Cell wall staining with Trypan blue enables quantitative analysis of morphological changes in yeast cells

Two-layer elastic models for single-yeast compressibility with flat microlevers

Unicellular organisms such as yeast can survive in very different environments, thanks to a polysaccharide wall that reinforces their extracellular membrane. This wall is not a static structure, as it is expected to be dynamically remodeled according to growth stage, division cycle, environmental osmotic pressure and ageing. It is therefore of great interest to study the mechanics of these organisms, but they are more difficult to study than other mammalian cells, in particular because of their small size (radius of a few microns) and their lack of an adhesion machinery. Using flat cantilevers, we perform compression experiments on single yeast cells (S. cerevisiae) on poly-L-lysine-coated grooved glass plates, in the limit of small deformation using an atomic force microscope (AFM). Thanks to a careful decomposition of force-displacement curves, we extract local scaling exponents that highlight the non-stationary characteristic of the yeast behavior upon compression. Our multi-scale nonlinear analysis of the AFM force-displacement curves provides evidence for non-stationary scaling laws. We propose to model these phenomena based on a two-component elastic system, where each layer follows a different scaling law..

Prevalent arbuscular mycorrhizae in roots and highly variable mycobiome in leaves of epiphytic subtropical fern Ophioderma pendulum

PREMISE

Endophytic and mycorrhizal fungi are crucial in facilitating plant nutrition acquisition and stress tolerance. In epiphytic habitats, plants face nutrition and water stress, but their roots are mostly nonmycorrhizal and especially lacking in arbuscular mycorrhizal associations. Ophioderma pendulum is an epiphytic fern with a partially mycoheterotrophic lifestyle, likely heavily reliant on symbiotic fungi. To characterize fungal associations in the sporophyte of O. pendulum, we focused on leaves and roots of O. pendulum, seeking to reveal the fungal communities in these organs.

METHODS

Roots and leaves from O. pendulum in a subtropical forest were examined microscopically to observe the morphology of fungal structures and determine the percentage of various fungal structures in host tissues. Fungal composition was profiled using metabarcoding techniques that targeted ITS2 of the nuclear ribosomal DNA.

RESULTS

Roots were consistently colonized by arbuscular mycorrhizal fungi (Glomeromycota), especially Acaulospora. Unlike previous findings on epiphytic ferns, dark septate endophytes were rare in O. pendulum roots. Leaves were predominantly colonized by Ascomycota fungi, specifically the classes Dothideomycetes (46.88%), Eurotiomycetes (11.51%), Sordariomycetes (6.23%), and Leotiomycetes (6.14%). Across sampling sites, fungal community compositions were similar in the roots but differed significantly in the leaves.

CONCLUSIONS

Ophioderma pendulum maintains stable, single-taxon-dominant communities in the roots, primarily featuring arbuscular mycorrhizal fungi, whereas the leaves may harbor opportunistic fungal colonizers. Our study underlines the significance of mycorrhizal fungi in the adaptation of epiphytic ferns.

Deletion of the transcription factors Hsf1, Msn2 and Msn4 in yeast uncovers transcriptional reprogramming in response to proteotoxic stress

The response to proteotoxic stresses such as heat shock allows organisms to maintain protein homeostasis under changing environmental conditions. We asked what happens if an organism can no longer react to cytosolic proteotoxic stress. To test this, we deleted or depleted, either individually or in combination, the stress-responsive transcription factors Msn2, Msn4, and Hsf1 in Saccharomyces cerevisiae. Our study reveals a combination of survival strategies, which together protect essential proteins. Msn2 and 4 broadly reprogram transcription, triggering the response to oxidative stress, as well as biosynthesis of the protective sugar trehalose and glycolytic enzymes, while Hsf1 mainly induces the synthesis of molecular chaperones and reverses the transcriptional response upon prolonged mild heat stress (adaptation).

John N, Zaidi F, Doyle F, Fasullo M. High-throughput screening of the Saccharomyces cerevisiae genome for 2-amino-3-methylimidazo [4,5-f] quinoline resistance identifies colon cancer-associated genes

Heterocyclic aromatic amines (HAAs) are potent carcinogenic agents found in charred meats and cigarette smoke. However, few eukaryotic resistance genes have been identified. We used Saccharomyces cerevisiae (budding yeast) to identify genes that confer resistance to 2-amino-3-methylimidazo[4,5-f] quinoline (IQ). CYP1A2 and NAT2 activate IQ to become a mutagenic nitrenium compound. Deletion libraries expressing human CYP1A2 and NAT2 or no human genes were exposed to either 400 or 800 µM IQ for 5 or 10 generations. DNA barcodes were sequenced using the Illumina HiSeq 2500 platform and statistical significance was determined for exactly matched barcodes. We identified 424 ORFs, including 337 genes of known function, in duplicate screens of the "humanized" collection for IQ resistance; resistance was further validated for a select group of 51 genes by growth curves, competitive growth, or trypan blue assays. Screens of the library not expressing human genes identified 143 ORFs conferring resistance to IQ per se. Ribosomal protein and protein modification genes were identified as IQ resistance genes in both the original and "humanized" libraries, while nitrogen metabolism, DNA repair, and growth control genes were also prominent in the "humanized" library. Protein complexes identified included the casein kinase 2 (CK2) and histone chaperone (HIR) complex. Among DNA Repair and checkpoint genes, we identified those that function in postreplication repair (RAD18, UBC13, REV7), base excision repair (NTG1), and checkpoint signaling (CHK1, PSY2). These studies underscore the role of ribosomal protein genes in conferring IQ resistance, and illuminate DNA repair pathways for conferring resistance to activated IQ.

Co-option of an Astacin Metalloprotease Is Associated with an Evolutionarily Novel Feeding Morphology in a Predatory Nematode

Animals consume a wide variety of food sources to adapt to different environments. However, the genetic mechanisms underlying the acquisition of evolutionarily novel feeding morphology remain largely unknown. While the nematode Caenorhabditis elegans feeds on bacteria, the satellite species Pristionchus pacificus exhibits predatory feeding behavior toward other nematodes, which is an evolutionarily novel feeding habit. Here, we found that the astacin metalloprotease Ppa-NAS-6 is required for the predatory killing by P. pacificus. Ppa-nas-6 mutants were defective in predation-associated characteristics, specifically the tooth morphogenesis and tooth movement during predation. Comparison of expression patterns and rescue experiments of nas-6 in P. pacificus and C. elegans suggested that alteration of the spatial expression patterns of NAS-6 may be vital for acquiring predation-related traits. Reporter analysis of the Ppa-nas-6 promoter in C. elegans revealed that the alteration in expression patterns was caused by evolutionary changes in cis- and trans-regulatory elements. This study suggests that the co-option of a metalloprotease is involved in an evolutionarily novel feeding morphology.

