Search

AbstractAntimicrobial resistance (AMR) has been recognized as an important health crisis in the twenty first century. Type IV secretion systems (T4SSs) play key roles in the dissemination of AMR plasmids. Novel strategies that combat AMR problem by targeting T4SS sprung up in recent years. Here, we focus on the strategy of male-specific phages that could target and kill bacteria carrying conjugative AMR plasmids encoding T4SSs. We reviewed the recent advances in male-specific phages, including anti-conjugation mechanisms, clinical isolation and identification methods, classification and characteristics, in vitro and in vivo anti-conjugation efficacy and improving strategies. Male-specific phages constitute exciting candidates for developing sustainable anti-resistance biocontrol applications. [ABSTRACT FROM AUTHOR]

Introduction: Horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs) is one of the primary routes of antimicrobial resistance (AMR) dissemination. In the One Health context, tracking the spread of mobile genetic elements (MGEs) carrying ARGs in agri-food ecosystems is pivotal in understanding AMR diffusion and estimating potential risks for human health. So far, little attention has been devoted to plant niches; hence, this study aimed to evaluate the conjugal transfer of ARGs to the bacterial community associated with the plant rhizosphere, a hotspot for microbial abundance and activity in the soil. We simulated a source of AMR determinants that could enter the food chain via plants through irrigation. Methods: Among the bacterial strains isolated from treated wastewater, the strain Klebsiella variicola EEF15 was selected as an ARG donor because of the relevance of Enterobacteriaceae in the AMR context and the One Health framework. The strain ability to recolonize lettuce, chosen as a model for vegetables that were consumed raw, was assessed by a rifampicin resistant mutant. K. variicola EEF15 was genetically manipulated to track the conjugal transfer of the broad host range plasmid pKJK5 containing a fluorescent marker gene to the natural rhizosphere microbiome obtained from lettuce plants. Transconjugants were sorted by fluorescent protein expression and identified through 16S rRNA gene amplicon sequencing. Results and discussion: K. variicola EEF15 was able to colonize the lettuce rhizosphere and inhabit its leaf endosphere 7 days past bacterial administration. Fluorescence stereomicroscopy revealed plasmid transfer at a frequency of 10−3; cell sorting allowed the selection of the transconjugants. The conjugation rates and the strain’s ability to colonize the plant rhizosphere and leaf endosphere make strain EEF15::lacIq -pLpp-mCherry-gmR with pKJK5::Plac::gfp an interesting candidate to study ARG spread in the agri-food ecosystem. Future studies taking advantage of additional environmental donor strains could provide a comprehensive snapshot of AMR spread in the One Health context. [ABSTRACT FROM AUTHOR]

Conjugative dissemination of mobile genetic elements (MGEs) among bacteria is initiated by assembly of the relaxosome at the MGE's origin‐of‐transfer (oriT) sequence. A critical but poorly defined step of relaxosome assembly involves recruitment of the catalytic relaxase to its DNA strand‐specific nicking site within oriT. Here, we present evidence by AlphaFold modeling, affinity pulldowns, and in vivo site‐directed photocrosslinking that the TraK Ribbon–Helix–Helix DNA‐binding protein recruits TraI to oriT through a dynamic interaction in which TraI's C‐terminal unstructured domain (TraICTD) wraps around TraK's C‐proximal tetramerization domain. Upon relaxosome assembly, conformational changes disrupt this contact, and TraICTD instead self‐associates as a prerequisite for relaxase catalytic functions or substrate engagement with the transfer channel. These findings delineate key early‐stage processing reactions required for conjugative dissemination of a model MGE. [ABSTRACT FROM AUTHOR]

Objectives: Subinhibitory concentration of antibiotics in the environment is an important risk factor for the horizontal transmission of antibiotic resistance genes (ARGs). The signaling mechanism of resistance gene transmission remains unknown. The aim of this study was to investigate whether indole could be used as a molecular signal to help the spread of ARGs under the stress of subinhibitory concentrations of antibiotics. Methods: The effect of indole on conjugation frequency was investigated through a conjugation test, and its effect on the Type IV secretion system and pili gene expression of E. coli was observed. Meanwhile, we were investigating the trend of changes in indole regulatory factors ibpA, tnaA, and concentration pumps. Subsequently, we predicted the receptors that specifically bind to indole. Finally, our study focused on elucidating the regulatory mechanism of indole synthesis. Results: Conjugate frequency was significantly increased under 1/5MIC concentration cefotaxime stress. The transferred ARGs were blaCTX-M and foxA. The mobile plasmid was IncY or IncI2. Meanwhile, the concentration of endogenous indole was also significantly increased. And, surprisingly, inhibition of endogenous indole production resulted in a significant decrease in conjugate frequency. However, the conjugate frequency increased once again when the strains reacquired the exogenous indole. Furthermore, the fluctuation trends of indole‐regulated factor (ibpA, tnaA) mRNA and concentration pumps (acrEF, mtr) mRNA consistently with that of indole. Then, we found that the receptors of indole may be four targets of TCSs: CreC, PhoB, AtoC, and UhpA. More than that, when strains retrieved the exogenous indole again, the mRNA levels of T4SS (virB2, virB6, and virD4) and pppA (coding Pili precursor) genes significantly increased. This indicates that there is a close relationship between indole and conjugated channels, which are necessary for horizontal transfer of genetic material. And then, the trends of indole and tnaA mRNA were consistent with that of ibpA (one of SOS response). So, this result confirmed that indole was regulated by SOS response under subinhibitory concentrations of antibiotics. Conclusions: It is always known that subinhibitory concentrations of antibiotics stimulate an SOS response in E. coli, which helps in the horizontal spread of ARGs by modulating indole. [ABSTRACT FROM AUTHOR]

Summary: Plum protein isolate obtained from plum cake after oil extraction had protein content over 90% and amino acid composition of 36% which about 13% were essential amino acids. Evaluation of functional properties of conjugates obtained by interaction between plum protein isolate and caffeic acid, in three different concentrations, was carried out in this study. The conjugation of proteins with phenols forms complexes of higher molecular weights as a result of cross‐linking. The solubility of obtained conjugates was increased with the increase a concentration of caffeic acid at alkaline pH (8–10) for about 50%. Moreover, emulsion properties also were improved by conjugation with caffeic acid. In vitro digestion is considered to characterise and understand 'fate' of food components after passing gastrointestinal conditions. The obtained conjugates were digestible and have a good bioavailability of bioactive compounds. [ABSTRACT FROM AUTHOR]

