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Crandall JG, Fisher KJ, Sato TK, Hittinger CT. Ploidy evolution in a wild yeast is linked to an interaction between cell type and metabolism. PLoS Biol 2023; 21:e3001909. [PMID: 37943740 PMCID: PMC10635434 DOI: 10.1371/journal.pbio.3001909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 10/06/2023] [Indexed: 11/12/2023] Open
Abstract
Ploidy is an evolutionarily labile trait, and its variation across the tree of life has profound impacts on evolutionary trajectories and life histories. The immediate consequences and molecular causes of ploidy variation on organismal fitness are frequently less clear, although extreme mating type skews in some fungi hint at links between cell type and adaptive traits. Here, we report an unusual recurrent ploidy reduction in replicate populations of the budding yeast Saccharomyces eubayanus experimentally evolved for improvement of a key metabolic trait, the ability to use maltose as a carbon source. We find that haploids have a substantial, but conditional, fitness advantage in the absence of other genetic variation. Using engineered genotypes that decouple the effects of ploidy and cell type, we show that increased fitness is primarily due to the distinct transcriptional program deployed by haploid-like cell types, with a significant but smaller contribution from absolute ploidy. The link between cell-type specification and the carbon metabolism adaptation can be traced to the noncanonical regulation of a maltose transporter by a haploid-specific gene. This study provides novel mechanistic insight into the molecular basis of an environment-cell type fitness interaction and illustrates how selection on traits unexpectedly linked to ploidy states or cell types can drive karyotypic evolution in fungi.
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Affiliation(s)
- Johnathan G. Crandall
- Laboratory of Genetics, Wisconsin Energy Institute, J. F. Crow Institute for the Study of Evolution, Center for Genomic Science Innovation, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Kaitlin J. Fisher
- Laboratory of Genetics, Wisconsin Energy Institute, J. F. Crow Institute for the Study of Evolution, Center for Genomic Science Innovation, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Trey K. Sato
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Chris Todd Hittinger
- Laboratory of Genetics, Wisconsin Energy Institute, J. F. Crow Institute for the Study of Evolution, Center for Genomic Science Innovation, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
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Badrane H, Cheng S, Dupont CL, Hao B, Driscoll E, Morder K, Liu G, Newbrough A, Fleres G, Kaul D, Espinoza JL, Clancy CJ, Nguyen MH. Genotypic diversity and unrecognized antifungal resistance among populations of Candida glabrata from positive blood cultures. Nat Commun 2023; 14:5918. [PMID: 37739935 PMCID: PMC10516878 DOI: 10.1038/s41467-023-41509-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 09/07/2023] [Indexed: 09/24/2023] Open
Abstract
The longstanding model is that most bloodstream infections (BSIs) are caused by a single organism. We perform whole genome sequencing of five-to-ten strains from blood culture (BC) bottles in each of ten patients with Candida glabrata BSI. We demonstrate that BCs contain mixed populations of clonal but genetically diverse strains. Genetically distinct strains from two patients exhibit phenotypes that are potentially important during BSIs, including differences in susceptibility to antifungal agents and phagocytosis. In both patients, the clinical microbiology lab recovered a fluconazole-susceptible index strain, but we identify mixed fluconazole-susceptible and -resistant populations. Diversity in drug susceptibility is likely clinically relevant, as fluconazole-resistant strains were subsequently recovered by the clinical laboratory during persistent or relapsing infections. In one patient, unrecognized respiration-deficient small colony variants are fluconazole-resistant and significantly attenuated for virulence during murine candidiasis. Our data suggest a population-based model of C. glabrata genotypic and phenotypic diversity during BSIs.
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Affiliation(s)
| | | | | | - Binghua Hao
- University of Pittsburgh, Pittsburgh, PA, USA
| | | | | | - Guojun Liu
- University of Pittsburgh, Pittsburgh, PA, USA
| | | | | | - Drishti Kaul
- J. Craig Venter Institute, La Jolla, CA, 92037, USA
| | | | - Cornelius J Clancy
- University of Pittsburgh, Pittsburgh, PA, USA
- VA Pittsburgh Healthcare System, Pittsburgh, PA, USA
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3
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Badrane H, Cheng S, Dupont CL, Hao B, Driscoll E, Morder K, Liu G, Newbrough A, Fleres G, Kaul D, Espinoza JL, Clancy CJ, Nguyen MH. Genotypic diversity and unrecognized antifungal resistance among populations of Candida glabrata from positive blood cultures. RESEARCH SQUARE 2023:rs.3.rs-2706400. [PMID: 37066226 PMCID: PMC10104189 DOI: 10.21203/rs.3.rs-2706400/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The longstanding paradigm is that most bloodstream infections (BSIs) are caused by a single organism. We performed whole genome sequencing of five-to-ten strains from blood culture (BC) bottles in each of ten patients with Candida glabrata BSI. We demonstrated that BCs contained mixed populations of clonal but genetically diverse strains. Genetically distinct strains from two patients exhibited phenotypes that were potentially important during BSIs, including differences in susceptibility to antifungal agents and phagocytosis. In both patients, the clinical microbiology lab recovered a fluconazole-susceptible index strain, but we identified mixed fluconazole-susceptible and â€"resistant populations. Diversity in drug susceptibility was likely clinically relevant, as fluconazole-resistant strains were subsequently recovered by the clinical laboratory during persistent or relapsing infections. In one patient, unrecognized respiration-deficient small colony variants were fluconazole-resistant and significantly attenuated for virulence during murine candidiasis. Our data suggest a new population-based paradigm of C. glabrata genotypic and phenotypic diversity during BSIs.