Biodegradation and reduction of toxicity of Azo Trypan Blue dye by Amazonian strains of gasteroid fungi (Basidiomycota)

Amazonian strains of Cyathus spp. and Geastrum spp. were studied for the ability to discolor the trypan blue azo dye and reduce its toxicity. Discoloration of trypan blue dye (0.05%) was evaluated in solid and aqueous medium over different periods. The reduction of dye toxicity after treatment was assessed by seed germination and the development of lettuce seedlings (Lactuca sativa L.) and toxicity test in Artemia salina (L.) larvae. All evaluated strains showed the potential to reduce the color intensity of trypan blue dye. Cyathus strains reached 96% discoloration, and C. albinus and C. limbatus also reduced dye toxicity. Geastrum strains showed a high efficiency degree in color reduction, reaching 98% discoloration, however, the by-products generated during the process presented toxicity and require further investigation. For the first time, Amazonian strains of gasteroid fungi degrading trypan blue are reported, some even reducing its toxicity. Thus, making them promising sources of enzymes of interest to bioremediation scenarios involving synthetic dyes.

The Role of Trypan Blue as a Conventional and Fluorescent Dye for the Diagnosis of Superficial Mycoses by Potassium Hydroxide (KOH) Testing

Direct microscopic examination of samples using potassium hydroxide (KOH) is a fast, simple, and inexpensive method to confirm clinical suspicion of superficial mycosis. However, the lack of color contrast in this test makes it difficult to separate any fungal structures from artifacts. The sensitivity of the KOH mount technique may be enhanced using both fluorochromes and conventional stains that highlight the fungal structures when observed under fluorescence microscopy and bright-field, respectively. Here we study the possibility of using Trypan Blue (TB), an azo dye which is often used as a live/dead marker, in the diagnosis of superficial mycoses by KOH testing. TB at 0.01% displayed a fluorescent staining pattern similar to that of Calcofluor White (CFW), the conventional cell wall fluorophore. Furthermore, by adjusting the TB concentration to 0.1-0.3%, in addition to maintaining the fluorescent staining pattern, the fungal elements were stained in blue under bright-field microscopy. Thus, we demonstrate for the first time that TB has the unique property as a fungal stain that can be used in both bright-field and fluorescence microscopy for diagnosis of superficial mycoses by direct microscopic examination.

Assessing chronological aging in Saccharomyces cerevisiae

Chronological age represents the time that passes between birth and a given date. To understand the complex network of factors contributing to chronological lifespan, a variety of model organisms have been implemented. One of the best studied organisms is the yeast Saccharomyces cerevisiae, which has greatly contributed toward identifying conserved biological mechanisms that act on longevity. Here, we discuss high- und low-throughput protocols to monitor and characterize chronological lifespan and chronological aging-associated cell death in S. cerevisiae. Included are propidium iodide staining with the possibility to quantitatively assess aging-associated cell death via flow cytometry or qualitative assessments via microscopy, cell viability assessment through plating and cell counting and cell death characterization via propidium iodide/AnnexinV staining and subsequent flow cytometric analysis or microscopy. Importantly, all of these methods combined give a clear picture of the chronological lifespan under different conditions or genetic backgrounds and represent a starting point for pharmacological or genetic interventions.

Fluorogenic properties of 4-dimethylaminocinnamaldehyde (DMACA) enable high resolution imaging of cell-wall-bound proanthocyanidins in plant root tissues

Proanthocyanidins (PAs) are polymeric phenolic compounds found in plants and used in many industrial applications. Despite strong evidence of herbivore and pathogen resistance-related properties of PAs, their in planta function is not fully understood. Determining the location and dynamics of PAs in plant tissues and cellular compartments is crucial to understand their mode of action. Such an approach requires microscopic localization with fluorescent dyes that specifically bind to PAs. Such dyes have hitherto been lacking. Here, we show that 4-dimethylaminocinnamaldehyde (DMACA) can be used as a PA-specific fluorescent dye that allows localization of PAs at high resolution in cell walls and inside cells using confocal microscopy, revealing features of previously unreported wall-bound PAs. We demonstrate several novel usages of DMACA as a fluorophore by taking advantage of its double staining compatibility with other fluorescent dyes. We illustrate the use of the dye alone and its co-localization with cell wall polymers in different Populus root tissues. The easy-to-use fluorescent staining method, together with its high photostability and compatibility with other fluorogenic dyes, makes DMACA a valuable tool for uncovering the biological function of PAs at a cellular level in plant tissues. DMACA can also be used in other plant tissues than roots, however care needs to be taken when tissues contain compounds that autofluoresce in the red spectral region which can be confounded with the PA-specific DMACA signal.

Cell Wall Destruction and Internal Cascade Synergistic Antifungal Strategy for Fungal Keratitis

Fungal keratitis is one of the most common blindness-causing diseases, but clinical antifungal treatment remains a challenge. The fungal cell wall and biofilm matrix which severely confine the drug preparation are the critical obstructive factors to therapeutic effects. Herein, we report ethylenediaminetetraacetic acid (EDTA) modified AgCu₂O nanoparticles (AgCuE NPs) to disrupt the cell wall and then eradicate C. albicans through the internal cascade synergistic effects of ion-released chemotherapy, chemodynamic therapy, photodynamic therapy, and mild photothermal therapy. AgCuE NPs exhibited excellent antifungal activity both in preventing biofilm formation and in destroying mature biofilms. Furthermore, AgCuE NP based gel formulations were topically applied to kill fungi, reduce inflammation, and promote wound healing, using optical coherence tomography and photoacoustic imaging to monitor nanogel retention and therapeutic effects on the infected murine cornea model. The AgCuE NP gel showed good biosafety and no obvious ophthalmic and systemic side effects. This study suggests that the AgCuE NP gel is an effective and safe antifungal strategy for fungal keratitis with a favorable prognosis and potential for clinical translation.

The Role of Phialocephala fortinii in Improving Plants' Phosphorus Nutrition: New Puzzle Pieces

Plants' mineral nutrition in acidic soils can be facilitated by phosphate solubilizing fungi inhabiting the root systems of these plants. We attempt to find dark septate endophyte (DSE) isolates in the roots of wild-heather plants, which are capable of improving plants' phosphorus nutrition levels. Bright-field and confocal laser scanning microscopy were used for the visualization of endophytes. A model system of co-cultivation with Vaccinium macrocarpon Ait. was used to study a fungal isolate's ability to supply plants with phosphorus. Fungal phytase activity and phosphorus content in plants were estimated spectrophotometrically. In V. vitis-idaea L. roots, we obtained a Phialocephala fortinii Wang, Wilcox DSE2 isolate with acid phytase activity (maximum 6.91 ± 0.17 U on 21st day of cultivation on potato-dextrose broth medium) and the ability to accumulate polyphosphates in hyphae cells. The ability of the isolate to increase both phosphorus accumulation and biomass in V. macrocarpon is also shown. The data obtained for the same isolate, as puzzle pieces put together, indicate the possible mediation of P. fortinii DSE2 isolate in the process of phosphorus intake from inorganic soil reserves to plants.

