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1.
Genetics ; 2024 Sep 06.
Artículo en Inglés | MEDLINE | ID: mdl-39239926

RESUMEN

Eukaryotic organisms are composed of different cell types with defined shapes and functions. Specific cell types are produced by the process of cell differentiation, which is regulated by signal transduction pathways. Signaling pathways regulate cell differentiation by sensing cues and controlling the expression of target genes whose products generate cell types with specific attributes. In studying how cells differentiate, fungi have proved valuable models because of their ease of genetic manipulation and striking cell morphologies. Many fungal species undergo filamentous growth-a specialized growth pattern where cells produce elongated tube-like projections. Filamentous growth promotes expansion into new environments, including invasion into plant and animal hosts by fungal pathogens. The same signaling pathways that regulate filamentous growth in fungi also control cell differentiation throughout eukaryotes and include highly conserved mitogen-activated protein kinase (MAPK) pathways, which is the focus of this review. In many fungal species, mucin-type sensors regulate MAPK pathways to control filamentous growth in response to diverse stimuli. Once activated, MAPK pathways reorganize cell polarity, induce changes in cell adhesion, and promote the secretion of degradative enzymes that mediate access to new environments. However, MAPK pathway regulation is complicated because related pathways can share components with each other yet induce unique responses (i.e. signal specificity). In addition, MAPK pathways function in highly integrated networks with other regulatory pathways (i.e. signal integration). Here, we discuss signal specificity and integration in several yeast models (mainly Saccharomyces cerevisiae and Candida albicans) by focusing on the filamentation MAPK pathway. Because of the strong evolutionary ties between species, a deeper understanding of the regulation of filamentous growth in established models and increasingly diverse fungal species can reveal fundamentally new mechanisms underlying eukaryotic cell differentiation.

2.
J Biol Chem ; 300(7): 107444, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38838772

RESUMEN

Candida albicans is an opportunistic fungal pathogen that can switch between yeast and hyphal morphologies depending on the environmental cues it receives. The switch to hyphal form is crucial for the establishment of invasive infections. The hyphal form is also characterized by the cell surface expression of hyphae-specific proteins, many of which are GPI-anchored and important determinants of its virulence. The coordination between hyphal morphogenesis and the expression of GPI-anchored proteins is made possible by an interesting cross-talk between GPI biosynthesis and the cAMP-PKA signaling cascade in the fungus; a parallel interaction is not found in its human host. On the other hand, in the nonpathogenic yeast, Saccharomyces cerevisiae, GPI biosynthesis is shut down when filamentation is activated and vice versa. This too is achieved by a cross-talk between GPI biosynthesis and cAMP-PKA signaling. How are diametrically opposite effects obtained from the cross-talk between two reasonably well-conserved pathways present ubiquitously across eukarya? This Review attempts to provide a model to explain these differences. In order to do so, it first provides an overview of the two pathways for the interested reader, highlighting the similarities and differences that are observed in C. albicans versus the well-studied S. cerevisiae model, before going on to explain how the different mechanisms of regulation are effected. While commonalities enable the development of generalized theories, it is hoped that a more nuanced approach, that takes into consideration species-specific differences, will enable organism-specific understanding of these processes and contribute to the development of targeted therapies.


Asunto(s)
Candida albicans , Proteínas Quinasas Dependientes de AMP Cíclico , AMP Cíclico , Hifa , Saccharomyces cerevisiae , Transducción de Señal , Candida albicans/metabolismo , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , AMP Cíclico/metabolismo , Hifa/metabolismo , Proteínas Fúngicas/metabolismo , Proteínas Fúngicas/genética , Glicosilfosfatidilinositoles/metabolismo , Glicosilfosfatidilinositoles/biosíntesis , Humanos , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética
4.
FEMS Yeast Res ; 242024 01 09.
Artículo en Inglés | MEDLINE | ID: mdl-38142225