Mating assays are common laboratory experiments for measuring the conjugation frequency, i.e. efficiency at which a plasmid transfers from a population of donor cells to a population of recipient cells. Selective plating remains a widely used quantification method to enumerate transconjugants at the end of such assays. However, conjugation frequencies may be inaccurately estimated because plasmid transfer can occur on transconjugant-selective plates rather than only during the intended mating duration. We investigated the influence of cell density on this phenomenon. We conducted mating experiments with IncPα plasmid RP4 harbored in Escherichia coli at a fixed cell density and mating conditions, inoculated a serial dilution of the mating mixture on transconjugant-selective plates or in transconjugant-selective broth, and compared the results to a model of cell-to-cell distance distribution. Our findings suggest that irrespective of the mating mode (liquid vs solid), the enumeration of transconjugants becomes significantly biased if the plated cell density exceeds 28 Colony Forming Unit (CFU)/mm2 (or 1.68•105 CFU/standard 9 cm Petri dish). This threshold is determined with a 95% confidence interval of ± 4 CFU/mm2 (± 2.46•104 CFU/standard 9 cm Petri dish). Liquid mating assays were more sensitive to this bias because the conjugation frequency of RP4 is several orders of magnitude lower in suspension compared to surface mating. Therefore, if selective plating is used, we recommend to plate at this density threshold and that negative controls are performed where donors and recipients are briefly mixed before plating at the same dilutions as for the actual mating assay. As an alternative, a liquid enumeration method can be utilized to increase the signal-to-noise ratio and allow for more accurate enumeration of transconjugants. [ABSTRACT FROM AUTHOR]

Optoelectronic properties of linear π‐conjugated polymers/oligomers are of great importance for the fabrication of organic photonic and electronic devices. To this end, the π‐conjugated polymers/oligomers need to meet both optoelectronic and key structural properties in order to fulfill their implementation as active components. In particular, they need to possess low bandgap and high thermal, conformational, and photochemical stabilities. So far, several strategies have been developed to attain such requirements including the covalent and non‐covalent rigidification concepts of the π‐conjugated systems. On the basis of these findings, we describe herein the theoretical studies of novel series of covalently bridged derivatives demonstrating the benefits of the strategy. Comparison of these derivatives with compounds previously described in the literature highlights enhanced optoelectronic properties and behaviors that would be beneficial for the construction and development of new linear π‐conjugated polymers. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION The process of Maillard conjugation occurs with plant proteins and sugars and can be influenced by several factors, such as processing time, pH, and shear force. By utilizing cavitation processes such as high‐pressure homogenization (HPH) and pH‐shifting, it is possible to regulate the degree of grafting, functional characteristics, and structural changes in the formation of conjugates. The present study aimed to improve the hemp protein concentrate (HPC) through two different conjugation techniques: HPH and pH‐shifting‐assisted processes.The best conjugation conditions for the conventional method were identified as a 1:2 HPC to xylose ratio, a pH of 10, and 3 h of treatment at 70 °C. The use of HPH and pH 12‐shifting methods resulted in a remarkable 2.5‐fold increase in grafting degree, requiring less processing time. Fourier transform infrared spectra confirmed the formation of conjugates. Conjugates produced through HPH with pH 12‐shifting (MPHX) transformed into soluble glycoproteins with a particle size of 74 nm. MPHX solubility increased by 5.7‐fold than HPC, reaching 85.7%, with a more negatively charged surface at −32.4 mV. Microimages showed cracked and sharp forms for conjugated proteins compared to untreated HPC. Additionally, MPHX conjugates demonstrated superior properties in emulsion stability, foaming capacity, and antioxidant activity compared to HPC and classical conjugates.The use of HPH and pH‐shifting‐assisted Maillard conjugation was highly effective in enhancing the functional attributes of hemp protein conjugates. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

In the past two to three decades, synthetic glycoconjugate vaccines have shown great potential in the prevention of severe infections and protection of high‐risk populations. Conjugation of synthetic oligosaccharide haptens to carrier proteins is the key step for the vaccine preparation. In this review, the conjugation methods currently used in the synthesis of glycoconjugate vaccines from synthetic/homogeneous oligosaccharide haptens are summarized with the focus on the reaction conditions (pH and sugar/protein ratio) and performance. This information can help researchers choose the appropriate conjugation methods. Further research directions toward site‐specific conjugations and fully homogeneous glycoconjugate vaccines are also discussed. [ABSTRACT FROM AUTHOR]

Recently, for the enhancement of the therapeutic qualities of peptides, proteins, small molecules, antibodies, or oligonucleotides, the conjugation technique has immerged as a new domain in drug delivery systems. Conjugated medications have a longer half-life, greater stability, fewer side effects, enhanced solubility, reduced immunogenicity, and a specific targeting approach. The present review discusses various conjugation methods, comparing cleavable and non-cleavable linkers and current advancements in linker technology. It focuses on the molecular characteristics of each component of drug conjugations and linker chemistry techniques. The correlation between in vitro and in vivo studies of these conjugated systems has also been discussed. [ABSTRACT FROM AUTHOR]

• Comparative analysis of the physicochemical stability of interchain cysteine ADCs that had matched DAR and identical linkers but differently charged auristatin payloads (neutral vs. acidic terminal group). • ADCs with negatively charged vcMMAF payloads showed higher aggregation than those with neutral but more hydrophobic vcMMAE payloads, both under shaking stress and after 2 weeks of storage at 40 °C. • Conjugation with vcMMAF decreased the pI, net charge, and electrostatic repulsion of the ADC compared with the parent antibody (mAb). • Surface pressure and apparent second virial coefficient data correlated with the aggregation propensities of the mAb, ADC-vcMMAE, and ADC-vcMMAF. Antibody-drug conjugates (ADCs) tend to be less stable than their parent antibodies, which is often attributed to the hydrophobic nature of their drug payloads. This study investigated how the payload charge affects ADC stability by comparing two interchain cysteine ADCs that had matched drug-to-antibody ratios and identical linkers but differently charged auristatin payloads, vcMMAE (neutral) and vcMMAF (negative). Both ADCs exhibited higher aggregation than their parent antibody under shaking stress and thermal stress conditions. However, conjugation with vcMMAF increased the aggregation rates to a greater extent than conjugation with uncharged but more hydrophobic vcMMAE. Consistent with the payload logD values, ADC-vcMMAE showed the greatest increase in hydrophobicity but minor changes in charge compared with the parent antibody, as indicated by hydrophobic interaction chromatography and capillary electrophoresis data. In contrast, ADC-vcMMAF showed a decrease in net charge and isoelectric point along with an increase in charge heterogeneity. This charge alteration likely contributed to a reduced electrostatic repulsion and increased surface activity in ADC-vcMMAF, thus affecting its aggregation propensity. These findings suggest that not only the hydrophobicity of the payload, but also its charge should be considered as a critical factor affecting the stability of ADCs. [ABSTRACT FROM AUTHOR]

Antibiotic-resistant microorganisms have become a serious threat to public health, resulting in hospital infections, the majority of which are caused by commonly used urinary tract catheters. Strategies for preventing bacterial adhesion to the catheters' surfaces have been potentially shown as effective methods, such as coating thesurface with antimicrobial biomolecules. Here, novel antimicrobial peptides (AMPs) were designed as potential biomolecules to prevent antibiotic-resistant bacteria from binding to catheter surfaces. Thiolated AMPs were synthesized using solid-phase peptide synthesis (SPPS), and prep-HPLC was used to obtain AMPs with purity greater than 90%. On the other side, the silicone catheter surface was activated by UV/ozone treatment, followed by functionalization with allyl moieties for conjugation to the free thiol group of cystein in AMPs using thiol-ene click chemistry. Peptide-immobilized surfaces were found to become more resistant to bacterial adhesion while remaining biocompatible with mammalian cells. The presence and site of conjugation of peptide molecules were investigated by immobilizing them to catheter surfaces from both ends (C-Pep and Pep-C). It was clearly demonstrated that AMPs conjugated to the surface via theirN terminus have a higher antimicrobial activity. This strategy stands out for its effective conjugation of AMPs to silicone-based implant surfaces for the elimination of bacterial infections. [ABSTRACT FROM AUTHOR]