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Affiliation(s)
| | - Shaoji Cheng
- University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | | | - Binghua Hao
- University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | | | | | - Guojun Liu
- University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | | | | | | | | | - Cornelius J Clancy
- University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- VA Pittsburgh Healthcare System, Pittsburgh, Pennsylvania, USA
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4
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Dereeper A, Allouch N, Guerlais V, Garnier M, Ma L, De Jonckheere JF, Joseph SJ, Ali IKM, Talarmin A, Marcelino I. Naegleria genus pangenome reveals new structural and functional insights into the versatility of these free-living amoebae. Front Microbiol 2023; 13:1056418. [PMID: 36817109 PMCID: PMC9928731 DOI: 10.3389/fmicb.2022.1056418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 12/21/2022] [Indexed: 02/04/2023] Open
Abstract
Introduction Free-living amoebae of the Naegleria genus belong to the major protist clade Heterolobosea and are ubiquitously distributed in soil and freshwater habitats. Of the 47 Naegleria species described, N. fowleri is the only one being pathogenic to humans, causing a rare but fulminant primary amoebic meningoencephalitis. Some Naegleria genome sequences are publicly available, but the genetic basis for Naegleria diversity and ability to thrive in diverse environments (including human brain) remains unclear. Methods Herein, we constructed a high-quality Naegleria genus pangenome to obtain a comprehensive catalog of genes encoded by these amoebae. For this, we first sequenced, assembled, and annotated six new Naegleria genomes. Results and Discussion Genome architecture analyses revealed that Naegleria may use genome plasticity features such as ploidy/aneuploidy to modulate their behavior in different environments. When comparing 14 near-to-complete genome sequences, our results estimated the theoretical Naegleria pangenome as a closed genome, with 13,943 genes, including 3,563 core and 10,380 accessory genes. The functional annotations revealed that a large fraction of Naegleria genes show significant sequence similarity with those already described in other kingdoms, namely Animalia and Plantae. Comparative analyses highlighted a remarkable genomic heterogeneity, even for closely related strains and demonstrate that Naegleria harbors extensive genome variability, reflected in different metabolic repertoires. If Naegleria core genome was enriched in conserved genes essential for metabolic, regulatory and survival processes, the accessory genome revealed the presence of genes involved in stress response, macromolecule modifications, cell signaling and immune response. Commonly reported N. fowleri virulence-associated genes were present in both core and accessory genomes, suggesting that N. fowleri's ability to infect human brain could be related to its unique species-specific genes (mostly of unknown function) and/or to differential gene expression. The construction of Naegleria first pangenome allowed us to move away from a single reference genome (that does not necessarily represent each species as a whole) and to identify essential and dispensable genes in Naegleria evolution, diversity and biology, paving the way for further genomic and post-genomic studies.
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Affiliation(s)
- Alexis Dereeper
- Institut Pasteur de la Guadeloupe, Unité TReD-Path, Les Abymes, Guadeloupe, France
| | - Nina Allouch
- Institut Pasteur de la Guadeloupe, Unité TReD-Path, Les Abymes, Guadeloupe, France
| | - Vincent Guerlais
- Institut Pasteur de la Guadeloupe, Unité TReD-Path, Les Abymes, Guadeloupe, France
| | - Maëlle Garnier
- Institut Pasteur de la Guadeloupe, Unité TReD-Path, Les Abymes, Guadeloupe, France
| | - Laurence Ma
- Institut Pasteur de Paris, Biomics, Paris, France
| | | | - Sandeep J. Joseph
- Centers for Disease Control and Prevention (CDC), Atlanta, GA, United States
| | - Ibne Karim M. Ali
- Centers for Disease Control and Prevention (CDC), Atlanta, GA, United States
| | - Antoine Talarmin
- Institut Pasteur de la Guadeloupe, Unité TReD-Path, Les Abymes, Guadeloupe, France
| | - Isabel Marcelino
- Institut Pasteur de la Guadeloupe, Unité TReD-Path, Les Abymes, Guadeloupe, France,*Correspondence: Isabel Marcelino,
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Todd RT, Soisangwan N, Peters S, Kemp B, Crooks T, Gerstein A, Selmecki A. Antifungal Drug Concentration Impacts the Spectrum of Adaptive Mutations in Candida albicans. Mol Biol Evol 2023; 40:6989826. [PMID: 36649220 PMCID: PMC9887641 DOI: 10.1093/molbev/msad009] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 12/06/2022] [Accepted: 01/04/2023] [Indexed: 01/18/2023] Open
Abstract
Invasive fungal infections are a leading global cause of human mortality. Only three major classes of antifungal drugs are widely used, and resistance to all three classes can arise rapidly. The most widely prescribed antifungal drug, fluconazole, disseminates rapidly and reaches a wide range of concentrations throughout the body. The impact of drug concentration on the spectrum and effect of mutations acquired during adaptation is not known for any fungal pathogen, and how the specific level of a given stress influences the distribution of beneficial mutations has been poorly explored in general. We evolved 144 lineages from three genetically distinct clinical isolates of Candida albicans to four concentrations of fluconazole (0, 1, 8, and 64 μg/ml) and performed comprehensive phenotypic and genomic comparisons of ancestral and evolved populations. Adaptation to different fluconazole concentrations resulted in distinct adaptive trajectories. In general, lineages evolved to drug concentrations close to their MIC50 (the level of drug that reduces growth by 50% in the ancestor) tended to rapidly evolve an increased MIC50 and acquired distinct segmental aneuploidies and copy number variations. By contrast, lineages evolved to drug concentrations above their ancestral MIC50 tended to acquire a different suite of mutational changes and increased in drug tolerance (the ability of a subpopulation of cells to grow slowly above their MIC50). This is the first evidence that different concentrations of drug can select for different genotypic and phenotypic outcomes in vitro and may explain observed in vivo drug response variation.
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Affiliation(s)
- Robert T Todd
- Present address: Department of Biology, Bard College, Annandale-on-Hudson, New York
| | | | - Sam Peters
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Bailey Kemp
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Taylor Crooks
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Aleeza Gerstein
- Department of Microbiology, The University of Manitoba, Winnipeg, Manitoba, Canada,Department of Statistics, The University of Manitoba, Winnipeg, Manitoba, Canada
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6
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Avramovska O, Smith AC, Rego E, Hickman MA. Tetraploidy accelerates adaptation under drug selection in a fungal pathogen. FRONTIERS IN FUNGAL BIOLOGY 2022; 3:984377. [PMID: 37746235 PMCID: PMC10512305 DOI: 10.3389/ffunb.2022.984377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 09/06/2022] [Indexed: 09/26/2023]
Abstract
Baseline ploidy significantly impacts evolutionary trajectories and, specifically, tetraploidy is associated with higher rates of adaptation relative to haploidy and diploidy. While the majority of experimental evolution studies investigating ploidy use the budding yeast Saccharomyces cerivisiae, the fungal pathogen Candida albicans is a powerful system to investigate ploidy dynamics, particularly in the context of acquiring antifungal drug resistance. C. albicans laboratory and clinical strains are predominantly diploid, but have been isolated as haploid and polyploid. Here, we evolved diploid and tetraploid C. albicans for ~60 days in the antifungal drug caspofungin. Tetraploid-evolved lines adapted faster than diploid-evolved lines and reached higher levels of caspofungin resistance. While diploid-evolved lines generally maintained their initial genome size, tetraploid-evolved lines rapidly underwent genome-size reductions and did so prior to caspofungin adaptation. While clinical resistance was largely due to mutations in FKS1, these mutations were caused by substitutions in diploid, and indels in tetraploid isolates. Furthermore, fitness costs in the absence of drug selection were significantly less in tetraploid-evolved lines compared to the diploid-evolved lines. Taken together, this work supports a model of adaptation in which the tetraploid state is transient but its ability to rapidly transition ploidy states improves adaptive outcomes and may drive drug resistance in fungal pathogens.
