regulator of the white-opaque switch, and we show that Wor1 also regulates switching in C. tropicalis; deletion of WOR1 locks a, α, and a/α cells in the white state, while WOR1 overexpression induces these cells to adopt the opaque state. Furthermore, we show that WOR1 overexpression promotes both filamentous growth and biofilm formation in C. tropicalis, independent of the white-opaque switch. These results demonstrate an expanded role for C. tropicalis Wor1, including the regulation of processes necessary for infection of the mammalian host. We discuss these findings in light of the ancestral role of Wor1 as a transcriptional regulator of the transition between yeast form and filamentous growth. The white-opaque phenotypic switch has been extensively characterized in the human fungal pathogen Candida albicans, where it plays a central role in regulating entry into sexual reproduction. This epigenetic switch is strictly regulated by the MTL locus so that only a or α cell types can switch to the opaque state, whereas a/α cells are locked in the white state. In contrast, we show that in the related pathogen C. tropicalis white cells are capable of sexual mating and that the white-opaque switch is independent of MTL control. Thus, MTLa, α, and a/α cells all undergo reversible switching between white and opaque states. Despite these differences, switching in both C. tropicalis and C. albicans is dependent on the expression of the Wor1 transcription factor. This factor is conserved amongst fungal ascomycetes and, in several species, acts as a master regulator of the yeast-to-filament transition. We show that, in addition to regulating the white-opaque switch in C. tropicalis, Wor1 expression also promotes filamentation and biofilm formation in this species. We therefore propose that C. tropicalis Wor1 has retained the ancestral role of this family of transcription factors while also gaining control over the more recently evolved white-opaque phenotypic switch.
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Affiliation(s)
- Allison M. Porman
- Department of Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
| | - Matthew P. Hirakawa
- Department of Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
| | - Stephen K. Jones
- Department of Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
| | - Na Wang
- Department of Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
| | - Richard J. Bennett
- Department of Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
- * E-mail:
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19
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20
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Yadav JSS, Bezawada J, Yan S, Tyagi RD, Surampalli RY. Candida krusei: biotechnological potentials and concerns about its safety. Can J Microbiol 2012; 58:937-52. [PMID: 22823163 DOI: 10.1139/w2012-077] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Yeasts have a tradition in biotechnological applications, and Saccharomyces species are the most dominating representatives. Among the yeast species, Candida krusei has been isolated from different habitats, and in recent years, it has gained increased interest because of its diverse biotechnological role. It is found in many fermented food items and dairy products and has also been exploited for production of biochemicals and enzymes. However, because of its opportunistic pathogenic nature, it draws scientific attention regarding the safety of its industrial exploitation. Candida krusei generally causes infections in immunocompromised patients, such as those suffering from Human immunodeficiency virus - acquired immune deficiency syndrome, and also in cancer patients. The recent increase in the use of immunosuppressive drugs has increased the chances of C. krusei infections. Candida krusei possesses an intrinsic resistance to many triazole antifungal drugs, especially fluconazole, which is a main drug used in antifungal therapy; therefore, there is serious concern regarding its safe industrial use.
