Changes In Membrane Permeability Research Articles

Low-intensity pulsed ultrasound in obstetrics and gynecology: advances in clinical application and research progress.

In the past decade, research on ultrasound therapy in obstetrics and gynecology has rapidly developed. Currently, high-intensity ultrasound has been widely used in clinical practice, while low-intensity ultrasound has gradually emerged as a new trend of transitioning from pre-clinical research to clinical applications. Low-intensity pulsed ultrasound (LIPUS), characterized by a non-invasive low-intensity pulse wave stimulation method, employs its non-thermal effects to achieve safe, economical, and convenient therapeutic outcomes. LIPUS converts into biochemical signals within cells through pathways such as cavitation, acoustic flow, and mechanical stimulation, regulating molecular biological mechanisms and exerting various biological effects. The molecular biology mechanisms underlying the application of LIPUS in obstetrics and gynecology mainly include signaling pathways, key gene expression, angiogenesis, inflammation inhibition, and stem cell differentiation. LIPUS plays a positive role in promoting soft tissue regeneration, bone regeneration, nerve regulation, and changes in cell membrane permeability. LIPUS can improve the treatment benefit of premature ovarian failure, pelvic floor dysfunction, nerve damage caused by intrauterine growth restriction, ovariectomized osteoporosis, and incomplete uterine involution through the above biological effects, and it also has application value in the adjuvant treatment of malignant tumors such as ovarian cancer and cervical cancer. This study outlines the biological mechanisms and applications of LIPUS in treating various obstetric and gynecologic diseases, aiming to promote its precise application and provide a theoretical basis for its use in the field.

Gallium Triggers Ferroptosis through a Synergistic Mechanism.

The gallium ion (Ga3+ ) has long been believed to disrupt ferric homeostasis in the body by competing with iron cofactors in metalloproteins, ultimately leading to cell death. This study revealed that through an indirect pathway, gallium can trigger ferroptosis, a type of non-apoptotic cell death regulated by iron. This is exemplified by the gallium complex of the salen ligand (Ga-1); we found that Ga-1 acts as an effective anion transporter that can affect the pH gradient and change membrane permeability, leading to mitochondrial dysfunction and the release of ferrous iron from the electron transfer chain (ETC). In addition, Ga-1 also targeted protein disulfide isomerases (PDIs) located in the endoplasmic reticulum (ER) membrane, preventing the repair of the antioxidant glutathione (GSH) system and thus enforcing ferroptosis. Finally, a combination treatment of Ga-1 and dietary polyunsaturated fatty acids (PUFAs), which enhances lipid peroxidation during ferroptosis, showed a synergistic therapeutic effect both in vitro and in vivo. This study provided us with a strategy to synergistically induce Ferroptosis in tumor cells, thereby enhancing the anti-neoplastic effect.

Gallium Triggers Ferroptosis through a Synergistic Mechanism

AbstractThe gallium ion (Ga3+) has long been believed to disrupt ferric homeostasis in the body by competing with iron cofactors in metalloproteins, ultimately leading to cell death. This study revealed that through an indirect pathway, gallium can trigger ferroptosis, a type of non‐apoptotic cell death regulated by iron. This is exemplified by the gallium complex of the salen ligand (Ga‐1); we found that Ga‐1 acts as an effective anion transporter that can affect the pH gradient and change membrane permeability, leading to mitochondrial dysfunction and the release of ferrous iron from the electron transfer chain (ETC). In addition, Ga‐1 also targeted protein disulfide isomerases (PDIs) located in the endoplasmic reticulum (ER) membrane, preventing the repair of the antioxidant glutathione (GSH) system and thus enforcing ferroptosis. Finally, a combination treatment of Ga‐1 and dietary polyunsaturated fatty acids (PUFAs), which enhances lipid peroxidation during ferroptosis, showed a synergistic therapeutic effect both in vitro and in vivo. This study provided us with a strategy to synergistically induce Ferroptosis in tumor cells, thereby enhancing the anti‐neoplastic effect.

Amyloid Precursor Protein Changes Arrangement in a Membrane and Its Structure Depending on the Cholesterol Content.