RESUMEN

The ∼1 200 known species in subphylum Saccharomycotina are a highly diverse clade of unicellular fungi. During its lifecycle, a typical yeast exhibits multiple cell types with various morphologies; these morphologies vary across Saccharomycotina species. Here, we synthesize the evolutionary dimensions of variation in cellular morphology of yeasts across the subphylum, focusing on variation in cell shape, cell size, type of budding, and filament production. Examination of 332 representative species across the subphylum revealed that the most common budding cell shapes are ovoid, spherical, and ellipsoidal, and that their average length and width is 5.6 µm and 3.6 µm, respectively. 58.4% of yeast species examined can produce filamentous cells, and 87.3% of species reproduce asexually by multilateral budding, which does not require utilization of cell polarity for mitosis. Interestingly, ∼1.8% of species examined have not been observed to produce budding cells, but rather only produce filaments of septate hyphae and/or pseudohyphae. 76.9% of yeast species examined have sexual cycle descriptions, with most producing one to four ascospores that are most commonly hat-shaped (37.4%). Systematic description of yeast cellular morphological diversity and reconstruction of its evolution promises to enrich our understanding of the evolutionary cell biology of this major fungal lineage.


Asunto(s)
Ascomicetos , Filogenia , Levaduras
5.
J Fungi (Basel) ; 9(7)2023 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-37504715

RESUMEN

The two fungal human pathogens, Candida auris and Candida albicans, possess a variety of virulence mechanisms. Among them are the formation of biofilms to protect yeast against harsh conditions through the development of (pseudo)hyphae whilst also facilitating the invasion of host tissues. In recent years, increased rates of antifungal resistance have been associated with C. albicans and C. auris, posing a significant challenge for the effective treatment of fungal infections. In the course of our ongoing search for novel anti-infectives, six selected azaphilones were tested for their cytotoxicity and antimicrobial effects as well as for their inhibitory activity against biofilm and hyphal formation. This study revealed that rubiginosin C, derived from stromata of the ascomycete Hypoxylon rubiginosum, effectively inhibited the formation of biofilms, pseudohyphae, and hyphae in both C. auris and C. albicans without lethal effects. Crystal violet staining assays were utilized to assess the inhibition of biofilm formation, while complementary microscopic techniques, such as confocal laser scanning microscopy, scanning electron microscopy, and optical microscopy, were used to investigate the underlying mechanisms. Rubiginosin C is one of the few substances known to effectively target both biofilm formation and the yeast-to-hyphae transition of C. albicans and C. auris within a concentration range not affecting host cells, making it a promising candidate for therapeutic intervention in the future.

6.
FEMS Microbes ; 4: xtad002, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37333439

RESUMEN

Saccharomyces cerevisiae can undergo filamentous growth in response to specific environmental stressors, particularly nitrogen-limitation, whereby cells undergo pseudohyphal differentiation, a process where cells transition from a singular ellipsoidal appearance to multicellular filamentous chains from the incomplete scission of the mother-daughter cells. Previously, it was demonstrated that filamentous growth in S. cerevisiae is co-regulated by multiple signaling networks, including the glucose-sensing RAS/cAMP-PKA and SNF pathways, the nutrient-sensing TOR pathway, the filamentous growth MAPK pathway, and the Rim101 pathway, and can be induced by quorum-sensing aromatic alcohols, such as 2-phenylethanol. However, the prevalent research on the yeast-pseudohyphal transition and its induction by aromatic alcohols in S. cerevisiae has been primarily limited to the strain Σ1278b. Due to the prospective influence of quorum sensing on commercial fermentation, the native variation of yeast-to-filamentous phenotypic transition and its induction by 2-phenylethanol in commercial brewing strains was investigated. Image analysis software was exploited to enumerate the magnitude of whole colony filamentation in 16 commercial strains cultured on nitrogen-limiting SLAD medium; some supplemented with exogenous 2-phenylethanol. The results demonstrate that phenotypic switching is a generalized, highly varied response occurring only in select brewing strains. Nevertheless, strains exhibiting switching behavior altered their filamentation response to exogenous concentrations of 2-phenylethanol.

