Yeast Form Research Articles (Page 1)

Pheromone MAPK pathway regulates the yeast-to-hypha transition in the parasitic mushroom Naematelia sinensis in a cell fusion-independent manner.

Chroman, pyridine, and coumarin in a new fused scaffold as α-glucosidase inhibitor: synthesis of new derivatives, in vitro, and in silico evaluations.

ABSTRACTSingle cell oils produced in microorganisms constitute appealing alternatives to plant oils. Oleaginous fungi accumulate triacylglycerols in lipid droplets (LD). Their biosynthesis is typically induced under nitrogen limitation. We exploit the fungal model Ustilago maydis for oil production. The stain 4,4‐difluoro‐1,3,5,7,8‐pentamethyl‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) can be used to track LD formation during cultivation but this expensive compound is only affordable at small‐scale. Therefore, mutant screening for optimization of oil production and composition would benefit from an inexpensive online monitoring system. Accordingly, we aimed at developing an intrinsic reporter that is suitable to track oil formation even in larger cultures. From three tested candidates, the potential delta(24)‐sterol C‐methyltransferase Erg6 turned out to be the best reporter. Fluorescence microscopy confirmed its localization at the LD membrane. After optimization, Erg6 fused to mKate2, expressed from a promoter derived from glycolipid biosynthesis, showed a good correlation of fluorescence with oil accumulation. Time course experiments in micro‐cultivators demonstrated that the fluorescence read‐out can be used to track oil formation starting at the onset of nitrogen limitation to approximate the LD amount. In essence, our study introduces a biosensor for oil monitoring that can easily be transferred to other oleaginous yeasts.SummaryMicrobial oils are promising, environmentally friendly alternatives to plant oils and have the potential of a huge market share once competitive production and isolation processes are accomplished.Online monitoring is key to efficient engineering of single cell oil producing microorganisms and bioprocess optimization in order to achieve competitive products.Here, we present an inexpensive, fluorescence‐based reporter that can be used to track the approximate oil accumulation of microbial cultures in vivo. This omits the use of expensive dyes or offline methodology with a high workload.While we established the biosensor in the yeast form of the fungal microorganism U. maydis, the evolutionary conservation of the underlying protein Erg6 will allow for a straightforward transfer of the methodology to other oleaginous yeasts.

Impact of high SAP2 expression on the invasion and adhesion abilities of Candida albicans in vaginal epithelial cells.

α-Glucosidase inhibitors play an important role in the treatment of type 2 diabetes mellitus. Inhibitors of the latter enzyme that are available on the market created gastrointestinal side effects and achieve to a high potent and low side effect potent α- glucosidase inhibitors is a valuable target for medicinal chemists. In this study, derivatives of benzimidazole-phenoxy-1,2,3-triazole-benzyl skeleton were introduced as new α-glucosidase inhibitors. Twelve derivatives 8a-l of target scaffold were synthesized via simple chemical reactions with a yield between 65 and 88%. The in vitro α-glucosidase inhibition activities of these compounds was evaluated against yeast form of this enzyme. After the determination of most potent compound, the interaction of this compound with α-glucosidase was evaluated in vitro by kinetic study and in silico by docking study. Drug-likeness, pharmacokinetics, and toxicity profiles of the most potent compound were predicted by an online software. Anti-α-glucosidase assay demonstrated that all synthesized derivatives 8a-l were more potent that standard inhibitor acarbose. Representatively, 2-(4-((1-benzyl-1H-1,2,3- triazol-4-yl)methoxy)phenyl)-1H-benzo[d]imidazole (compound 8a) as the most potent derivative was 150-times more potent than positive control. Kinetic study of compound 8a revealed that this compound is an uncompetitive inhibitor against α-glucosidase. Furthermore, molecular docking study showed that compound 8a with favorable binding energy attached to important residues in the α-glucosidase active site. This compound also can be an oral drug with favorable toxicity profile. Benzimidazole-phenoxy-1,2,3-triazole-benzyl derivatives 8a-l synthesized and evaluated for anti-α-glucosidase activity. All these compounds were excellent α-glucosidase inhibitor, and compound 8a demonstrated the most significant inhibition effect when compared with positive control.

