Confocal Laser Scanning Microscopy Observation Research Articles

From Antagonism to Enhancement: Triton X-100 Surfactant Affects Phenanthrene Interfacial Biodegradation by Mycobacteria through a Shift in Uptake Mechanisms.

Polycyclic aromatic hydrocarbons (PAHs), as persistent environmental pollutants, often reside in nonaqueous-phase liquids (NAPLs). Mycobacterium sp. WY10, boasting highly hydrophobic surfaces, can adsorb to the oil-water interface, stabilizing the Pickering emulsion and directly accessing PAHs for biodegradation. We investigated the impact of Triton X-100 (TX100) on this interfacial uptake of phenanthrene (PHE) by Mycobacteria, using n-tetradecane (TET) and bis-(2-ethylhexyl) phthalate (DEHP) as NAPLs. Interfacial tension, phase behavior, and emulsion stability studies, alongside confocal laser scanning microscopy and electron microscope observations, unveiled the intricate interplay. In surfactant-free systems, Mycobacteria formed stable W/O Pickering emulsions, directly degrading PHE within the NAPLs because of their intimate contact. Introducing low-dose TX100 disrupted this relationship. Preferentially binding to the cells, the surfactant drastically increased the cell hydrophobicity, triggering desorption from the interface and phase separation. Consequently, PAH degradation plummeted due to hindered NAPL access. Higher TX100 concentrations flipped the script, creating surfactant-stabilized O/W emulsions devoid of interfacial cells. Surprisingly, PAH degradation remained efficient. This paradox can be attributed to NAPL emulsification, driven by the surfactant, which enhanced mass transfer and brought the substrate closer to the cells, despite their absence at the interface. This study sheds light on the complex effect of surfactants on Mycobacteria and PAH uptake, revealing an antagonistic effect at low concentrations that ultimately leads to enhanced degradation through emulsification at higher doses. These findings offer valuable insights into optimizing bioremediation strategies in PAH-contaminated environments.

Reactive oxygen species-sensitive chondroitin sulfate A-cholesteryl hemisuccinate micelles for targeted doxorubicin delivery in tumor therapy

The efficient drug release triggered by the tumor microenvironment is challenging in the development of stimuli-sensitive nanomedicine. In this study, we developed novel polymeric micelles sensitive to reactive oxygen species (ROS) for targeted delivery of doxorubicin (DOX) in tumor therapy. Hydrophilic chondroitin sulfate A (CSA) was conjugated with cholesteryl hemisuccinate (CHS) via a ROS-cleavable thioketal (TK) bond. The resulting CSA-TK-CHS could form self-assembled micelles, and DOX-loaded CSA-TK-CHS (CSA-TK-CHS/DOX) micelles displayed a nearly spherical shape with an average hydrodynamic diameter of 324 nm. The bioresponsive DOX release of CSA-TK-CHS/DOX micelles was evaluated in an H2O2-containing phosphate buffer solution (PBS). CSA-TK-CHS/DOX micelles showed higher cellular uptake than free DOX in 4T1 cells by confocal laser scanning microscopy (CLSM) observation. And CSA-TK-CHS/DOX improved DOX cytotoxicity against CD44-overexpressed 4T1 and CT26 tumor cells. Notably, CSA-TK-CHS/DOX micelles displayed significantly stronger potency (P < 0.01) in antitumor activity than DOX·HCl in orthotropic 4T1-bearing Balb/c mice. Overall, these findings indicate that amphiphilic CSA-TK-CHS micelles are a promising targeted and intelligent drug carrier for tumor therapy.

