scholarly journals Host association induces genome changes in Candida albicans which alters its virulence

2020 ◽  
Author(s):  
Amanda C. Smith ◽  
Meleah A. Hickman
Keyword(s):  
Genetic Variation ◽  
Candida Albicans ◽  
Loss Of Heterozygosity ◽  
Genetic Background ◽  
Large Scale ◽  
Environment Impact ◽  
Host Association ◽  
Parasexual Cycle ◽  
Genomic Changes

AbstractCandida albicans is an opportunistic fungal pathogen of humans that is typically diploid yet, has a highly labile genome that is 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 stress environments, like those encountered in the host. Genetic variation occurs via stress-induced mutagenesis or can be generated through its parasexual cycle, which includes mating between diploids or stress-induced mitotic defects to produce tetraploids and non-meiotic ploidy reduction. However, it remains largely unknown how genetic background contributes to C. albicans genome instability in vitro or in vivo. Here, we tested how genetic background, ploidy and host environment impact 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 strains. We also assessed whether host-induced genomic changes resulted in any consequences on growth rate and virulence phenotypes and found that many host derived isolates had significant changes compared to their parental strains. Interestingly, host derivatives from diploid C. albicans predominantly displayed increased virulence, whereas host derivatives from tetraploid C. albicans had mostly reduced virulence. Together, these results are important for understanding how host-induced genomic changes in C. albicans alter the relationship between the host and C. albicans.

scholarly journals Host-Induced Genome Instability Rapidly Generates Phenotypic Variation across Candida albicans Strains and Ploidy States

mSphere ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Amanda C. Smith ◽  
Meleah A. Hickman
Keyword(s):  
Genetic Variation ◽  
Candida Albicans ◽  
Genome Size ◽  
Genetic Background ◽  
Genome Instability ◽  
Content Type ◽  
Host Environment ◽  
Genomic Changes ◽  
Opportunistic Fungal Pathogen

ABSTRACT 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. IMPORTANCE 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.

scholarly journals The Evolution of Fluoroquinolone-Resistance inMycobacterium tuberculosisis Modulated by the Genetic Background

2019 ◽  
Author(s):  
Rhastin A. D. Castro ◽  
Amanda Ross ◽  
Lujeko Kamwela ◽  
Miriam Reinhard ◽  
Chloé Loiseau ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Genetic Background ◽  
Natural Populations ◽  
Genomic Analysis ◽  
Experimental Treatment ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Treatment Regimens ◽  
Resistance Evolution

AbstractFluoroquinolones (FQ) form the backbone in experimental treatment regimens against drug-susceptible tuberculosis. However, little is known on whether the genetic variation present in natural populations ofMycobacterium tuberculosis(Mtb) affects the evolution of FQ-resistance (FQ-R). To investigate this question, we used a set ofMtbstrains that included nine genetically distinct drug-susceptible clinical isolates, and measured their frequency of resistance to the FQ ofloxacin (OFX)in vitro. We found that theMtbgenetic background led to differences in the frequency of OFX-resistance (OFX-R) that spanned two orders of magnitude and substantially modulated the observed mutational profiles for OFX-R. Furtherin vitroassays showed that the genetic background also influenced the minimum inhibitory concentration and the fitness effect conferred by a given OFX-R mutation. To test the clinical relevance of ourin vitrowork, we surveyed the mutational profile for FQ-R in publicly available genomic sequences from clinicalMtbisolates, and found substantialMtblineage-dependent variability. Comparison of the clinical and thein vitromutational profiles for FQ-R showed that 45% and 19% of the variability in the clinical frequency of FQ-RgyrAmutations in Lineage 2 and Lineage 4 strains, respectively, can be attributed to howMtbevolves FQ-Rin vitro. As theMtbgenetic background strongly influenced the evolution of FQ-Rin vitro, we conclude that the genetic background ofMtbalso impacts the evolution of FQ-R in the clinic.SignificanceNewer generations of fluoroquinolones form the backbone in many experimental treatment regimens againstM. tuberculosis(Mtb). While the genetic variation in natural populations ofMtbcan influence resistance evolution to multiple different antibiotics, it is unclear whether it modulates fluoroquinolone-resistance evolution as well. Using a combination ofin vitroassays coupled with genomic analysis of clinical isolates, we provide the first evidence illustrating theMtbgenetic background’s substantial role in fluoroquinolone-resistance evolution, and highlight the importance of bacterial genetics when studying the prevalence of fluoroquinolone-resistance inMtb. Our work may provide insights into how to maximize the timespan in which fluoroquinolones remain effective in clinical settings, whether as part of current standardized regimens, or in new regimens againstMtb.