The Vilsmeier–Haack reaction of ketones with DMF and POCl3- produced 3-chloroacrylcarbaldehydes, which were converted into the corresponding (Z)-4-[(Z)- or (Z)-4-[(E)-3-chloroallylidene)-2-phenyloxazol-5(4 H)-ones] (azlactones) or their isomeric mixtures when heated with hippuric acid in propionic anhydride. It was shown that the alcoholysis products of these compounds, resulting from the opening of the oxazolone ring, undergo copper-catalyzed intramolecular cross-coupling reactions with the formation of methyl 1 H -pyrrole-2-carboxylates. Thus, a one-pot method was developed for the synthesis of methyl 1 H -pyrrole-2-carboxylates starting from 4-(3-chloroallylidene)-2-phenyloxazol-5(4 H)-ones. [ABSTRACT FROM AUTHOR]

An operator T ∈ L (H) is said to be C-normal if there exists a conjugation C on H such that the commutator [ (C T) # , C T ] equals zero, where [ R , S ] : = R S - S R and R # is a Hermitian adjont operator of R as in (1). If there exists a conjugation C with respect to which T ∈ L (H) is C-normal, then T is called a conjugation-normal operator. In this paper, we study properties of conjugation-normal operator matrices. In particular, we focus on the conjugation-normality of the component operators of operator matrices which are conjugation-normal. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effect of low concentration of Wenyang Tonglin Decoction (WTD) on the binding conditions of R45 plasmid conjugative transfer under liquid phase conjugation and its mechanism. Methods: Escherichia coli CP9 (R45) and Staphylococcus aureus RN450RF were cultured in medium containing WTD, and their minimum inhibitory concentration (MIC) values were obtained. Using promoter fusion technology, E. coli CP9 (R45) containing a promoter fusion was obtained. β-Galactosidase activity of TrfAp and TrbBp was tested, and the mRNA expression of regulatory factors (TrbA, KorA, and KorB) was detected by real-time fluorescent quantitative polymerase chain reaction. Results: The MIC of E. coli CP9 (R45) was 400 g/L and that of S. aureus RN450RF was 200 g/L. When the drug concentration in the culture medium was 200 g/L, the highest number of conjugants was (3.47 ±0.20) × 107 CFU/mL At 90 h of conjugation, the maximum number of conjugants was (1.15 ±0.06) × 108 CFU/mL When the initial bacterial concentration was 108 CFU/mL, the maximum number of conjugants was (3.47 ± 0.20) × 107 CFU/mL. When the drug concentration was 200 g/L, the β-galactosidase activity of TrfAp and TrbBp significantly increased; the relative quantification of TrbA, KorA and KorB were significantly inhibited. Conclusion: Low concentration of WTD promoted the development of bacterial resistance by affecting promoters and inhibiting the expression of regulatory factors. [ABSTRACT FROM AUTHOR]

Emerging pollutants such as microplastics in water environments readily accumulate microorganisms on their surfaces, forming biofilms and concentrating antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Consequently, microplastic biofilms have attracted the attention of researchers. Horizontal gene transfer (HGT) of ARGs is one of the primary ways that bacteria acquire antibiotic resistance. Most studies focus on the effects of nanomaterials on suspended bacteria, but microplastic biofilms as hotspots for horizontal gene transfer also warrant significant investigation. This study primarily explored and compared the effects of nano-titanium dioxide on the conjugation transfer frequency of ARGs in suspended bacteria and microplastic biofilms. Nano-titanium dioxide could promote ARG conjugation in both suspended bacteria and microplastic biofilms, with a greater effect on the former. The mechanism involved nano-titanium dioxide promoting the production of reactive oxygen species (ROS) in suspended and biofilm bacteria, increasing the synthesis of outer membrane proteins, enhancing the cell membrane permeability, and elevating the expression levels of conjugation-related genes, thereby facilitating the conjugation transfer of ARGs. Biofilm bacteria, being heavily encased and protected by extracellular polymeric substances (EPS), exhibit greater resistance to external environmental pressure, resulting in the weaker impact of nano-titanium dioxide on biofilm bacteria compared to suspended bacteria. This study reveals the risk of ARG conjugation transfer within microplastic biofilms induced by nanomaterials, providing valuable insights into the risks of microplastic and antibiotic resistance dissemination in water environments. [ABSTRACT FROM AUTHOR]

A delivery system was developed according to maillard reaction using mung bean protein and maltodextrin for encapsulation and sustain release of curcumin. The ultrasound assisted (150 W, 80 °C, 10 min) and classic wet heating (80 °C, 60 min), were used to prepare conjugates at three different ratios of Mung bean protein isolate to maltodextrin. Degree of conjugation was measured using OPA method Uv-visible spectroscopy was used to estimate the final products of maillard reaction. Different amounts of curcumin (0, 0.2, 0.4 and 0.6 mg. mL-1 was loaded using ethanol and change in pH. Primary analysis showed that the optimized samples were obtained when 0. 4 mg. mL-1 of curcumin was encapsulated using pH change method. FTIR spectra confirmed the conjugation of the MPI and MD and showed the electrostatic and hydrophobic interactions as well as hydrogen bonding are the main reasons of conjugates stability and curcumin encapsulation. The prepared curcumin containing conjugates under optimized method showed the higher DPPH radical scavenging activity. Our results showed that the release rate of encapsulated curcumin under simulated condition of gastrointestinal tract (GIT) was controlled and lower than that which encapsulated in mung bean protein. [ABSTRACT FROM AUTHOR]

Quaternion algebra ℍ is a noncommutative associative algebra. In recent years, quaternionic Fourier analysis has received increasing attention due to its applications in signal analysis and image processing. This paper addresses conjugate phase retrieval problem in the quaternion Euclidean space ℍ M with M ≥ 2 . Write ℂ η = { ξ : ξ = ξ 0 + β ⁢ η , ξ 0 , β ∈ ℝ } for η ∈ { i , j , k } . We remark that not only ℂ η M -vectors cannot allow traditional conjugate phase retrieval in ℍ M , but also ℂ i M ∪ ℂ j M -complex vectors cannot allow phase retrieval in ℍ M . We are devoted to conjugate phase retrieval of ℂ i M ∪ ℂ j M -complex vectors in ℍ M , where "conjugate" is not the traditional conjugate. We introduce the notions of conjugation, maximal commutative subset and conjugate phase retrieval. Using the phase lifting techniques, we present some sufficient conditions on complex vectors allowing conjugate phase retrieval. And some examples are also provided to illustrate the generality of our theory. [ABSTRACT FROM AUTHOR]