Cell density and extracellular matrix composition mitigate bacterial biofilm sensitivity to UV-C LED irradiation

Ultraviolet-C light-emitting diodes (UV-C LEDs) are an emerging technology for decontamination applications in different sectors. In this study, the inactivation of bacterial biofilms was investigated by applying an UV-C LED emitting at 280 nm and by measuring both the influence of the initial cell density (load) and presence of an extracellular matrix (biofilm). Two bacterial strains exposing diverging matrix structures and biochemical compositions were used: Pseudomonas aeruginosa and Leuconostoc citreum. UV-C LED irradiation was applied at three UV doses (171 to 684 mJ/cm2) on both surface-spread cells and on 24-h biofilms and under controlled cell loads, and bacterial survival was determined. All surface-spread bacteria, between 105 and 109 CFU/cm2, and biofilms at 108 CFU/cm2 showed that bacterial response to irradiation was dose-dependent. The treatment efficacy decreased significantly for L. citreum surface-spread cells when the initial cell load was high, while no load effect was observed for P. aeruginosa. Inactivation was also reduced when bacteria were grown under a biofilm form, especially for P. aeruginosa: a protective effect could be attributed to abundant extracellular DNA and proteins in the matrix of P. aeruginosa biofilms, as revealed by Confocal Laser Scanning Microscopy observations. This study showed that initial cell load and exopolymeric substances are major factors influencing UV-C LED antibiofilm treatment efficacy.Key points• Bacterial cell load (CFU/cm2) could impact UV-C LED irradiation efficiency• Characteristics of the biofilm matrix have a paramount importance on inactivation• The dose to be applied can be predicted based on biofilm propertiesGraphical

Physicochemical and foam properties of ovalbumin-carboxymethylcellulose mixtures after mild heat treatment: Comparison of electrostatic repulsion and attraction

The effects of electrostatic repulsion (pH6.5) and attraction (pH4.6) between biopolymers on the physicochemical and foam properties of ovalbumin (OVA)/carboxymethylcellulose (CMC) mixtures subjected to mild heat treatment (60–75 °C) were comparatively investigated. It was found that electrostatic binding between OVA and CMC at pH 4.6 resulted in an increase in the peak temperature of thermal denaturation (Td) of OVA from 71.3 °C to 74.4 °C, while no significant effect was observed at pH 6.5. Thus, 60 and 65 °C below Td were chosen to further investigate the effects of heating on the degree of thermal aggregation, protein conformation and foam properties of OVA/CMC mixtures. Confocal laser scanning microscopy observations and rheological results indicated that electrostatic binding between OVA and CMC at pH 4.6 significantly reduced the degree of protein thermal aggregation, while on the contrary, electrostatic repulsion between proteins and polysaccharides at pH 6.5 promoted OVA thermal aggregation. Raman spectroscopic characterisation indicated that mild heat treatment mainly led to a change in the microenvironment polarity of OVA tyrosine and tryptophan residues, as well as an increase in the content of random coil in the amide III band irrespective of pH. Moreover, after heating at 65 °C for 20 min, The foaming ability of the OVA/CMC mixtures at pH 6.5 and 4.6 increased by approximately 32% and 36% respectively compared to pure OVA. These findings have a positive value for enhancing the heat sterilisation strength of egg white proteins.

Antilisterial Effectiveness of Origanum vulgare var. hirtum and Coridothymus capitatus Essential Oils and Hydrolates Alone and in Combination.

The antimicrobial activity of Origanum vulgare var. hirtum (O) and Coridothymus capitatus (C) essential oils (EOs) and hydrolates (HYs) of the same botanical species was evaluated on sixteen L. monocytogenes strains from food and clinical origins. The antimicrobial activity was assessed by Minimum Inhibitory Concentration (MIC) determination, viable cell enumeration over time up to 60 min, and evaluation of the cellular damage through Confocal Laser Scanning Microscope (CLSM) analysis. EOs exhibited antimicrobial activity with MIC values ranging from 0.3125 to 10 µL/mL. In contrast, HYs demonstrated antimicrobial effectiveness at higher concentrations (125-500 µL/mL). The effect of HYs was rapid after the contact with the cells, and the cell count reduction over 60 min of HY treatment was about 1.2-1.7 Log CFU/mL. L. monocytogenes cells were stressed by HY treatment, and red cell aggregates were revealed through CLSM observation. Moreover, the combinations of EOs and HYs had an additive antilisterial effect in most cases and allowed the concentration of use to be reduced, while maintaining or improving the antimicrobial effectiveness. The combined use of EOs and HYs can offer novel opportunities for applications, thereby enhancing the antimicrobial effectiveness and diminishing the concentration of use. This provides the added benefit of reducing toxicity and mitigating any undesirable sensory effects.

