Plasmids encode and can mobilize onion pathogenicity in Pantoea agglomerans.

Pantoea agglomerans is one of four Pantoea species reported in the USA to cause bacterial rot of onion bulbs. However, not all P. agglomerans strains are pathogenic to onion.

A hierarchical pathway for assembly of the distal appendages that organize primary cilia.

Distal appendages are nine-fold symmetric blade-like structures attached to the distal end of the mother centriole. These structures are critical for formation of the primary cilium, by regulating at least four critical steps: ciliary vesicle recruitment, recruitment and initiation of intraflagellar transport (IFT), and removal of CP110. While specific proteins that localize to the distal appendages have been identified, how exactly each protein functions to achieve the multiple roles of the distal appendages is poorly understood.

A comprehensive mechanistic investigation of sustainable carbene N-H insertion catalyzed by engineered His-ligated heme proteins.

Engineered heme proteins possess excellent biocatalytic carbene N-H insertion abilities for sustainable synthesis, and most of them have His as the Fe axial ligand. However, information on the basic reaction mechanisms is limited, and ground states of heme carbenes involved in the prior computational mechanistic studies are under debate. A comprehensive quantum chemical reaction pathway study was performed for the heme model with a His analogue as the axial ligand and carbene from the widely used precursor ethyl diazoacetate with aniline as the substrate.

Sex in aging matters: exercise and chronic stress differentially impact females and males across the lifespan.

Assessing sex as a biological variable is critical to determining the influence of environmental and lifestyle risks and protective factors mediating behavior and neuroplasticity across the lifespan. We investigated sex differences in affective behavior, memory, and hippocampal neurogenesis following short- or long-term exposure to exercise or chronic mild stress in young and aged mice. Male and female mice were assigned control, running, or chronic stress rearing conditions for 1 month (young) or for 15 months (aged), then underwent a behavioral test battery to assess activity, affective behavior, and memory.

A Multidisciplinary Multimodal Aligned Dataset for Academic Data Processing.

Academic data processing is crucial in scientometrics and bibliometrics, such as research trending analysis and citation recommendation. Existing datasets in this domain have predominantly concentrated on textual data, overlooking the importance of visual elements. To bridge this gap, we introduce a multidisciplinary multimodal aligned dataset (MMAD) specifically designed for academic data processing.

Structure and mechanism of vitamin-K-dependent γ-glutamyl carboxylase.

γ-Glutamyl carboxylase (GGCX) is the sole identified enzyme that uses vitamin K (VK) as a cofactor in humans. This protein catalyses the oxidation of VK hydroquinone to convert specific glutamate residues to γ-carboxyglutamate residues in VK-dependent proteins (VDPs), which are involved in various essential biological processes and diseases. However, the working mechanism of GGCX remains unclear.

A reagent to access methyl sulfones.

A chemical reagent to access methyl sulfones has been developed. Its reaction with various bis-nucleophiles leads to the rapid formation of previously unknown heteroaromatic methyl sulfones. Analogous strategy can also be used to construct alkyl-, CHF-, CF- and even bicyclo[1.

Large exciton binding energy in a bulk van der Waals magnet from quasi-1D electronic localization.

Excitons, bound electron-hole pairs, influence the optical properties in strongly interacting solid-state systems and are typically most stable and pronounced in monolayer materials. Bulk systems with large exciton binding energies, on the other hand, are rare and the mechanisms driving their stability are still relatively unexplored. Here, we report an exceptionally large exciton binding energy in single crystals of the bulk van der Waals antiferromagnet CrSBr.

Derivatization of ophiobolin A and cytotoxicity toward breast and glioblastoma cancer stem cells: Varying the ketone and unsaturated aldehyde moieties.

To gain further insights into the importance of the unsaturated 1,4-ketoaldehyde moiety of ophiobolin A (OpA) for the potency and selectivity observed toward cancer stem cells, several derivatives were synthesized through controlled reduction and oxidations of the unsaturated aldehyde and ketone moieties. Structure elucidation of these new OpA derivatives was achieved through detailed NMR studies and comparison to OpA and known isolated congeners possessing variations in these regions. The relative stereochemistry of the newly generated stereocenters was determined by coupling constants in conjunction with conformational analyses (DFT) of the synthetic derivatives.

Structural insights into 2-oxindole-forming monooxygenase MarE: Divergent architecture and substrate positioning versus tryptophan dioxygenases.

MarE, a heme-dependent enzyme, catalyzes a unique 2-oxindole-forming monooxygenation reaction from tryptophan metabolites. To elucidate its enzyme-substrate interaction mode, we present the first X-ray crystal structures of MarE in complex with its prime substrate, (2S,3S)-β-methyl-L-tryptophan and cyanide at 1.89 Å resolution as well as a truncated yet catalytically active version in complex with the substrate at 2.

Role of the Mobile Active Site Flap in IMP Dehydrogenase Inhibitor Binding.

Inosine 5'-monophosphate dehydrogenase (IMPDH) is a promising antibiotic target. This enzyme catalyzes the NAD-dependent oxidation of inosine 5'-monophosphate (IMP) to xanthosine 5'-monophosphate (XMP), which is the rate-limiting step in guanine nucleotide biosynthesis. Bacterial IMPDH-specific inhibitors have been developed that bind to the NAD site.