One of the hallmarks of Alzheimer's disease (AD) is the accumulation of amyloid beta (Aβ) peptides in the brain. The processing of amyloid precursor protein (APP) into Aβ is dependent on the location of APP in the membrane, membrane lipid composition and, possibly, presence of lipid rafts. In this study, we used atomic force microscopy (AFM) to investigate the interaction between transmembrane fragment APP672-726 (corresponding to Aβ1-55) and its amyloidogenic mutant L723P with membranes combining liquid-ordered and liquid-disordered lipid phases. Our results demonstrated that most of the APP672-726 is located either in the liquid-disordered phase or at the boundary between ordered and disordered phases, and hardly ever in rafts. We did not notice any major changes in the domain structure induced by APP672-726. In membranes without cholesterol APP672-726, and especially its amyloidogenic mutant L723P formed annular structures and clusters rising above the membrane. Presence of cholesterol led to the appearance of concave membrane regions up to 2 nm in depth that were deeper for wild type APP672-726. Thus, membrane cholesterol regulates changes in membrane structure and permeability induced by APP that might be connected with further formation of membrane pores.

An Impedance-Based Approach for Sensing Cyclodextrin-Mediated Modulation of Membrane Cholesterol.

Cyclodextrin molecules are increasingly being used in biological research and as therapeutic agents to alter membrane cholesterol content, yet there is much to learn about their interactions with cell membranes. We present a biomembrane-based organic electronic platform capable of detecting interactions of cell membrane constituents with methyl-β-cyclodextrin (MβCD). This approach enables label-free sensing and quantification of changes in membrane integrity resulting from such interactions. In this work, we employ cholesterol-containing supported lipid bilayers (SLBs) formed on conducting polymer-coated electrodes to investigate how MβCD impacts membrane resistance. By examining the outcomes of MβCD interactions with SLBs of varying cholesterol content, we demonstrate that changes in membrane permeability or resistance can be used as a functional measure for predicting cyclodextrin-mediated cholesterol extraction from cellular membranes. Furthermore, we use the SLB platforms to electronically monitor cholesterol delivery to membranes following exposure to MβCD pre-loaded with cholesterol, observing that cholesterol enrichment is commensurate with an increase in resistance. This biomembrane-based bioelectronic sensing system offers a tool to quantify the modulation of membrane cholesterol content using membrane resistance and provides information regarding MβCD-mediated changes in membrane integrity. Given the importance of membrane integrity for barrier function in cells, such knowledge is essential for our fundamental understanding of MβCD as a membrane cholesterol modulator and therapeutic delivery vehicle.

Evaluating pesticide ecotoxicity using a stimuli-response model in liposomes

Pesticides are widely used around the home and in agriculture to control unwanted populations; however, they may also be toxic to non-targeted organisms. Because traditional methods of assessing pesticide toxicity are expensive, lengthy, and ethically questionable, we evaluated pesticide toxicities using stimuli-responses in liposomes. Pesticide ecotoxicity was evaluated using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes. Changes in membrane permeability were measured using calcein leakage assays as stimuli-responses in the presence of six pesticides (Chlorpyrifos-methyl, fluometuron, imidacloprid, pirimicarb, pyrethrin, and quizalofop-ethyl), for which the calcein release rate was analyzed using a first-order kinetics equation. The calcein release rate constants of the DPPC liposomes were used to classify the pesticides into lower and higher toxicity groups. In each group, the initial calcein release rate from the DPPC/DOPC liposomes mixed with 33 ​mol% DOPC correlated well with previously reported pesticide toxicities. The DOPC liposomes underwent lateral phase separation in a different manner between the two toxicity groups. Pesticides with lower toxicities were partitioned in the DPPC-enriched phase, disrupting the gel phase order through their hydrophobicity, whereas pesticides with higher toxicity were partitioned in the DOPC-enriched phase and stabilizing the liquid disordered phase owing to their hydrophobicity and molecular shape. The toxicity of each pesticide was well represented by an equation that combined the calcein release rate constant of the DPPC liposomes and the initial calcein release rate of the 33 ​mol% DOPC mixed liposomes. The findings indicate that stimuli-response assays using liposomes can be used to complement traditional ecotoxicity assessments.

A semi purified hydroalcoholic fraction from Caesalpinia bonduc seeds causes ergosterol biosynthesis inhibition in Candida albicans resulting in cell membrane damage.