Polyhexamethylene biguanide promotes adaptive cross-resistance to gentamicin in Escherichia coli biofilms.

Antimicrobial resistance is a critical public health issue that requires a thorough understanding of the factors that influence the selection and spread of antibiotic-resistant bacteria. Biocides, which are widely used in cleaning and disinfection procedures in a variety of settings, may contribute to this resistance by inducing similar defense mechanisms in bacteria against both biocides and antibiotics. However, the strategies used by bacteria to adapt and develop cross-resistance remain poorly understood, particularly within biofilms -a widespread bacterial habitat that significantly influences bacterial tolerance and adaptive strategies. Using a combination of adaptive laboratory evolution experiments, genomic and RT-qPCR analyses, and biofilm structural characterization using confocal microscopy, we investigated in this study how Escherichia coli biofilms adapted after 28 days of exposure to three biocidal active substances and the effects on cross-resistance to antibiotics. Interestingly, polyhexamethylene biguanide (PHMB) exposure led to an increase of gentamicin resistance (GenR) phenotypes in biofilms formed by most of the seven E. coli strains tested. Nevertheless, most variants that emerged under biocidal conditions did not retain the GenR phenotype after removal of antimicrobial stress, suggesting a transient adaptation (adaptive resistance). The whole genome sequencing of variants with stable GenR phenotypes revealed recurrent mutations in genes associated with cellular respiration, including cytochrome oxidase (cydA, cyoC) and ATP synthase (atpG). RT-qPCR analysis revealed an induction of gene expression associated with biofilm matrix production (especially curli synthesis), stress responses, active and passive transport and cell respiration during PHMB exposure, providing insight into potential physiological responses associated with adaptive crossresistance. In addition, confocal laser scanning microscopy (CLSM) observations demonstrated a global effect of PHMB on biofilm architectures and compositions formed by most E. coli strains, with the appearance of dense cellular clusters after a 24h-exposure. In conclusion, our results showed that the PHMB exposure stimulated the emergence of an adaptive cross-resistance to gentamicin in biofilms, likely induced through the activation of physiological responses and biofilm structural modulations altering gradients and microenvironmental conditions in the biological edifice.

Antibiofouling polyethersulfone ultrafiltration membranes functionalized with MoS2 nanosheets and self-cleaning with hydrogen peroxide

The development of biofouling mitigation and cleaning strategy is of paramount importance for ultrafiltration (UF) membrane biofouling. In this study, polyethersulfone (PES) UF membrane was functionalized, namely MoS2/PES composite membrane. The MoS2/PES composite membrane exhibited superior antifouling property as evidenced by antibacterial circle, static and dynamic biofouling experiments. The permeate fluxes of the pristine PES and MoS2/PES composite membrane respectively decreased by 76% and 31% at the end of 3-h filtration. After exposure of E. coli to MoS2, inhibited cell growth led to reduced membrane biofouling. The biofilm formation was retarded under the dynamic flow condition, which were further confirmed by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) observations. As for the enhanced biofouling removal by cleaning with H2O2, 62% of the flux recovery rate for the MoS2/PES composite membrane was much higher than the pristine PES membrane (24%). The peroxidase-like properties of MoS2 were responsible for the enhancement of the superior cleaning performance. The use of H2O2 to trigger the in-situ catalytic function of the MoS2 nano-enzyme generated more ROS and O2 for inducing bacterial cells death and facilitating detachment of biofilm. This work will be helpful to provide important insights into developing more effective strategies for biofouling control and cleaning using advanced nanomaterials in membrane-based water treatment processes.

