The nickel-catalyzed reaction of N-aryl amides with hydroborane or diboron reagents resulted in the formation of the corresponding reduction or borylation products, respectively. Mechanistic studies ...revealed that these reactions proceeded via the activation of the C(aryl)–N bonds of simple, electronically neutral substrates and did not require the presence of an ortho directing group.
The environmental DNA (eDNA) technique is expected to become a powerful, non-invasive tool for estimating the distribution and biomass of organisms. This technique was recently shown to be applicable ...to aquatic vertebrates by collecting extraorganismal DNA floating in the water or absorbed onto suspended particles. However, basic information on eDNA release rate is lacking, despite it being essential for practical applications. In this series of experiments with bluegill sunfish (Lepomis macrochirus), we examined the effect of fish developmental stage on eDNA release rate. eDNA concentration reached equilibrium 3 days after the individual fish were introduced into the separate containers, enabling calculation of the eDNA release rate (copies h-1) from individual fish on the assumption that the number of eDNA released from the fish per unit time equals total degradation in the container (copies h-1). The eDNA release rate was 3-4 times higher in the adult (body weight: 30-75 g) than in the juvenile group (0.5-2.0 g). Such positive relationship between fish size and eDNA release rate support the possibility of biomass rather than density estimation using eDNA techniques. However, the eDNA release rate per fish body weight (copies h-1 g-1) was slightly higher in the juvenile than the adult group, which is likely because of the ontogenetic reduction in metabolic activity. Therefore, quantitative eDNA data should be carefully interpreted to avoid overestimating biomass when the population is dominated by juveniles, because the age structure of the focal population is often variable and unseen in the field. eDNA degradation rates (copies l-1 h-1), calculated by curve fitting of time-dependent changes in eDNA concentrations after fish removal, were 5.1-15.9% per hour (half-life: 6.3 h). This suggests that quantitative eDNA data should be corrected using a degradation curve attained in the target field.
In recent decades, phage therapy has been overshadowed by the widespread use of antibiotics in Western countries. However, it has been revitalized as a powerful approach due to the increasing ...prevalence of antimicrobial-resistant bacteria. Although bacterial resistance to phages has been reported in clinical cases, recent studies on the fitness trade-offs between phage and antibiotic resistance have revealed new avenues in the field of phage therapy. This strategy aims to restore the antibiotic susceptibility of antimicrobial-resistant bacteria, even if phage-resistant variants develop. Here, we summarize the basic virological properties of phages and their applications within the context of antimicrobial resistance. In addition, we review the occurrence of phage resistance in clinical cases, and examine fitness trade-offs between phage and antibiotic sensitivity, exploring the potential of an evolutionary fitness cost as a countermeasure against phage resistance in therapy. Finally, we discuss future strategies and directions for phage-based therapy from the aspect of fitness trade-offs. This approach is expected to provide robust options when combined with antibiotics in this era of phage ‘re’-discovery.
A new method has been developed for the nickel-catalyzed homocoupling of methoxyarenes via C–O bond cleavage using a diboron reagent. The use of 1,3-dicyclohexylimidazol-2-ylidene as a ligand was ...found to be critical to the success of the reaction. This new method allows the synthesis of a wide range of biaryl compounds.
A method of quantifying glyphosate (Gly) in human urine by means of MonoSpin TiO extraction and 9-fluorenylmethoxycarbonyl chloride (FMOC-Cl) derivatization with isotope dilution mass spectrometry ...(IDMS) was investigated and optimized. The method’s quantification limit under optimized conditions was 0.3 µg/kg for FMOC-Gly, which was comparable to or lower than those described in previous studies. When a spike test using human urine samples was carried out with optimized analytical conditions, the trueness for FMOC-Gly was as follows: 101.6–104.9% for a spike level of 0.5 µg/kg and 99.2–101.0% for a spike level of 30 µg/kg. The intra-day repeatability and inter-day reproducibility were <6.5%. The spike test results for validation between the “with” and “without” derivatization methods were comparable at 1 µg/kg. Our results indicate that using MonoSpin TiO extraction and FMOC-Cl derivatization with IDMS is an accurate method for analyzing Gly in human urine.
The bactericidal effect of various types of photoirradiated polyphenols against Gram-positive and -negative bacteria was evaluated in relation to the mode of action. Gram-positive bacteria ...(Enterococcus faecalis, Staphylococcus aureus, and Streptococcus mutans) and Gram-negative bacteria (Aggregatibacter actinomycetemcomitans, Escherichia coli, and Pseudomonas aeruginosa) suspended in a 1 mg/mL polyphenol aqueous solution (caffeic acid, gallic acid, chlorogenic acid, epigallocatechin, epigallocatechin gallate, and proanthocyanidin) were exposed to LED light (wavelength, 400 nm; irradiance, 260 mW/cm2) for 5 or 10 min. Caffeic acid and chlorogenic acid exerted the highest bactericidal activity followed by gallic acid and proanthocyanidin against both Gram-positive and -negative bacteria. It was also demonstrated that the disinfection treatment induced oxidative damage of bacterial DNA, which suggests that polyphenols are incorporated into bacterial cells. The present study suggests that blue light irradiation of polyphenols could be a novel disinfection treatment.