Investigations of the nature and degree of antiaromaticity of cycloheptatrienyl anion derivatives using both experimental and computational tools are presented. The ground state of cycloheptatrienyl anion in the gas phase is triplet, planar and Baird‐aromatic. In DMSO, it assumes a singlet distorted allylic form with a paratropic ring current. The other derivatives in both phases assume either allylic or diallylic conformations depending on the substituent pattern. A combination of experimental and computational methods was used to determine the pKa values of 16 derivatives in DMSO, which ranged from 36 to −10.7. We revealed that the stronger stabilization of the anionic system, which correlates with acidity, does not necessarily imply a lower degree of antiaromaticity in terms of magnetic properties. Conversely, the substitution pattern first affects the geometry of the ring through the bulkiness of the substituents and their better conjugation with a more distorted system. Consequently, the distortion reduces the cyclic conjugation in the π‐system and thereby decreases the paratropic current in a magnetic field, which manifests itself as a decrease in the NICS. The triplet‐state geometries and magnetic properties are nearly independent on the substitution pattern, which is typical for simple aromatic systems. [ABSTRACT FROM AUTHOR]

We introduce the C-decomposition property for reducible bounded linear operators on a Hilbert space, and prove that an arbitrary idempotent operator has the C-decomposition property with respect to a particular space decomposition, which is related to Halmos’ two projections theory. Using this, we obtain a general explicit description for all the conjugations C such that a given idempotent operator is a C-projection. We also present a characterization of the ranges of C-projections for any conjugation C. [ABSTRACT FROM AUTHOR]

4,16‐para‐substituted [2.2]paracylophanes with naphthalene (PCP‐NAP), anthracene (PCP‐ANTH), and tetraphenylethylene (PCP‐TPE), as new through‐space conjugated dimers, were prepared by the Suzuki‐Miyaura cross‐coupling reaction of 4,16‐diboryl[2.2]paracyclophane and the corresponding bromo derivative using Pd(PPh3)4 as a catalyst and KOH as a base. The synthesized compounds were fully characterized by NMR and HR‐MS, and their photophysical and electrochemical properties were studied. The photoluminescence quantum yield of PCP‐NAP, PCP‐ANTH were determined to be 0.21, 0.50, and for PCP‐TPE in aggregated state 0.31, respectively. PCP‐TPE exhibited aggregation‐induced emission characteristics when the water fraction was greater than 50 % in THF/water mixtures. PCP‐ANTH and PCP‐TPE were also characterized by X‐ray crystallography, PCP‐ANTH crystallizes in centrosymmetric monoclinic space group C2/c and PCP‐TPE crystallizes in the centrosymmetric triclinic space group P‐1 with one molecule residing at the inversion center. The observed properties of these π‐stacked dimers were compared with respect to through‐space conjugation and conjugation length in the structure. [ABSTRACT FROM AUTHOR]

Glycoconjugation is a well-established technology for vaccine development: linkage of the polysaccharide (PS) antigen to an appropriate carrier protein overcomes the limitations of PS T-independent antigens, making them effective in infants and providing immunological memory. Glycoconjugate vaccines have been successful in reducing the burden of different diseases globally. However, many pathogens still require a vaccine, and many of them display a variety of glycans on their surface that have been proposed as key antigens for the development of high-valency glycoconjugate vaccines. CDAP chemistry represents a generic conjugation strategy that is easily applied to PS with different structures. This chemistry utilizes common groups to a large range of PS and proteins, e.g., hydroxyl groups on the PS and amino groups on the protein. Here, new fast analytical tools to study CDAP reaction have been developed, and reaction conditions for PS activation and conjugation have been extensively investigated. Mathematical models have been built to identify reaction conditions to generate conjugates with wanted characteristics and successfully applied to a large number of bacterial PSs from different pathogens, e.g., Klebsiella pneumoniae, Salmonella Paratyphi A, Salmonella Enteritidis, Salmonella Typhimurium, Shighella sonnei and Shigella flexneri. Furthermore, using Salmonella Paratyphi A O-antigen and CRM197 as models, a design of experiment approach has been used to study the impact of conjugation conditions and conjugate features on immunogenicity in rabbits. The approach used can be rapidly extended to other PSs and accelerate the development of high-valency glycoconjugate vaccines. [ABSTRACT FROM AUTHOR]

The study delves into the use of the thiol-yne click reaction to enhance (bio)conjugation methodologies, particularly focusing on immobilizing biomolecules onto PLLA surfaces. The thiol-yne click reaction, known for its efficiency, selectivity, and versatility in forming carbon-sulfur bonds under mild conditions without transition metal catalysts, is explored for conjugating the fluorophore dansyl onto PLLA surfaces. This approach aims to broaden bioconjugation strategies beyond traditional methods like the Michael-type reaction, expanding their applicability to diverse biomolecules. Utilizing a photoinitiator and specific light for photo-immobilization, the thiol-yne click reaction offers spatial and temporal control, with the absence of transition metal catalysts mitigating concerns of cytotoxicity and metal contamination, rendering it suitable for biomedical applications. The objectives of this research encompass demonstrating the feasibility of the thiol-yne click reaction for surface functionalization and enriching bioconjugation strategies for tailoring PLLA surfaces, ultimately advancing biomedical technologies through precise control over surface properties and functionality. For this purpose, PLLA surfaces were activated through hydrolysis and amidation to introduce the activated alkyne moiety (PLLA-Alkyne), followed by photo-induced dansyl immobilization (PLLA-Dns) with Irgacure 651. Various surface characterization techniques, including SEM, WCA, XPS, ATR-FTIR, and fluorescence microscopy and spectroscopy, validated the successful conjugation. This metal-free method preserves the material's bulk properties while enabling thiol-containing molecule immobilization. [ABSTRACT FROM AUTHOR]

Public health faces daily challenges due to increasing reports of pathogenic microorganisms with new antimicrobial resistance. Klebsiella michiganensis, an emerging pathogen, poses difficulty in its identification using conventional techniques. This study presents the first documented case of NDM-1-producing K. michiganensis in Brazil, identified as the new ST418. Initially, the isolate from a tracheal secretion was misidentified as K. oxytoca. However, accurate identification was achieved through ANI analyses. Whole-genome sequencing was conducted to characterize the genetic context of the resistance genes, to identify virulence factors, and to construct a phylogenetic tree. The blaNDM-1 gene was found to be harbored on an IncFIB plasmid approximately 112 kb in length, which was transferable in conjugation assays. The detection of carbapenem resistance genes in this species highlights the importance of public health vigilance, as it may serve as a reservoir and disseminator of significant resistance genes. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) is a major public health threat, exacerbated by the ability of bacteria to rapidly disseminate antimicrobial resistance genes (ARG). Since conjugative plasmids of the incompatibility group P (IncP) are ubiquitous mobile genetic elements that often carry ARG and are broad-host-range, they are important targets to prevent the dissemination of AMR. Plasmid-dependent phages infect plasmid-carrying bacteria by recognizing components of the conjugative secretion system as receptors. We sought to isolate plasmid-dependent phages from wastewater using an avirulent strain of Salmonella enterica carrying the conjugative IncP plasmid pKJK5. Irrespective of the site, we only obtained bacteriophages belonging to the genus Alphatectivirus. Eleven isolates were sequenced, their genomes analyzed, and their host range established using S. enterica, Escherichia coli, and Pseudomonas putida carrying diverse conjugative plasmids. We confirmed that Alphatectivirus are abundant in domestic and hospital wastewater using culture-dependent and culture-independent approaches. However, these results are not consistent with their low or undetectable occurrence in metagenomes. Therefore, overall, our results emphasize the importance of performing phage isolation to uncover diversity, especially considering the potential of plasmid-dependent phages to reduce the spread of ARG carried by conjugative plasmids, and to help combat the AMR crisis. [ABSTRACT FROM AUTHOR]