Effect of roasting and high-pressure homogenization on texture, rheology, and microstructure of walnut yogurt

The effect of roasting and high-pressure homogenization on the quality of yogurt made from peeled walnut kernels was explored in this study. The G' and G'' values of yogurt made from walnuts roasted at high temperatures were reduced. The water-holding capacity and hardness of walnut yogurt were reduced to 47.73% and 24.22 g, respectively. Increasing the homogenization pressure reduced the particle size of the walnut yogurt to 20.50 μm. Homogenized walnut milk at 150 MPa increased the viscosity, hardness, and consistency of yogurt product from 11.71 to 16.74 Pa.s, from 30.01 to 71.63 g and from 283.17 to 455.24 g·s, respectively. The confocal laser scanning microscope observation demonstrated a reduction in the size of fat and protein micelles in the homogenized yogurt samples, resulting in a compact structure. This study will contribute valuable scientific insights to the advancement of plant-based yogurt quality.

Some Considerations on Austenite Grain Growth Kinetics from High‐Temperature Laser Scanning Confocal Microscopy Observations

For more than 20 years, high‐temperature laser scanning confocal microscopy (HT‐LSCM) has become worldwide a proven technique for observing various metallurgical phenomena in situ. HT‐LSCM turns out to be a reliable and effective method for the observation of quantification austenite grain growth kinetics in steel, being highly relevant in casting and steel processing. In the present article, the measurement technique is briefly introduced followed by some basics on austenite grain growth. Finally, selected examples of recent research activities are discussed, including investigations into pure iron and the systems Fe–P, Fe–C, Fe–Al–N, and Fe–C–Nb–N. The influence of P on the grain growth kinetics is remarkable. At 1350 °C, the final grain size decreases from 255 μm in pure iron to 145 μm by adding 0.044 wt% P. In contrast, C enhances the grain growth in specific alloying ranges (0–0.30 wt%C), particularly at elevated temperatures. For a Al content of 0.025 wt% and only 50 wt ppm N, AlN loses the pinning effect above 1150 °C. In case of Nb(C,N), an elevated Nb content (0.085 wt%) provides stabilization of Nb(C,N) at 1150 °C, but at 1250 °C, no pinning of Nb(C,N) is visible anymore.

The seven rice vacuolar sorting receptors localize to prevacuolar compartments

Vacuolar sorting is critically important in plants as it regulates the mobilization of proteins and plays a major role in important agricultural traits like yield and seed protein content. Vacuolar sorting receptors (VSRs) are integral membrane proteins that mediate protein trafficking from the Golgi apparatus to the vacuole via the intermediate membrane-bound prevacuolar compartment (PVC)/multivesicular body (MVB). VSR proteins, such as an 80 kD (BP-80) from pea, also serve as markers for PVC/MVB. Dissecting VSR-mediated protein trafficking pathways may provide ways to enhance agronomic traits and crop yield. Green fluorescence protein (GFP) fusions with the seven Arabidopsis (Arabidopsis thaliana) VSRs were previously shown to localize to PVCs in transgenic tobacco BY-2 cells. The Rice (Oryza sativa) genome contains seven VSRs (OsVSR1-7), but little is known about their subcellular localizations. Here we studied the subcellular localization of OsVSR1-7 b y using a reporter approach, in which GFP-OsVSR1-7 fusions containing the transmembrane domain (TMD) and cytoplasmic tail (CT) of individual OsVSR were expressed in the protoplasts of rice, transgenic tobacco BY-2 cells and transgenic rice plants. Immunofluorescent labelling studies and confocal laser scanning microscope observation demonstrated that the seven OsVSRs are localized to PVCs and form ring-like structures upon wortmannin treatment. Therefore, we have verified the subcellular localization of OsVSR1-7 in this study. The OsVSRs tagged with GFP can serve as PVCs/MVBs markers in rice for the future studies.