7.
Clin Microbiol Infect ; 29(8): 1031-1038, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37187349

RESUMEN

BACKGROUND: Invasive fungal infections are an important cause of morbidity and mortality in a broad range of patients. Adequate and early diagnosis is a challenge and of importance for improved survival. New molecular-based diagnostic methods are trendsetting, yet with the drawback that conventional tests receive less attention, in the laboratory as well as in the clinical setting. OBJECTIVES: We aimed to provide a useful recommendation for direct microscopy for effectively managing numerous specimens related to fungal infections, mainly covering opportunistic pathogens. SOURCES: A PubMed literature search covering direct fungal microscopy was performed with no restrictions on publication dates. CONTENT: Best practise recommendations targeting the role of direct microscopy in diagnosing fungal infections are given. This review highlights when to perform direct microscopy, displays the main fungal morphologies, discusses the pitfalls related to microscopy, and recommends how to best report the results to clinicians. IMPLICATION: In many samples, the performance of direct microscopy provides an important diagnostic benefit that is greater than culture alone. Fluorescent dyes improve sensitivity and allow a fast and rapid read. Reporting includes the presence or absence of yeast forms, septate or non-septate hyphae, pigmentation, cellular location, or any other specific structures being present. The visualization of fungal elements from a sterile body site is proof of an infection, independent of other test reports.


Asunto(s)
Microscopía , Micosis , Humanos , Micosis/diagnóstico , Levaduras
8.
Microbiol Res ; 272: 127373, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37058783

RESUMEN

BACKGROUND: Treatment of Candida albicans associated infections is often ineffective in the light of resistance, with an urgent need to discover novel antimicrobials. Fungicides require high specificity and can contribute to antifungal resistance, so inhibition of fungal virulence factors is a good strategy for developing new antifungals. OBJECTIVES: Examine the impact of four plant-derived essential oil components (1,8-cineole, α-pinene, eugenol, and citral) on C. albicans microtubules, kinesin motor protein Kar3 and morphology. METHODS: Microdilution assays were used to determine minimal inhibitory concentrations, microbiological assays assessed germ tube, hyphal and biofilm formation, confocal microscopy probed morphological changes and localization of tubulin and Kar3p, and computational modelling was used to examine the theoretical binding of essential oil components to tubulin and Kar3p. RESULTS: We show for the first time that essential oil components delocalize the Kar3p, ablate microtubules, and induce psuedohyphal formation with reduced biofilm formation. Single and double deletion mutants of kar3 were resistant to 1,8-cineole, sensitive to α-pinene and eugenol, but unimpacted by citral. Strains with homozygous and heterozygous Kar3p disruption had a gene-dosage effect for all essential oil components, resulting in enhanced resistance or susceptibility patterns that were identical to that of cik1 mutants. The link between microtubule (αß-tubulin) and Kar3p defects was further supported by computational modeling, showing preferential binding to αß-tubulin and Kar3p adjacent to their Mg2+-binding sites. CONCLUSION: This study highlights how essential oil components interfere with the localization of the kinesin motor protein complex Kar3/Cik1 and disrupt microtubules, leading to their destabilization which results in hyphal and biofilm defects.


Asunto(s)
Aceites Volátiles , Proteínas de Saccharomyces cerevisiae , Candida albicans/metabolismo , Cinesinas/metabolismo , Proteínas Asociadas a Microtúbulos/metabolismo , Tubulina (Proteína)/genética , Tubulina (Proteína)/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Aceites Volátiles/farmacología , Eugenol/metabolismo , Eucaliptol/metabolismo , Microtúbulos/metabolismo , Antifúngicos/farmacología , Antifúngicos/metabolismo , Proteínas de Microtúbulos/metabolismo
9.
Curr Genet ; 69(2-3): 77-89, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-36947241