Darling's disease, another name for oral histoplasmosis, is an uncommon but important form of Histoplasma capsulatum infection that can appear as oral cavity lesions that frequently mimic cancers like squamous cell carcinoma. Immunocompromised people, notably those with HIV, are most vulnerable to this fungal infection, while immunocompetent patients can still get it. Because of their appearance and chronic nature, the clinical presentation usually consists of painful, ulcerative lesions that could be mistakenly diagnosed as cancer. In the uncommon instance described in this analysis, an 80-years-old man who had no known addictions or comorbidities showed up with a non-bleeding ulcero-proliferative lesion on his tongue that had been there for two months. The lesion was eventually determined to be oral histoplasmosis after being misdiagnosed as mouth cancer. The diagnostic difficulties associated with this illness were highlighted by the histopathological investigation, which showed granulomatous inflammation and the distinctive yeast forms of Histoplasma. Inappropriate treatment plans and delays in efficient management can result from misdiagnosis. This example emphasizes how crucial it is to take oral histoplasmosis into account when making a differential diagnosis for oral lesions, especially in areas where it is endemic. To get positive results and avoid consequences from misdiagnosis, early detection and adequate antifungal medication are essential.

Exploring the efficacy of an artificial intelligence model for fungal screening in bronchoalveolar lavage cytology specimens.

The dimorphic transition between yeast and hyphal forms in Talaromyces marneffei is a critical adaptive mechanism that underpins its pathogenicity, particularly in response to environmental cues such as temperature. In this study, we elucidated the role of the MADS-box transcription factor family and discovered that its members collaboratively regulate dimorphic transitions by assuming distinct roles in the morphogenesis, enhancing the understanding of the thermal adaptation of T. marneffei and the functional roles of the MADS-box gene family outside the plant.

This study assessed the biofilm formation of C. albicans on milled and 3D-printed denture resin surfaces and compared it to a control group of conventional heat-polymerized polymethylmethacrylate (PMMA) resin group. Three groups of denture resin samples (n = 27) were fabricated: milled (Ivotion, Ivoclar Vivadent), 3D-printed (Saremco Print Denturetec), and heat-polymerized PMMA controls. Samples (8 mm × 3 mm) were CAD-designed, manufactured, quality-checked, and sterilized. C. albicans (GEGE1122.01) biofilms were grown on resin discs, incubated at 37 °C for 16 h, detached, and quantified. SEM analysis assessed biofilm morphology. Statistical analysis was conducted using non-parametric tests (p < 0.05). The lowest median biofilm attachment (1.2 × 10⁶ CFU/biofilm, IQR: 3.4 × 10⁵ - 5.6 × 10⁶) with high variability was observed in the control group. The milled group displayed significantly higher biofilm formation (6.4 × 10⁶ CFU/biofilm, IQR: 5.9 × 10⁶ - 7.6 × 10⁶, p = 0.0051) with least variation. The biofilm attachment on 3D-printed discs (4.8 × 10⁶ CFU/biofilm, IQR: 3.6 × 10⁶ - 6.2 × 10⁶) was intermediate between the control and milled groups. SEM findings revealed sparse microcolonies with dense, multi-layered biofilms of yeast and pseudohyphal forms in the control and milled groups. 3D-printed group had moderately dense biofilms, where yeast and pseudohyphae were dominant, but true hyphae were also consistently observed. This study reveals significant differences in the C. albicans biofilm formation across the resin types, with 3D-printed surfaces showing increased hyphal growth and potential for higher virulence. Understanding the impact of fabrication methods on microbial colonization is essential for improving denture hygiene and patient outcomes. Dentists and prosthodontists should consider these findings when selecting materials for patients at high risk of fungal infections, such as immunocompromised individuals or elderly denture wearers.

Due to the paucity of fungal elements in the tissue, the sensitivity of histopathological tests for the diagnosis of cutaneous sporotrichosis remains low, particularly for low-virulent Sporothrix species. We retrospectively analysed and re-evaluated the role of histopathological examination in the diagnosis of cutaneous sporotrichosis caused by Sporothrix globosa. Retrospective analysis and pathological reassessment were conducted for 69 sporotrichosis cases caused by S. globosa between 2013 and 2024. Statistical analysis using prevalence ratios was conducted to characterise the clinicopathological and epidemiological aspects. Histopathological examination revealed mixed inflammatory cell infiltration and granulomatous changes in all cases. Periodic acid-Schiff (PAS) staining was performed in 29 tissue specimens, with positivity observed in 4 cases (13.8%, 4/29). Following supplemental staining and re-evaluation of the slides, PAS staining revealed positivity in 50.7% (35/69) of cases, demonstrating yeast forms (91.4%, 32/35) with asteroid bodies (n = 2) and rare hyphae (n = 1). Currently, the role of histopathological examination in the diagnosis of sporotrichosis is limited. Our study showed that the frequency of detecting S. globosa based on histopathological examination is considerably high. Nevertheless, achieving high positive rates necessitates the collaborative efforts of experienced mycologists. The predominance of suppurative granulomas or neutrophils is related to the presence of the fungus in tissue sections from human patients.