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Affiliation(s)
- Ognenka Avramovska
- Department of Biology, Emory University, Atlanta, GA, United States
- Department of Genetics, Harvard Medical School, Boston, MA, United States
| | - Amanda C. Smith
- Department of Biology, Emory University, Atlanta, GA, United States
- Division of Viral Disease, CDC Foundation, Atlanta, GA, United States
| | - Emily Rego
- Department of Biology, Emory University, Atlanta, GA, United States
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7
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Gostinčar C, Sun X, Černoša A, Fang C, Gunde-Cimerman N, Song Z. Clonality, inbreeding, and hybridization in two extremotolerant black yeasts. Gigascience 2022; 11:giac095. [PMID: 36200832 PMCID: PMC9535773 DOI: 10.1093/gigascience/giac095] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/29/2022] [Accepted: 09/12/2022] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND The great diversity of lifestyles and survival strategies observed in fungi is reflected in the many ways in which they reproduce and recombine. Although a complete absence of recombination is rare, it has been reported for some species, among them 2 extremotolerant black yeasts from Dothideomycetes: Hortaea werneckii and Aureobasidium melanogenum. Therefore, the presence of diploid strains in these species cannot be explained as the product of conventional sexual reproduction. RESULTS Genome sequencing revealed that the ratio of diploid to haploid strains in both H. werneckii and A. melanogenum is about 2:1. Linkage disequilibrium between pairs of polymorphic loci and a high degree of concordance between the phylogenies of different genomic regions confirmed that both species are clonal. Heterozygosity of diploid strains is high, with several hybridizing genome pairs reaching the intergenomic distances typically seen between different fungal species. The origin of diploid strains collected worldwide can be traced to a handful of hybridization events that produced diploids, which were stable over long periods of time and distributed over large geographic areas. CONCLUSIONS Our results, based on the genomes of over 100 strains of 2 black yeasts, show that although they are clonal, they occasionally form stable and highly heterozygous diploid intraspecific hybrids. The mechanism of these apparently rare hybridization events, which are not followed by meiosis or haploidization, remains unknown. Both extremotolerant yeasts, H. werneckii and even more so A. melanogenum, a close relative of the intensely recombining and biotechnologically relevant Aureobasidium pullulans, provide an attractive model for studying the role of clonality and ploidy in extremotolerant fungi.
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Affiliation(s)
- Cene Gostinčar
- Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
- Lars Bolund Institute of Regenerative Medicine, BGI-Qingdao, Qingdao 266555, China
| | - Xiaohuan Sun
- BGI-Shenzhen, Beishan Industrial Zone, Shenzhen 518083, China
| | - Anja Černoša
- Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Chao Fang
- BGI-Shenzhen, Beishan Industrial Zone, Shenzhen 518083, China
| | - Nina Gunde-Cimerman
- Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Zewei Song
- BGI-Shenzhen, Beishan Industrial Zone, Shenzhen 518083, China
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8
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Mullis MN, Ghione C, Lough-Stevens M, Goldstein I, Matsui T, Levy SF, Dean MD, Ehrenreich IM. Complex genetics cause and constrain fungal persistence in different parts of the mammalian body. Genetics 2022; 222:6698696. [PMID: 36103708 PMCID: PMC9630980 DOI: 10.1093/genetics/iyac138] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 08/26/2022] [Indexed: 12/05/2022] Open
Abstract
Determining how genetic polymorphisms enable certain fungi to persist in mammalian hosts can improve understanding of opportunistic fungal pathogenesis, a source of substantial human morbidity and mortality. We examined the genetic basis of fungal persistence in mice using a cross between a clinical isolate and the lab reference strain of the budding yeast Saccharomyces cerevisiae. Employing chromosomally encoded DNA barcodes, we tracked the relative abundances of 822 genotyped, haploid segregants in multiple organs over time and performed linkage mapping of their persistence in hosts. Detected loci showed a mix of general and antagonistically pleiotropic effects across organs. General loci showed similar effects across all organs, while antagonistically pleiotropic loci showed contrasting effects in the brain vs the kidneys, liver, and spleen. Persistence in an organ required both generally beneficial alleles and organ-appropriate pleiotropic alleles. This genetic architecture resulted in many segregants persisting in the brain or in nonbrain organs, but few segregants persisting in all organs. These results show complex combinations of genetic polymorphisms collectively cause and constrain fungal persistence in different parts of the mammalian body.
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Affiliation(s)
- Martin N Mullis
- University of Southern California Molecular and Computational Biology Section, Department of Biological Sciences, , Los Angeles, CA 90089, USA
| | - Caleb Ghione
- University of Southern California Molecular and Computational Biology Section, Department of Biological Sciences, , Los Angeles, CA 90089, USA
| | - Michael Lough-Stevens
- University of Southern California Molecular and Computational Biology Section, Department of Biological Sciences, , Los Angeles, CA 90089, USA
| | - Ilan Goldstein
- University of Southern California Molecular and Computational Biology Section, Department of Biological Sciences, , Los Angeles, CA 90089, USA
| | - Takeshi Matsui
- Stanford University Joint Initiative for Metrology in Biology, , CA 94305, USA
- SLAC National Accelerator Laboratory , Menlo Park, CA, 94025, USA
- Stanford University Department of Genetics, , Stanford, CA 94305, USA
| | - Sasha F Levy
- Stanford University Joint Initiative for Metrology in Biology, , CA 94305, USA
- SLAC National Accelerator Laboratory , Menlo Park, CA, 94025, USA
- Stanford University Department of Genetics, , Stanford, CA 94305, USA
| | - Matthew D Dean
- University of Southern California Molecular and Computational Biology Section, Department of Biological Sciences, , Los Angeles, CA 90089, USA
| | - Ian M Ehrenreich
- University of Southern California Molecular and Computational Biology Section, Department of Biological Sciences, , Los Angeles, CA 90089, USA
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9
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Smith AC, Rizvi H, Hickman MA, Morran LT. Increased Virulence and Large-Scale Reduction in Genome Size of Tetraploid Candida albicans Evolved in Nematode Hosts. FRONTIERS IN FUNGAL BIOLOGY 2022; 3:903135. [PMID: 37746173 PMCID: PMC10512209 DOI: 10.3389/ffunb.2022.903135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 05/05/2022] [Indexed: 09/26/2023]
Abstract
Candida albicans is an opportunistic fungal pathogen of humans, yet the within-host dynamics of C. albicans infection are not clear. While C. albicans is commonly diploid, it exhibits a range of ploidies, including tetraploidy. Previous work found that tetraploid C. albicans populations exhibited rapid adaptation and significant genome instability when evolved in vitro. Host immune function alters the rate and magnitude of C. albicans virulence evolution, but the effects of the host immunity on tetraploid C. albicans populations are unclear. Here, we tested the effects of the host immunity on genome stability and virulence evolution of tetraploid C. albicans using experimental evolution. We selected for C. albicans increased virulence within either immunocompetent or immunocompromised Caenorhabditis elegans hosts. After nine passages we observed a response to selection for increased virulence. Both populations exposed to either immunocompetent or immunocompromised hosts increased virulence after passage through C. elegans hosts. However, the C. albicans populations passaged through immunocompetent hosts under selection exhibited unique temporal dynamics, a rapid increase in virulence and then subsequent loss of virulence. Most C. albicans populations exhibited genome size reduction within six passages, however populations exposed to immunocompetent hosts exhibited the most rapid transition to ~diploid. Therefore, we found that tetraploids rapidly increase in virulence and decrease genome size within host environments. Further, the combination of selection for greater virulence in the presence of immunocompetent hosts results in major virulence fluctuations and genome size changes. Thus, host immunity significantly impacts the evolutionary trajectories of tetraploid C. albicans.