Systemic resistance induced by plant growth-promoting rhizobacteria in Bhut Jolokia (Capsicum chinense Jacq.) suppressed the collar rot disease

Collar rot disease caused by Rhizoctonia solani is a major constraint to the commercial cultivation of Bhut Jolokia (Capsicum chinense Jacq.) in North-East India. However, the management of the disease is not addressed comprehensively in this plant. Some plant growth-promoting rhizobacteria (PGPR) could control plant diseases by triggering induction of resistance systemically, and emerge as a highly promising approach to reduce the use of chemical fungicides. Therefore, five selected PGPRs were tested for plant growth promotion and induced systemic resistance (ISR) for controlling the disease. Induced systemic resistance was determined in vivo condition. Confocal laser scanning microscopic observation was done to see any harmful effects on cells in the induced plant. The PGPRs could significantly improve plant growth as well as suppress the disease and boost defense-related enzymes activity in the induced plants. Bacillus megaterium JPR68 triggered the maximum ISR in the plant. Expression of the defense-related genes was analyzed which were highly expressed in ISR plants. Microscopic observation revealed that no internal changes occurred in PGPR treated plant cells similar to the untreated plant, and indicated no harmful effect of the bacteria in the host cell. The study demonstrates the possible application of B. megaterium JPR68 as a biocontrol agent for sustainable management of the disease. To our knowledge, this is the first report of ISR against any fungal disease in Bhut Jolokia.

Effect of Pretreatments on Releasing of Bound Phenolics from Dried Bamboo Shoots during Simulated In Vitro Colonic Fermentation

Salt-dried bamboo shoots (SDBS), steamed dried bamboo shoots (TDBS), fumigation-dried bamboo shoots (UDBS), and fermentation-dried bamboo shoots (FDBS) are four popular types of dried bamboo shoots (DBS) enjoyed by Chinese people. In this work, we aimed at investigating the release pattern of bound phenolics from DBS prepared by different processes on simulated in vitro colonic fermentation. The results showed that nine phenolic compounds were identified from DBS, including seven phenolic acids and two flavonoids. Also, the contents of chlorogenic acid, p-coumaric acid, and ferulic acid were higher. Among the four types of DBS, FDBS exhibited the highest release of bound phenolics during colonic fermentation, with a value of 3.619 mg GAE/g DW. In addition, all the DBS produced four short-chain fatty acids (SCFAs), with the highest content of acetic acid at 7.721 mmol/L, followed by propionic acid and valeric acid, and the lowest content of butyric acid at only 0.023 mmol/L, along with a gradual decrease in their cellulose, hemicellulose, and lignin contents. Concurrently, confocal laser scanning microscopy (CLSM) observation images showed that reduced red fluorescence exhibited a decrease in bound phenolics content, while reduced green fluorescence indicated a decrease in fiber content. A significant positive correlation ( P &lt; 0.05) was observed between the release of bound phenolics and total SCFA production during colonic fermentation of SDBS, TDBS, UDBS, and FDBS, with correlation coefficients of 0.632, 0.844, 0.717, and 0.916, respectively, and a significant negative correlation ( P &lt; 0.05) with the IC50 values for the inhibition of α-amylase and α-glucosidase, with correlation coefficients of −0.643, −0.613, −0.823, and −0.839, respectively. The four DBS were ranked in descending order of bound phenolic release, SCFA production, dietary fiber reduction, and inhibitory activity associated with the metabolic syndrome: FDBS, TDBS, SDBS, and UDBS. DBS released large amounts of bound phenolics and produced SCFAs during colonic fermentation, which might be potentially beneficial for maintaining intestinal microbiota balance.

Enhanced Removal of Photoresist Films through Swelling and Dewetting Using Pluronic Surfactants.