The increasing resistance to conventional antifungal agents, such as Amphotericin B (AmB), has led to a growing demand for alternative therapeutic approaches for Candida albicans, an opportunistic fungal pathogen responsible for infections in immunocompromised patients. This study aimed to evaluate the effectiveness of photodynamic inactivation (PDI) in combination with AmB for controlling C. albicans growth, particularly in its yeast and hyphal forms, and to assess the impact of multiple PDI doses. C. albicans (ATCC 90028) was cultured in yeast and hyphal suspensions that were adjusted to 108 CFU/mL and treated with AmB at varying concentrations (0.065-1.04 μg/mL), with and without PDI. PDI was performed using the photosensitizer curcumin (2.5 μM), activated by a 450 nm LED light source at a fluence of 15 J/cm2. The effect of single and repeated PDI doses was evaluated in the fungal biomolecules, which were assessed using Fourier transform infrared (FTIR) spectroscopy. Optical density (OD) measurements quantified fungal growth reduction at 540 nm. The combination of AmB and PDI significantly reduced C. albicans growth, achieving a 75% reduction in the yeast form and an 87.5% reduction in the hyphal form. Two doses of PDI further enhanced antifungal efficacy, particularly against hyphae, which exhibited higher sensitivity to treatment. These findings suggest that PDI enhances the antifungal action of AmB, particularly in more resistant C. albicans forms such as hyphae and biofilms. The observed synergistic effect supports the potential use of PDI as an effective strategy to combat antifungal resistance in clinical applications.

The objective of this study was to compare the properties and performance of invertase enzyme isolated from baker's yeast, both in free and immobilized form on a starch-copper nanocomposite (SCN). The SCN was synthesized using starch as a reducing agent for the biological production of copper nanoparticles (CuNPs). The Characterization of SCN was performed using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction to confirm nanoparticle formation and structural properties. The immobilization of invertase onto SCN was optimized by varying nanoparticle concentration, pH, incubation time, and temperature to maximize enzyme attachment and activity. Enzyme activity was measured for both free and immobilized forms to determine the immobilization efficiency. The study found that the high levels of enzyme immobilization were observed at pH = 9, temperature T = 30, and 3% SCN concentration. For both free and immobilized invertase, the ideal reaction temperatures were 35°C and 40°C, with corresponding pH values of 5 and 4.5. Reusability experiments revealed that the immobilized enzyme retained 49% of its activity after ten cycles, demonstrating improved stability and potential for repeated use. The results suggest that enzyme immobilization on SCN occurs through non-covalent interactions, providing a practical and sustainable approach for biocatalytic applications. This research highlights the potential of starch-based nanocomposites for enzyme stabilization, offering a cost-effective and environmentally friendly solution for industrial and biotechnological applications.

Carbohydrate polymers in their cellular context display highly polymorphic structures and dynamics essential to their diverse functions, yet they are challenging to analyze biochemically. Proton-detection solid-state NMR spectroscopy offers high isotopic abundance and sensitivity, enabling the rapid and high-resolution structural characterization of biomolecules. Here, an array of 2D/3D 1H-detection solid-state NMR techniques are tailored to investigate polysaccharides in fully protonated or partially deuterated cells of three prevalent pathogenic fungi: Rhizopus delemar, Aspergillus fumigatus, and Candida albicans, representing filamentous species and yeast forms. Selective detection of acetylated carbohydrates reveals 15 forms of N-acetylglucosamine units in R. delemar chitin, which coexists with chitosan, and associates with proteins only at limited sites. This is supported by distinct order parameters and effective correlation times of their motions, analyzed through relaxation measurements and model-free analysis. Five forms of α-1,3-glucan with distinct structural origins and dynamics were identified in A. fumigatus, important for this buffering polysaccharide to perform diverse roles of supporting wall mechanics and regenerating a soft matrix under antifungal stress. Eight α-1,2-mannan side chain variants in C. albicans were resolved, highlighting the crucial role of mannan side chains in maintaining interactions with other cell wall polymers to preserve structural integrity. These methodologies provide novel insights into the functional structures of key fungal polysaccharides and create new opportunities for exploring carbohydrate biosynthesis and modifications across diverse organisms.