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Affiliation(s)
- Amanda C. Smith
- PhD Program in Genetics and Molecular Biologist, Emory University, Atlanta, GA, United States
- ORISE Fellow, Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN, United States
| | - Hassan Rizvi
- Department of Biology, Emory University, Atlanta, GA, United States
| | - Meleah A. Hickman
- PhD Program in Genetics and Molecular Biologist, Emory University, Atlanta, GA, United States
- Department of Biology, Emory University, Atlanta, GA, United States
| | - Levi T. Morran
- Department of Biology, Emory University, Atlanta, GA, United States
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10
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Genome plasticity in Candida albicans: A cutting-edge strategy for evolution, adaptation, and survival. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2022; 99:105256. [PMID: 35231665 DOI: 10.1016/j.meegid.2022.105256] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 09/12/2021] [Accepted: 02/22/2022] [Indexed: 12/15/2022]
Abstract
Candida albicans is the most implicated fungal species that grows as a commensal or opportunistic pathogen in the human host. It is associated with many life-threatening infections, especially in immunocompromised persons. The genome of Candida albicans is very flexible and can withstand a wide assortment of variations in a continuously changing environment. Thus, genome plasticity is central to its adaptation and has long been of considerable interest. C. albicans has a diploid heterozygous genome that is highly dynamic and can display variation from small to large scale chromosomal rearrangement and aneuploidy, which have implications in drug resistance, virulence, and pathogenicity. This review presents an up-to-date overview of recent genomic studies involving C. albicans. It discusses the accumulating evidence that shows how mitotic recombination events, ploidy dynamics, aneuploidy, and loss of heterozygosity (LOH) influence evolution, adaptation, and survival in C. albicans. Understanding the factors that affect the genome is crucial for a proper understanding of species and rapid development and adjustment of therapeutic strategies to mitigate their spread.
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11
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Thomson GJ, Kakade P, Hirakawa MP, Ene IV, Bennett RJ. Adaptation to the dietary sugar D-tagatose via genome instability in polyploid Candida albicans cells. G3-GENES GENOMES GENETICS 2021; 11:6219300. [PMID: 33836061 PMCID: PMC8495922 DOI: 10.1093/g3journal/jkab110] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 03/25/2021] [Indexed: 02/06/2023]
Abstract
The opportunistic fungal pathogen Candida albicans undergoes an unusual parasexual cycle wherein diploid cells mate to form tetraploid cells that can generate genetically diverse progeny via a non-meiotic program of chromosome loss. The genetic diversity afforded by parasex impacts clinically relevant features including drug resistance and virulence, and yet the factors influencing genome instability in C. albicans are not well defined. To understand how environmental cues impact genome instability, we monitored ploidy change following tetraploid cell growth in a panel of different carbon sources. We found that growth in one carbon source, D-tagatose, led to high levels of genomic instability and chromosome loss in tetraploid cells. This sugar is a stereoisomer of L-sorbose which was previously shown to promote karyotypic changes in C. albicans. However, while expression of the SOU1 gene enabled utilization of L-sorbose, overexpression of this gene did not promote growth in D-tagatose, indicating differences in assimilation of the two sugars. In addition, genome sequencing of multiple progeny recovered from D-tagatose cultures revealed increased relative copy numbers of chromosome 4, suggestive of chromosome-level regulation of D-tagatose metabolism. Together, these studies identify a novel environmental cue that induces genome instability in C. albicans, and further implicate chromosomal changes in supporting metabolic adaptation in this species.
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Affiliation(s)
- Gregory J Thomson
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA
| | - Pallavi Kakade
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA
| | - Matthew P Hirakawa
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA.,Department of Systems Biology, Sandia National Laboratories, Livermore, CA 94550, USA
| | - Iuliana V Ene
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA.,Mycology Department, Pasteur Institute, Paris 75015, France
| | - Richard J Bennett
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA
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12
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Gerstein AC, Sharp NP. The population genetics of ploidy change in unicellular fungi. FEMS Microbiol Rev 2021; 45:6121427. [PMID: 33503232 DOI: 10.1093/femsre/fuab006] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 01/14/2021] [Indexed: 12/23/2022] Open
Abstract
Changes in ploidy are a significant type of genetic variation, describing the number of chromosome sets per cell. Ploidy evolves in natural populations, clinical populations, and lab experiments, particularly in fungi. Despite a long history of theoretical work on this topic, predicting how ploidy will evolve has proven difficult, as it is often unclear why one ploidy state outperforms another. Here, we review what is known about contemporary ploidy evolution in diverse fungal species through the lens of population genetics. As with typical genetic variants, ploidy evolution depends on the rate that new ploidy states arise by mutation, natural selection on alternative ploidy states, and random genetic drift. However, ploidy variation also has unique impacts on evolution, with the potential to alter chromosomal stability, the rate and patterns of point mutation, and the nature of selection on all loci in the genome. We discuss how ploidy evolution depends on these general and unique factors and highlight areas where additional experimental evidence is required to comprehensively explain the ploidy transitions observed in the field and the lab.
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Affiliation(s)
- Aleeza C Gerstein
- Dept. of Microbiology, Dept. of Statistics, University of Manitoba Canada
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13
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Experimental Evolution Identifies Adaptive Aneuploidy as a Mechanism of Fluconazole Resistance in Candida auris. Antimicrob Agents Chemother 2020; 65:AAC.01466-20. [PMID: 33077664 DOI: 10.1128/aac.01466-20] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 10/14/2020] [Indexed: 12/22/2022] Open
Abstract
Candida auris is a newly emerging fungal pathogen of humans and has attracted considerable attention from both the clinical and basic research communities. Clinical isolates of C. auris are often resistant to one or more antifungal agents. To explore how antifungal resistance develops, we performed experimental evolution assays using a fluconazole-susceptible isolate of C. auris (BJCA001). After a series of passages through medium containing increasing concentrations of fluconazole, fungal cells acquired resistance. By sequencing and comparing the genomes of the parental fluconazole-susceptible strain and 26 experimentally evolved strains of C. auris, we found that a portion of fluconazole-resistant strains carried one extra copy of chromosome V. In the absence of fluconazole, C. auris cells rapidly became susceptible and lost the extra copy of chromosome V. Genomic and transcriptome sequencing (RNA-Seq) analyses indicate that this chromosome carries a number of drug resistance-related genes, which were transcriptionally upregulated in the resistant, aneuploid strains. Moreover, missense mutations were identified in the genes TAC1B, RRP6, and SFT2 in all experimentally evolved strains. Our findings suggest that the gain of an extra copy of chromosome V is associated with the rapid acquisition of fluconazole resistance and may represent an important evolutionary mechanism of antifungal resistance in C. auris.