Organic photoresist coatings, primarily composed of resins, are commonly used in the electronics industry to protect inorganic underlayers. Conventional photoresist strippers, such as amine-type agents, have shown high removal performance but led to environmental impact and substrate corrosiveness. Therefore, this trade-off must be addressed. In this study, we characterized the removal mechanism of a photoresist film using a nonionic triblock Pluronic surfactant [poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)] in a ternary mixture of ethylene carbonate (EC), propylene carbonate (PC), and water. In particular, the removal dynamics determined by using a quartz crystal microbalance with dissipation monitoring was compared with those determined by performing confocal laser scanning microscopy and visual observation to analyze the morphology, adsorption mass, and viscoelasticity of the photoresist film. In the absence of the Pluronic surfactant, the photoresist film in the ternary solvent exhibited a three-step process: (i) film swelling caused by the penetration of a good solvent (EC and PC), (ii) formation of photoresist particles through dewetting, and (iii) particle aggregation on the substrate. This result was correlated to the Hansen solubility parameters. The addition of the Pluronic surfactant not only prevented photoresist aggregation in the third step but also promoted desorption from the substrate. This effect was dependent on the concentration of the Pluronic surfactant, which influenced diffusion to the interface between the photoresist and the bulk solution. Finally, we proposed a novel photoresist stripping mechanism based on the synergy between dewetting driven by an EC/PC-to-water mixture and adsorption by the Pluronic surfactant.

Optimization of Antibacterial Activity and Biosafety through Ultrashort Peptide/Cyclodextrin Inclusion Complexes.

Engineered ultrashort peptides, serving as an alternative to natural antimicrobial peptides, offer benefits of simple and modifiable structures, as well as ease of assembly. Achieving excellent antibacterial performance and favorable biocompatibility through structural optimization remains essential for further applications. In this study, we assembled lipoic acid (LA)-modified tripeptide RWR (LA-RWR) with β-cyclodextrin (β-CD) to form nano-inclusion complexes. The free cationic tripeptide region in the nano-inclusion complex provided high antibacterial activity, while β-CD enhanced its biocompatibility. Compared with peptides (LA-RWR, LA-RWR-phenethylamine) alone, inclusion complexes exhibited lower minimum inhibitory concentrations/minimum bactericidal concentrations (MICs/MBCs) against typical Gram-negative/Gram-positive bacteria and fungi, along with improved planktonic killing kinetics and antibiofilm efficiency. The antibacterial mechanism of the nano-inclusion complexes was confirmed through depolarization experiments, outer membrane permeability experiments, and confocal laser scanning microscopy observations. Furthermore, biological evaluations indicated that the hemolysis rate of the inclusion complexes decreased to half or even lower at high concentrations, and cell viability was superior to that of the non-included peptides. Preliminary in vivo studies suggested that the inclusion complexes, optimized for antibacterial activity and biosafety, could be used as promising antibacterial agents for potential applications.

Self‐Adaptive MoO3−x Subnanometric Wires Incorporated Scaffolds for Osteosarcoma Therapy and Bone Regeneration

AbstractResidual tumor cells and bone tissue defects are two critical challenges in clinical osteosarcoma treatment. Herein, a subnanomedicine concept is proposed by developing a self‐adaptive functional tissue engineering scaffold constructed by integrating MoO3−x subnanometric wires onto 3D printing bioactive glass scaffolds. The MoO3−x subnanometric wires are synthesized by a one‐pot hydrothermal method, which aggregate in an acidic tumor microenvironment and react with hydrogen peroxide to produce reactive oxygen species for specific chemodynamic therapy. However, they can degrade rapidly under physiological conditions without causing toxicity. Moreover, self‐adaptively enhanced photothermal conversion enables tumor‐targeting photothermal therapy while enhancing chemodynamic therapy. Additionally, the Mo5+‐Mo6+ transition enables lipid peroxide accumulation and glutathione depletion, thereby resulting in the deactivation of glutathione peroxidase 4 protein and ferroptosis through Western blot analysis, confocal laser scanning microscopy observation, and mRNA transcriptome analysis. In addition to its robustness against osteosarcoma, the constructed scaffolds can stimulate rat bone mesenchymal stem cell differentiation and proliferation as well as promote osteogenesis in bone defects. Therefore, this multifunctional scaffold not only validates the subnanomedicine concept but also provides a promising clinical strategy for bone tissue engineering.

