Cell Wall Changes Research Articles

Transcriptomic analysis reveals the mechanism underlying salinity-induced morphological changes in Skeletonema subsalsum

Diatom cell walls are diverse and unique, providing the basis for species identification and supporting the ecological and economic value of diatoms. However, these important structures sometimes change in response to environmental fluctuations, especially under salt adaptation. Although studies have shown that salinity induces morphological plasticity changes in diatom cell walls, most research has focused on physiological responses rather than molecular mechanisms. In this study, Skeletonema subsalsum was cultured under four salinity conditions (0, 3, 6, 12). Through morphological and physiological methods, we found that salinity increased the cell diameter, protrusion lengths, distance between adjacent cells (DBCs), and nanopore size, while reducing cell height and silicification degree. To further investigate the mechanism underlying morphological changes in S. subsalsum, complementary transcriptome analysis was performed. In total, 20,138 differentially expressed genes (DEGs) were identified among the four treatments. Among them, 231 DEGs were screened and found to be closely associated with morphological changes, of which 107 were downregulated and 124 were upregulated. The findings demonstrated that elevated salinity inhibited silicon transport and deposition via downregulating the expression of DEGs involved in functions including chitin metabolism, putrescine metabolism, and vesicle transport, resulting in reduced silicon content and cell height. Increased salinity promoted the expression of DEGs related to microtubules (MTs), actin, and ubiquitin, which synchronously induced morphological changes. These findings provide a more comprehensive understanding of the salt tolerance of algae and a foundation for future studies on cell wall morphogenesis.

Zygospore formation in Zygnematophyceae predates several land plant traits.

Recent research on a special type of sexual reproduction and zygospore formation in Zygnematophyceae, the sister group of land plants, is summarized. Within this group, gamete fusion occurs by conjugation. Zygospore development in Mougeotia, Spirogyra and Zygnema is highlighted, which has recently been studied using Raman spectroscopy, allowing chemical imaging and detection of changes in starch and lipid accumulation. Three-dimensional reconstructions after serial block-face scanning electron microscopy (SBF-SEM) or focused ion beam SEM (FIB-SEM) made it possible to visualize and quantify cell wall and organelle changes during zygospore development. The zygospore walls undergo strong modifications starting from uniform thin cell walls to a multilayered structure. The mature cell wall is composed of a cellulosic endospore and exospore and a central mesospore built up by aromatic compounds. In Spirogyra, the exospore and endospore consist of thick layers of helicoidally arranged cellulose fibrils, which are otherwise only known from stone cells of land plants. While starch is degraded during maturation, providing building blocks for cell wall formation, lipid droplets accumulate and fill large parts of the ripe zygospores, similar to spores and seeds of land plants. Overall, data show similarities between streptophyte algae and embryophytes, suggesting that the genetic toolkit for many land plant traits already existed in their shared algal ancestor. This article is part of the theme issue 'The evolution of plant metabolism'.

Production and technical performance of scrimber composite manufactured from industrial low-value wood for structural applications

Development of scrimber composites and other engineered wood products from low-value wood and wood waste provides an effective opportunity to preserve natural resources, minimize waste, and innovate the production of higher-performance, environment-friendly construction materials. In this study, peeler cores, which are the center of poplar logs remaining after the peeling process in the veneer production, were utilized to develop scrimber composites. This study investigated the effects of different resins, including phenol-formaldehyde (PF) and urea formaldehyde (UF), as well as hydrothermal treatments at various temperatures (60 °C and 130 °C), on the physical and mechanical properties of the scrimber composites. Chemical changes in wood components and morphological changes in wood cell walls resulting from hydrothermal treatment were analyzed using Fourier transform infrared spectroscopy and scanning electron microscopy. To clarify how resin type and hydrothermal treatment affect structural performance, several physical and mechanical properties of scrimber composites, including thickness swelling, water absorption, internal bond strength, bending modulus of elasticity, and modulus of rupture, were measured. The test results revealed that hydrothermally treated wood scrims at 130 °C, when bonded with PF resin, produced scrimber composites with superior structural performance.