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14
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Feistel DJ, Elmostafa R, Hickman MA. Virulence phenotypes result from interactions between pathogen ploidy and genetic background. Ecol Evol 2020; 10:9326-9338. [PMID: 32953064 PMCID: PMC7487253 DOI: 10.1002/ece3.6619] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 07/02/2020] [Accepted: 07/06/2020] [Indexed: 12/25/2022] Open
Abstract
Studying fungal virulence is often challenging and frequently depends on many contexts, including host immune status and pathogen genetic background. However, the role of ploidy has often been overlooked when studying virulence in eukaryotic pathogens. Since fungal pathogens, including the human opportunistic pathogen Candida albicans, can display extensive ploidy variation, assessing how ploidy impacts virulence has important clinical relevance. As an opportunistic pathogen, C. albicans causes nonlethal, superficial infections in healthy individuals, but life-threatening bloodstream infections in individuals with compromised immune function. Here, we determined how both ploidy and genetic background of C. albicans impacts virulence phenotypes in healthy and immunocompromised nematode hosts by characterizing virulence phenotypes in four near-isogenic diploid and tetraploid pairs of strains, which included both laboratory and clinical genetic backgrounds. We found that C. albicans infections decreased host survival and negatively impacted host reproduction, and we leveraged these two measures to survey both lethal and nonlethal virulence phenotypes across the multiple C. albicans strains. In this study, we found that regardless of pathogen ploidy or genetic background, immunocompromised hosts were susceptible to fungal infection compared to healthy hosts. Furthermore, for each host context, we found a significant interaction between C. albicans genetic background and ploidy on virulence phenotypes, but no global differences between diploid and tetraploid pathogens were observed.
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Abstract
Diversity within the fungal kingdom is evident from the wide range of morphologies fungi display as well as the various ecological roles and industrial purposes they serve. Technological advances, particularly in long-read sequencing, coupled with the increasing efficiency and decreasing costs across sequencing platforms have enabled robust characterization of fungal genomes. These sequencing efforts continue to reveal the rampant diversity in fungi at the genome level. Here, we discuss studies that have furthered our understanding of fungal genetic diversity and genomic evolution. These studies revealed the presence of both small-scale and large-scale genomic changes. In fungi, research has recently focused on many small-scale changes, such as how hypermutation and allelic transmission impact genome evolution as well as how and why a few specific genomic regions are more susceptible to rapid evolution than others. High-throughput sequencing of a diverse set of fungal genomes has also illuminated the frequency, mechanisms, and impacts of large-scale changes, which include chromosome structural variation and changes in chromosome number, such as aneuploidy, polyploidy, and the presence of supernumerary chromosomes. The studies discussed herein have provided great insight into how the architecture of the fungal genome varies within species and across the kingdom and how modern fungi may have evolved from the last common fungal ancestor and might also pave the way for understanding how genomic diversity has evolved in all domains of life.
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Affiliation(s)
- Shelby J. Priest
- Department of Molecular Genetics and Microbiology, Duke University Medical Centre, Durham, NC, USA
| | - Vikas Yadav
- Department of Molecular Genetics and Microbiology, Duke University Medical Centre, Durham, NC, USA
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Centre, Durham, NC, USA
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16
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Todd RT, Selmecki A. Expandable and reversible copy number amplification drives rapid adaptation to antifungal drugs. eLife 2020; 9:e58349. [PMID: 32687060 PMCID: PMC7371428 DOI: 10.7554/elife.58349] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/09/2020] [Indexed: 12/13/2022] Open
Abstract
Previously, we identified long repeat sequences that are frequently associated with genome rearrangements, including copy number variation (CNV), in many diverse isolates of the human fungal pathogen Candida albicans (Todd et al., 2019). Here, we describe the rapid acquisition of novel, high copy number CNVs during adaptation to azole antifungal drugs. Single-cell karyotype analysis indicates that these CNVs appear to arise via a dicentric chromosome intermediate and breakage-fusion-bridge cycles that are repaired using multiple distinct long inverted repeat sequences. Subsequent removal of the antifungal drug can lead to a dramatic loss of the CNV and reversion to the progenitor genotype and drug susceptibility phenotype. These findings support a novel mechanism for the rapid acquisition of antifungal drug resistance and provide genomic evidence for the heterogeneity frequently observed in clinical settings.
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Affiliation(s)
- Robert T Todd
- Department of Microbiology and Immunology, University of Minnesota Medical SchoolMinneapolis, MinnesotaUnited States
| | - Anna Selmecki
- Department of Microbiology and Immunology, University of Minnesota Medical SchoolMinneapolis, MinnesotaUnited States
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17
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Candida albicans Genetic Background Influences Mean and Heterogeneity of Drug Responses and Genome Stability during Evolution in Fluconazole. mSphere 2020; 5:5/3/e00480-20. [PMID: 32581072 PMCID: PMC7316494 DOI: 10.1128/msphere.00480-20] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Antimicrobial resistance is an evolutionary phenomenon with clinical implications. We tested how replicates from diverse strains of Candida albicans, a prevalent human fungal pathogen, evolve in the commonly prescribed antifungal drug fluconazole. Replicates on average increased in fitness in the level of drug they were evolved to, with the least fit parental strains improving the most. Very few replicates increased resistance above the drug level they were evolved in. Notably, many replicates increased in genome size and changed in drug tolerance (a drug response where a subpopulation of cells grow slowly in high levels of drug), and variability among replicates in fitness, tolerance, and genome size was higher in strains that initially were more sensitive to the drug. Genetic background influenced the average degree of adaptation and the evolved variability of many phenotypes, highlighting that different strains from the same species may respond and adapt very differently during adaptation. The importance of within-species diversity in determining the evolutionary potential of a population to evolve drug resistance or tolerance is not well understood, including in eukaryotic pathogens. To examine the influence of genetic background, we evolved replicates of 20 different clinical isolates of Candida albicans, a human fungal pathogen, in fluconazole, the commonly used antifungal drug. The isolates hailed from the major C. albicans clades and had different initial levels of drug resistance and tolerance to the drug. The majority of replicates rapidly increased in fitness in the evolutionary environment, with the degree of improvement inversely correlated with parental strain fitness in the drug. Improvement was largely restricted to up to the evolutionary level of drug: only 4% of the evolved replicates increased resistance (MIC) above the evolutionary level of drug. Prevalent changes were altered levels of drug tolerance (slow growth of a subpopulation of cells at drug concentrations above the MIC) and increased diversity of genome size. The prevalence and predominant direction of these changes differed in a strain-specific manner, but neither correlated directly with parental fitness or improvement in fitness. Rather, low parental strain fitness was correlated with high levels of heterogeneity in fitness, tolerance, and genome size among evolved replicates. Thus, parental strain background is an important determinant in mean improvement to the evolutionary environment as well as the diversity of evolved phenotypes, and the range of possible responses of a pathogen to an antimicrobial drug cannot be captured by in-depth study of a single strain background. IMPORTANCE Antimicrobial resistance is an evolutionary phenomenon with clinical implications. We tested how replicates from diverse strains of Candida albicans, a prevalent human fungal pathogen, evolve in the commonly prescribed antifungal drug fluconazole. Replicates on average increased in fitness in the level of drug they were evolved to, with the least fit parental strains improving the most. Very few replicates increased resistance above the drug level they were evolved in. Notably, many replicates increased in genome size and changed in drug tolerance (a drug response where a subpopulation of cells grow slowly in high levels of drug), and variability among replicates in fitness, tolerance, and genome size was higher in strains that initially were more sensitive to the drug. Genetic background influenced the average degree of adaptation and the evolved variability of many phenotypes, highlighting that different strains from the same species may respond and adapt very differently during adaptation.