Two regioisomeric extended tetrathiafulvalenes (TTFs) incorporating diindeno‐fused corannulene spacers were synthesized from suitable dione precursors using Horner‐Wadsworth‐Emmons olefination reactions. Both compounds are strong chromophores with a longest‐wavelength absorption that exhibited some degree of charge‐transfer character as inferred from solvatochromic behaviors and frontier orbital calculations. The compounds underwent two reversible one‐electron oxidations and a quasi‐reversible third oxidation during cyclic voltammetry conditions. The mono‐ and dications had characteristic NIR absorptions and both were EPR active. The dications with potential diradicaloid characters underwent reactions when generated in bulk. [ABSTRACT FROM AUTHOR]

Can order markets lead participants towards price-taking equilibrium? Viewing market sessions as steps of iterative algorithms, this paper indicates positive prospects for convergence. Mathematical arguments turn on convolution, efficiency and generalized gradients. Economic arguments revolve around reservation costs, derived from indifference or threshold payments for quantities supplied or demanded. [ABSTRACT FROM AUTHOR]

Antimicrobial-resistance genes (ARGs) are spread among bacteria by horizontal gene transfer, however, the effect of environmental factors on the dynamics of the ARG in water environments has not been very well understood. In this systematic review, we employed the regression tree algorithm to identify the environmental factors that facilitate/inhibit the transfer of ARGs via conjugation in planktonic/biofilm-formed bacterial cells based on the results of past relevant research. Escherichia coli strains were the most studied genus for conjugation experiments as donor/recipient in the intra-genera category. Conversely, Pseudomonas spp. Acinetobacter spp. and Salmonella spp. were studied primarily as recipients across inter-genera bacteria. The conjugation efficiency (ce) was found to be highly dependent on the incubation period. Some antibiotics, such as nitrofurantoin (at ≥0.2 µg ml−1) and kanamycin (at ≥9.5 mg l−1) as well as metallic compounds like mercury (II) chloride (HgCl2, ≥3 µmol l−1), and vanadium (III) chloride (VCl3, ≥50 µmol l−1) had enhancing effect on conjugation. The highest ce value (−0.90 log10) was achieved at 15°C–19°C, with linoleic acid concentrations <8 mg l−1, a recognized conjugation inhibitor. Identifying critical environmental factors affecting ARG dissemination in aquatic environments will accelerate strategies to control their proliferation and combat antibiotic resistance. [ABSTRACT FROM AUTHOR]

Based on the properties of the conjugated p-electron system in cyclic polyenes, possible steric and electronic structures of transition states in thermal isomerizations of pyridine and phosphinine in an oxygen-free atmosphere have been determined by DFT calculations using B3LYP functional and 6-31G* basis set. The degree of stabilization of the transition states depends on the level of p-electron conjugation. Schemes of the thermal isomerizations of pyridine and phosphinine have been constructed, and potential barriers to these transformations have been calculated. The study of the reactivities of pyridine and phosphinine in the thermal isomerization processes has revealed lower aromaticity of phosphinine compared to pyridine. [ABSTRACT FROM AUTHOR]

Amanita phalloides is the primary species responsible for fatal mushroom poisoning, as its main toxin, α-amanitin, irreversibly and potently inhibits eukaryotic RNA polymerase II (RNAP II), leading to cell death. There is no specific antidote for α-amanitin, which hinders its clinical application. However, with the advancement of precision medicine in oncology, including the development of antibody–drug conjugates (ADCs), the potential value of various toxic small molecules has been explored. These ADCs ingeniously combine the targeting precision of antibodies with the cytotoxicity of small-molecule payloads to precisely kill tumor cells. We searched PubMed for studies in this area using these MeSH terms "Amanitins, Alpha-Amanitin, Therapeutic use, Immunotherapy, Immunoconjugates, Antibodies" and did not limit the time interval. Recent studies have conducted preclinical experiments on ADCs based on α-amanitin, showing promising therapeutic effects and good tolerance in primates. The current challenges include the not fully understood toxicological mechanism of α-amanitin and the lack of clinical studies to evaluate the therapeutic efficacy of ADCs developed based on α-amanitin. In this article, we will discuss the role and therapeutic efficacy of α-amanitin as an effective payload in ADCs for the treatment of various cancers, providing background information for the research and application strategies of current and future drugs. [ABSTRACT FROM AUTHOR]

Photocatalysis technology is an economical and effective new energy technology which depends on the conversion and storage of light energy through an energy transfer process or charge transfer process. Recently, organic semiconductor photocatalytic materials with the advantages of controllable structure, broad spectral response, designability, and flexibility have received wide attention. In particular, the organic polymeric materials containing poly-perylene diimides (PDI) show significant promise in the realm of photocatalysis due to their impressive catalytic capabilities and wide spectral reactivity. However, a poor charge separation and transportation (CST) process undermines their photocatalytic efficiency in most polymer photocatalysts, as well as in PDI photocatalysts. In this context, we propose a new strategy through regulating the monomer symmetry to construct highly efficient PDI photocatalysts. As proof-of-concept, a series of new PDI-based organic supramolecular photocatalytic materials with full visible spectral response from the perspectives of both the π-π conjugated structure and the symmetry of chain structure are successfully synthesized. Meanwhile, the structural compositions, morphology features, electrical properties, and photocatalytic performances of those obtained PDI photocatalysts were systematically studied. The results shown that the as-prepared PDI-1,5NDA exhibits 1.6-fold and 3.7-fold higher levels of photosynthesis of H2O2 activity than those of PDI-1,4NDA and PDI-PDA, respectively, which could be ascribe to its lower symmetry and large π-conjugate systems greatly enhances the separation of charge carriers. [ABSTRACT FROM AUTHOR]

We determine which bipartite graphs embedded in a torus are move-reduced. In addition, we classify equivalence classes of such move-reduced graphs under square/spider moves. This extends the class of minimal graphs on a torus studied by Goncharov–Kenyon, and gives a toric analog of Postnikov's and Thurston's results on a disk. [ABSTRACT FROM AUTHOR]