Candida species are currently developing resistance to prevailing commercially available drugs, which raises an instantaneous need to discover novel antifungals. To cope with this shocking situation, phytochemicals are the richest, safest, and most potent source of excellent antimicrobials with broad-spectrum activity. The aim of the current study is to explore the anticandidal potential of the various fractions purified from the hydroalcoholic extract of C. bonduc seed. Out of five fractions purified from the hydroalcoholic extract, fraction 3 (Fr. 3) recorded the best activity against C. albicans (8μg/mL) and thus this species was chosen for further mechanism of action studies. The phytochemical examination reveals that Fr. 3 was found to contain steroids and triterpenoids. This was further supported by LC-QTOF-MS and GCMS analyses. Our findings show that Fr. 3 targets the ergosterol biosynthesis pathway in C. albicans by inhibiting the lanosterol 14-α demethylase enzyme and downregulating expression of its related gene ERG11. Molecular docking outcomes disclosed favorable structural dynamics of the compounds, implying that the compounds present in Fr. 3 would be able to successfully bind to the lanosterol 14-α demethylase, as evidenced by the docked compounds' strong interaction with the target enzyme's amino acid residues. Considering virulence factors, the Fr. 3 recorded significant antibiofilm activity as well as germ-tube reduction potential. Furthermore, Fr. 3 enhances the production of intracellular reactive oxygen species (ROS). This suggests that the antifungal activity of Fr. 3 was associated with membrane damage and the induction of ROS production, resulting in cell death. Fluorescence microscopic analysis of PI stained Candida further showed changes in the plasma membrane permeability, which causes severe loss of intracellular material and osmotic balance. This was demonstrated by the potassium ion leakage and release of genetic materials. Finally, the erythrocyte lysis assay confirmed the low cytotoxicity of Fr. 3. Both in silico and in vitro results suggest that Fr. 3 has the potential to propel forward novel antifungal drug discovery programmes.

Effect of a dietary antioxidant supplementation on semen characteristics of the Colombian horse

Cooling equine semen increases production of reactive oxygen species (ROS). Elevated concentrations of ROS have detrimental consequences by causing changes in membrane permeability. Although there are reports of antioxidant supplementation to improve sperm quality in horses, there are few reports on the Colombian breed. The objective of this study was to evaluate the effect of nutritional supplementation with a variety of antioxidants on semen characteristics of Colombian horses. Six (n=6) Colombian Creole stallions aged between 5 and 15 years were collected 3 times a week using a Missouri artificial vagina for 20 weeks. Stallions were randomly allocated into a control (C) or a supplementation group (SG) with Natural Fertility®. Cobalamin 0.36 mg/day; pyridoxin 16 mg/day; retinoic acid 366799 IU/day; alpha tocopherol 1600 IU/day; ascorbic acid 4000 mg/day; folic acid 1200 mg/day; lysine 640 mg/day; methionine 960 mg/day; threonine 400 mg/day; arginine 400 mg/day; L-Carnitine 10000 mg/day; omega 3 3200 mg/day; zinc 1200 mg/day; copper 44 mg/day, chromium 6 mg/day and selenium 8 mg/day, was added to the basal diet (hay, mineralized salt, 2 kg of grain and water). Repeated measures design with a wash-out period of 2 weeks between treatments was used. During a periodof 8 weeks, semen was analyzed twice a week for motility and kinetics using a Sperm Class Analyzer (SCA®) system; sperm vitality (SV) and acrosomal Integrity (AI) by fluorescent microscopy, abnormal morphology (AM) by supravital stain, and plasmatic membrane Integrity by hypoosmotic test (HOST). Reactive oxygen species and total antioxidant capacity (TAC) by ferric reducing antioxidant power assay (FRAP) were assessed by spectrofluorimetry. Comparison of means was performed using Tukey's test with p≤0.05; using SAS program 3.81. SG increased the beat cross frequency of semen with 36.68 Hz ± 0.89 vs. 32.67 Hz ± 0.73 (C). In addition, a higher AI was found for SG (82.92 ± 0.72 %) compared to C (78.51% ± 0.83). SG also increased the TAC of seminal plasma (15.35± 0.92 μmol Trolox/L) compared to C (18.86± 1.75 μmol Trolox/L). In the individual analysis it was found that SG increased the total and progressive motility of the semen of two horses, however it reduced both parameters for two other individuals, compared to C. In conclusion, supplementation of the diet of horses with a supplement that provides vitamins, minerals, amino acids, and omega 3 can increase the antioxidant capacity of seminal plasma, as well as sperm quality, however this may be subject to a differential effect on each horse.