RESUMEN

Candida albicans is a commensal organism of the human gastrointestinal tract and a prevalent opportunistic pathogen. It exhibits different morphogenic forms to survive in different host niches with distinct environmental conditions (pH, temperature, oxidative stress, nutrients, serum, chemicals, radiation, etc.) and genetic factors (transcription factors and genes). The different morphogenic forms of C. albicans are yeast, hyphal, pseudohyphal, white, opaque, and transient gray cells, planktonic and biofilm forms of cells. These forms differ in the parameters like cellular phenotype, colony morphology, adhesion to solid surfaces, gene expression profile, and the virulent traits. Each form is functionally distinct and responds discretely to the host immune system and antifungal drugs. Hence, morphogenic plasticity is the key to virulence. In this review, we address the characteristics, the pathogenic potential of the different morphogenic forms and the conditions required for morphogenic transitions.


Asunto(s)
Candida albicans , Factores de Transcripción , Humanos , Candida albicans/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Levaduras/metabolismo , Virulencia/genética , Biopelículas , Hifa/genética , Hifa/metabolismo , Regulación Fúngica de la Expresión Génica
10.
Food Microbiol ; 112: 104217, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-36906300

RESUMEN

Brettanomyces bruxellensis is the most damaging spoilage yeast in the wine industry because of its negative impact on the wine organoleptic qualities. The strain persistence in cellars over several years associated with recurrent wine contamination suggest specific properties to persist and survive in the environment through bioadhesion phenomena. In this work, the physico-chemical surface properties, morphology and ability to adhere to stainless steel were studied both on synthetic medium and on wine. More than 50 strains representative of the genetic diversity of the species were considered. Microscopy techniques made it possible to highlight a high morphological diversity of the cells with the presence of pseudohyphae forms for some genetic groups. Analysis of the physico-chemical properties of the cell surface reveals contrasting behaviors: most of the strains display a negative surface charge and hydrophilic behavior while the Beer 1 genetic group has a hydrophobic behavior. All strains showed bioadhesion abilities on stainless steel after only 3 h with differences in the concentration of bioadhered cells ranging from 2.2 × 102 cell/cm2 to 7.6 × 106 cell/cm2. Finally, our results show high variability of the bioadhesion properties, the first step in the biofilm formation, according to the genetic group with the most marked bioadhesion capacity for the beer group.


Asunto(s)
Brettanomyces , Vino , Microbiología de Alimentos , Acero Inoxidable/análisis , Brettanomyces/metabolismo , Vino/análisis , Saccharomyces cerevisiae
11.
Antibiotics (Basel) ; 12(1)2023 Jan 06.
Artículo en Inglés | MEDLINE | ID: mdl-36671307

RESUMEN

Invasive candidiasis is an important cause of morbidity and mortality, and its occurrence is increasing due to the growing complexity of patients. In particular, Candida albicans exhibits several virulence factors that facilitate yeast colonization in humans. In this sense, the photodynamic inactivation of yeasts is a promising new alternative to eliminate fungal infections. Herein, the photodynamic activity sensitized by a free-base chlorin (TPCF16) and its complexes with Zn(II) (ZnTPCF16) and Pd(II) (PdTPCF16) was investigated in order to eliminate C. albicans under different forms of cell cultures. A decrease in cell survival of more than 5 log was found in planktonic cells incubated with 5 µM TPCF16 or ZnTPCF16 upon 15 min of white-light irradiation. The mechanism of action mainly involved a type II pathway in the inactivation of C. albicans cells. In addition, the photodynamic action induced by these chlorins was able to suppress the growth of C. albicans in a culture medium. These photosensitizers were also effective to photoinactivate C. albicans pseudohyphae suspended in PBS. Furthermore, the biofilms of C. albicans that incorporated the chlorins during the proliferation stage were completely eradicated using 5 µM TPCF16 or ZnTPCF16 after 60 min of light irradiation. The studies indicated that these chlorins are effective photosensitizing agents to eliminate C. albicans as planktonic cells, pseudohyphae, and biofilms.