Sugar composition of pectin-containing cell wall fractions is altered in ‘Fuji’ apples in response to calcium dips and controlled atmosphere storage

Cell wall changes in untreated and calcium-treated ‘Fuji Kiku-8’ apples harvested at commercial maturity were examined after cold storage during 19 and 31 weeks under either air or ultra-low oxygen atmosphere (ULO), followed by 7 d at 20 ºC to simulate commercial shelf life. Postharvest calcium treatment was applied by immersion in a 2 % (w/v) CaCl2 solution prior to cold storage. Both ULO storage and calcium dips attenuated firmness loss in comparison with untreated fruit stored in air, particularly for the shorter period, in parallel to higher retention of both chelator- and sodium carbonate-soluble fractions. After hydrolysis, the analysis of these fractions revealed higher retention of arabinose and uronic acids in response to ULO storage and calcium treatment. Results indicate that the contents of uronic acids and arabinose in pectin-containing fractions were strongly correlated, suggesting that removal of arabinosyl residues from pectin sidechains be a key event in the process of postharvest pectin solubilization.

Comparative Metabolome and Transcriptome Analysis of Rapeseed (Brassica napus L.) Cotyledons in Response to Cold Stress.

Cold stress affects the seed germination and early growth of winter rapeseed, leading to yield losses. We employed transmission electron microscopy, physiological analyses, metabolome profiling, and transcriptome sequencing to understand the effect of cold stress (0 °C, LW) on the cotyledons of cold-tolerant (GX74) and -sensitive (XY15) rapeseeds. The mesophyll cells in cold-treated XY15 were severely damaged compared to slightly damaged cells in GX74. The fructose, glucose, malondialdehyde, and proline contents increased after cold stress in both genotypes; however, GX74 had significantly higher content than XY15. The pyruvic acid content increased after cold stress in GX74, but decreased in XY15. Metabolome analysis detected 590 compounds, of which 32 and 74 were differentially accumulated in GX74 (CK vs. cold stress) and XY15 (CK vs. cold stressed). Arachidonic acid and magnoflorine were the most up-accumulated metabolites in GX74 subjected to cold stress compared to CK. There were 461 and 1481 differentially expressed genes (DEGs) specific to XY15 and GX74 rapeseeds, respectively. Generally, the commonly expressed genes had higher expressions in GX74 compared to XY15 in CK and cold stress conditions. The expression changes in DEGs related to photosynthesis-antenna proteins, chlorophyll biosynthesis, and sugar biosynthesis-related pathways were consistent with the fructose and glucose levels in cotyledons. Compared to XY15, GX74 showed upregulation of a higher number of genes/transcripts related to arachidonic acid, pyruvic acid, arginine and proline biosynthesis, cell wall changes, reactive oxygen species scavenging, cold-responsive pathways, and phytohormone-related pathways. Taken together, our results provide a detailed overview of the cold stress responses in rapeseed cotyledons.

Study of fungal cell wall evolution through its monosaccharide composition: An insight into fungal species interacting with plants

Every fungal cell is encapsulated in a cell wall, essential for cell viability, morphogenesis, and pathogenesis. Most knowledge of the cell wall composition in fungi has focused on ascomycetes, especially human pathogens, but considerably less is known about early divergent fungal groups, such as species in the Zoopagomycota and Mucoromycota phyla. To shed light on evolutionary changes in the fungal cell wall, we studied the monosaccharide composition of the cell wall of 18 species including early diverging fungi and species in the Basidiomycota and Ascomycota phyla with a focus on those with pathogenic lifestyles and interactions with plants. Our data revealed that chitin is the most characteristic component of the fungal cell wall, and was found to be in a higher proportion in the early divergent groups. The Mucoromycota species possess few glucans, but instead have other monosaccharides such as fucose and glucuronic acid that are almost exclusively found in their cell walls. Additionally, we observed that hexoses (glucose, mannose and galactose) accumulate in much higher proportions in species belonging to Dikarya. Our data demonstrate a clear relationship between phylogenetic position and fungal cell wall carbohydrate composition and lay the foundation for a better understanding of their evolution and their role in plant interactions.