A natural product noraucupatin against multidrug-resistant Enterococcus faecium: an inhibition mechanism study

Background: This work elucidates the antimicrobial activity and mechanism of action of the natural product noraucupatin against MDR Enterococcus faecium. E. faecium has become a major opportunistic pathogen with the worldwide spread of multidrug-resistant (MDR) isolates, especially vancomycin-resistant enterococci (VRE), belongs to “ESKAPE” organisms causing significant problems widely. Hence, there is a pressing need to discover new promising drugs or alternative therapies. Fortunately, we found a natural product noraucupatin (C13H12O3, a biphenyl compound) with “extremely encouraging” anti-clinical drug-resistant bacterial activity isolated from yeast-induced Rowan suspension cells. A comprehensive and in-depth exploration of antimicrobial mechanisms will bring fresh insights for researchers to develop novel antimicrobial strategies against MDR bacteria.Methods: The antibacterial effect of noraucupatin against MDR E. faecium is investigated from a microbial metabolism perspective using microcalorimetry. The antibacterial effect is determined based on the thermodynamic parameters. Based on spectroscopic techniques, microscopy techniques and confocal scanning laser microscopy with membrane probes, the antibacterial mechanism is elucidated definitely.Results: Comparing with the IC50 of noraucupatin against MDR Enterococcus faecalis, MRSA, CRPA, the IC50 of noraucupatin against MDR E. faecium was just 67.54 μM. The growth rate of MDR E. faecium decreases with the increase of concentration of noraucupatin. The bacterial intracellular structure entirely collapses and the slurries flow out under the influence of high levels of noraucupatin by TEM. The changes of membrane potential, permeability and evidences of nucleic acid leakage was obtained by CSLM and UV, the mechanism of noraucupatin against MDR E. faecium we explored.Conclusion: The present study highlights the excellent antibacterial activity of noraucupatin against MDR E. faecium by altering the permeability of the membrane and disrupting the membrane potential leading to electrolyte permeation. In addition, noraucupatin has excellent biocompatibility through its haemolytic activity in rabbit erythrocyte. These findings suggest that noraucupatin could be used in infectious diseases caused by MDR E. faecium.

Drug Resistance Mechanism and Detection Method of Salmonella

As an important zoonotic food-borne pathogen, Salmonella is a concern for public health authorities. In particular, bacteria that are resistant to multiple antimicrobials can confuse the efficacy of treatment for infectious diseases. Drug-resistant bacteria have a variety of drug-resistant molecular and cellular mechanisms. These antimicrobial resistance mechanisms include antibiotic efflux, permeability changes in cell membranes, enzymatic drug inactivation, biofilm formation, drug target changes, and protection of antimicrobial targets. In this paper, the mechanisms of antimicrobial resistance in salmonella and the techniques of detecting antibiotic resistance by traditional and molecular methods are reviewed, with emphasis on their advantages and disadvantages, as well as the validity and reliability of the results.

Biocontrol potential of lipopeptides produced by Paenibacillus polymyxa AF01 against Neoscytalidium dimidiatum in pitaya.

Pitaya canker, caused by Neoscytalidium dimidiatum, is one of the most important fungal diseases that cause significant losses in production. To replace chemical pesticides, the use of biocontrol strains to manage plant diseases has been the focus of research. In this study, the bacterial strain AF01, identified as Paenibacillus polymyxa, exhibited significant antifungal effects against N. dimidiatum and four other pitaya fungal pathogens. The strain P. polymyxa AF01 produces 13 fusaricidins, which directly inhibit mycelial growth, spore germination and germ tube elongation by causing the membrane integrity and cell ultrastructure to incur irreversible damage. Pot experiment and yield test confirmed that AF01 provided preservative effects by reducing the disease index. In comparison to the untreated control groups, RNA-seq data showed that P. polymyxa AF01 selectively blocked some transcription and translation processes and inhibited RNA and DNA structural dynamics, energy production and conversion, and signal transduction, particularly cell wall biosynthesis, changes in membrane permeability, and impairment of protein biosynthesis. Thus, P. polymyxa AF01 could be potentially useful as a suitable biocontrol agent for pitaya canker.