Withania somnifera (L.) Dunal whole-plant extracts exhibited anti-sporotrichotic effects by destabilizing peripheral integrity of Sporothrix globosa yeast cells

Chronic topical cases of Sporotrichosis, a chronic fungal infection caused by the ubiquitously present cryptic members of the Sporothrix species complex, are treated with oral administrations of itraconazole. However, severe pulmonary or disseminated cases require repeated intra-venous doses of amphotericin B or even surgical debridement of the infected tissue. The unavoidable adverse side-effects of the current treatments, besides the growing drug resistance among Sporothrix genus, demands exploration of alternative therapeutic options. Medicinal herbs, due to their multi-targeting capacity, are gaining popularity amidst the rising antimicrobial recalcitrance. Withania somnifera is a well-known medicinal herb with reported antifungal activities against several pathogenic fungal genera. In this study, the antifungal effect of the whole plant extract of W. somnifera (WSWE) has been explored for the first time, against an itraconazole resistant strain of S. globosa. WSWE treatment inhibited S. globosa yeast form growth in a dose-dependent manner, with IC₅₀ of 1.40 mg/ml. Minimum fungicidal concentration (MFC) was found to be 50 mg/ml. Sorbitol protection and ergosterol binding assays, revealed that anti-sporotrichotic effects of WSWE correlated well with the destabilization of the fungal cell wall and cell membrane. This observation was validated through dose-dependent decrease in overall ergosterol contents in WSWE-treated S. globosa cells. Compositional analysis of WSWE through high performance liquid chromatography (HPLC) exhibited the presence of several anti-microbial phytochemicals like withanone, withaferin A, withanolides A and B, and withanoside IV and V. Withanone and withaferin A, purified from WSWE, were 10–20 folds more potent against S. globosa than WSWE, thus, suggesting to be the major phytocompounds responsible for the observed anti-sporotrichotic activity. In conclusion, this study has demonstrated the anti-sporotrichotic property of the whole plant extract of W. somnifera against S. globosa that could be further explored for the development of a natural antifungal agent against chronic Sporotrichosis.

Sporotrichosis, commonly known as ‘rose gardener’s disease’ is a rare but chronic fungal infection caused by several pathogenic members of Sporothrix. Although rare, Sporotrichosis can spread to the lungs or whole body, and thus, could be fatal. However, due to low frequency of its occurrence, scientific research on Sporotrichosis has been rather limited. To exacerbate the situation, many Sporothrix members have developed resistance against the common anti-fungal agents used to treat fungal infections. Many medicinal herbs are being explored for their effectiveness against drug-resistant microorganisms. In this connection, the well-known medicinal plant, Withania somnifera, commonly known as Winter cherry in English and Ashwagandha in Hindi, has been explored for its anti-fungal potentials against several pathogenic fungi. However, to the best of our knowledge, anti-fungal effect of W. somnifera against Sporothrix has not been assessed yet. Therefore, this study was conducted to investigate the anti-fungal potentials of Withania somnifera whole plant extract (WSWE) against Sporothrix globosa, known to cause Sporotrichosis in Asia. This study demonstrated significant anti-sporotrichotic effect of WSWE, which could be further explored for developing an alternative natural treatment for Sporotrichosis.

Potassium deficiency inhibits leaf growth and promotes leaf necrotic spots in Neolamarckia cadamba (Roxb.) Bosser

Leaves, being a key plant organ involved in photosynthesis, play an important role in plant growth and development. Although there have been a few studies on the effects of potassium (K+) deficiency on the leaves of woody plants, knowledge about mechanism of necrotic spot formation on leaves during K+ deficiency is scarce. We used a hydroponics setup to understand the effects of K+ deficiency on Neolamarckia cadamba (Roxb.) Bosser. K+ deficiency resulted in smaller leaves and necrotic spots on the older leaves, whereas regulatory modules of the differentially expressed genes (DEGs) involved in cell proliferation, cell cycle and cell expansion were downregulated. K+ deficiency increased the activity of reactive oxygen species scavenging enzymes such as superoxide dismutase, ascorbate peroxidases and malondialdehyde, and expression of DEGs related to these was also upregulated. Strong diaminobenzidine staining was observed on the older leaves showing accumulation of H2O2 during K+ deficiency treatment. In addition, putrescine and ethylene synthesis genes were upregulated. Fifteen DEGs in response to ethylene signaling, including ETR1, ETR2, EBF1, ERF1 and ERF2, were upregulated in the third week. The leaf growth changes caused by K+ deficiency in N. cadamba were well demonstrated by our findings.

TORC1 Signaling Controls the Stability and Function of α-Arrestins Aly1 and Aly2

Nutrient supply dictates cell signaling changes, which in turn regulate membrane protein trafficking. To better exploit nutrients, cells relocalize membrane transporters via selective protein trafficking. Key in this reshuffling are the α-arrestins, selective protein trafficking adaptors conserved from yeast to man. α-Arrestins bind membrane proteins, controlling the ubiquitination and endocytosis of many transporters. To prevent the spurious removal of membrane proteins, α-arrestin-mediated endocytosis is kept in check through phospho-inhibition. This phospho-regulation is complex, with up to 87 phospho-sites on a single α-arrestin and many kinases/phosphatases targeting α-arrestins. To better define the signaling pathways controlling paralogous α-arrestins, Aly1 and Aly2, we screened the kinase and phosphatase deletion (KinDel) library, which is an array of all non-essential kinase and phosphatase yeast deletion strains, for modifiers of Aly-mediated phenotypes. We identified many Aly regulators, but focused our studies on the TORC1 kinase, a master regulator of nutrient signaling across eukaryotes. We found that TORC1 and its signaling effectors, the Sit4 protein phosphatase and Npr1 kinase, regulate the phosphorylation and stability of Alys. When Sit4 is lost, Alys are hyperphosphorylated and destabilized in an Npr1-dependent manner. These findings add new dimensions to our understanding of TORC1 regulation of α-arrestins and have important ramifications for cellular metabolism.