Comparison of the transcriptome, lipidome, and c-di-GMP production between BCGΔBCG1419c and BCG, with Mincle- and Myd88-dependent induction of proinflammatory cytokines in murine macrophages

We have previously reported the transcriptomic and lipidomic profile of the first-generation, hygromycin-resistant (HygR) version of the BCGΔBCG1419c vaccine candidate, under biofilm conditions. We recently constructed and characterized the efficacy, safety, whole genome sequence, and proteomic profile of a second-generation version of BCGΔBCG1419c, a strain lacking the BCG1419c gene and devoid of antibiotic markers. Here, we compared the antibiotic-less BCGΔBCG1419c with BCG. We assessed their colonial and ultrastructural morphology, biofilm, c-di-GMP production in vitro, as well as their transcriptomic and lipidomic profiles, including their capacity to activate macrophages via Mincle and Myd88. Our results show that BCGΔBCG1419c colonial and ultrastructural morphology, c-di-GMP, and biofilm production differed from parental BCG, whereas we found no significant changes in its lipidomic profile either in biofilm or planktonic growth conditions. Transcriptomic profiling suggests changes in BCGΔBCG1419c cell wall and showed reduced transcription of some members of the DosR, MtrA, and ArgR regulons. Finally, induction of TNF-α, IL-6 or G-CSF by bone-marrow derived macrophages infected with either BCGΔBCG1419c or BCG required Mincle and Myd88. Our results confirm that some differences already found to occur in HygR BCGΔBCG1419c compared with BCG are maintained in the antibiotic-less version of this vaccine candidate except changes in production of PDIM. Comparison with previous characterizations conducted by OMICs show that some differences observed in BCGΔBCG1419c compared with BCG are maintained whereas others are dependent on the growth condition employed to culture them.

Homogalacturonan Pectins Tuned as an Effect of Susceptible rbohD, Col-0-Reactions, and Resistance rbohF-, rbohD/F-Reactions to TuMV.

The plant cell wall is an actively reorganized network during plant growth and triggered immunity in response to biotic stress. While the molecular mechanisms managing perception, recognition, and signal transduction in response to pathogens are well studied in the context of damaging intruders, the current understanding of plant cell wall rebuilding and active defense strategies in response to plant virus infections remains poorly characterized. Pectins can act as major elements of the primary cell wall and are dynamic compounds in response to pathogens. Homogalacturonans (HGs), a main component of pectins, have been postulated as defensive molecules in plant-pathogen interactions and linked to resistance responses. This research focused on examining the regulation of selected pectin metabolism components in susceptible (rbohD-, Col-0-TuMV) and resistance (rbohF-, rbohD/F-TuMV) reactions. Regardless of the interaction type, ultrastructural results indicated dynamic cell wall rebuilding. In the susceptible reaction promoted by RbohF, there was upregulation of AtPME3 (pectin methylesterase) but not AtPME17, confirmed by induction of PME3 protein deposition. Moreover, the highest PME activity along with a decrease in cell wall methylesters compared to resistance interactions in rbohD-TuMV were noticed. Consequently, the susceptible reaction of rbohD and Col-0 to TuMV was characterized by a significant domination of low/non-methylesterificated HGs. In contrast, cell wall changes during the resistance response of rbohF and rbohD/F to TuMV were associated with dynamic induction of AtPMEI2, AtPMEI3, AtGAUT1, and AtGAUT7 genes, confirmed by significant induction of PMEI2, PMEI3, and GAUT1 protein deposition. In both resistance reactions, a dynamic decrease in PME activity was documented, which was most intense in rbohD/F-TuMV. This decrease was accompanied by an increase in cell wall methylesters, indicating that the domination of highly methylesterificated HGs was associated with cell wall rebuilding in rbohF and rbohD/F defense responses to TuMV. These findings suggest that selected PME with PMEI enzymes have a diverse impact on the demethylesterification of HGs and metabolism as a result of rboh-TuMV interactions, and are important factors in regulating cell wall changes depending on the type of interaction, especially in resistance responses. Therefore, PMEI2 and PMEI3 could potentially be important signaling resistance factors in the rboh-TuMV pathosystem.