Catechin potentiates the antifungal effect of miconazole in Candida glabrata

The rising number of invasive fungal infections caused by drug-resistant Candida strains is one of the greatest challenges for the development of novel antifungal strategies. The scarcity of available antifungals has drawn attention to the potential of natural products as antifungals and in combinational therapies. One of these is catechins—polyphenolic compounds—flavanols, found in a variety of plants. In this work, we evaluated the changes in the susceptibility of Candida glabrata strain characterized at the laboratory level and clinical isolates using the combination of catechin and antifungal azoles. Catechin alone had no antifungal activity within the concentration range tested. Its use in combination with miconazole resulted in complete inhibition of growth in the sensitive C. glabrata isolate and a significant growth reduction in the azole resistant C. glabrata clinical isolate. Simultaneous use of catechin and miconazole leads to increased intracellular ROS generation. The enhanced susceptibility of C. glabrata clinical isolates to miconazole by catechin was accompanied with the intracellular accumulation of ROS and changes in the plasma membrane permeability, as measured using fluorescence anisotropy, affecting the function of plasma membrane proteins.

Lyososome Membrane Permeabilization Induces Plasma Membrane Macropores to Activate K +-Efflux-Dependent NLRP3 Inflammasomes in Murine Dendritic Cells

Abstract NLRP3 is a cytosolic sensor protein in myeloid leukocytes that recruits the adaptor protein ASC and activates caspase-1 in functional NLRP3 inflammasomes. Caspase-1 coordinately cleaves pro-IL-1β to bioactive IL-1β and gasdermin D (GSDMD) to induce N-GSDMD macropores in the plasma membrane (PM). The latter mediate efflux of mature IL-1β and initiate progression to pyroptosis, a lytic cell death. NLRP3 activation is triggered by perturbed cellular homeostasis with decreased cytosolic [K +] being the best-characterized signal. The required K +efflux is typically induced by the ionophore nigericin or extracellular ATP as an agonist for P2X7 receptor channels. K +efflux-dependent activation of NLRP3 is also triggered by soluble or particulate agents which accumulate in lysosomes to induce lysosomal membrane permeabilization (LMP) and release of hydrolytic enzymes into the cytosol; particulates include alum widely used as a vaccine adjuvant. The mechanisms by which LMP rapidly triggers changes in plasma membrane permeability remain undefined. We used a model of murine bone marrow derived dendritic cells (BMDC) treated with the soluble LMP agent Leu-Leu-O-methyl ester (LLME) to elicit K+ efflux and NLRP3 activation. Notably, this K+ efflux was coincident with a rapidly induced influx of propidiumiodide (PI), a 668 Da organic salt routinely used to track assembly of plasma membrane macropores such as GSDMD. Equivalent LLME-induced PI influx was observed in wildtype and Gsdmd−/−BMDC and was unaffected by inhibition of NLRP3 or caspase-1. These observations indicate that LMP triggers rapid activation of an endogenous pore-forming protein distinct from GSDMD. Current studies are evaluating gasdermin E or pannexin-1 as candidates. Supported by grants from the NIH (P01-AI141350 and R01-EY014362)

Antibiotic synergist OM19r reverses aminoglycoside resistance in multidrug-resistant Escherichia coli.