scholarly journals Stress-Induced Loss of Heterozygosity in Candida: a Possible Missing Link in the Ability to Evolve

mBio ◽  
2011 ◽  
Vol 2 (5) ◽  
Author(s):  
Susan M. Rosenberg
Keyword(s):  
Genetic Variation ◽  
Candida Albicans ◽  
Loss Of Heterozygosity ◽  
Dna Sequence ◽  
Cancer Development ◽  
Missing Link ◽  
Content Type ◽  
Entire Chromosome ◽  
Development And Evolution

ABSTRACT Diploid organisms are buffered against the effects of mutations by carrying two sets of each gene, which allows compensation if one is mutated. But recombination between “mom” and “dad” chromosomes causes loss of heterozygosity (LOH), stretches of “mom-only” or “dad-only” DNA sequence, suddenly revealing effects of mutations accumulated in entire chromosome arms. LOH creates new phenotypes from old mutations, drives cancer development and evolution, and, in a new study by Forche et al., is shown to be induced by stress in Candida albicans [Forche A, et al, mBio 2(4):e00129-11, 2011]. Stress-induced LOH could speed evolution of Candida specifically when it is poorly adapted to its environment. Moreover, the findings may provide a missing link between recombination-dependent mutagenesis in bacteria and yeast, suggesting that both might be stress induced, both maximizing genetic variation when populations could benefit most from diversity.

scholarly journals Exposure to the oral host niche yields rapid phenotypic and genotypic diversification in Candida albicans

2018 ◽  
Author(s):  
A. Forche ◽  
G. Cromie ◽  
A.C. Gerstein ◽  
N. V. Solis ◽  
Z. Pisithkul ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Oral Cavity ◽  
De Novo ◽  
Phenotypic Diversity ◽  
Pathogenic Fungi ◽  
Genomic Changes ◽  
Phenotypic Changes ◽  
Standing Variation

AbstractIn vitro studies suggest that stress may generate random standing variation, and that different cellular and ploidy states may evolve more rapidly under stress. Yet this idea has not been tested with pathogenic fungi growing within their host niche in vivo. Here, we analyzed the generation of both genotypic and phenotypic diversity during exposure of Candida albicans to the mouse oral cavity. Ploidy, aneuploidy, loss of heterozygosity (LOH) and recombination were determined using flow cytometry and ddRADseq. Colony phenotypic changes (CPs) in size and filamentous growth were evident without selection, and were enriched among colonies selected for LOH of the GAL1 marker. Aneuploidy and LOH occurred on all chromosomes (Chrs), with aneuploidy more frequent for smaller Chrs and whole Chr LOH more frequent for larger Chrs. Large genome shifts in ploidy to haploidy often maintained one or more heterozygous disomic Chrs, consistent with random Chr missegregation events. Most isolates displayed several different types of genomic changes, suggesting that the oral environment rapidly generates diversity de novo. In sharp contrast, following in vitro propagation isolates were not enriched for multiple LOH events, except in those that underwent haploidization and/or had high levels of Chr loss. The frequency of events was overall 100 times higher for C. albicans populations following in vivo passage compared to in vitro. These hyperdiverse in vivo isolates likely provide C. albicans with the ability to adapt rapidly to the diversity of stress environments it encounters inside the host.Author summaryAdaption is a continuous dynamic process that requires genotypic and phenotypic variation. Here we studied the effects of a single passage in a mouse oropharyngeal model of infection on the appearance of diversity in C. albicans, a common commensal of the human oral cavity and GI tract. We found that variation could be rapidly detected following oral colonization, with the frequency of genome change being considerably higher with pre-selection for recombination and colony phenotypic changes. Importantly, one third of all isolates had multiple genome changes, significantly higher than expected by chance alone. We suggest that some cells in the population are naturally hypervariable and that they are a major source of diversity upon which selection can act in stressful conditions in vivo and in vitro.

Looking for New Antifungal Drugs from Flavonoids: Impact of the Genetic Diversity of Candida albicans on the in-vitro Response

2019 ◽  
Vol 26 (27) ◽  
pp. 5108-5123 ◽  
Author(s):  
Maria Rosa Felice ◽  
Letterio Giuffrè ◽  
Lamya El Aamri ◽  
Majida Hafidi ◽  
Giuseppe Criseo ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Candida Albicans ◽  
Fungal Pathogens ◽  
Antimicrobial Agents ◽  
Biological Activities ◽  
Antifungal Drugs ◽  
Microbial Pathogens ◽  
Beneficial Effects