Effect of Carbamazepine, Ibuprofen, Triclosan and Sulfamethoxazole on Anaerobic Bioreactor Performance: Combining Cell Damage, Ecotoxicity and Chemical Information

Pharmaceuticals and personal care products (PPCPs) are partially degraded in wastewater treatment plants (WWTPs), thereby leading to the formation of more toxic metabolites. Bacterial populations in bioreactors operated in WWTPs are sensitive to different toxics such as heavy metals and aromatic compounds, but there is still little information on the effect that pharmaceuticals exert on their metabolism, especially under anaerobic conditions. This work evaluated the effect of selected pharmaceuticals that remain in solution and attached to biosolids on the metabolism of anaerobic biomass. Batch reactors operated in parallel under the pressure of four individual and mixed PPCPs (carbamazepine, ibuprofen, triclosan and sulfametoxazole) allowed us to obtain relevant information on anaerobic digestion performance, toxicological effects and alterations to key enzymes involved in the biodegradation process. Cell viability was quantitatively evaluated using an automatic analysis of confocal microscopy images, and showed that triclosan and mixed pollutants caused higher toxicity and cell death than the other individual compounds. Both individual pollutants and their mixture had a considerable impact on the anaerobic digestion process, favoring carbon dioxide production, lowering organic matter removal and methane production, which also produced microbial stress and irreversible cell damage.

Potential of Flow Cytometric Approaches for Rapid Microbial Detection and Characterization in the Food Industry-A Review

As microbial contamination is persistent within the food and bioindustries and foodborne infections are still a significant cause of death, the detection, monitoring, and characterization of pathogens and spoilage microorganisms are of great importance. However, the current methods do not meet all relevant criteria. They either show (i) inadequate sensitivity, rapidity, and effectiveness; (ii) a high workload and time requirement; or (iii) difficulties in differentiating between viable and non-viable cells. Flow cytometry (FCM) represents an approach to overcome such limitations. Thus, this comprehensive literature review focuses on the potential of FCM and fluorescence in situ hybridization (FISH) for food and bioindustry applications. First, the principles of FCM and FISH and basic staining methods are discussed, and critical areas for microbial contamination, including abiotic and biotic surfaces, water, and air, are characterized. State-of-the-art non-specific FCM and specific FISH approaches are described, and their limitations are highlighted. One such limitation is the use of toxic and mutagenic fluorochromes and probes. Alternative staining and hybridization approaches are presented, along with other strategies to overcome the current challenges. Further research needs are outlined in order to make FCM and FISH even more suitable monitoring and detection tools for food quality and safety and environmental and clinical approaches.

Set4 regulates stress response genes and coordinates histone deacetylases within yeast subtelomeres

The yeast chromatin protein Set4 is a member of the Set3-subfamily of SET domain proteins which play critical roles in the regulation of gene expression in diverse developmental and environmental contexts. We previously reported that Set4 promotes survival during oxidative stress and regulates expression of stress response genes via stress-dependent chromatin localization. In this study, global gene expression analysis and investigation of histone modification status identified a role for Set4 in maintaining gene repressive mechanisms within yeast subtelomeres under both normal and stress conditions. We show that Set4 works in a partially overlapping pathway to the SIR complex and the histone deacetylase Rpd3 to maintain proper levels of histone acetylation and expression of stress response genes encoded in subtelomeres. This role for Set4 is particularly critical for cells under hypoxic conditions, where the loss of Set4 decreases cell fitness and cell wall integrity. These findings uncover a new regulator of subtelomeric chromatin that is key to stress defense pathways and demonstrate a function for Set4 in regulating repressive, heterochromatin-like environments.

Modular biosynthesis of plant hemicellulose and its impact on yeast cells

BACKGROUND

The carbohydrate polymers that encapsulate plants cells have benefited humans for centuries and have valuable biotechnological uses. In the past 5 years, exciting possibilities have emerged in the engineering of polysaccharide-based biomaterials. Despite impressive advances on bacterial cellulose-based hydrogels, comparatively little is known about how plant hemicelluloses can be reconstituted and modulated in cells suitable for biotechnological purposes.

RESULTS

Here, we assembled cellulose synthase-like A (CSLA) enzymes using an optimized Pichia pastoris platform to produce tunable heteromannan (HM) polysaccharides in yeast. By swapping the domains of plant mannan and glucomannan synthases, we engineered chimeric CSLA proteins that made β-1,4-linked mannan in quantities surpassing those of the native enzymes while minimizing the burden on yeast growth. Prolonged expression of a glucomannan synthase from Amorphophallus konjac was toxic to yeast cells: reducing biomass accumulation and ultimately leading to compromised cell viability. However, an engineered glucomannan synthase as well as CSLA pure mannan synthases and a CSLC glucan synthase did not inhibit growth. Interestingly, Pichia cell size could be increased or decreased depending on the composition of the CSLA protein sequence. HM yield and glucose incorporation could be further increased by co-expressing chimeric CSLA proteins with a MANNAN-SYNTHESIS-RELATED (MSR) co-factor from Arabidopsis thaliana.

CONCLUSION

The results provide novel routes for the engineering of polysaccharide-based biomaterials that are needed for a sustainable bioeconomy. The characterization of chimeric cellulose synthase-like enzymes in yeast offers an exciting avenue to produce plant polysaccharides in a tunable manner. Furthermore, cells modified with non-toxic plant polysaccharides such as β-mannan offer a modular chassis to produce and encapsulate sensitive cargo such as therapeutic proteins.

Cytotoxicity and Genotoxicity of Metal Oxide Nanoparticles in Human Pluripotent Stem Cell-Derived Fibroblasts

Advances in the use of nanoparticles (NPs) has created promising progress in biotechnology and consumer-care based industry. This has created an increasing need for testing their safety and toxicity profiles. Hence, efforts to understand the cellular responses towards nanomaterials are needed. However, current methods using animal and cancer-derived cell lines raise questions on physiological relevance. In this aspect, in the current study, we investigated the use of pluripotent human embryonic stem cell- (hESCs) derived fibroblasts (hESC-Fib) as a closer representative of the in vivo response as well as to encourage the 3Rs (replacement, reduction and refinement) concept for evaluating the cytotoxic and genotoxic effects of zinc oxide (ZnO), titanium dioxide (TiO2) and silicon-dioxide (SiO2) NPs. Cytotoxicity assays demonstrated that the adverse effects of respective NPs were observed in hESC-Fib beyond concentrations of 200 µg/mL (SiO2 NPs), 30 µg/mL (TiO2 NPs) and 20 µg/mL (ZnO NPs). Flow cytometry results correlated with increased apoptosis upon increase in NP concentration. Subsequently, scratch wound assays showed ZnO (10 µg/mL) and TiO2 (20 µg/mL) NPs inhibit the rate of wound coverage. DNA damage assays confirmed TiO2 and ZnO NPs are genotoxic. In summary, hESC-Fib could be used as an alternative platform to understand toxicity profiles of metal oxide NPs.