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18
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Host-Induced Genome Instability Rapidly Generates Phenotypic Variation across Candida albicans Strains and Ploidy States. mSphere 2020; 5:5/3/e00433-20. [PMID: 32493724 PMCID: PMC7273350 DOI: 10.1128/msphere.00433-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Candida albicans is an opportunistic fungal pathogen of humans. The ability to generate genetic variation is essential for adaptation and is a strategy that C. albicans and other fungal pathogens use to change their genome size. Stressful environments, including the host, induce C. albicans genome instability. Here, we investigated how C. albicans genetic background and ploidy state impact genome instability, both in vitro and in a host environment. We show that the host environment induces genome instability, but the magnitude depends on C. albicans genetic background. Furthermore, we show that tetraploid C. albicans is highly unstable in host environments and rapidly reduces in genome size. These reductions in genome size often resulted in reduced virulence. In contrast, diploid C. albicans displayed modest host-induced genome size changes, yet these frequently resulted in increased virulence. Such studies are essential for understanding how opportunistic pathogens respond and potentially adapt to the host environment. Candida albicans is an opportunistic fungal pathogen of humans that is typically diploid yet has a highly labile genome tolerant of large-scale perturbations including chromosomal aneuploidy and loss-of-heterozygosity events. The ability to rapidly generate genetic variation is crucial for C. albicans to adapt to changing or stressful environments, like those encountered in the host. Genetic variation occurs via stress-induced mutagenesis or can be generated through its parasexual cycle, in which tetraploids arise via diploid mating or stress-induced mitotic defects and undergo nonmeiotic ploidy reduction. However, it remains largely unknown how genetic background contributes to C. albicans genome instability in vitro or in the host environment. Here, we tested how genetic background, ploidy, and the host environment impacts C. albicans genome stability. We found that host association induced both loss-of-heterozygosity events and genome size changes, regardless of genetic background or ploidy. However, the magnitude and types of genome changes varied across C. albicans strain background and ploidy state. We then assessed if host-induced genomic changes resulted in fitness consequences on growth rate and nonlethal virulence phenotypes and found that many host-derived isolates significantly changed relative to their parental strain. Interestingly, diploid host-associated C. albicans predominantly decreased host reproductive fitness, whereas tetraploid host-associated C. albicans increased host reproductive fitness. Together, these results are important for understanding how host-induced genomic changes in C. albicans alter its relationship with the host. IMPORTANCECandida albicans is an opportunistic fungal pathogen of humans. The ability to generate genetic variation is essential for adaptation and is a strategy that C. albicans and other fungal pathogens use to change their genome size. Stressful environments, including the host, induce C. albicans genome instability. Here, we investigated how C. albicans genetic background and ploidy state impact genome instability, both in vitro and in a host environment. We show that the host environment induces genome instability, but the magnitude depends on C. albicans genetic background. Furthermore, we show that tetraploid C. albicans is highly unstable in host environments and rapidly reduces in genome size. These reductions in genome size often resulted in reduced virulence. In contrast, diploid C. albicans displayed modest host-induced genome size changes, yet these frequently resulted in increased virulence. Such studies are essential for understanding how opportunistic pathogens respond and potentially adapt to the host environment.
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19
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Beekman CN, Ene IV. Short-term evolution strategies for host adaptation and drug escape in human fungal pathogens. PLoS Pathog 2020; 16:e1008519. [PMID: 32407384 PMCID: PMC7224449 DOI: 10.1371/journal.ppat.1008519] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Chapman N. Beekman
- Department of Molecular Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
| | - Iuliana V. Ene
- Department of Molecular Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
- * E-mail:
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20
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The Magnitude of Candida albicans Stress-Induced Genome Instability Results from an Interaction Between Ploidy and Antifungal Drugs. G3-GENES GENOMES GENETICS 2019; 9:4019-4027. [PMID: 31585926 PMCID: PMC6893200 DOI: 10.1534/g3.119.400752] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Organismal ploidy and environmental stress impact the rates and types of mutational events. The opportunistic fungal pathogen Candida albicans, serves as a clinically relevant model for studying the interaction between eukaryotic ploidy and drug-induced mutagenesis. In this study, we compared the rates and types of genome perturbations in diploid and tetraploid C. albicans following exposure to two different classes of antifungal drugs; azoles and echinocandins. We measured mutations at three different scales: point mutation, loss-of-heterozygosity (LOH), and total DNA content for cells exposed to fluconazole and caspofungin. We found that caspofungin induced higher mutation rates than fluconazole, although this is likely an indirect consequence of stress-associated cell wall perturbations, rather than an inherent genotoxicity. Surprisingly, we found that antifungal drugs disproportionately elevated genome and ploidy instability in tetraploid C. albicans compared to diploids. Taken together, our results suggest that the magnitude of stress-induced mutagenesis results from an interaction between ploidy and antifungal drugs. These findings have both clinical and evolutionary implications for how fungal pathogens generate mutations in response to antifungal drug stress and how these mutations may facilitate the emergence of drug resistance.