Immunomodulatory mechanisms of an acidic polysaccharide from the fermented burdock residue by Rhizopus nigricans in RAW264.7 cells and cyclophosphamide-induced immunosuppressive mice

RBAPS is an acidic polysaccharide extracted from the burdock residue fermentation by Rhizopus nigricans. In RBAPS-activated RAW264.7 cells, transcriptome analysis identified a total of 1520 differentially expressed genes (DEGs), including 1223 down-regulated genes and 297 up-regulated genes. DEGs were enriched in the immune-related biological processes, involving in Mitogen-activated protein kinase (MAPK) and Toll-like receptor (TLR) signaling pathway, according to Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. The results of the confocal laser scanning microscope (CLSM) observation, antibody neutralization and Western blot verified that RBAPS modulated macrophages activation and cytokines secretion mainly via TLR4/MAPK/NF-κB signaling pathway. The immunomodulatory activity in vivo of RBAPS was investigated in cyclophosphamide (CTX)-induced immunosuppressive mice. RBAPS promoted the counts of white blood cells (WBC), red blood cells (RBC) and platelets (PLT) as well as the levels of immunoglobulins and cytokines (IgG, IgM, TNF-α, and IL-2) in immunosuppressive mice. RBAPS protected the spleen and thymus from CTX-induced injury by increasing the organ indexes, attenuating pathological damage, and promoting splenic lymphocytes proliferation. Importantly, RBAPS ameliorated the intestine integrity and function by promoting the expression of Occuldin, Claudin-5, Atg5, and Atg7, activating TLR4/MAPK signaling pathway in CTX-induced mice. This study suggested that RBAPS was a prime candidate of immunologic adjuvant in chemotherapy for the nutraceutical and pharmaceutical application.

Insight into the absorption and migration of polystyrene nanoplastics in Eichhornia crassipes and related photosynthetic responses

Nanoplastics, as emerging contaminants are being released into aquatic environments with their increasing applications, and induce potential hazards to aquatic ecosystem. In this work, we investigated the removal process of polystyrene nanoparticles (PS NPs) by Eichhornia crassipes and the related photosynthetic responses of E. crassipes. Results showed that both sizes of PS NPs (20 and 200 nm) with 50 mg/L induced the prominent damage on the root epidermis after 48 h exposure, and smaller size PS NPs caused the greater damage. PS NPs has been entered the roots of E. crassipes and migrated from the epidermis, cortex, to vascular system by using confocal laser scanning microscopy observation. Scanning electron microscope images confirmed the distribution of PS NPs (200 nm) in the roots. The crack at sites of primary-lateral root junction was an important way for the uptake of PS NPs, which destroyed the defense of Casparian strip, and promoted the migration of PS NPs into the vascular system. PS NPs entered the submerged leaves by stomata and the intercellular spaces of lower epidermis. Moreover, PS NPs in the plants showed significant inhibition on net photosynthetic rate, intercellular CO2 concentration, stomatal conductance, and transpiration rate. This study concluded the absorption and migration processes of PS NPs by E. crassipes, and the negative effects on photosynthesis, which will be useful for guiding the floating plants application for PS NPs removal in aqueous environment and ecological improvement.

Behavior of host-cell-protein-rich aggregates in antibody capture and polishing chromatography