Transcriptomic analysis of a cold‐resistant Nordic microalga: unraveling the mechanisms underlying adaptation to low temperatures

AbstractCold stress imposes a great physiological impact on most photosynthetic organisms. The acclimation to cold is very poorly studied in microalgae, even though understanding the molecular mechanisms underlying their cold tolerance has implications for biotechnological applications, such as the development of cold‐tolerant strains for industrial purposes. Scenedesmus sp. B2‐2 is a Nordic strain of green freshwater microalgae that thrives in cold conditions. Here, we analyzed transcriptomic changes of B2‐2 when exposed to the cold (5°C) and compared it to a control grown at 25°C. The aim was to understand more about the mechanisms underlying B2‐2's adaptation to low temperatures. We studied differentially expressed genes (DEGs) related to lipid synthesis, carbon metabolism and photosynthesis. Scenedesmus sp. B2‐2 produced more lipids when exposed to cold conditions and did not reduce its carbon metabolism or photosynthetic processes. 24 putative cold‐responsive genes were found to be non‐responsive in Scenedesmus sp. B2‐2 when grown at 5°C. These genes could serve as targets for genetic engineering to enhance cold tolerance in algal strains used in biotechnology. We also studied B2‐2´s cell wall changes in response to cold by measuring cell wall thickness at 1, 4, 12, 24, 48, 72, 120 and 240 hours of cold exposure and correlating the results to the transcriptomic data. The results show that the cell wall thickens with increased duration of cold exposure. Several glycosyltransferases were found to be significantly up‐regulated throughout cold exposure and may play a role in cell wall thickening.

Structural and chemical changes in hardwood cell walls during early stages of flash pyrolysis

Structural and chemical changes in hardwood cell walls during early stages of flash pyrolysis

Gapless Genome Assembly of ZH8015 and Preliminary Multi-Omics Analysis to Investigate ZH8015’s Responses Against Brown Planthopper Infestation

Accurate genomic information is essential for advancing genetic breeding research in specific rice varieties. This study presented a gapless genome assembly of the indica rice cultivar Zhonghui 8015 (ZH8015) using PacBio HiFi, Hi-C, and ONT (Oxford Nanopore Technologies) ultra-long sequencing technologies, annotating 43 037 gene structures. Subsequently, utilizing this genome along with transcriptomic and metabolomic techniques, we explored ZH8015’s response to brown planthopper (BPH) infestation. Continuous transcriptomic sampling indicated significant changes in gene expression levels around 48 h after BPH feeding. Enrichment analysis revealed particularly significant alterations in genes related to reactive oxygen species scavenging and cell wall formation. Metabolomic results demonstrated marked increases in levels of several monosaccharides, which are components of the cell wall and dramatic changes in flavonoid contents. Omics association analysis identified differentially expressed genes associated with key metabolites, shedding light on ZH8015’s response to BPH infestation. In summary, this study constructed a reliable genome sequence resource for ZH8015, and the preliminary multi-omics results will guide future insect-resistant breeding research.

Diverging cell wall strategies for drought adaptation in two maize inbreds with contrasting lodging resistance.