Phosphoglycerate mutase and methionine synthase act as adhesins of Candida albicans to the corneal epithelium, altering their expression during the tissue adhesion process.

Talaromyces marneffei is a dimorphic fungus that transitions from a filamentous form at 25 °C to a pathogenic yeast form at 37 °C, demonstrating pathogenicity mostly in immunocompromised individuals, such as those with human immunodeficiency virus/AIDS. Though it is one of the most severe infectious fungi in Southeast Asia, the lack of comprehensive genomic analysis has hindered advancement in strain differentiation, diagnosis and treatment. In this study, we assembled a high-quality genome of T. marneffei ATCC 18224, resulting in a 28.9 Mb genome distributed across 11 contigs, using third-generation Oxford Nanopore Technologies sequencing reads. Notably, we identified a strain-specific 740-kb segmental duplication in strain ATCC 18224, potentially mediated by inserting a Ty1/Copia long terminal repeat (LTR) retrotransposon. This segmental duplication includes various functional genes, with 75 differentially expressed during its dimorphic transition. Comparative genomic analysis revealed large-scale rearrangements in strains PM1 and 11CN-20-091, which were inconsistent with the phylogenomic trees of six T. marneffei strains and required further investigation. Additionally, we observed substantial genetic structural variations in LTR retrotransposons, particularly within the Ty1/Copia family, including two significant recent expansions in strain ATCC 18224. In summary, the identification and characterization of these extensive genomic structural variations in T. marneffei contribute to a deep understanding of its genetic diversity and will facilitate improvements in genotyping, classification and genomic surveillance.

Pathogenic fungi that exhibit the ability to alternate between hyphal and yeast morphology in response to environmental stimuli are considered dimorphic. Under saprobic conditions, some fungi exist as filamentous hyphae, producing conidia. When conidia are inhaled by mammals or traumatically inoculated, body temperature (37 °C) triggers dimorphism into yeast cells. This shift promotes fungal dissemination and immune evasion. Some fungal pathogens undergo dimorphism in the contrary way, forming pseudohyphae and hyphae within the host. While temperature is a major driver of dimorphism, other factors, including CO2 concentration, pH, nitrogen sources, and quorum-sensing molecules, also contribute to morphological shifts. This morphological transition is associated with increased expression of virulence factors that aid in adhesion, colonization, and immune evasion. Candida albicans is a fungus that is commonly found as a commensal on human mucous membranes but has the potential to be an opportunistic fungal pathogen of immunocompromised patients. C. albicans exhibits a dimorphic change from the yeast form to the hyphal form when it becomes established as a pathogen. In contrast, Histoplasma capsulatum is an environmental dimorphic fungus where human infection begins when conidia or hyphal fragments of the fungus are inhaled into the alveoli, where the dimorphic change to yeast occurs, this being the morphology associated with its pathogenic phase. This review examines the main signaling pathways that have been mostly related to fungal dimorphism, using as a basis the information available in the literature on H. capsulatum and C. albicans because these fungi have been widely studied for the morphological transition from hypha to yeast and from yeast to hypha, respectively. In addition, we have included the reported findings of these signaling pathways associated with the dimorphism of other pathogenic fungi, such as Paracoccidioides brasiliensis, Sporothrix schenckii, Cryptococcus neoformans, and Blastomyces dermatitis. Understanding these pathways is essential for advancing therapeutic approaches against systemic fungal infections.

Carbohydrate polymers in their cellular context display highly polymorphic structures and dynamics essential to their diverse functions, yet they are challenging to analyze biochemically. Proton-detection solid-state NMR spectroscopy offers high isotopic abundance and sensitivity, enabling rapid and high-resolution structural characterization of biomolecules. Here, an array of 2D/3D 1H-detection solid-state NMR techniques are tailored to investigate polysaccharides in fully protonated or partially deuterated cells of three prevalent pathogenic fungi: Rhizopus delemar, Aspergillus fumigatus, and Candida albicans, representing filamentous species and yeast forms. Selective detection of acetylated carbohydrates reveals fifteen forms of N-acetylglucosamine units in R. delemar chitin, which coexists with chitosan as separate domains or polymers and associates with proteins only at limited sites. This is supported by distinct order parameters and effective correlation times of their motions, analyzed through relaxation measurements and model-free analysis. Five forms of α−1,3-glucan with distinct structural origins and dynamics were identified in A. fumigatus, important for this buffering polysaccharide to perform diverse roles of supporting wall mechanics and regenerating soft matrix under antifungal stress. Eight α−1,2-mannan sidechain variants in C. albicans were resolved, highlighting the crucial role of mannan sidechains in maintaining interactions with other cell wall polymers to preserve structural integrity. These methodologies provide novel insights into the functional structures of key fungal polysaccharides and create new opportunities for exploring carbohydrate biosynthesis and modifications across diverse organisms.