12.
Folia Microbiol (Praha) ; 68(4): 571-577, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-36656405

RESUMEN

The pathogen Candida albicans is pleiomorphic and grows in yeast and filamentous forms but the relationship between the regulation of different filamentous forms is unclear. BRG1 encodes a DNA binding protein which is an important regulator of morphology. Mutants lacking BRG1 grow as yeast under all conditions tested and over-expressing BRG1 drives hyphal growth even in the absence of inducing signals. A number of genetic mutants in repressors of filamentation form pseudohyphae under yeast conditions and some of these mutants can form hyphae under hypha-inducing conditions. This study examines the position of BRG1 in the regulatory networks that govern filamentation by examining the effect of over-expressing BRG1 in pseudohyphal mutants.


Asunto(s)
Candida albicans , Proteínas Fúngicas , Candida albicans/genética , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulación Fúngica de la Expresión Génica , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Hifa
13.
Mol Biol Rep ; 49(10): 9387-9396, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-35908239

RESUMEN

BACKGROUND: Diploid cells of Saccharomyces cerevisiae undergo either pseudohyphal differentiation or sporulation in response to depletion of carbon and nitrogen sources. Distinct signaling pathways regulate filamentation and sporulation in response to nutrient limitation. How these pathways are coordinated for implementing distinct cell fate decisions in response to similar nutritional cues is an enigma. Although the role of trehalose pathway in sporulation has been extensively studied, it's possible role in pseudohyphal differentiation has been unexplored. METHODS AND RESULTS: Briefly, tps1 and tps2 mutants were tested for their ability to form pseudohyphae independently as well as in the background of GPR1 and RAS2 mutations. Here, we demonstrate that disruption of TPS1 but not TPS2 inhibits pseudohyphae formation. Interestingly, deletion of GPR1 suppresses the above defect. Further genetic analysis revealed that TPS1 and TPS2 exert opposing effects in triggering filamentation. CONCLUSION: We provide new insights into the role of an otherwise well-known pathway of trehalose biosynthesis in pseudohyphal differentiation. Based on additional data we propose that downstream signaling, mediated by cAMP may be modulated by nutrient mediated differential regulation of RAS2 by TPS1 and TPS2.


Asunto(s)
Saccharomyces cerevisiae , Trehalosa , Vías Biosintéticas , Carbono/metabolismo , Glucosiltransferasas/genética , Nitrógeno/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Trehalosa/metabolismo
14.
Microorganisms ; 10(1)2022 Jan 13.
Artículo en Inglés | MEDLINE | ID: mdl-35056611

RESUMEN

The recent technological advancements in synthetic biology have demonstrated the extensive potential socio-economic benefits at laboratory scale. However, translations of such technologies to industrial scale fermentations remains a major bottleneck. The existence and lack of understanding of the major discrepancies in cultivation conditions between scales often leads to the selection of suboptimal bioprocessing conditions, crippling industrial scale productivity. In this study, strategic design of experiments approaches were coupled with state-of-the-art bioreactor tools to characterize and overcome nutritional stress for the enhanced production of precursors to the blockbuster chemotherapy drug, Taxol, in S. cerevisiae cell factories. The batch-to-batch variation in yeast extract composition was found to trigger nutritional stress at a mini-bioreactor scale, resulting in profound changes in cellular morphology and the inhibition of taxane production. The cells shifted from the typical budding morphology into striking pseudohyphal cells. Doubling initial yeast extract and peptone concentrations (2×YP) delayed filamentous growth, and taxane accumulation improved to 108 mg/L. Through coupling a statistical definitive screening design approach with the state-of-the-art high-throughput micro-bioreactors, the total taxane titers were improved a further two-fold, compared to the 2×YP culture, to 229 mg/L. Filamentous growth was absent in nutrient-limited microscale cultures, underlining the complex and multifactorial nature of yeast stress responses. Validation of the optimal microscale conditions in 1L bioreactors successfully alleviated nutritional stress and improved the titers to 387 mg/L. Production of the key Taxol precursor, T5αAc, was improved two-fold to 22 mg/L compared to previous maxima. The present study highlights the importance of following an interdisciplinary approach combining synthetic biology and bioprocessing technologies for effective process optimization and scale-up.