The plant cell wall is a plastic structure of variable composition that constitutes the first line of defence against environmental challenges. Lodging and drought are two stressful conditions that severely impact maize yield. In a previous work, we characterised the cell walls of two maize inbreds, EA2024 (susceptible) and B73 (resistant) to stalk lodging. Here, we show that drought induces distinct phenotypical, physiological, cell wall, and transcriptional changes in the two inbreds, with B73 exhibiting lower tolerance to this stress than EA2024. In control conditions, EA2024 stalks had higher levels of cellulose, uronic acids and p-coumarate than B73. However, upon drought EA2024 displayed increased levels of arabinose-enriched polymers, such as pectin-arabinans and arabinogalactan proteins, and a decreased lignin content. By contrast, B73 displayed a deeper rearrangement of cell walls upon drought, including modifications in lignin composition (increased S subunits and S/G ratio; decreased H subunits) and an increase of uronic acids. Drought induced more substantial changes in gene expression in B73 compared to EA2024, particularly in cell wall-related genes, that were modulated in an inbred-specific manner. Transcription factor enrichment assays unveiled inbred-specific regulatory networks coordinating cell wall genes expression. Altogether, these findings reveal that B73 and EA2024 inbreds, with opposite stalk-lodging phenotypes, undertake different cell wall modification strategies in response to drought. We propose that the specific cell wall composition conferring lodging resistance to B73, compromises its cell wall plasticity, and renders this inbred more susceptible to drought.

The legacy of terrestrial plant evolution on cell wall fine structure.

The evolution of land flora was an epochal event in the history of planet Earth. The success of plants, and especially flowering plants, in colonizing all but the most hostile environments required multiple mechanisms of adaptation. The mainly polysaccharide-based cell walls of flowering plants, which are indispensable for water transport and structural support, are one of the most important adaptations to life on land. Thus, development of vasculature is regarded as a seminal event in cell wall evolution, but the impact of further refinements and diversification of cell wall compositions and architectures on radiation of flowering plant families is less well understood. We approached this from a glyco-profiling perspective and, using carbohydrate microarrays and monoclonal antibodies, studied the cell walls of 287 plant species selected to represent important evolutionary dichotomies and adaptation to a variety of habitats. The results support the conclusion that radiation of flowering plant families was indeed accompanied by changes in cell wall fine structure and that these changes can obscure earlier evolutionary events. Convergent cell wall adaptations identified by our analyses do not appear to be associated with plants with similar lifestyles but that are taxonomically distantly related. We conclude that cell wall structure is linked to phylogeny more strongly than to habitat or lifestyle and propose that there are many approaches of adaptation to any given ecological niche.

Analysis of phenotypic changes in high temperature and low pH extreme conditions of Alicyclobacillus sendaiensis PA2 related with the cell wall and sporulation genes.

The A. sendaiensis PA2 is a polyextremophile bacterium. In this study, we analyze the A. sendaiensis PA2 genome. The genome was assembled and annotated. The A. sendaiensis PA2 genome structure consists of a 2,956,928bp long chromosome and 62.77% of G + C content. 3056 CDSs were predicted, and 2921 genes were assigned to a putative function. The ANIm and ANIb value resulted in 97.17% and 96.65%, the DDH value was 75.5%, and the value of TETRA (Z-score) was 0.98. Comparative genomic analyses indicated that three systems are enriched in A. sendaiensis PA2. This strain has phenotypic changes in cell wall during batch culture at 65°C, pH 5.0 and without carbon and nitrogen source. The presence of unique genes of cell wall and sporulation subsystem could be related to the adaptation of A. sendaiensis PA2 to hostile conditions.