We report a case of acute/subacute form of paracoccidioidomycosis in a Venezuelan migrant confirmed by the detection of the typical ‘pilot wheel/mariner’s wheel’ or ‘Mickey Mouse’ appearance of the budding yeast form of Paracoccidioides in biopsies of a cervical lymph node and a skin lesion.

Background. Modern animal breeding and fodder production aim to create favourable conditions and provide a balanced diet, including feed additives that positively affect the growth and development of farm animals and poultry. Yeast has gained attention due to the beneficial effects of its cellular components and biologically active compounds. Purpose. Review and analysis of scientific publications on the use of various forms of yeast, namely Saccharomyces cerevisiae, as a feed additive for farm animals and poultry. Materials and methods. To achieve the objective, we conducted a review of the scientific literature on the topic under study. This involved searching for evaluating, selecting and analyzing data. Results. This review provides a brief description of the main bioactive components of yeast cells, which are believed to be responsible for the positive effects on animal health, including improved productivity, immune response, antioxidant status, and rumen and intestinal condition. These effects are largely attributed to the ability of yeast cells to modulate the microbiota of the gastrointestinal tract, promoting the growth of beneficial bacteria and reducing colonisation by pathogens. Conclusion. Although there is a significant amount of data demonstrating the positive effects of yeast, contradictions exist that make it impossible to fully assess its safety for the organism. Therefore, it is not recommended for use in officially approved diets on an industrial scale until further studies have been conducted to better understand and dissect the effects and mechanisms of action of yeast and its components. EDN: GVBWDL

The cAMP-dependent protein kinase A (PKA) plays important roles in a wide range of biological processes in eukaryotic organisms. In the fungal pathogen Candida albicans, PKA is a critical regulator of morphological transitions, which are a key virulence trait. PKA is composed of two catalytic isoforms, Tpk1 and Tpk2, which are often thought to act together in a complex with the regulatory subunit Bcy1. Although Tpk1 and Tpk2 have some redundant functions, they also have distinct cellular functions for which the mechanistic underpinnings remain largely elusive. Here, we constructed functional GFP-tagged fusion proteins for Tpk1, Tpk2, and Bcy1 to explore the localization of PKA isoforms. We observed that the PKA holoenzyme is mainly found in the cytoplasm, as Bcy1 is always excluded from the nucleus. Under glucose-replete conditions, both Tpk1 and Tpk2 translocate into the nucleus from the cytosol. In the presence of glycerol, Tpk1 resides in the cytosol, whereas Tpk2 and Bcy1 become enriched on the vacuolar membrane. As the C-terminal domains of Tpk are highly homologous, we investigated the localization and function of hybrid Tpk proteins with exchanged N-terminal domains. We found the catalytic C-terminus of Tpk1 is required for morphogenesis in solid medium, whereas the C-terminus of Tpk2 is critical for filamentation in liquid. Interestingly, the N-terminus of Tpk2 drives its localization to the vacuolar membrane. Our work highlights environmentally contingent localization patterns for the PKA subunits and suggests that the nuclear localization of Tpk is not sufficient to induce the filamentation program in a leading fungal pathogen of humans.IMPORTANCEFungal pathogens have a devastating impact on human health worldwide. They infect billions of people and kill more than 2.5 million per year. Candida albicans is a leading human fungal pathogen responsible for causing life-threatening systemic disease in immunocompromised individuals. A key virulence trait in C. albicans is the ability to switch between yeast and filamentous forms. The conserved protein kinase A (PKA) regulates diverse functions in the cell, including growth and filamentation. Although PKA has been studied in C. albicans for decades, the subcellular localization of PKA has not been thoroughly investigated. Here, we constructed functional GFP-tagged PKA subunits to explore their localization. We identified differential localization patterns for the PKA subunits that are carbon-source dependent and report that these proteins localize into foci in response to diverse environmental stresses. These findings further our understanding of a critical regulator of growth and virulence in C. albicans.