15.
mBio ; 12(5): e0272921, 2021 10 26.
Artículo en Inglés | MEDLINE | ID: mdl-34663094

RESUMEN

Candida auris is a globally emerging multidrug-resistant fungal pathogen. Its pathogenicity-related signaling networks are largely unknown. Here, we characterized the pathobiological functions of the cyclic AMP (cAMP)/protein kinase A (PKA) signaling pathway in C. auris. We focused on adenylyl cyclase (CYR1), the PKA regulatory subunit (BCY1), and the PKA catalytic subunits (TPK1 and TPK2). We concluded that PKA acts both dependently and independently of Cyr1 in C. auris. Tpk1 and Tpk2 have major and minor roles, respectively, in PKA activity and functions. Both Cyr1 and PKA promote growth, thermotolerance, filamentous growth, and resistance to stress and antifungal drugs by regulating expression of multiple effector genes. In addition, Cyr1 and PKA subunits were involved in disinfectant resistance of C. auris. However, deletion of both TPK1 and TPK2 generally resulted in more severe defects than CYR1 deletion, indicating that Cyr1 and PKA play redundant and distinct roles. Notably, Tpk1 and Tpk2 have redundant but Cyr1-independent roles in haploid-to-diploid cell transition, which increases virulence of C. auris. However, Tpk1 and Tpk2 often play opposing roles in formation of biofilms and the cell wall components chitin and chitosan. Surprisingly, deletion of CYR1 or TPK1/TPK2, which resulted in severe in vitro growth defects at 37°C, did not attenuate virulence, and BCY1 deletion reduced virulence of C. auris in a systemic murine infection model. In conclusion, this study provides comprehensive insights into the role of the cAMP/PKA pathway in drug resistance and pathogenicity of C. auris and suggests a potential therapeutic option for treatment of C. auris-mediated candidemia. IMPORTANCE Despite the recently growing concern of pan-resistant Candida auris infection, the pathogenicity of this ascomycetous fungal pathogen and the signaling circuitries governing its resistance to antifungal drugs are largely unknown. Therefore, we analyzed the pathobiological functions of cyclic AMP (cAMP)/protein kinase A (PKA) signaling pathway in C. auris, which plays conserved roles in the growth and virulence of fungal pathogens. We show that adenylyl cyclase Cyr1 and PKA have pleiotropic roles in growth, morphogenesis, stress responses, antifungal drug and disinfectant resistance, and ploidy shifts of C. auris. Notably, however, we observed that the tpk1Δ tpk2Δ mutant generally exhibited more disrupted phenotypes than the cyr1Δ mutant, and we suggest Tpk1 and Tpk2 have both cAMP-dependent and -independent roles in this pathogen. Most surprisingly, we observed that hyperactivation, not inhibition, of the cAMP/PKA pathway reduced virulence of C. auris. Based on our results, we suggest and discuss potential therapeutic strategies for candidiasis caused by C. auris.


Asunto(s)
Adenilil Ciclasas/metabolismo , Candida auris/efectos de los fármacos , Candida auris/patogenicidad , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Farmacorresistencia Fúngica , Transducción de Señal , Adenilil Ciclasas/clasificación , Adenilil Ciclasas/genética , Animales , Antifúngicos/farmacología , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Candida auris/genética , Candida auris/crecimiento & desarrollo , Candidiasis/microbiología , AMP Cíclico/metabolismo , Proteínas Quinasas Dependientes de AMP Cíclico/genética , Femenino , Regulación Fúngica de la Expresión Génica , Ratones , Fenotipo , Virulencia
16.
Cureus ; 12(5): e8141, 2020 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-32550061