Antifungal activity of nanoemulsion from Cleome viscosa essential oil against food-borne pathogenic Candida albicans

Pathogenic and spoilage fungi cause enormous challenges to food related fatal infections. Plant essential oil based classical emulsions can functions as antifungal agents. To investigate the antifungal spectrum, that is the scope of the nanoemulsion composed of Cleome viscosa essential oil and Triton-x-100 fabricated by ultrasonication method. Minimum inhibitory and fungicidal concentration of essential oil nanoemulsion (EONE) was tested against food borne pathogenic C. albicans. The MIC and MFC values ranged from 16.5 to 33 µl/ml with significant reduction on biofilm of C. albicans isolates. The alteration of molecular fingerprints was confirmed by Fourier transformed infrared spectroscopy and subsequent reduction of chitin levels in cell walls was noted by spectroscopic analysis. The EONE and their bioactive compounds cause collateral damage on C. albicans cells.

Consolidated bioprocessing of cellulose to itaconic acid by a co-culture of Trichoderma reesei and Ustilago maydis

BACKGROUND

Itaconic acid is a bio-derived platform chemical with uses ranging from polymer synthesis to biofuel production. The efficient conversion of cellulosic waste streams into itaconic acid could thus enable the sustainable production of a variety of substitutes for fossil oil based products. However, the realization of such a process is currently hindered by an expensive conversion of cellulose into fermentable sugars. Here, we present the stepwise development of a fully consolidated bioprocess (CBP), which is capable of directly converting recalcitrant cellulose into itaconic acid without the need for separate cellulose hydrolysis including the application of commercial cellulases. The process is based on a synthetic microbial consortium of the cellulase producer Trichoderma reesei and the itaconic acid producing yeast Ustilago maydis. A method for process monitoring was developed to estimate cellulose consumption, itaconic acid formation as well as the actual itaconic acid production yield online during co-cultivation.

RESULTS

The efficiency of the process was compared to a simultaneous saccharification and fermentation setup (SSF). Because of the additional substrate consumption of T. reesei in the CBP, the itaconic acid yield was significantly lower in the CBP than in the SSF. In order to increase yield and productivity of itaconic acid in the CBP, the population dynamics was manipulated by varying the inoculation delay between T. reesei and U. maydis. Surprisingly, neither inoculation delay nor inoculation density significantly affected the population development or the CBP performance. Instead, the substrate availability was the most important parameter. U. maydis was only able to grow and to produce itaconic acid when the cellulose concentration and thus, the sugar supply rate, was high. Finally, the metabolic processes during fed-batch CBP were analyzed in depth by online respiration measurements. Thereby, substrate availability was again identified as key factor also controlling itaconic acid yield. In summary, an itaconic acid titer of 34 g/L with a total productivity of up to 0.07 g/L/h and a yield of 0.16 g/g could be reached during fed-batch cultivation.

CONCLUSION

This study demonstrates the feasibility of consortium-based CBP for itaconic acid production and also lays the fundamentals for the development and improvement of similar microbial consortia for cellulose-based organic acid production.

Genome Profiling for Aflatoxin B1 Resistance in Saccharomyces cerevisiae Reveals a Role for the CSM2/SHU Complex in Tolerance of Aflatoxin B1-Associated DNA Damage

Exposure to the mycotoxin aflatoxin B1 (AFB₁) strongly correlates with hepatocellular carcinoma (HCC). P450 enzymes convert AFB₁ into a highly reactive epoxide that forms unstable 8,9-dihydro-8-(N7-guanyl)-9-hydroxyaflatoxin B1 (AFB₁-N ⁷-Gua) DNA adducts, which convert to stable mutagenic AFB₁ formamidopyrimidine (FAPY) DNA adducts. In CYP1A2-expressing budding yeast, AFB₁ is a weak mutagen but a potent recombinagen. However, few genes have been identified that confer AFB₁ resistance. Here, we profiled the yeast genome for AFB₁ resistance. We introduced the human CYP1A2 into ∼90% of the diploid deletion library, and pooled samples from CYP1A2-expressing libraries and the original library were exposed to 50 μM AFB₁ for 20 hs. By using next generation sequencing (NGS) to count molecular barcodes, we initially identified 86 genes from the CYP1A2-expressing libraries, of which 79 were confirmed to confer AFB₁ resistance. While functionally diverse genes, including those that function in proteolysis, actin reorganization, and tRNA modification, were identified, those that function in postreplication DNA repair and encode proteins that bind to DNA damage were over-represented, compared to the yeast genome, at large. DNA metabolism genes also included those functioning in checkpoint recovery and replication fork maintenance, emphasizing the potency of the mycotoxin to trigger replication stress. Among genes involved in postreplication repair, we observed that CSM2, a member of the CSM2 (SHU) complex, functioned in AFB₁-associated sister chromatid recombination while suppressing AFB₁-associated mutations. These studies thus broaden the number of AFB₁ resistance genes and have elucidated a mechanism of error-free bypass of AFB₁-associated DNA adducts.

Pseudohyphal growth in Saccharomyces cerevisiae involves protein kinase-regulated lipid flippases

Lipid flippases of the P4 ATPase family establish phospholipid asymmetry in eukaryotic cell membranes and are involved in many essential cellular processes. The yeast Saccharomyces cerevisiae contains five P4 ATPases, among which Dnf3p is poorly characterized. Here, we demonstrate that Dnf3p is a flippase that catalyzes translocation of major glycerophospholipids, including phosphatidylserine, towards the cytosolic membrane leaflet. Deletion of the genes encoding Dnf3p and the distantly related P4 ATPases Dnf1p and Dnf2p results in yeast mutants with aberrant formation of pseudohyphae, suggesting that the Dnf1p-Dnf3p proteins have partly redundant functions in the control of this specialized form of polarized growth. Furthermore, as previously demonstrated for Dnf1 and Dnf2p, the phospholipid flipping activity of Dnf3p is positively regulated by flippase kinase 1 (Fpk1p) and Fpk2p. Phylogenetic analyses demonstrate that Dnf3p belongs to a subfamily of P4 ATPases specific for fungi and are likely to represent a hallmark of fungal evolution.