The search for better energy storage systems that are less expensive, resource-abundant, and safer has sparked intense research into zinc ion batteries (ZIBs). Organic materials, especially quinones-based ZIBs, improved the rate performances by providing structural flexibility for the movement of zinc ions. In this work, a highly conjugated quinone molecule, tetrakis-lawsone (TLS), with multiple active sites, was used to enhance the capacity of the ZIBs. The non-planar geometry of TLS due to the different orientations of all four lawsone units of TLS provided a sufficient void for the Zn2+ movement, making it a suitable host cathode material for the ZIBs. TLS molecule consists of four LS units, which are aligned differently, thus, creating many empty void spaces in its matrix. Hence, it facilitates the Zn2+ ion movement within its lattice and thereby maximizes the utilization of TLS for energy storage. [ABSTRACT FROM AUTHOR]

A total of 55 food and clinical S. Schwarzengrund isolates were assayed for plasmid content, among which an IncFIB-IncFIC(FII) fusion plasmid, conferring streptomycin resistance, was detected in 17 isolates. Among the 17 isolates, 9 were food isolates primarily collected from poultry meat, and 8 clinical isolates collected from stool, urine, and gallbladder. SNP--based phylogenetic analyses showed that the isolates carrying the fusion plasmid formed a subclade indicating the plasmid was acquired and is now maintained by the lineage. Phylogenetic analysis of the plasmid suggested it is derived from avian pathogenic plasmids and might confer an adaptive advantage to the S. Schwarzengrund isolates within birds. IncFIB-IncFIC(FII) fusion plasmids from all food and three clinical isolates were self-conjugative and successfully transferred into E. coli J53 by conjugation. Food and clinical isolates had similar virulome profiles and were able to invade human Caco-2 cells. However, the IncFIB-IncFIC(FII) plasmid did not significantly add to their invasion and persistence potential in human Caco-2 cells. [ABSTRACT FROM AUTHOR]

Streptavidin is a tetrameric protein with high specificity and affinity for biotin. The interaction between avidin and biotin has become a valuable tool in nanotechnology. In recent years, the site‐specific biotin modification of proteins using biotin ligases, such as BirA, has attracted attention. This study established an in vivo method for achieving the complete biotinylation of target proteins using a single plasmid co‐expressing BirA and its target proteins. Specifically, a biotin‐modified protein was produced in Escherichia coli strain BL21(DE3) using a single plasmid containing genes encoding both BirA and a protein fused to BirA's substrate sequence, Avitag. This approach simplifies the production of biotinylated proteins in E. coli and allows the creation of various biotinylated protein types through gene replacement. Furthermore, the biotin modification rate of the obtained target protein could be evaluated using Native‐PAGE without performing complicated isolation operations of biotinylated proteins. In Native‐PAGE, biotin‐modified proteins and unmodified proteins were confirmed as clearly different bands, and it was possible to easily derive the modification rate from the respective band intensities. [ABSTRACT FROM AUTHOR]

1Laboratorio de Investigaciones en Mecanismos de Resistencia a Antibio´ ticos, Instituto de Investigaciones en Microbiologı ´a y Parasitologı ´a Me´ dica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Cientı ´ficas y Tecnolo´ gicas (IMPaM, UBACONICET), Buenos Aires, Argentina, [ABSTRACT FROM AUTHOR]

Drug conjugation to an antibody can affect its stability, which depends on factors such as the conjugation technique used, drug-linker properties, and stress encountered. This study focused on the effects of agitation stress on the physical stability of two lysine (ADC-K) and two interchain cysteine (ADC-C) conjugates of an IgG 1 monoclonal antibody (mAb) linked to either ∼4 MMAE or DM1 payloads. During agitation, all antibody–drug conjugates (ADCs) exhibited higher aggregation than the mAb, which was dependent on the conjugation technique (aggregation of ADC-Ks > ADC-Cs) and drug-linker (aggregation of ADCs with MMAE > ADCs with DM1). The aggregation propensities correlated well with higher self-interaction, hydrophobicity, and surface activity of ADCs relative to the mAb. The intermediate reduced mAb (mAb-SH) showed even higher aggregation than the final product ADC-Cs. However, blocking mAb-SH's free thiols with N-ethylmaleimide (NEM) strongly reduced its aggregation, suggesting that free thiols should be minimized in cysteine ADCs. Further, this study demonstrates that a low-volume surface tension method can be used for estimating agitation-induced aggregation of ADCs in early development phases. Identifying liabilities to agitation stress and their relationship to biophysical properties may help optimize ADC stability. [ABSTRACT FROM AUTHOR]

Overcoming the blood–brain barrier (BBB) remains a significant hurdle in effective drug delivery to the brain. While the BBB serves as a crucial protective barrier, it poses challenges in delivering therapeutic agents to their intended targets within the brain parenchyma. To enhance drug delivery for the treatment of neurological diseases, several delivery technologies to circumvent the BBB have been developed in the last few years. Among them, nanoparticles (NPs) are one of the most versatile and promising tools. Here, we summarize the characteristics of NPs that facilitate BBB penetration, including their size, shape, chemical composition, surface charge, and importantly, their conjugation with various biological or synthetic molecules such as glucose, transferrin, insulin, polyethylene glycol, peptides, and aptamers. Additionally, we discuss the coating of NPs with surfactants. A comprehensive overview of the common in vitro and in vivo models of the BBB for NP penetration studies is also provided. The discussion extends to discussing BBB impairment under pathological conditions and leveraging BBB alterations under pathological conditions to enhance drug delivery. Emphasizing the need for future studies to uncover the inherent therapeutic properties of NPs, the review advocates for their role beyond delivery systems and calls for efforts translating NPs to the clinic as therapeutics. Overall, NPs stand out as a highly promising therapeutic strategy for precise BBB targeting and drug delivery in neurological disorders. [ABSTRACT FROM AUTHOR]

In this research work, we designed a smart biodegradable PEG-coated MnO2 nanoparticles conjugated with doxorubicin (PMnO2-Dox NPs) for dual chemo-photodynamic therapy and magnetic resonance imaging (MRI) application. This highly sensitive pH-responsive PMnO2-Dox NPs causes effective drug release under acidic pH environment. PMnO2-Dox NPs not only improves the efficacy of chemo-photodynamic therapy due to synergistic response as well as improved MRI imaging via boosting T1 MRI contrast. Manifold characterization techniques have been employed for materials investigation. Crystallography of PMnO2-Dox NPs were performed by using XRD analysis, which confirmed tetragonal crystal structure with an approximate crystallite size of 20–30 nm. Surface morphology was confirmed via SEM analysis, results indicated the spherical and asymmetric agglomerated nanocluster of PMnO2-Dox NPs. In in vitro bioassay, the anticancer activity of PMnO2-Dox NPs were tested against breast cancer (MCF-7) cell line using MTT test. Moreover, it can also inhibit the growth of primary and secondary cancers without light exposure. Results suggested that PMnO2-Dox NPs not only convenient for cancer treatment via combined chemo-photodynamic therapy but also address the way towards a comprehensive strategy for MRI application via bright contrast agent T1 after overcoming the problem of multidrug resistance (MDR) and synergistic response of therapeutic analysis.