Recent work has shown that aggregates in monoclonal antibody (mAb) solutions may be made up not just of mAb oligomers but can also harbor hundreds of host-cell proteins (HCPs), suggesting that aggregate persistence through downstream purification operations may be related to HCP clearance. We have examined this in a primary analysis of aggregate persistence through processing steps that are typically implemented for HCP reduction, demonstrating that the phenomenon is relevant to depth filtration, protein A chromatography and flow-through anion-exchange (AEX) polishing. Confocal laser scanning microscopy observations show that aggregates compete with the mAb to adsorb specifically in protein A chromatography and that this competitive interaction is integral to the efficacy of protein A washes. Column chromatography reveals that the protein A elution tail can have a relatively high concentration of aggregates, which corroborates analogous observations from recent HCP studies. Similar measurements in flow-through AEX chromatography show that relatively large aggregates that harbor HCPs and that persist into the protein A eluate can be retained to an extent that appears to depend primarily on the resin surface chemistry. The total aggregate mass fraction of both protein A eluate pools (∼ 2.4 – 3.6%) and AEX flow-through fractions (∼ 1.5 – 3.2%) correlates generally with HCP concentrations measured using enzyme-linked immunosorbent assay (ELISA) as well as the number of HCPs that may be identified in proteomic analysis. This suggests that quantification of the aggregate mass fraction may serve as a convenient albeit imperfect surrogate for informing early process development decisions regarding HCP clearance strategies.

Antibacterial and Antibiofilm Efficacy and Mechanism of Ginger (Zingiber officinale) Essential Oil against Shewanella putrefaciens.

Ginger (Zingiber officinale) has unique medicinal value and can be used to treat colds and cold-related diseases. The chemical composition and antibacterial activity of ginger essential oil (GEO) against Shewanella putrefaciens were determined in the present study. Zingiberene, α-curcumene, and zingerone were the main active compounds of GEO. GEO displayed significant antibacterial activity against S. putrefaciens, with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 2.0 and 4.0 μL/mL, respectively. Changes in intracellular ATP content, nucleic acid and protein structure, exopolysaccharides (EPS) content, and extracellular protease production indicated that GEO disrupted the membrane integrity of S. putrescens. At the same time, changes in biofilm metabolic activity content and the growth curve of biofilm showed that GEO could destroy the biofilm. Both scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) observations confirmed that GEO destroyed the cell membrane and lead to the leakage of the constituents. The above results indicate that GEO entered the cells via contact with bacterial membranes, and then inhibited the growth of S. putrefaciens and its biofilms by increasing membrane permeability and inhibiting various virulence factors such as EPS. The findings showed that GEO could destroy the structure of cell membrane and biofilm of tested S. putrefaciens, indicating its potential as a natural food preservative.

Appearance of a transparent protrusion containing two pairs of legs on the apodous ring preceding the anamorphic molt in a millipede, Niponia nodulosa

BackgroundArthropods gradually change their forms through repeated molting events during postembryonic development. Anamorphosis, i.e., segment addition during postembryonic development, is seen in some arthropod lineages. In all millipede species (Myriapoda, Diplopoda), for example, postembryonic processes go through anamorphosis. Jean-Henri Fabre proposed 168 years ago the “law of anamorphosis”, that is, “new rings appear between the penultimate ring and the telson” and “all apodous rings in a given stadium become podous rings in the next stadium”, but the developmental process at the anamorphic molt remains largely unknown. In this study, therefore, by observing the morphological and histological changes at the time of molting, the detailed processes of leg- and ring-addition during anamorphosis were characterized in a millipede, Niponia nodulosa (Polydesmida, Cryptodesmidae).ResultsIn the preparatory period, a few days before molting, scanning electron microscopy, confocal laser scanning microscopy, and histological observations revealed that two pairs of wrinkled leg primordia were present under the cuticle of each apodous ring. In the rigidation period, just prior to molt, observations of external morphology showed that a transparent protrusion was observed on the median line of the ventral surface on each apodous ring. Confocal laser scanning microscopy and histological observations revealed that the transparent protrusion covered by an arthrodial membrane contained a leg bundle consisting of two pairs of legs. On the other hand, ring primordia were observed anterior to the telson just before molts.ConclusionsPreceding the anamorphic molt in which two pairs of legs are added on an apodous ring, a transparent protrusion containing the leg pairs (a leg bundle) appears on each apodous ring. The morphogenetic process of the rapid protrusion of leg bundles, that is enabled by thin and elastic cuticle, suggested that millipedes have acquired a resting period and unique morphogenesis to efficiently add new legs and rings.