Resistance Mechanisms of Saccharomyces cerevisiae to Commercial Formulations of Glyphosate Involve DNA Damage Repair, the Cell Cycle, and the Cell Wall Structure

The use of glyphosate-based herbicides is widespread and despite their extensive use, their effects are yet to be deciphered completely. The additives in commercial formulations of glyphosate, though labeled inert when used individually, have adverse effects when used in combination with other additives along with the active ingredient. As a species, Saccharomyces cerevisiae has a wide range of resistance to glyphosate-based herbicides. To investigate the underlying genetic differences between sensitive and resistant strains, global changes in gene expression were measured, when yeast were exposed to a glyphosate-based herbicide (GBH). Expression of genes involved in numerous pathways crucial to the cell's functioning, such as DNA replication, MAPK signaling, meiosis, and cell wall synthesis changed. Because so many diverse pathways were affected, these strains were then subjected to in-lab-evolutions (ILE) to select mutations that confer increased resistance. Common fragile sites were found to play a role in adaptation to resistance to long-term exposure of GBHs. Copy number increased in approximately 100 genes associated with cell wall proteins, mitochondria, and sterol transport. Taking ILE and transcriptomic data into account it is evident that GBHs affect multiple biological processes in the cell. One such component is the cell wall structure which acts as a protective barrier in alleviating the stress caused by exposure to inert additives in GBHs. Sed1, a GPI-cell wall protein, plays an important role in tolerance of a GBH. Hence, a detailed study of the changes occurring at the genome and transcriptome levels is essential to better understand the effects of an environmental stressor such as a GBH, on the cell as a whole.

Autolysis, plasmolysis and enzymatic hydrolysis of baker's yeast (Saccharomyces cerevisiae): a comparative study

Saccharomyces cerevisiae is being used for long as a rich source of proteins, sugars, nucleotides, vitamins and minerals. Autolyzed and hydrolyzed yeast biomass has found numerous applications in the health food industry as well as livestock feeds. Here, we have compared three lysis methods for production of yeast lysates using autolysis, plasmolysis (ethyl acetate 1.5%), and enzymatic hydrolysis (Alcalase 0.2%). The efficiency of each process was compared according to soluble solid and protein contents, cell lysis monitoring, and release of intracellular materials, cell viability and microscopic analysis. Results showed that plasmolysis by ethyl acetate was found to be more efficient compared to autolysis, with a higher recovery of yeast extract (YE) content. In comparison, the content of released solids and proteins were higher during the enzymatic hydrolysis using Alcalase compared to autolysis and plasmolysis treatments. The highest decrease in optical density of 600 nm was monitored for the hydrolyzed cells. Besides, we defined "Degree of Leakage (DL)" as a new index of the lysis process, referring to the percentage of total released proteins from the cells and it was estimated to about 65.8%, which represents an appropriate indicator of the cell lysis. The biochemical and biophysical properties of the hydrolyzed yeast product as well as its biological activity (free radical scavenging activity and bacterial binding capacity) suggest that Alcalase could be used to accelerate the lysis of yeast cells and release the valuable intracellular components used for foodstuffs, feed and fermentation media applications. Production of baker's yeast lysates using autolysis, plasmolysis, and enzymatic hydrolysis methods.

High-throughput method for detection and quantification of lesions on leaf scale based on trypan blue staining and digital image analysis

BACKGROUND

Field-grown leafy vegetables can be damaged by biotic and abiotic factors, or mechanically damaged by farming practices. Available methods to evaluate leaf tissue damage mainly rely on colour differentiation between healthy and damaged tissues. Alternatively, sophisticated equipment such as microscopy and hyperspectral cameras can be employed. Depending on the causal factor, colour change in the wounded area is not always induced and, by the time symptoms become visible, a plant can already be severely affected. To accurately detect and quantify damage on leaf scale, including microlesions, reliable differentiation between healthy and damaged tissue is essential. We stained whole leaves with trypan blue dye, which traverses compromised cell membranes but is not absorbed in viable cells, followed by automated quantification of damage on leaf scale.

RESULTS

We present a robust, fast and sensitive method for leaf-scale visualisation, accurate automated extraction and measurement of damaged area on leaves of leafy vegetables. The image analysis pipeline we developed automatically identifies leaf area and individual stained (lesion) areas down to cell level. As proof of principle, we tested the methodology for damage detection and quantification on two field-grown leafy vegetable species, spinach and Swiss chard.

CONCLUSIONS

Our novel lesion quantification method can be used for detection of large (macro) or single-cell (micro) lesions on leaf scale, enabling quantification of lesions at any stage and without requiring symptoms to be in the visible spectrum. Quantifying the wounded area on leaf scale is necessary for generating prediction models for economic losses and produce shelf-life. In addition, risk assessments are based on accurate prediction of the relationship between leaf damage and infection rates by opportunistic pathogens and our method helps determine the severity of leaf damage at fine resolution.

Recent advances in synthesis and biosensors of two-dimensional MoS2

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted tremendous research interests due to their exciting optical properties, large surface area, intercalatable morphologies and excellent electrochemically catalytic activity. Acting as the most typical member in TMDCs family, layer-dependent molybdenum disulfide (MoS₂) with particular direct bandgap of 1.8 eV in monolayer has been widely applied in various biosensors with high sensitivity and selectivity. In this review, the preparation methods of MoS₂, together with MoS₂-based biosensors for detecting cells and biomolecules (such as glucose, DNA and antigens) would be summarized. In addition, the current challenges and future perspectives are outlined for the applications of biosensors based on 2D MoS₂.

Non-invasive Quantification of Cell Wall Porosity by Fluorescence Quenching Microscopy

All bacteria, fungi and plant cells are surrounded by a cell wall. This complex network of polysaccharides and glycoproteins provides mechanical support, defines cell shape, controls cell growth and influences the exchange of substances between the cell and its surroundings. Despite its name, the cell wall is a flexible, dynamic structure. However, due to the lack of non-invasive methods to probe the structure, relatively little is known about the synthesis and dynamic remodeling of cell walls. Here, we describe a non-invasive method that quantifies a key physiological parameter of cell walls, the porosity, i.e., the size of spaces between cell wall components. This method measures the porosity-dependent decrease of the plasma membrane-localized fluorescent dye FM4-64 in the presence of the extracellular quencher Trypan blue. This method is applied to bacteria, fungi and plant cell walls to detect dynamic changes of porosity in response to environmental cues.

Single pot bioprocessing for ethanol production from biogenic municipal solid waste

Burgeoning global energy demand and rapid diminution of fossil fuel reserves urged to seek for a sustainable energy source like bioethanol. Single pot bioprocessing (SPB) strategy employing in-house laccase, cellulase plus xylanase and amylase along with hexose and pentose sugar fermenting yeasts (Saccharomyces cerevisiae and Pichia stipitis) is designed in this study for ethanol production from biogenic municipal solid waste (BMSW). BMSW when subjected to simultaneous pretreatment and saccharification (SPS) resulted in 79.69% enzymatic digestibility and fared better compared to alkali pretreated counterparts (14.03%-51.10%). The maximum total sugar release in case of SPS was 146.9 g/L in 24 h. The maximum ethanol concentration of 5.24% (v/v) in 30 h was obtained from SPB of BMSW at 25% (w/v) solid loading. SPB for ethanol production from BMSW is an interesting and effective alternative to MSW going to landfill or incineration with an added perk of waste to wealth conversion.