Physiological, transcriptome and metabolome analyses provide molecular insights to seasonal development in Ginkgo biloba xylem

Ginkgo biloba’s wood has high economic value; however, little is known about the molecular response of its xylem seasonal development. Based on physiological change in secondary cell wall (SCW) components, non-structural carbohydrates (NC), and endogenous phytohormones (EP) concentrations during development seasons, we performed transcriptome and metabolome sequencing on current- and second-year xylem to explore the molecular physiological responses of Ginkgo developing xylem induced by seasonal effects. Results revealed that SCW component, NC, and EP showed distinct seasonal patterns in concentration change. The expression profiles of corresponding differentially expressed genes (DEGs) and differentially abundant metabolites (DAMs) in phenylpropanoid (monolignol) biosynthesis (14 DEGs), plant hormone biosynthesis (10 DAMs), signaling (37 DEGs) and carbohydrate metabolism (37 DEGs and 8 DAMs) were revealed. Most of these DEGs were up-regulated in spring (May) to summer (July), while down-regulated in winter (December). Trend cluster showed that 15 DEGs in brassinolide (BR) biosynthesis and signaling, jasmonic acid (JA), and auxin (IAA) signaling were clustered into top 2 profiles with most DEGs in lignin biosynthesis. Correlation analysis indicated that BR concentration was negatively related with lignin content, while positively associated with 8 DEGs in lignin biosynthesis, suggesting that BR had a potential to coordinate lignin deposition. Additionally, the expression levels of DEGs in (abscisic acid) ABA signaling had positive association with those of DEGs related starch and sucrose biosynthesis, while had inverse correlation with DEGs related glucose and galactose biosynthesis. Also, ABA concentration was positively correlated with NC content, implying the dominant role of ABA in seasonal carbohydrate metabolism, conjoint analysis of DEGs and DAMs also supported this finding. Our study provided a new foundation for endogenous hormone-mediated seasonal development of xylem.

Helium Cold Atmospheric Plasma Causes Morphological and Biochemical Alterations in Candida albicans Cells

(1) Background: Previous studies reported the promising inhibitory effect of cold atmospheric plasma (CAP) on Candida albicans. However, the exact mechanisms of CAP’s action on the fungal cell are still poorly understood. This study aims to elucidate the CAP effect on C. albicans cell wall, by evaluating the alterations on its structure and biochemical composition; (2) Methods: C. albicans cells treated with Helium-CAP were analyzed by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) in order to detect morphological, topographic and biochemical changes in the fungal cell wall. Cells treated with caspofungin were also analyzed for comparative purposes; (3) Results: Expressive morphological and topographic changes, such as increased roughness and shape modification, were observed in the cells after CAP exposure. The alterations detected were similar to those observed after the treatment with caspofungin. The main biochemical changes occurred in polysaccharides content, and an overall decrease in glucans and an increase in chitin synthesis were detected; (4) Conclusions: Helium-CAP caused morphological and topographic alterations in C. albicans cells and affected the cell wall polysaccharide content.

Improving enzyme accessibility in the aqueous enzymatic extraction process by microwave-induced porous cell walls to increase oil body and protein yields

Aqueous enzymatic extraction (AEE) is a green and sustainable extraction method. However, the intact cell wall hinders the accessibility of enzymes, severely limiting the efficiency and application of the AEE method. In this study, microwave-assisted aqueous enzymatic extraction (MAAEE) was used to degrade the peanut cell wall and improve the yield of oil and protein. Transmission electron microscopy, scanning electron microscopy, BET-specific surface area, Fourier transform infrared spectroscopy, X-ray diffraction, and chemical composition analysis were used to characterize the structure and chemical changes of the peanut cell wall. The results showed that microwave treatment could break the structure of the peanut cell wall, increase the porosity of raw materials, accelerate the efficiency of enzymatic hydrolysis, and promote the extraction of oil and protein. Compared with raw peanut powder (MC-0), microwaved peanut powder (MC-4) had a higher oil body yield (>44%) and protein release rate (>76%). At the microscopic level, cell wall rupture, oil accumulation, and cell contents scattered outside the cell were observed. The mean pore size, pore volume, and specific surface area increased by 54.1%, 149.4%, and 63.5%, respectively, while the crystallinity decreased by 4.4%. The content of hemicellulose and CDTA-soluble pectin (CSP) decreased by 18.6% and 32.9%, respectively. The degradation rates of cellulase and pectinase on cell wall components were significantly increased by 8.5%–43.2% (p < 0.05). In summary, microwave-induced porous cell walls could significantly improve enzyme accessibility, accelerate enzymatic hydrolysis efficiency, and promote oil and protein extraction.