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21
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Raghavan V, Aquadro CF, Alani E. Baker's Yeast Clinical Isolates Provide a Model for How Pathogenic Yeasts Adapt to Stress. Trends Genet 2019; 35:804-817. [PMID: 31526615 PMCID: PMC6825890 DOI: 10.1016/j.tig.2019.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/07/2019] [Accepted: 08/19/2019] [Indexed: 12/26/2022]
Abstract
Global outbreaks of drug-resistant fungi such as Candida auris are thought to be due at least in part to excessive use of antifungal drugs. Baker's yeast Saccharomyces cerevisiae has gained importance as an emerging opportunistic fungal pathogen that can cause infections in immunocompromised patients. Analyses of over 1000 S. cerevisiae isolates are providing rich resources to better understand how fungi can grow in human environments. A large percentage of clinical S. cerevisiae isolates are heterozygous across many nucleotide sites, and a significant proportion are of mixed ancestry and/or are aneuploid or polyploid. Such features potentially facilitate adaptation to new environments. These observations provide strong impetus for expanding genomic and molecular studies on clinical and wild isolates to understand the prevalence of genetic diversity and instability-generating mechanisms, and how they are selected for and maintained. Such work can also lead to the identification of new targets for antifungal drugs.
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Affiliation(s)
- Vandana Raghavan
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Charles F Aquadro
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Eric Alani
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA.
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22
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Aouizerat T, Gelman D, Szitenberg A, Gutman I, Glazer S, Reich E, Schoemann M, Kaplan R, Saragovi A, Hazan R, Klutstein M. Eukaryotic Adaptation to Years-Long Starvation Resembles that of Bacteria. iScience 2019; 19:545-558. [PMID: 31470363 PMCID: PMC6722386 DOI: 10.1016/j.isci.2019.08.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 02/12/2019] [Accepted: 08/01/2019] [Indexed: 12/18/2022] Open
Abstract
The Growth Advantage in Stationary Phase (GASP) phenomenon, described in bacteria, reflects the genetic adaptation of bacteria to stress, including starvation, for a long time. Unlike in stationary phase where no cell division occurs, GASP harbors active cell division, concurrent with genetic adaptation. Here we show that GASP occurs also in eukaryotes. Two strains of Saccharomyces cerevisiae (Sc404 and Sc424) have been isolated from 2-year-old sealed bottles of beer. These strains presented advantage in survival and growth over the parent during stress. The differences between the strains are irreversible and therefore genetic in origin rather than epigenetic. Direct competition assays show that Sc404 and Sc424 outcompete the parent in direct competition. DNA sequencing shows changes of the genome: the TOR complexes are mutated, and DNA repair gene mutations confer a mutator phenotype. The differences between the strains are reflected in a difference in taste between beers brewed from them. Yeast genetically adapts to long-term starvation in a similar way to bacteria Adaptation to long-term starvation in yeast includes multi-stress tolerance Adaptation to long-term starvation in yeast includes mutations in TORC Adaptation to long-term starvation in yeast includes a mutator phenotype
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Affiliation(s)
- Tzemach Aouizerat
- Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, P.O.B. 12272, Ein Kerem, Jerusalem 9112001, Israel
| | - Daniel Gelman
- Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, P.O.B. 12272, Ein Kerem, Jerusalem 9112001, Israel
| | - Amir Szitenberg
- Microbial and Metagenomics Division, Dead Sea and Arava Science Center, Masada 8698000, Israel
| | - Itay Gutman
- Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, P.O.B. 12272, Ein Kerem, Jerusalem 9112001, Israel
| | - Shunit Glazer
- Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, P.O.B. 12272, Ein Kerem, Jerusalem 9112001, Israel
| | - Eli Reich
- Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, P.O.B. 12272, Ein Kerem, Jerusalem 9112001, Israel
| | - Miriam Schoemann
- Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, P.O.B. 12272, Ein Kerem, Jerusalem 9112001, Israel
| | - Rachel Kaplan
- Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, P.O.B. 12272, Ein Kerem, Jerusalem 9112001, Israel
| | - Amijai Saragovi
- The Lautenberg Center for Immunology and Cancer Research, The Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel
| | - Ronen Hazan
- Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, P.O.B. 12272, Ein Kerem, Jerusalem 9112001, Israel.
| | - Michael Klutstein
- Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, P.O.B. 12272, Ein Kerem, Jerusalem 9112001, Israel.
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23
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Ene IV, Bennett RJ, Anderson MZ. Mechanisms of genome evolution in Candida albicans. Curr Opin Microbiol 2019; 52:47-54. [PMID: 31176092 DOI: 10.1016/j.mib.2019.05.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 04/25/2019] [Accepted: 05/03/2019] [Indexed: 11/25/2022]
Abstract
The fungus Candida albicans exists as a prevalent commensal and an important opportunistic pathogen that can infect multiple niches of its human host. Recent studies have examined the diploid genome of C. albicans by performing both short-term microevolution studies and comparative genomics on collections of clinical isolates. Common mechanisms driving genome dynamics include accumulation of point mutations, loss of heterozygosity (LOH) events, large-scale chromosomal rearrangements, and even ploidy change, with important consequences for both drug resistance and host adaptation. Evidence for recombination between C. albicans lineages also highlights a role for (para)sex in shaping the species population structure. Ongoing work will continue to define the contributions of genome evolution to phenotypic variation and the role of host pressures in driving adaptive processes.
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Affiliation(s)
- Iuliana V Ene
- Molecular Microbiology and Immunology Department, Brown University, Providence, RI 02912, USA
| | - Richard J Bennett
- Molecular Microbiology and Immunology Department, Brown University, Providence, RI 02912, USA
| | - Matthew Z Anderson
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA; Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210, USA.
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24
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Legrand M, Jaitly P, Feri A, d'Enfert C, Sanyal K. Candida albicans: An Emerging Yeast Model to Study Eukaryotic Genome Plasticity. Trends Genet 2019; 35:292-307. [PMID: 30826131 DOI: 10.1016/j.tig.2019.01.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 01/25/2019] [Accepted: 01/25/2019] [Indexed: 01/07/2023]
Abstract
Saccharomyces cerevisiae and Schizosaccharomyces pombe have served as uncontested unicellular model organisms, as major discoveries made in the field of genome biology using yeast genetics have proved to be relevant from yeast to humans. The yeast Candida albicans has attracted much attention because of its ability to switch between a harmless commensal and a dreaded human pathogen. C. albicans bears unique features regarding its life cycle, genome structure, and dynamics, and their links to cell biology and adaptation to environmental challenges. Examples include a unique reproduction cycle with haploid, diploid, and tetraploid forms; a distinctive organisation of chromosome hallmarks; a highly dynamic genome, with extensive karyotypic variations, including aneuploidies, isochromosome formation, and loss-of-heterozygosity; and distinctive links between the response to DNA alterations and cell morphology. These features have made C. albicans emerge as a new and attractive unicellular model to study genome biology and dynamics in eukaryotes.
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Affiliation(s)
- Mélanie Legrand
- Fungal Biology and Pathogenicity Unit, Department of Mycology, Institut Pasteur, INRA, Paris, France
| | - Priya Jaitly
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Adeline Feri
- Fungal Biology and Pathogenicity Unit, Department of Mycology, Institut Pasteur, INRA, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris, France; Current address: Pathoquest, BioPark, 11 rue Watt, 75013 Paris, France
| | - Christophe d'Enfert
- Fungal Biology and Pathogenicity Unit, Department of Mycology, Institut Pasteur, INRA, Paris, France.
| | - Kaustuv Sanyal
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India.