Sida cordifolia accelerates wound healing process delayed by dexamethasone in rats: Effect on ROS and probable mechanism of action

ETHNO PHARMACOLOGICAL RELEVANCE

Sida cordifolia is used commonly in traditional systems of medicine (TSM) and as folk remedies for treating the wounds (both external and internal), infected area, rheumatic disorders, muscular weakness, tuberculosis, heart problems, bronchitis, neurological problems etc. Therefore, in order to authenticate the claims, a mechanism-oriented investigation of the wound healing properties of this plant is essential.

AIM OF THE STUDY

The overall aim of the present research is to understand the precise unknown cellular and molecular mechanism by which S. cordifolia accelerates wound healing delay caused by the steroidal drug dexamethasone. Here, we have also tried to quantify intracellular superoxide with the help of a unique fluoroprobe MitoSOX based on fluorescence measurements in yeast MATERIALS AND METHODS: Wound healing property of successive extracts (ethyl acetate, methanol and aqueous) of S. cordifolia against dexamethasone-induced retardation of wound healing in rats was studied. The various extracts of S. cordifolia were characterised by determining the various phytochemicals and quantifying the total phenolic content and flavonoidal content by High throughput assays. In order to know the probable mechanism of action of the successive fractionates, assessed the antioxidant activity both by in-vitro (DPPH-assay) and in-vivo methods in wild-type Saccharomyces cerevisiae BY 4743 (WT) and knock-out strain (Δtrx2) against H₂O₂-induced stress mediated damages. The cell survival was evaluated after exposure to the oxidizing reagent (4 mM H₂O₂) by two methods which included the ability of cells to proliferate on solid or liquid medium. The cell membrane integrity/amount of mitochondrial ROS was determined by treating the strains with extract/standard in presence of H₂O₂ and propidium iodide (PI)/MitoSOX Red RESULTS: During the preliminary in-vivo wound healing study, the period for complete re-epithelialization of the wound tissue was reduced significantly (pin the treatment groups as compared to the negative control group. The formulation HF₃ containing aqueous extract of S. cordifolia (SCA) showed highest wound healing potential against dexamethasone-retarded wounds in rats which justifies its traditional use. In the growth curve assay, the H₂O₂-induced growth arrest was restored by aqueous extract of S. cordifolia (SCA) in a concentration-dependent(pmanner both in the WT and Δtrx2 strains similar to the standard (ascorbic acid), H₂O₂ after 24 hours incubation which was also confirmed by the findings of CFU method. We got almost similar results of cell viability when stained with PI. The lower level of mitochondrial superoxide was indicated by a significant (preduction in the amount of MitoSOX stained cells, in the extract-treated group in contrast to the H₂O₂-stressed group.

CONCLUSION

It was concluded that HF₃ can be applied topically in hydrogel form in the case of delayed wound healing caused by the steroidal drug-dexamethasone, aptly justifying its traditional use. Regarding its mechanism of action, our findings report that the potent adaptive response of SCA-treated WT and Δtrx2 strains towards intracellular ROS specifically mitochondrial-ROS confirms its antioxidant potential. Moreover, as SCA was able to rescue the Δtrx2 strains from stress, it can be inferred that it might be able to induce the enzyme thioredoxin-II to restore redox homeostasis. The findings with the conditional mutant ∆trx2 are the first proof linking SCA action related to particular cellular pathways which may be because of the phenols and flavonoids and their synergistic effect.

Novel tool to quantify cell wall porosity relates wall structure to cell growth and drug uptake

Even though cell walls have essential functions for bacteria, fungi, and plants, tools to investigate their dynamic structure in living cells have been missing. Here, it is shown that changes in the intensity of the plasma membrane dye FM4-64 in response to extracellular quenchers depend on the nano-scale porosity of cell walls. The correlation of quenching efficiency and cell wall porosity is supported by tests on various cell types, application of differently sized quenchers, and comparison of results with confocal, electron, and atomic force microscopy images. The quenching assay was used to investigate how changes in cell wall porosity affect the capability for extension growth in the model plant Arabidopsis thaliana Results suggest that increased porosity is not a precondition but a result of cell extension, thereby providing new insight on the mechanism plant organ growth. Furthermore, it was shown that higher cell wall porosity can facilitate the action of antifungal drugs in Saccharomyces cerevisiae, presumably by facilitating uptake.

A comparison of conventional rapid methods in diagnosis of superficial and cutaneous mycoses based on KOH, Chicago sky blue 6B and calcofluor white stains

BACKGROUND AND OBJECTIVES

Rapid confirmation of dermatomycoses is desirable, as it allows the clinicians to initiate appropriate therapy immediately. In this study, the utility of a novel contrast stain, Chicago sky blue stain, was compared with potassium hydroxide mount and calcofluor white stain to determine the causative fungal elements in the rapid detection method.

MATERIALS AND METHODS

In this survey, 189 samples of suspected dermatomycosis infections were assessed in 3 incubation times of 30 minutes, 2 hours, and > 6 hours.

RESULTS

Positive cases were shown in Chicago sky blue 6B (55%), calcofluor white (53.4%), and potassium hydroxide (36%), with 30-minute incubation. Positive results increased in other incubation times. Sensitivity, specificity, PPV, NPV and accuracy of Chicago sky blue 6B were 97%, 100%, 100%, 96% and 98% and, for potassium hydroxide, they were 66%, 98%, 97%, 98%, 80% versus CFW, respectively.

CONCLUSION

This study provides evidence that the Chicago sky blue 6B stain is a simple, fast and cost-effective method.

Chitinases and thaumatin-like proteins in Sauvignon Blanc and Chardonnay musts during alcoholic fermentation

Protein precipitation, also referred to as protein instability, may lead to haziness in bottled wines and result in significant commercial losses. To avoid problems of this nature, fining finished wines with clay (bentonite) is the most commonly applied methodology. However, bentonite fining reduces yield and may affect wine quality. Protein haze has been primarily linked to grape pathogenesis-related proteins, in particular chitinases and thaumatin-like proteins. To better understand the persistence of these proteins during fermentation, reverse phase chromatography was used to monitor the evolution of total grape proteins as well as of chitinases and thaumatin-like proteins during alcoholic fermentation. The data confirm a previously reported significant decrease in total protein content during fermentation. This reduction in total protein levels was observed throughout fermentation, and was affected by factors such as fermentation temperature, yeast strain or grape cultivar. However, significant changes in the concentration of free chitinases were observed in a yeast strain-dependent manner. The data thus confirm the correlation between the levels of yeast cell wall chitin and changes in chitinase concentration, and suggest that it is primarily the amount of lateral chitin, and not the chitin in bud scars, that is responsible for this activity.