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Affiliation(s)
- Jay Shankar Singh Yadav
- Institut national de la recherche scientifique - Eau Terre Environnement, Université du Québec, 490, rue de la Couronne, Québec, QC G1K 9A9, Canada
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21
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Ankarklev J, Svärd SG, Lebbad M. Allelic sequence heterozygosity in single Giardia parasites. BMC Microbiol 2012; 12:65. [PMID: 22554281 PMCID: PMC3438080 DOI: 10.1186/1471-2180-12-65] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 05/03/2012] [Indexed: 12/17/2022] Open
Abstract
Background Genetic heterogeneity has become a major inconvenience in the genotyping and molecular epidemiology of the intestinal protozoan parasite Giardia intestinalis, in particular for the major human infecting genotype, assemblage B. Sequence-based genotyping of assemblage B Giardia from patient fecal samples, where one or several of the commonly used genotyping loci (beta-giardin, triosephosphate isomerase and glutamate dehydrogenase) are implemented, is often hampered due to the presence of sequence heterogeneity in the sequencing chromatograms. This can be due to allelic sequence heterozygosity (ASH) and /or co-infections with parasites of different assemblage B sub-genotypes. Thus, two important questions have arisen; i) does ASH occur at the single cell level, and/or ii) do multiple sub-genotype infections commonly occur in patients infected with assemblage B, G. intestinalis isolates? Results We used micromanipulation in order to isolate single Giardia intestinalis, assemblage B trophozoites (GS isolate) and cysts from human patients. Molecular analysis at the tpi loci of trophozoites from the GS lineage indicated that ASH is present at the single cell level. Analyses of assemblage B Giardia cysts from clinical samples at the bg and tpi loci also indicated ASH at the single cell level. Additionally, alignment of sequence data from several different cysts that originated from the same patient yielded different sequence patterns, thus suggesting the presence of multiple sub-assemblage infections in congruence with ASH within the same patient. Conclusions Our results conclusively show that ASH does occur at the single cell level in assemblage B Giardia. Furthermore, sequence heterogeneity generated during sequence-based genotyping of assemblage B isolates may possess the complexity of single cell ASH in concurrence with co-infections of different assemblage B sub-genotypes. These findings explain the high abundance of sequence heterogeneity commonly found when performing sequence based genotyping of assemblage B Giardia, and illuminates the necessity of developing new G. intestinalis genotyping tools.
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Affiliation(s)
- Johan Ankarklev
- Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden.
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22
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Berman J, Hadany L. Does stress induce (para)sex? Implications for Candida albicans evolution. Trends Genet 2012; 28:197-203. [PMID: 22364928 DOI: 10.1016/j.tig.2012.01.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/19/2012] [Accepted: 01/26/2012] [Indexed: 01/09/2023]
Abstract
Theory predicts that stress is a key factor in explaining the evolutionary role of sex in facultatively sexual organisms, including microorganisms. Organisms capable of reproducing both sexually and asexually are expected to mate more frequently when stressed, and such stress-induced mating is predicted to facilitate adaptation. Here, we propose that stress has an analogous effect on the parasexual cycle in Candida albicans, which involves alternation of generations between diploid and tetraploid cells. The parasexual cycle can generate high levels of diversity, including aneuploidy, yet it apparently occurs only rarely in nature. We review the evidence that stress facilitates four major steps in the parasexual cycle and suggest that parasex occurs much more frequently under stress conditions. This may explain both the evolutionary significance of parasex and its apparent rarity.
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Affiliation(s)
- Judith Berman
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
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23
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Discovery of a phenotypic switch regulating sexual mating in the opportunistic fungal pathogen Candida tropicalis. Proc Natl Acad Sci U S A 2011; 108:21158-63. [PMID: 22158989 DOI: 10.1073/pnas.1112076109] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Sexual reproduction can promote genetic diversity in eukaryotes, and yet many pathogenic fungi have been labeled as obligate asexual species. It is becoming increasingly clear, however, that cryptic sexual programs may exist in some species, and that efficient mating requires the necessary developmental switch to be triggered. In this study we investigate Candida tropicalis, an important human fungal pathogen that has been reported to be asexual. Significantly, we demonstrate that C. tropicalis uses a phenotypic switch to regulate a cryptic program of sexual mating. Thus, diploid a and α cells must undergo a developmental transition to the mating-competent form, and only then does efficient cell-cell conjugation take place resulting in the formation of stable a/α tetraploids. We show that both the phenotypic switch and sexual mating depend on the conserved transcriptional regulator Wor1, which is regulated by temperature in other fungal species. In contrast, C. tropicalis mating occurs efficiently at both 25 °C and 37 °C, suggesting that it could occur in the mammalian host and have direct consequences for the outcome of an infection. Transcriptional profiling further reveals that ≈ 400 genes are differentially expressed between the two phenotypic states, including the regulatory factor Wor1. Taken together, our results demonstrate that C. tropicalis has a unique sexual program, and that entry to this program is controlled via a Wor1-mediated, metastable switch. These observations have direct implications for the regulation and evolution of cryptic sexual programs in related fungal pathogens.