RESUMEN

Subcutaneous swelling is one of the common cases seen in surgical practice. The pathology of the subcutaneous swellings is varied ranging from epidermal inclusion cyst to malignant swelling. Fungal infections producing subcutaneous swelling are relatively rare. They occur in immunocompromised patients. We report a case of phaeohyphomycosis (PHM) which is characterized by the presence of pseudohyphae, hyphae, brown yeast-like cells, and melanin in their cell walls, presenting as subcutaneous swelling. A 34-year-old male presented with a swelling over the anterior aspect of left knee joint for three months, which was initially painless. He gave a history of purulent discharge from the swelling 20 days back. He was a known case of myasthenia gravis on regular treatment with steroids. On examination, the swelling was firm, nontender, and mobile in subcutaneous plane. The skin over the swelling showed a healed puckered scar, fine needle aspiration cytology (FNAC) of the swelling showed slender, septate hyphae with variable branching bulbous ends, and few of the hyphae showed pigmentation morphologically suggestive of PHM. The swelling was excised with clear margin. Subcutaneous mycosis is common in tropical and subtropical countries like India. Strong suspicion of this diagnosis is warranted especially in immunocompromised patients. Surgical excision is the treatment of choice to achieve early cure.

17.
J Microbiol Methods ; 175: 105973, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32522492

RESUMEN

In industrial yeast fermentation processes, single-cell yeast suspensions are usually preferable to cells in aggregates, as single cells exhibit a larger contact area with the nutrient medium, which in many cases helps optimize the process. In addition to affecting fermentation time and efficiency, cell aggregates (e.g., pseudohyphal yeast morphology) may also impair centrifugation systems, one of the most expensive and complex steps of the production process that involves the recovery of yeast cells for subsequent fermentation cycles. To date, no standard technique allows for a systematic diagnosis of yeast morphology in real time during sugarcane biofuel fermentation. Accordingly, we investigate an in situ microscope (ISM) for online monitoring of the density and morphology of an industrial Saccharomyces cerevisiae strain widely used in Brazilian distilleries (PE-2). During batch and repeated batch sugarcane molasses fermentation, the instrument revealed single cells, budding yeast cells, and pseudohyphae, all in a variety of sizes and shapes. The ISM image analysis indicated that the volume of single yeast cells increased by roughly 40% over the lag phase before budding and remained approximately constant thereafter. Pseudohyphae with three and more cells appeared mostly during the stationary phase. Cooling problems were simulated by raising the temperature from 33 to 45 °C. During this thermal stress, single cells as well as budding cells and pseudohyphae forming cells became smaller and exhibited intracellular inhomogeneities. From these results, we conclude that an ISM is a useful tool for monitoring yeast morphology during sugarcane fermentation. Atypical morphologies can be detected early and be used as an automatic warning system.


Asunto(s)
Microbiología Industrial/métodos , Microscopía/métodos , Saccharomyces cerevisiae/fisiología , Medios de Cultivo , Fermentación , Melaza , Saccharum
18.
Trends Microbiol ; 28(11): 922-933, 2020 11.
Artículo en Inglés | MEDLINE | ID: mdl-32474010

RESUMEN

Fungal infections are on the rise due to new medical procedures that have increased the number of immune compromised patients, antibacterial antibiotics that disrupt the microbiome, and increased use of indwelling medical devices that provide sites for biofilm formation. Key to understanding the mechanisms of pathogenesis is to determine how fungal morphology impacts virulence strategies. For example, small budding cells use very different strategies to disseminate compared with long hyphal filaments. Furthermore, cell morphology must be monitored in the host, as many fungal pathogens change their shape to disseminate into new areas, acquire nutrients, and avoid attack by the immune system. This review describes the shape-shifting alterations in morphogenesis of human fungal pathogens and how they influence virulence strategies.