The occurrence of extended-spectrum β-lactamase (ESBL)/AmpC β-lactamase-producing Salmonella conferring resistance to third-generation cephalosporin has emerged as a global public health concern. In this study, we aimed to investigate the prevalence and molecular characterization of third-generation cephalosporin-resistant Salmonella enterica serovar Infantis. In total, 409 S. Infatis isolates were collected from the feces and carcasses of healthy and diseased food animals, including chickens (n = 348), pigs (n = 48), cattle (n = 8), and ducks (n = 5) between 2010 and 2022 nationwide in South Korea. Among them, 61.9 % (253/409) of S. Infantis strains displayed resistance to ceftiofur, with the most resistant isolates obtained from chickens (98.4 %, 249/253). Moreover, S. Infantis isolates showed high resistance (47.7–67.2 %) to streptomycin, ampicillin, nalidixic acid, sulfisoxazole, chloramphenicol, tetracycline, and trimethoprim/sulfamethoxazole. Additionally, the multidrug resistance (MDR) was significantly greater in the ceftiofur-resistant isolates compared to the ceftiofur-susceptible isolates (p

IntroductionHorizontal gene transfer (HGT) of antibiotic resistance genes (ARGs) is one of the primary routes of antimicrobial resistance (AMR) dissemination. In the One Health context, tracking the spread of mobile genetic elements (MGEs) carrying ARGs in agri-food ecosystems is pivotal in understanding AMR diffusion and estimating potential risks for human health. So far, little attention has been devoted to plant niches; hence, this study aimed to evaluate the conjugal transfer of ARGs to the bacterial community associated with the plant rhizosphere, a hotspot for microbial abundance and activity in the soil. We simulated a source of AMR determinants that could enter the food chain via plants through irrigation.MethodsAmong the bacterial strains isolated from treated wastewater, the strain Klebsiella variicola EEF15 was selected as an ARG donor because of the relevance of Enterobacteriaceae in the AMR context and the One Health framework. The strain ability to recolonize lettuce, chosen as a model for vegetables that were consumed raw, was assessed by a rifampicin resistant mutant. K. variicola EEF15 was genetically manipulated to track the conjugal transfer of the broad host range plasmid pKJK5 containing a fluorescent marker gene to the natural rhizosphere microbiome obtained from lettuce plants. Transconjugants were sorted by fluorescent protein expression and identified through 16S rRNA gene amplicon sequencing.Results and discussionK. variicola EEF15 was able to colonize the lettuce rhizosphere and inhabit its leaf endosphere 7 days past bacterial administration. Fluorescence stereomicroscopy revealed plasmid transfer at a frequency of 10−3; cell sorting allowed the selection of the transconjugants. The conjugation rates and the strain’s ability to colonize the plant rhizosphere and leaf endosphere make strain EEF15::lacIq-pLpp-mCherry-gmR with pKJK5::Plac::gfp an interesting candidate to study ARG spread in the agri-food ecosystem. Future studies taking advantage of additional environmental donor strains could provide a comprehensive snapshot of AMR spread in the One Health context.

Empirical studies revealed the EFL students’ writing problems, such as incomplete paragraph development and conjugation accuracy. These problems affected the overall text coherence. These problems have inspired teacher researchers to investigate alternative instructional techniques to improve the flow of ideas and conjugation accuracy of EFL students' paragraphs. This current research aims to investigate mood and paragraph structure analysis effectiveness to develop the conjugation accuracy and flow of ideas fluency in EFL students' paragraphs. This study followed an experimental design utilizing control and experimental groups. The research subjects comprised 30 2nd-year undergraduate EFL learners who were at an intermediate level of English proficiency. Data for this research were collected using multiple methods, including tests, documentation, and interviews. The research results revealed that mood analysis and paragraph-structure analysis were effective techniques for improving the conjugation accuracy and idea flow fluency of EFL students' writing. Thus, it is recommended that mood and paragraph structure analyses be alternative techniques to teach paragraph writing.

Background: Our objective was to investigate the prevalence of plasmid-mediated quinolone resistance (PMQR) genes in fluoroquinolone-nonsusceptible Klebsiella pneumoniae (FQNSKP) in Taiwan, 1999–2022. Methods: A total of 938 FQNSKP isolates were identified from 1966 isolates. The presence of PMQR and virulence genes, antimicrobial susceptibility, capsular types, and PMQR-plasmid transferability were determined. Results: An increasing number of PMQR-containing FQNSKP isolates were observed over the study period. Our results showed that 69.0% (647 isolates) of FQNSKP isolates contained at least one PMQR gene, and 40.6%, 37.0%, and 33.9% of FQNSKP carried aac(6′)-Ib-cr, qnrB, and qnrS, respectively. None of FQNSKP carried qepA and qnrC. The most common combination of PMQR genes was aac(6′)-Ib-cr and qnrB (12.3%). The presence of PMQR genes is strongly related to resistance to aminoglycoside, cephalosporin, tetracycline, and sulfamethoxazole/trimethoprim in FQNSKP. The capsular serotype K64 is the most common serotype we tested in both the non-PMQR and PMQR FQNSKP isolates, while K20 showed a higher prevalence in PMQR isolates. The magA and peg-344 genes showed a significantly higher prevalence rate in non-PMQR isolates than in PMQR isolates. Eleven isolates that carried the PMQR and carbapenemase genes were identified; however, three successful transconjugants showed that the PMQR and carbapenemase genes were not located on the same plasmid. Conclusions: Our results indicated an increasing prevalence of PMQR genes, especially qnrB and qnrS, in FQNSKP in Taiwan. Moreover, the distribution of PMQR genes was associated with capsular serotypes and antimicrobial resistance gene and virulence gene distribution in FQNSKP.

The article is dedicated to the research approach of аcademician S. S. Averintsev, which is widely discussed in modern humanitarian science. Averintsev’s “method” is one of the problems in modern theory and history of culture. In this article it is considered basing on the principles of his approach outlined by famous modern scientists. Averintsev’s “method” is one of the problems in modern theory and history of culture. In this article it is considered basing on the principles of Averintsev’s approach outlined by famous modern scientists. The purpose of the article is to consider a symbol, the central concept of Averintsev, the interpretation of which, according to the scientist, is the main aim of a humanitarian researcher. The research methods used in the article are: comparative — so that to identify the peculiarities of understanding the symbol relative to other concepts (for example, Paul Tillich); contextual — to define disciplinary boundaries (or their absence) of the concept symbol; theological — to identify the doctrinal foundations of Averintsev’s definitions; structural-practical — to show the effectiveness of Averintsev’s approach and the correspondence of the methodological vector given by him to the specific study of one of the basic symbols of Russian spiritual culture — Sophia the Wisdom. The concept of a symbol in Averintsev’s representations turns out to be not just a universal unit of aesthetics, but also a method of Christian thinking that expresses its dogmatic basis. The essence of the phenomenon of the “symbol” turns out to be the “conjugation” of the material and the otherworldly in the image of God’s descent into the world, that is, it corresponds to the Chalcedonian dogma. The composition and structure of the symbol, thus, sets a methodological and ethical norm for the humanitarian, philologist, culturologist, philosopher or theologian. As an illustration, the article provides an analysis of the article by S. S. Averintsev “To clarify the meaning of the inscription over the konha of the central apse of Sofia of Kyiv”, which shows the relevance and fruitfulness of Averintsev’s symbolology.