The continued emergence and spread of multidrug-resistant (MDR) bacterial pathogens require a new strategy to improve the efficacy of existing antibiotics. Proline-rich antimicrobial peptides (PrAMPs) could also be used as antibacterial synergists due to their unique mechanism of action. Utilizing a series of experiments on membrane permeability, In vitro protein synthesis, In vitro transcription and mRNA translation, to further elucidate the synergistic mechanism of OM19r combined with gentamicin. A proline-rich antimicrobial peptide OM19r was identified in this study and its efficacy against Escherichia coli B2 (E. coli B2) was evaluated on multiple aspects. OM19r increased antibacterial activity of gentamicin against multidrug-resistance E. coli B2 by 64 folds, when used in combination with aminoglycoside antibiotics. Mechanistically, OM19r induced change of inner membrane permeability and inhibited translational elongation of protein synthesis by entering to E. coli B2 via intimal transporter SbmA. OM19r also facilitated the accumulation of intracellular reactive oxygen species (ROS). In animal models, OM19r significantly improved the efficacy of gentamicin against E. coli B2. Our study reveals that OM19r combined with GEN had a strong synergistic inhibitory effect against multi-drug resistant E. coli B2. OM19r and GEN inhibited translation elongation and initiation, respectively, and ultimately affected the normal protein synthesis of bacteria. These findings provide a potential therapeutic option against multidrug-resistant E. coli.

Lipophilicity Modulations by Fluorination Correlate with Membrane Partitioning

AbstractBioactive compounds generally need to cross membranes to arrive at their site of action. The octanol‐water partition coefficient (lipophilicity, logPOW) has proven to be an excellent proxy for membrane permeability. In modern drug discovery, logPOW and bioactivity are optimized simultaneously, for which fluorination is one of the relevant strategies. The question arises as to which extent the often subtle logP modifications resulting from different aliphatic fluorine‐motif introductions also lead to concomitant membrane permeability changes, given the difference in molecular environment between octanol and (anisotropic) membranes. It was found that for a given compound class, there is excellent correlation between logPOW values with the corresponding membrane molar partitioning coefficients (logKp); a study enabled by novel solid‐state 19F NMR MAS methodology using lipid vesicles. Our results show that the factors that cause modulation of octanol‐water partition coefficients similarly affect membrane permeability.

Lipophilicity Modulations by Fluorination Correlate with Membrane Partitioning.

Bioactive compounds generally need to cross membranes to arrive at their site of action. The octanol-water partition coefficient (lipophilicity, logPOW ) has proven to be an excellent proxy for membrane permeability. In modern drug discovery, logPOW and bioactivity are optimized simultaneously, for which fluorination is one of the relevant strategies. The question arises as to which extent the often subtle logP modifications resulting from different aliphatic fluorine-motif introductions also lead to concomitant membrane permeability changes, given the difference in molecular environment between octanol and (anisotropic) membranes. It was found that for a given compound class, there is excellent correlation between logPOW values with the corresponding membrane molar partitioning coefficients (logKp ); a study enabled by novel solid-state 19 F NMR MAS methodology using lipid vesicles. Our results show that the factors that cause modulation of octanol-water partition coefficients similarly affect membrane permeability.

The Role of Efflux Pumps in Antibiotic Resistance of Gram Negative Rods

Antibiotic resistance is an important public health problem today, causing increased morbidity and mortality. Resistance to antibiotics in bacteria can develop by various mechanisms such as a change in the target site of the drug, a change in the outer membrane permeability, enzymatic defusing of the drug and efflux of the antimicrobial compound. Some bacteria have the potential to develop resistance to more than one drug by using several mechanisms together. One of the important resistance mechanisms of bacteria is active efflux pumps (EPs). EPs are pump proteins found in all cell types, located in the cell membrane. They are responsible for the excretion of various intracellular and extracellular substances (antibiotics, etc.) out of the cell. There is much research on various antimicrobials that cause antibiotic resistance in Gram negative rods, but studies on EPs are relatively few. Due to the concern that antibiotics will be insufficient in the treatment of diseases, a good understanding of EPs and the discovery of new EP inhibitors will shed light on the future of humanity. In this review, the structure of bacterial EPs in Gram negative bacteria, the role of EPs in multidrug resistance, the importance of EP inhibitors in the fight against antibiotic resistance and the phenotypic and genotypic detection methods of EPs are discussed.