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Lin CH, Choi A, Bennett RJ. Defining pheromone-receptor signaling in Candida albicans and related asexual Candida species. Mol Biol Cell 2011; 22:4918-30. [PMID: 21998194 PMCID: PMC3237633 DOI: 10.1091/mbc.e11-09-0749] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The pheromone response in Candida albicans is mediated by the Ste2 receptor. Intracellular (IC) loop 3 and C-terminal tail regions of Ste2 are required for signaling, whereas the large IC1 region is dispensable. Heterologous expression of receptors from asexual species can also drive signaling in C. albicans, allowing functional pheromone-receptor couples to be analyzed. Candida albicans is an important human fungal pathogen in which sexual reproduction is under the control of the novel white–opaque switch. Opaque cells are the mating-competent form, whereas white cells do not mate but can still respond to pheromones, resulting in biofilm formation. In this study, we first define the domains of the α-pheromone receptor Ste2 that are necessary for signaling in both white and opaque forms. Both cell states require the IC loop 3 (IC3) and the C-terminal tail of Ste2 for the cellular response, whereas the first IC loop (IC1) of Ste2 is dispensable for signaling. To also address pheromone-receptor interactions in related species, including apparently asexual Candida species, Ste2 orthologues were heterologously expressed in Candida albicans. Ste2 receptors from multiple Candida clade species were functional when expressed in C. albicans, whereas the Ste2 receptor of Candida lusitaniae was nonfunctional. Significantly, however, expression of a chimeric C. lusitaniae Ste2 receptor containing the C-terminal tail of Ste2 from C. albicans generated a productive response to C. lusitaniae pheromone. This system has allowed us to characterize pheromones from multiple Candida species and indicates that functional pheromone-receptor couples exist in fungal species that have yet to be shown to undergo sexual mating.
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Affiliation(s)
- Ching-Hsuan Lin
- Molecular Microbiology and Immunology Department, Brown University, Providence, RI 02912, USA
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25
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Jones SK, Bennett RJ. Fungal mating pheromones: choreographing the dating game. Fungal Genet Biol 2011; 48:668-76. [PMID: 21496492 PMCID: PMC3100450 DOI: 10.1016/j.fgb.2011.04.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 02/23/2011] [Accepted: 04/05/2011] [Indexed: 01/11/2023]
Abstract
Pheromones are ubiquitous from bacteria to mammals - a testament to their importance in regulating inter-cellular communication. In fungal species, they play a critical role in choreographing interactions between mating partners during the program of sexual reproduction. Here, we describe how fungal pheromones are synthesized, their interactions with G protein-coupled receptors, and the signals propagated by this interaction, using Saccharomyces cerevisiae as a reference point. Divergence from this model system is compared amongst the ascomycetes and basidiomycetes, which reveals the wealth of information that has been gleaned from studying pheromone-driven processes across a wide spectrum of the fungal kingdom.
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Affiliation(s)
- Stephen K. Jones
- Graduate Program in Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI 02912
| | - Richard J. Bennett
- Graduate Program in Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI 02912
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912
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26
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Interspecies pheromone signaling promotes biofilm formation and same-sex mating in Candida albicans. Proc Natl Acad Sci U S A 2011; 108:2510-5. [PMID: 21262815 DOI: 10.1073/pnas.1017234108] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The opportunistic pathogen Candida albicans undergoes a parasexual mating cycle in which cells must switch from the conventional "white" form to the alternative "opaque" form to become mating competent. Pheromones secreted by opaque cells induce the formation of polarized mating projections and result in cell-cell conjugation. In contrast, white cells are unable to undergo mating, but can still respond to pheromone by expression of adhesion genes that promote biofilm formation. In this study, we have analyzed the dual ability of pheromones to activate mating by opaque cells and biofilm formation by white cells. We first show that there is considerable plasticity in interactions between the α pheromone and its receptor, Ste2, by analysis of analogs of the α pheromone. Significantly, substituted forms of α pheromone can induce a response in opaque cells and this is sufficient to drive same-sex a-a cell fusion and homothallic mating. In addition, pheromone analogs were able to induce adhesion and biofilm formation in white cells of C. albicans. Because of the observed plasticity in pheromone signaling, we subsequently tested putative pheromones from multiple Candida species and identified nonnative ligands that can induce self-mating and biofilm responses in C. albicans. Our findings demonstrate that environmental signals can initiate C. albicans parasexual reproduction and biofilm formation, and highlight the role of the pheromone-signaling apparatus in mediating these functions.
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