The role of monoclonal antibodies as vehicles to deliver payloads has evolved as a powerful tool in cancer therapy in recent years. The clinical development of therapeutic antibody conjugates with precise payloads holds great promise for targeted therapeutic interventions. The use of affinity‐peptide mediated functionalization of native off‐the‐shelf antibodies offers an effective approach to selectively modify IgG antibodies with a drug–antibody ratio (DAR) of 2. Here, we report the traceless, peptide‐directed attachment of two hydroxylamines to native IgGs followed by chemoselective potassium acyltrifluoroborate (KAT) ligation with quinolinium acyltrifluoroborates (QATs), which provide enhanced ligation rates with hydroxylamines under physiological conditions. By applying KAT ligation to the modified antibodies, conjugation of small molecules, proteins, and oligonucleotides to off‐the‐shelf IgGs proceeds efficiently, in good yields, and with simultaneous cleavage of the affinity peptide‐directing moiety. [ABSTRACT FROM AUTHOR]

A wide range of nano-objects is found in many applications of our everyday life. Recognition of their peculiar properties and ease of functionalization has prompted their engineering into multifunctional platforms that are supposed to afford efficient tools for the development of biomedical applications. However, bridging the gap between bench to bedside cannot be expected without a good knowledge of their behaviour in vivo, which can be obtained through non-invasive imaging techniques, such as positron emission tomography (PET). Their radiolabelling with [18F]-fluorine, a technique already well established and widely used routinely for PET imaging, with [18F]-FDG for example, and in preclinical investigation using [18F]-radiolabelled biological macromolecules, has, therefore, been developed. In this context, this review highlights the various nano-objects studied so far, the reasons behind their radiolabelling, and main in vitro and/or in vivo results obtained thereof. Then, the methods developed to introduce the radioelement are presented. Detailed indications on the chemical steps involved are provided, and the stability of the radiolabelling is discussed. Emphasis is then made on the techniques used to purify and analyse the radiolabelled nano-objects, a point that is rarely discussed despite its technical relevance and importance for accurate imaging. The pros and cons of the different methods developed are finally discussed from which future work can develop. [ABSTRACT FROM AUTHOR]

Microcystins (MCs), natural hepatotoxic compounds produced by cyanobacteria, pose significant risks to water quality, ecosystem stability, and the well-being of animals, plants, and humans when present in elevated concentrations. The escalating contamination of irrigation water with MCs presents a growing threat to terrestrial plants. The customary practice of irrigating crops from local water sources, including lakes and ponds hosting cyanobacterial blooms, serves as a primary conduit for transferring these toxins. Due to their high chemical stability and low molecular weight, MCs have the potential to accumulate in various parts of plants, thereby increasing health hazards for consumers of agricultural products, which serve as the foundation of the Earth's food chain. MCs can bioaccumulate, migrate, potentially biodegrade, and pose health hazards to humans within terrestrial food systems. This study highlights that MCs from irrigation water reservoirs can bioaccumulate and come into contact with plants, transferring into the food chain. Additionally, it investigates the natural mechanisms that organisms employ for conjugation and the microbial processes involved in MC degradation. To gain a comprehensive understanding of the role of MCs in the terrestrial food chain and to elucidate the specific health risks associated with consuming crops irrigated with water contaminated with these toxins, further research is necessary. [ABSTRACT FROM AUTHOR]

Sexual reproduction of Zygnematophyceae by conjugation is a less investigated topic due to the difficulties of the induction of this process and zygospore ripening under laboratory conditions. For this study, we collected field sampled zygospores of Spirogyra mirabilis and three additional Spirogyra strains in Austria and Greece. Serial block-face scanning electron microscopy was performed on high pressure frozen and freeze substituted zygospores and 3D reconstructions were generated, allowing a comprehensive insight into the process of zygospore maturation, involving storage compound and organelle rearrangements. Chloroplasts are drastically changed, while young stages contain both parental chloroplasts, the male chloroplasts are aborted and reorganised as 'secondary vacuoles' which initially contain plastoglobules and remnants of thylakoid membranes. The originally large pyrenoids and the volume of starch granules is significantly reduced during maturation (young: 8 ± 5 µm³, mature: 0.2 ± 0.2 µm³). In contrast, lipid droplets (LDs) increase significantly in number upon zygospore maturation, while simultaneously getting smaller (young: 21 ± 18 µm³, mature: 0.1 ± 0.2 and 0.5 ± 0.9 µm³). Only in S. mirabilis the LD volume increases (34 ± 29 µm³), occupying ~50% of the zygospore volume. Mature zygospores contain barite crystals as confirmed by Raman spectroscopy with a size of 0.02 - 0.05 µm³. The initially thin zygospore cell wall (~0.5 µm endospore, ~0.8 µm exospore) increases in thickness and develops a distinct, electron dense mesospore, which has a reticulate appearance (~1.4 µm) in Spirogyra sp. from Greece. The exo- and endospore show cellulose microfibrils in a helicoidal pattern. In the denser endospore, pitch angles of the microfibril layers were calculated: ~18 ± 3° in S. mirabilis, ~20 ± 3° in Spirogyra sp. from Austria and ~38 ± 8° in Spirogyra sp. from Greece. Overall this study gives new insights into Spirogyra sp. zygospore development, crucial for survival during dry periods and dispersal of this genus. [ABSTRACT FROM AUTHOR]

Dental diseases, including conditions affecting oral structures, have become more common due to unhealthy lifestyle choices. Traditional antibiotic treatments face challenges related to the development of antibiotic resistance in bacteria. Photodynamic antibacterial chemotherapy is emerging as a promising alternative using photosensitizers to generate reactive oxygen species upon exposure to light. This article examines the photosensitizer Rose Bengal (RB) immobilized in hyaluronic acid (HA) for prolonged antibacterial action. The RB-HA conjugate demonstrated a molar ratio of approximately three RB residues to each of the ten units of HA. RB-HA exhibited a high singlet oxygen quantum yield (ΔΦ = 0.90), suggesting its efficacy in photodynamic treatment. A photostability analysis revealed slower photobleaching of RB-HA, which is essential for prolonged application. Under visible light and ultrasonic treatment, RB-HA exhibited effective antibacterial activity against Gram-positive S. aureus and Gram-negative E. coli bacteria for at least 80 days. The gradual release of RB ensured sustained bactericidal concentration. The study establishes RB-HA as a promising candidate for antimicrobial photodynamic and sonodynamic therapy in dental and other medical fields, providing enhanced stability and prolonged antibacterial efficacy. [ABSTRACT FROM AUTHOR]