The roles of membrane permeability and efflux pumps in the toxicity of bisphenol S analogues (2,4-bisphenol S and bis-(3-allyl-4-hydroxyphenyl) sulfone) to Escherichia coli K12

Bisphenol S (BPS) analogues are a group of recently reported emerging contaminants in the environment. Bacteria are important components of food webs. However, the potential risks of BPS analogues in bacteria have not been fully addressed. The toxicity effects and related mechanisms of two BPS analogues with different molecular weights (2,4-bisphenol S (2,4-BPS) and bis-(3-allyl-4-hydroxyphenyl) sulfone (TGSA)) on Escherichia coli K12 were compared. The minimum inhibitory concentration (MIC) of 2,4-BPS in the wild-type of E. coli K12 was lower than that of TGSA. The membrane permeability of the wild-type increased significantly after exposed to the same concentrations (0.5–50 nmol L−1) of 2,4-BPS and TGSA. In addition, 2,4-BPS induced more significant changes in membrane permeability than TGSA. Hormetic effects of 2,4-BPS and TGSA in the wild-type strain were noted in the levels of outer membrane proteins (ompC and ompF), multidrug efflux pump acriflavine resistance B (acrB) and type II topoisomerases. Transcriptomic results indicated these two BPS analogues inhibited the function of ABC transporters. In contrast to TGSA, 2,4-BPS affected DNA replication, tricarboxylic acid cycle, oxidative phosphorylation, and inhibited energy metabolism. Compared with wild-type strain, the ΔacrB mutant strain showed enhanced susceptibility to 2,4-BPS and TGSA with their MICs reduced by 20% and 11%, respectively. Deletion of the acrB affected the growth characteristics and induced stronger oxidative stress than the wild-type strain when exposed to 2,4-BPS or TGSA. The results suggested that 2,4-BPS were more toxic to E. coli K12 than TGSA in the concentration range of 0.5–50 nmol L−1, which was supported by the evidence from their impacts on membrane permeability and efflux pumps.

Macrolactin R from Bacillus siamensis and its antifungal activity against Botrytis cinerea.

Botrytis cinerea is listed among the most important fungal pathogens infecting strawberries. The use of biological control agents, such as Bacillus species, offers an alternative and effective way to reduce airborne pathogens. The aim of this research was to select the macrolactin R produced by Bacillus siamensis with potential for using as biological agents against the pathogenetic fungi (Botrytis cinerea) of strawberries, and to assess the mechanisms involved. Macrolactin R had significant inhibitory effects on spore germination, germ tube elongation, and mycelial growth of Botrytis cinerea. The MICs of macrolactin R inhibitions in vitro was 12.5mg/L and The EC50 value of NJ08-3 to Botrytis cinerea spores and mycelial was 1.93 and 2.88mg/L, respectively. Macrolactin R impacted the membrane structure of Botrytis cinerea, resulting in changes in membrane permeability and leakage of proteins and nucleic acids, then cell death. The application of the macrolactin R of Bacillus siamensis reduced the disease severity index of gray mold on strawberries. This study demonstrated that the production of macrolactin R produced by Bacillus siamensis are involved in the antifungal activity against Botrytis cinerea.

Cytotoxicity and Oxidative Stress Effects of Indene on Coelomocytes of Earthworm (Eisenia foetida): Combined Analysis at Cellular and Molecular Levels.

Indene (IND) is a kind of important aromatic hydrocarbon that is extracted from coal tar and has important applications in industry and biology. In the process of production and utilization, it is easy to enter the soil and produce toxic effects on the soil or organisms. The earthworm is an important organism in the soil. The toxicity of indene on earthworm coelomocytes is rarely studied, and the oxidative stress effects of IND on earthworm coelomocytes remain unclear. In this study, coelomocytes from earthworms and antioxidant enzymes were selected as the research targets. In addition, IND caused oxidative stress, and its related toxic effects and mechanisms were systematically studied and evaluated at the cellular and molecular levels. The results showed that IND destroyed the redox balance in earthworm coelomocytes, and the large accumulation of reactive oxygen species (ROS) significantly inhibited the activities of the antioxidant system, including superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), and caused lipid peroxidation and membrane permeability changes, resulting in a decrease in cell viability to 74.5% of the control group. At the molecular level, IND was bound to SOD by the arene-H bond, and the binding constant was 4.95 × 103. IND changed the secondary structure of the SOD and led to a loosening of the structure of the SOD peptide chain. Meanwhile, IND caused SOD fluorescence sensitization, and molecular simulation showed that IND was mainly bound to the junction of SOD subunits. We hypothesized that the changes in SOD structure led to the increase in SOD activity. This research can provide a scientific basis for IND toxicity evaluation.