Asunto(s)
Hongos/crecimiento & desarrollo , Hongos/patogenicidad , Micosis/microbiología , Animales , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Hongos/genética , Hongos/metabolismo , Regulación Fúngica de la Expresión Génica , Humanos , Hifa/genética , Hifa/crecimiento & desarrollo , Hifa/metabolismo , Virulencia
19.
Curr Genet ; 66(5): 901-910, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32322930

RESUMEN

Saccharomyces cerevisiae adapts to oxidative, osmotic stress and nutrient deprivation through transcriptional changes, decreased proliferation, and entry into other developmental pathways such as pseudohyphal formation and sporulation. Inositol pyrophosphates are necessary for these cellular responses. Inositol pyrophosphates are molecules composed of the phosphorylated myo-inositol ring that carries one or more diphosphates. Mutations in the enzymes that metabolize these molecules lead to altered patterns of stress resistance, altered morphology, and defective sporulation. Mechanisms to alter the synthesis of inositol pyrophosphates have been recently described, including inhibition of enzyme activity by oxidation and by phosphorylation. Cells with increased levels of 5-diphosphoinositol pentakisphosphate have increased nuclear localization of Msn2 and Gln3. The altered localization of these factors is consistent with the partially induced environmental stress response and increased expression of genes under the control of Msn2/4 and Gln3. Other transcription factors may also exhibit increased nuclear localization based on increased expression of their target genes. These transcription factors are each regulated by TORC1, suggesting that TORC1 may be inhibited by inositol pyrophosphates. Inositol pyrophosphates affect stress responses in other fungi (Aspergillus nidulans, Ustilago maydis, Schizosaccharomyces pombe, and Cryptococcus neoformans), in human and mouse, and in plants, suggesting common mechanisms and possible novel drug development targets.


Asunto(s)
Difosfatos/metabolismo , Fosfatos de Inositol/metabolismo , Saccharomyces cerevisiae/fisiología , Estrés Fisiológico , Núcleo Celular/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Regulación Fúngica de la Expresión Génica , Respuesta al Choque Térmico , Histona Desacetilasa 1/genética , Histona Desacetilasa 1/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Presión Osmótica , Estrés Oxidativo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Transducción de Señal , Factores de Transcripción/genética , Factores de Transcripción/metabolismo
20.
J Appl Microbiol ; 128(4): 1038-1049, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31816165

RESUMEN

AIM: The purpose of this study was to uncover insights into the mechanism of action of the 8-hydroxyquinoline derivatives PH151 and PH153. In addition, with the future perspective of developing a topical drug for the treatment of candidiasis and dermatophytosis, the antifungal activity of a nanoemulsion formulation containing the most active compound (PH151) is also presented here. METHODS AND RESULTS: Sorbitol protection assay and scanning electron microscopy indicate that the 8-hydroxyquinoline derivatives act on the cell wall of Candida sp. and dermatophytes and they inhibit the pseudohyphae formation of C. albicans. These findings demonstrate a strong effect of these compounds on C. albicans morphogenesis, which can be considered a potential mode of action for this molecule. Besides, the nanoemulsion formulation MIC values ranged from 0·5 to 4 µg ml-1 demonstrating the significant antifungal activity when incorporated into a pharmaceutical formulation. CONCLUSIONS: Taken together, the results support the potential of these molecules as promising antifungal candidates for the treatment of candidiasis and dermatophytosis. SIGNIFICANCE AND IMPACT OF THE STUDY: There is an emerging need to fill the pipeline with new antifungal drugs due to the limitations presented by the currently used drugs. In this study, we have described a novel formulation with a 8-hydroxyquinoline-5-sulfonamide derivative which has presented a great potency in providing a finished product. Furthermore, the derivative has shown a selective mechanism of action confirming its potential to be developed into a new drug candidate.


Asunto(s)
Antifúngicos/farmacología , Arthrodermataceae/efectos de los fármacos , Dermatomicosis/microbiología , Oxiquinolina/farmacología , Sulfonamidas/farmacología , Antifúngicos/química , Arthrodermataceae/crecimiento & desarrollo , Candida albicans/efectos de los fármacos , Candida albicans/crecimiento & desarrollo , Candidiasis/tratamiento farmacológico , Candidiasis/microbiología , Pared Celular/efectos de los fármacos , Dermatomicosis/tratamiento farmacológico , Hifa/efectos de los fármacos , Hifa/crecimiento & desarrollo , Pruebas de Sensibilidad Microbiana , Oxiquinolina/química , Sulfonamidas/química
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