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25
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Blischak PD, Mabry ME, Conant GC, Pires JC. Integrating Networks, Phylogenomics, and Population Genomics for the Study of Polyploidy. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2018. [DOI: 10.1146/annurev-ecolsys-121415-032302] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Duplication events are regarded as sources of evolutionary novelty, but our understanding of general trends for the long-term trajectory of additional genomic material is still lacking. Organisms with a history of whole genome duplication (WGD) offer a unique opportunity to study potential trends in the context of gene retention and/or loss, gene and network dosage, and changes in gene expression. In this review, we discuss the prevalence of polyploidy across the tree of life, followed by an overview of studies investigating genome evolution and gene expression. We then provide an overview of methods in network biology, phylogenomics, and population genomics that are critical for advancing our understanding of evolution post-WGD, highlighting the need for models that can accommodate polyploids. Finally, we close with a brief note on the importance of random processes in the evolution of polyploids with respect to neutral versus selective forces, ancestral polymorphisms, and the formation of autopolyploids versus allopolyploids.
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Affiliation(s)
- Paul D. Blischak
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Makenzie E. Mabry
- Division of Biological Sciences and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211, USA
| | - Gavin C. Conant
- Division of Animal Sciences, University of Missouri, Columbia, Missouri 65211, USA
- Current affiliation: Bioinformatics Research Center, Program in Genetics and Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - J. Chris Pires
- Division of Biological Sciences and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211-7310, USA
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26
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Fisher KJ, Buskirk SW, Vignogna RC, Marad DA, Lang GI. Adaptive genome duplication affects patterns of molecular evolution in Saccharomyces cerevisiae. PLoS Genet 2018; 14:e1007396. [PMID: 29799840 PMCID: PMC5991770 DOI: 10.1371/journal.pgen.1007396] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 06/07/2018] [Accepted: 05/07/2018] [Indexed: 11/19/2022] Open
Abstract
Genome duplications are important evolutionary events that impact the rate and spectrum of beneficial mutations and thus the rate of adaptation. Laboratory evolution experiments initiated with haploid Saccharomyces cerevisiae cultures repeatedly experience whole-genome duplication (WGD). We report recurrent genome duplication in 46 haploid yeast populations evolved for 4,000 generations. We find that WGD confers a fitness advantage, and this immediate fitness gain is accompanied by a shift in genomic and phenotypic evolution. The presence of ploidy-enriched targets of selection and structural variants reveals that autodiploids utilize adaptive paths inaccessible to haploids. We find that autodiploids accumulate recessive deleterious mutations, indicating an increased susceptibility for nonadaptive evolution. Finally, we report that WGD results in a reduced adaptation rate, indicating a trade-off between immediate fitness gains and long-term adaptability. Whole genome duplications—the simultaneous doubling of each chromosome—can have a profound influence on evolution. Evidence of ancient whole genome duplications can be seen in most modern genomes. Experimental evolution, the long-term propagation of organisms under well-controlled laboratory conditions, yields valuable insight into the processes of adaptation and genome evolution. One interesting, and common, outcome of laboratory evolution experiments that start with haploid yeast populations is the emergence of diploid lineages via whole genome duplication. We show that, under our laboratory conditions, whole genome duplication provides a direct fitness benefit, and we identify several consequences of whole genome duplication on adaptation. Following whole-genome duplication, the rate of adaptation slows, the biological targets of selection change, and aneuploidies, copy-number variants and recessive lethal mutations accumulate. By studying the effect of whole genome duplication on adaptation, we can better understand how selection acts on ploidy, a fundamental biological parameter that varies considerably across life.
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Affiliation(s)
- Kaitlin J. Fisher
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, United States of America
| | - Sean W. Buskirk
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, United States of America
| | - Ryan C. Vignogna
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, United States of America
| | - Daniel A. Marad
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, United States of America
| | - Gregory I. Lang
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, United States of America
- * E-mail:
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27
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Abstract
Ploidy is considered a very stable cellular characteristic. Although rare, changes in ploidy play important roles in the acquisition of long-term adaptations. Since these duplications allow the subsequent loss of individual chromosomes and accumulation of mutations, changes in ploidy can also cause genomic instability, and have been found to promote cancer. Despite the importance of the subject, measuring the rate of whole-genome duplications has proven extremely challenging. We have recently measured the rate of diploidization in yeast using long-term, in-lab experiments. We found that spontaneous diploidization occurs frequently, by two different mechanisms: endoreduplication and mating type switching. Despite its common occurrence, spontaneous diploidization is usually selected against, although it can be advantageous under some stressful conditions. Our results have implications for the understanding of evolutionary processes, as well as for the use of yeast cells in biotechnological applications.
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28
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Abstract
The ability of an organism to replicate and segregate its genome with high fidelity is vital to its survival and for the production of future generations. Errors in either of these steps (replication or segregation) can lead to a change in ploidy or chromosome number. While these drastic genome changes can be detrimental to the organism, resulting in decreased fitness, they can also provide increased fitness during periods of stress. A change in ploidy or chromosome number can fundamentally change how a cell senses and responds to its environment. Here, we discuss current ideas in fungal biology that illuminate how eukaryotic genome size variation can impact the organism at a cellular and evolutionary level. One of the most fascinating observations from the past 2 decades of research is that some fungi have evolved the ability to tolerate large genome size changes and generate vast genomic heterogeneity without undergoing canonical meiosis.
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Spontaneous Changes in Ploidy Are Common in Yeast. Curr Biol 2018; 28:825-835.e4. [PMID: 29502947 DOI: 10.1016/j.cub.2018.01.062] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 12/11/2017] [Accepted: 01/22/2018] [Indexed: 12/19/2022]
Abstract
Changes in ploidy are relatively rare, but play important roles in the development of cancer and the acquisition of long-term adaptations. Genome duplications occur across the tree of life, and can alter the rate of adaptive evolution. Moreover, by allowing the subsequent loss of individual chromosomes and the accumulation of mutations, changes in ploidy can promote genomic instability and/or adaptation. Although many studies have been published in the last years about changes in chromosome number and their evolutionary consequences, tracking and measuring the rate of whole-genome duplications have been extremely challenging. We have systematically studied the appearance of diploid cells among haploid yeast cultures evolving for over 100 generations in different media. We find that spontaneous diploidization is a relatively common event, which is usually selected against, but under certain stressful conditions may become advantageous. Furthermore, we were able to detect and distinguish between two different mechanisms of diploidization, one that requires whole-genome duplication (endoreduplication) and a second that involves mating-type switching despite the use of heterothallic strains. Our results have important implications for our understanding of evolution and adaptation in fungal pathogens and the development of cancer, and for the use of yeast cells in biotechnological applications.
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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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