Background:In an era in which antimicrobial resistance is increasing at an alarming pace, it is very important to find new antimicrobial agents effective against pathogenic microrganisms resistant to traditional treatments. Among the notable breakthroughs in the past years of research in natural-drug discovery, there is the identification and testing of flavonoids, a group of plant-derived substances capable of promoting many beneficial effects on humans. These compounds show different biological activities such as inhibition of neuroinflammation and tumor growth as well as antimicrobial activity against many microbial pathogens.Methods:We undertook a review of protocols and standard strains used in studies reporting the inhibitory effects of flavonoids against Candida albicans by focusing our attention on genetic characterization of the strains examined. Moreover, using the C. albicans MLST-database, we performed a phylogenetic analysis showing the genetic variation occurring in this species.Results:Today, we have enough information to estimate genetic diversity within microbial species and recent data revealed that most of fungal pathogens show complex population structures in which not a single isolate can be designated as representative of the entire taxon. This is especially true for the highly divergent fungal pathogen C. albicans, in which the assumption that one or few “standard strains” can represent the whole species is overly unrealistic and should be laid to rest.Conclusion:The goal of this article is to shed light on the extent of genetic variation in C. albicans and how this phenomenon can largely influence the activity of flavonoids against this species.

scholarly journals Analysis of the Candida albicans Phosphoproteome

2015 ◽  
Vol 14 (5) ◽  
pp. 474-485 ◽  
Author(s):  
S. D. Willger ◽  
Z. Liu ◽  
R. A. Olarte ◽  
M. E. Adamo ◽  
J. E. Stajich ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Large Scale ◽  
Cytoskeletal Proteins ◽  
Mediator Complex ◽  
Phosphorylation Sites ◽  
Content Type ◽  
Targeted Analysis ◽  
Protein Components ◽  
Content Regulation

ABSTRACTCandida albicansis an important human fungal pathogen in both immunocompetent and immunocompromised individuals.C. albicansregulation has been studied in many contexts, including morphological transitions, mating competence, biofilm formation, stress resistance, and cell wall synthesis. Analysis of kinase- and phosphatase-deficient mutants has made it clear that protein phosphorylation plays an important role in the regulation of these pathways. In this study, to further our understanding of phosphorylation inC. albicansregulation, we performed a deep analysis of the phosphoproteome inC. albicans. We identified 19,590 unique peptides that corresponded to 15,906 unique phosphosites on 2,896 proteins. The ratios of serine, threonine, and tyrosine phosphosites were 80.01%, 18.11%, and 1.81%, respectively. The majority of proteins (2,111) contained at least two detected phosphorylation sites. Consistent with findings in other fungi, cytoskeletal proteins were among the most highly phosphorylated proteins, and there were differences in Gene Ontology (GO) terms for proteins with serine and threonine versus tyrosine phosphorylation sites. This large-scale analysis identified phosphosites in protein components of Mediator, an important transcriptional coregulatory protein complex. A targeted analysis of the phosphosites in Mediator complex proteins confirmed the large-scale studies, and furtherin vitroassays identified a subset of these phosphorylations that were catalyzed by Cdk8 (Ssn3), a kinase within the Mediator complex. These data represent the deepest single analysis of a fungal phosphoproteome and lay the groundwork for future analyses of theC. albicansphosphoproteome and specific phosphoproteins.

scholarly journals Comparative Population Genomics Analysis of the Mammalian Fungal PathogenPneumocystis

mBio ◽  
2018 ◽  
Vol 9 (3) ◽  
pp. e00381-18 ◽  
Author(s):  
Ousmane H. Cissé ◽  
Liang Ma ◽  
Da Wei Huang ◽  
Pavel P. Khil ◽  
John P. Dekker ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Large Scale ◽  
Population Genomics ◽  
Demographic History ◽  
Natural Populations ◽  
Severe Pneumonia ◽  
Population Declines ◽  
Host Shifts ◽  
Rats And Mice

ABSTRACTPneumocystisspecies are opportunistic mammalian pathogens that cause severe pneumonia in immunocompromised individuals. These fungi are highly host specific and uncultivablein vitro. HumanPneumocystisinfections present major challenges because of a limited therapeutic arsenal and the rise of drug resistance. To investigate the diversity and demographic history of natural populations ofPneumocystisinfecting humans, rats, and mice, we performed whole-genome and large-scale multilocus sequencing of infected tissues collected in various geographic locations. Here, we detected reduced levels of recombination and variations in historical demography, which shape the global population structures. We report estimates of evolutionary rates, levels of genetic diversity, and population sizes. Molecular clock estimates indicate thatPneumocystisspecies diverged before their hosts, while the asynchronous timing of population declines suggests host shifts. Our results have uncovered complex patterns of genetic variation influenced by multiple factors that shaped the adaptation ofPneumocystispopulations during their spread across mammals.IMPORTANCEUnderstanding how natural pathogen populations evolve and identifying the determinants of genetic variation are central issues in evolutionary biology.Pneumocystis, a fungal pathogen which infects mammals exclusively, provides opportunities to explore these issues. In humans,Pneumocystiscan cause a life-threatening pneumonia in immunosuppressed individuals. In analysis of differentPneumocystisspecies infecting humans, rats, and mice, we found that there are high infection rates and that natural populations maintain a high level of genetic variation despite low levels of recombination. We found no evidence of population structuring by geography. Our comparisons of the times of divergence of these species to their respective hosts suggest thatPneumocystismay have undergone recent host shifts. The results demonstrate thatPneumocystisstrains are widely disseminated geographically and provide a new understanding of the evolution of these pathogens.