Phage therapy has re-emerged in modern medicine as a robust antimicrobial strategy in response to the increasing prevalence of antimicrobial-resistant bacteria. However, bacterial resistance to ...phages can also arise via a variety of molecular mechanisms. In fact, several clinical studies on phage therapy have reported the occurrence of phage-resistant variants, representing a significant concern for the successful development of phage-based therapies. In this context, the fitness trade-offs between phage and antibiotic resistance have revealed new avenues in the field of phage therapy as a countermeasure against phage resistance. This strategy forces to restore the antibiotic susceptibility of antimicrobial-resistant bacteria as compensation for the development of phage resistance. Here, we present the key achievements of these fitness trade-offs, notably focusing on the enhancement of antibiotic sensitivity through the induction of large chromosomal deletions by bacteriophage infection. We also describe the challenges of this strategy that need to be overcome to promote favorable therapeutic outcomes and discuss future directions. The insights gained from the trade-offs between phage and antibiotic sensitivity will help maximize the potential of phage therapy for the treatment of infectious diseases.
CoO x is a promising hole-extracting layer (HEL) for inverted planar perovskite solar cells with device configuration ITO/CoO x /CH3NH3PbI3/PCBM/Ag. The devices fabricated according to a simple ...solution procedure showed the best photovoltaic performance attaining power conversion efficiency (PCE) of 14.5% under AM 1.5 G 1 sun irradiation, which is significantly superior to those of materials fabricated with a traditional HEL such as PEDOT:PSS (12.2%), NiO x (10.2%), and CuO x (9.4%) under the same experimental conditions. We characterized the chemical compositions with XPS, crystal structures with XRD, and film morphology with SEM/AFM techniques. Photoluminescence (PL) spectra and the corresponding PL decays for perovskite deposited on varied HEL films were recorded to obtain the hole-extracting characteristics, for which the hole-extracting times show the order CoO x (2.8 ns) < PEDOT:PSS (17.5 ns) < NiO x (22.8 ns) < CuO x (208.5 ns), consistent with the trend of their photovoltaic performances. The reproducibility and enduring stability of those devices were examined to show the outstanding long-term stability of the devices made of metal oxide HEL, for which the CoO x device retained PCE ≈ 12% for over 1000 h.
Synthetic composite hydrogels comprising supramolecular fibers and covalent polymers have attracted considerable attention because their properties are similar to biological connective tissues. ...However, an in-depth analysis of the network structures has not been performed. In this study, we discovered the composite network can be categorized into four distinct patterns regarding morphology and colocalization of the components using in situ, real-time confocal imaging. Time-lapse imaging of the network formation process reveals that the patterns are governed by two factors, the order of the network formation and the interactions between the two different fibers. Additionally, the imaging studies revealed a unique composite hydrogel undergoing dynamic network remodeling on the scale of a hundred micrometers to more than one millimeter. Such dynamic properties allow for fracture-induced artificial patterning of a network three dimensionally. This study introduces a valuable guideline to the design of hierarchical composite soft materials.
Multicomponent self-assembly is a fascinating strategy for the construction of smart soft materials. Among them, supramolecular hydrogels comprising self-sorting nanofibers have recently attracted ...significant attention owing to their rationally incorporated stimulus responsiveness. However, there have been limited investigations of the crucial factors that control the self-sorting phenomena. Here, we describe an imaging-based approach to evaluate the factors that control the formation of self-sorting nanofibers from peptide- and lipid-type hydrogelators. We screened a small library of hydrogelators with distinct chemical properties by direct visualization of their self-assembly behavior by using confocal laser scanning microscopy. Our systematic research identified two important factors that influence the self-sorting behavior of nanofibers: (i) the surface charge of the hydrogelators; and (ii) the hydrophobicity of the side chain on the peptide-type hydrogelators. We determined that the same net/surface charge on the hydrogelators and side chains with a lower hydrophobicity on the peptide-type hydrogelators were preferred. These findings, in combination with the previously reported kinetic factors, were used to design and successfully prepare a three-component orthogonal self-assembly composed of supramolecular nanofibers from peptide- and lipid-type hydrogelators and a cationic organorhodium complex. Our findings would be beneficial for the design of intelligent soft materials based on self-sorting phenomena.
PDF