Dissecting the Role of Cell Wall Changes in Chilling Injury-Induced Gel Formation, Rubberiness, and Mealiness in Apricots

In apricots and other stonefruit, chilling injury (CI) symptoms like mealiness, rubberiness, and gel formation are associated with cell wall properties. Apricots were stored at 0 °C for 5 weeks and ripened at 20 °C to induce CI and compared with fruit ripened at 20 °C from harvest at similar firmness. In those apricots without CI, degradation of middle-lamella pectin during softening weakened cell-cell adhesion and intercellular junctions. Pectin was still present in middle lamella regions but pectin that filled the intercellular spaces at harvest had disappeared. Fruit with combinations of CI symptoms showed different pectin solubilities, molecular weight distribution, and differences in pectin staining compared with fruit that were severely chilling-injured, exhibiting all symptoms. The perception of mealiness correlated with the presence of pectin in the cell lumen, and rubberiness with the presence of pectin in tricellular corners. We concluded that in chilling-injured apricots, the normal softening process is not being resumed after fruit have been taken out of cold storage. Cell wall degradation is disrupted, affecting the normal weakening of cell walls during softening. Hence, cell walls were less likely to break open during chewing, and when cells did break, any juice released might be bound by pectin present in the cell walls and cell lumen, leaving a sensation of rubberiness and mealiness.

Ex-chitin-g news on drug-induced fungal epitope unmasking.

The microbial cell wall is an essential cellular organelle commonly targeted by antimicrobials. It is also a battleground of innate immune recognition where microbes can evade immune recognition by masking essential cell wall components. A recent study (A. S. Wagner, S. W. Lumsdaine, M. M. Mangrum, and T. B. Reynolds, mBio https://doi.org/10.1128/mbio.00074-23, 2023) provides insight into how echinocandin antifungals cause exposure of proinflammatory β(1,3)-glucan by driving excess chitin production in the weakened cell wall. Although many environmental and biological activities perturb cell wall integrity and regulate β(1,3)-glucan exposure, we still know little about which intracellular signaling components regulate the cell wall changes that result in disrupted cell wall architecture. Wagner et al. showed that calcineurin and the Mkc1p kinase regulate chitin deposition and β(1,3)-glucan unmasking. They further identified chitin synthesis as a key driving force in cell wall structure disruption leading to epitope exposure. Their findings highlight how fungal cell wall dynamics have important implications for antifungal immunity and future drug development.

Investigation of cell damage of periodontopathic bacteria exposed to silver, zirconium oxide, and silicon oxide nanoparticles as antibacterial agents

AbstractAntibiotic resistance is one of the biggest public health problems of our time. The nanoparticles are a powerful alternative to these antibiotics. Engineered nanoparticles show toxic effects on bacteria by different mechanisms. The bacteria–cell interaction of engineered nanoparticles exerts their toxic effects through changes in cell wall, cell membrane, and cytoplasm content/density. Thus, death occurs as a result of cell deformation. In this study, the cellular damage of silver nanoparticles, which are known to have strong antibacterial properties, and zirconium oxide and silicon oxide engineering nanoparticles, which are less known, on periodontopathic (Prevotella intermedia and Aggregatibacter actinomycetemcomitans) bacteria, were investigated by ultrastructural changes. The lysis of the cytoplasm and separation of the membrane cytoplasm were observed. Both types of bacteria treated with Ag ENP show more hollow cytoplasm than bacteria treated with the other two nanoparticles.