scholarly journals Selection of Candida albicans Trisomy during Oropharyngeal Infection Results in a Commensal-Like Phenotype

2019 ◽  
Author(s):  
Anja Forche ◽  
Norma V. Solis ◽  
Marc Swidergall ◽  
Robert Thomas ◽  
Alison Guyer ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Post Infection ◽  
Large Scale ◽  
De Novo ◽  
Point Mutations ◽  
Oral Epithelial Cells ◽  
Oropharyngeal Infection ◽  
Oropharyngeal Cavity ◽  
Oral Epithelial

AbstractWhen the fungus Candida albicans proliferates in the oropharyngeal cavity during experimental oropharyngeal candidiasis (OPC), it undergoes large-scale genome changes at a much higher frequency than when it grows in vitro. Previously, we identified a specific whole chromosome amplification, trisomy of Chr 6 (Chr6x3), that was highly overrepresented among strains recovered from the tongues of mice with OPC. To determine the functional significance of this trisomy, we assessed the virulence of two Chr6 trisomic strains and a Chr5 trisomic strain in the mouse model of OPC. We also analyzed the expression of virulence-associated traits in vitro. All three trisomic strains exhibited characteristics of a commensal during OPC in mice. They achieved the same oral fungal burden as the diploid progenitor strain but caused significantly less weight loss and elicited a significantly lower inflammatory host response. In vitro, all three trisomic strains had reduced capacity to adhere to and invade oral epithelial cells and increased susceptibility to neutrophil killing. Whole genome sequencing of pre- and post-infection isolates found that the trisomies were usually maintained. Most post-infection isolates also contained de novo point mutations, but these were not conserved. While in vitro growth assays did not reveal phenotypes specific to de novo point mutations, they did reveal novel phenotypes specific to each lineage. These data reveal that during OPC, clones that are trisomic for Chr5 or Chr6 are selected and they facilitate a commensal-like phenotype.

Purification of the Antihemophilic Factor by Gel Filtration on Agarose

1969 ◽  
Vol 22 (03) ◽  
pp. 577-583 ◽  
Author(s):  
M.M.P Paulssen ◽  
A.C.M.G.B Wouterlood ◽  
H.L.M.A Scheffers
Keyword(s):  
Factor Viii ◽  
Plasma Proteins ◽  
Large Scale ◽  
Gel Filtration ◽  
Large Scale Preparation ◽  
Scale Preparation ◽  
Antihemophilic Factor

SummaryFactor VIII can be isolated from plasma proteins, including fibrinogen by chromatography on agarose. The best results were obtained with Sepharose 6B. Large scale preparation is also possible when cryoprecipitate is separated by chromatography. In most fractions containing factor VIII a turbidity is observed which may be due to the presence of chylomicrons.The purified factor VIII was active in vivo as well as in vitro.

Genetic background of cholesterol absorption efficacy. The role of Niemann–Pick C1-like 1 receptor and its genetic variation in lipid metabolism

2010 ◽  
Vol 151 (34) ◽  
pp. 1376-1383 ◽  
Author(s):  
Mariann Harangi ◽  
István Balogh ◽  
János Harangi ◽  
György Paragh
Keyword(s):  
Genetic Variation ◽  
Lipid Metabolism ◽  
Genetic Background ◽  
Cholesterol Absorption ◽  
Niemann Pick

A Niemann–Pick C1-like-1 egy szterolfelismerő domént tartalmazó membránfehérje, amelyet nagy számban expresszálnak csúcsi felszínükön a bélhámsejtek. Az utóbbi évek vizsgálatai azt igazolták, hogy ez a fehérje szükséges a szabad koleszterin bejutásához a bélhámsejtekbe a bél lumenéből. Biokémiai vizsgálatok azt igazolták, hogy a Niemann–Pick C1-like-1-hez kötődik az ezetimib, amely egy hatékony koleszterinfelszívódást gátló szer. A bélből történő koleszterinfelszívódás ütemében és az ezetimibkezelés hatékonyságában tapasztalt egyéni eltérések hátterében felmerült néhány Niemann–Pick C1-like-1 génvariáció oki szerepe.

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