Efficient isolation and observation of the most complex human commensal, Demodex spp

Demodex spp. mites are an often neglected member of the human skin microbiome. Mostly they are commensals, although their pathophysiological role in rosacea, spinulosis folliculorum, and other skin diseases is recognized. Little is known about their life cycle, biology, and physiology. Demodex mites cannot be cultivated in vitro, thereby complicating research immensely. The manual extraction from human sebum is laborious and death can only be detected by surrogate markers like ceased movement or loss of fluorescence. Here we present a new approach for the extraction of larger mite numbers and the hitherto most precise way to detect death. The extraction of mites from sebum and debris by hand can be accelerated by a factor 10 using sucrose gradient centrifugation, which is well tolerated by the mites. Staining with propidium iodide allows for easy identification of dead mites, excluding frail mites that stopped moving, and has no negative effect on overall mite survival. We anticipate our methods to be a starting point for more sophisticated research and ultimately in vitro cultivation of Demodex spp. mites.

Azole-induced cell wall carbohydrate patches kill Aspergillus fumigatus

Azole antifungals inhibit the fungal ergosterol biosynthesis pathway, resulting in either growth inhibition or killing of the pathogen, depending on the species. Here we report that azoles have an initial growth-inhibitory (fungistatic) activity against the pathogen Aspergillus fumigatus that can be separated from the succeeding fungicidal effects. At a later stage, the cell wall salvage system is induced. This correlates with successive cell integrity loss and death of hyphal compartments. Time-lapse fluorescence microscopy reveals excessive synthesis of cell wall carbohydrates at defined spots along the hyphae, leading to formation of membrane invaginations and eventually rupture of the plasma membrane. Inhibition of β-1,3-glucan synthesis reduces the formation of cell wall carbohydrate patches and delays cell integrity failure and fungal death. We propose that azole antifungals exert their fungicidal activity by triggering synthesis of cell wall carbohydrate patches that penetrate the plasma membrane, thereby killing the fungus. The elucidated mechanism may be potentially exploited as a novel approach for azole susceptibility testing.

Azole antifungals inhibit fungal ergosterol biosynthesis. Here, Geißel et al. show that the fungicidal activity of azoles involves excessive synthesis of cell wall carbohydrates at defined spots along the hyphae, leading to formation of membrane invaginations and eventually rupture of the plasma membrane.

Digital Image Analysis of Yeast Single Cells Growing in Two Different Oxygen Concentrations to Analyze the Population Growth and to Assist Individual-Based Modeling

Nowadays control of the growth of Saccharomyces to obtain biomass or cellular wall components is crucial for specific industrial applications. The general aim of this contribution is to deal with experimental data obtained from yeast cells and from yeast cultures to attempt the integration of the two levels of information, individual and population, to progress in the control of yeast biotechnological processes by means of the overall analysis of this set of experimental data, and to assist in the improvement of an individual-based model, namely, INDISIM-Saccha. Populations of S. cerevisiae growing in liquid batch culture, in aerobic and microaerophilic conditions, were studied. A set of digital images was taken during the population growth, and a protocol for the treatment and analyses of the images obtained was established. The piecewise linear model of Buchanan was adjusted to the temporal evolutions of the yeast populations to determine the kinetic parameters and changes of growth phases. In parallel, for all the yeast cells analyzed, values of direct morphological parameters, such as area, perimeter, major diameter, minor diameter, and derived ones, such as circularity and elongation, were obtained. Graphical and numerical methods from descriptive statistics were applied to these data to characterize the growth phases and the budding state of the yeast cells in both experimental conditions, and inferential statistical methods were used to compare the diverse groups of data achieved. Oxidative metabolism of yeast in a medium with oxygen available and low initial sugar concentration can be taken into account in order to obtain a greater number of cells or larger cells. Morphological parameters were analyzed statistically to identify which were the most useful for the discrimination of the different states, according to budding and/or growth phase, in aerobic and microaerophilic conditions. The use of the experimental data for subsequent modeling work was then discussed and compared to simulation results generated with INDISIM-Saccha, which allowed us to advance in the development of this yeast model, and illustrated the utility of data at different levels of observation and the needs and logic behind the development of a microbial individual-based model.

Anti-Candida Activity of Bursera morelensis Ramirez Essential Oil and Two Compounds, α-Pinene and γ-Terpinene-An In Vitro Study

The candidiasis caused by C. albicans is a public health problem. The abuse of antifungals has contributed to the development of resistance. B. morelensis has demonstrated antibacterial and antifungal activities. In this work the activity of the essential oil of B. morelensis was evaluated and for its two pure compounds with analysis of the different mechanisms of pathogenesis important for C. albicans. The essential oil was obtained by the hydro-distillation method and analyzed using GC–MS. The anti-Candida activity was compared between to essential oil, α-Pinene and γ-Terpinene. GC–MS of the essential oil demonstrated the presence of 13 compounds. The essential oil showed antifungal activity against four C. albicans strains. The most sensitive strain was C. albicans 14065 (MFC 2.0 mg/mL and MIC₅₀ 0.125 mg/mL) with α-Pinene and γ-Terpinene having MFCs of 4.0 and 16.0 mg/mL respectively. The essential oil inhibited the growth of the germ tube in 87.94% (8.0 mg/mL). Furthermore, it was observed that the essential oil diminishes the transcription of the gene INT1. This work provides evidence that confirms the anti-Candida activity of the B. morelensis essential oil and its effect on the growth of the germ tube and transcription of the gene INT1.

A novel method for primary neuronal culture and characterization under different high temperature

Heatstroke is a big threat to human health; however, the characteristic of pathological changes of neurons during heatstroke development remains unclear. Here, using an in vitro model of primary cultured neurons from newborn Wistar rats, we investigated the effects of the different combinations of high temperature (37, 39, 41, 43, 45, and 47°C) and exposure time (45 min and 1 h) on the neurons. We found that, under the treatment of 45 min-heat, the neurons could resist high temperature up to 45°C, and under the treatment of 1 h-heat, the mortality of neurons increased as the temperature rises. After heating for 1 h, only a small minority of the neurons died under 41 and 43°C, which primarily occurred in the form of apoptosis. Up to 45°C for 1 h, most neurons occurred to necrosis. Meaningfully, some necrotic neurons expressed specific fried egg-like morphology. Our findings suggest that different high temperatures and exposure times were two key factors influencing the death of neurons. Under the high temperature (below 43°C for 1 h) similar to heatstroke, it just led a small percentage of neurons to apoptosis, and anti-apoptosis controls for preventing and treating heatstroke are promising.