Ketogenesis supports hepatic polyunsaturated fatty acid homeostasis via fatty acid elongation.

Ketogenesis is a dynamic metabolic conduit supporting hepatic fat oxidation particularly when carbohydrates are in short supply. Ketone bodies may be recycled into anabolic substrates, but a physiological role for this process has not been identified. Here, we use mass spectrometry-based C-isotope tracing and shotgun lipidomics to establish a link between hepatic ketogenesis and lipid anabolism.

Integrating ex situ biomimetic extraction analyses into contaminated sediment assessment and management decisions.

This study evaluated a novel ex situ passive sampling biomimetic extraction (BE) method to estimate toxic potency in sediments. Gas chromatography with flame ionization detection (GC-FID) analysis of polydimethylsiloxane fibers equilibrated with field sediments was used to quantify bioavailable polyaromatic hydrocarbons (PAHs) and other unresolved, site-specific contaminant mixtures. This method is biomimetic because contaminants partition to the fiber based on hydrophobicity and abundance, and GC-FID quantification accounts for all constituents absorbed to the fiber that may contribute to toxicity.

Structural analysis of extracellular ATP-independent chaperones of streptococcal species and protein substrate interactions.

Unlabelled: During infection, bacterial pathogens rely on secreted virulence factors to manipulate the host cell. However, in gram-positive bacteria, the molecular mechanisms underlying the folding and activity of these virulence factors after membrane translocation are not clear. Here, we solved the protein structures of two secreted parvulin and two secreted cyclophilin-like peptidyl-prolyl isomerase (PPIase) ATP-independent chaperones found in gram-positive streptococcal species.

Redox-Detecting Deep Learning for Mechanism Discernment in Cyclic Voltammograms of Multiple Redox Events.

In electrochemical analysis, mechanism assignment is fundamental to understanding the chemistry of a system. The detection and classification of electrochemical mechanisms in cyclic voltammetry set the foundation for subsequent quantitative evaluation and practical application, but are often based on relatively subjective visual analyses. Deep-learning (DL) techniques provide an alternative, automated means that can support experimentalists in mechanism assignment.

Optically Transparent Carbon Electrodes for Single Entity Electrochemistry.

We demonstrate the application and benefit of optically transparent carbon electrodes (OTCEs) for single entity nanoelectrochemistry. OTCEs are prepared by pyrolyzing thin photoresist films on fused quartz coverslips to create conductive, transparent, thin films. Optical, electrical, topographical, and electrochemical properties of OTCEs are characterized to evaluate their suitability for single entity electrochemistry.

Transient Triplet Metallopnictinidenes M-Pn (M = Pd, Pt; Pn = P, As, Sb): Characterization and Dimerization.

Nitrenes (R-N) have been subject to a large body of experimental and theoretical studies. The fundamental reactivity of this important class of transient intermediates has been attributed to their electronic structures, particularly the accessibility of triplet vs singlet states. In contrast, electronic structure trends along the heavier pnictinidene analogues (R-Pn; Pn = P-Bi) are much less systematically explored.

Anisotropic hydrogel microelectrodes for intraspinal neural recordings in vivo.

Creating durable, motion-compliant neural interfaces is crucial for accessing dynamic tissues under in vivo conditions and linking neural activity with behaviors. Utilizing the self-alignment of nano-fillers in a polymeric matrix under repetitive tension, here, we introduce conductive carbon nanotubes with high aspect ratios into semi-crystalline polyvinyl alcohol hydrogels, and create electrically anisotropic percolation pathways through cyclic stretching. The resulting anisotropic hydrogel fibers (diameter of 187 ± 13 µm) exhibit fatigue resistance (up to 20,000 cycles at 20% strain) with a stretchability of 64.

Triethylamine-mediated protonation-deprotonation unlocks dual-drug self assembly to suppress breast cancer progression and metastasis.

Carrier-free nanomedicines exhibited significant potential in elevating drug efficacy and safety for tumor management, yet their self assembly typically relied on chemical modifications of drugs or the incorporation of surfactants, thereby compromising the drug's inherent pharmacological activity. To address this challenge, we proposed a triethylamine (TEA)-mediated protonation-deprotonation strategy that enabled the adjustable-proportion self assembly of dual drugs without chemical modification, achieving nearly 100% drug loading capacity. Molecular dynamic simulations, supported by experiment evidence, elucidated the underlying self-assembly mechanism.

A planar-sheet nongraphitic zero-bandgap sp carbon phase made by the low-temperature reaction of γ-graphyne.

The highest sheet symmetry form of graphyne, with one triple bond between each neighboring hexagon in graphene, irreversibly transforms exothermically at ambient pressure and low temperatures into a nongraphitic, planar-sheet, zero-bandgap phase consisting of intrasheet-bonded sp carbons. The synthesis of this sp carbon phase is demonstrated, and other carbon phases are described for possible future synthesis from graphyne without breaking graphyne bonds. While measurements and theory indicate that the reacting graphyne becomes nonplanar because of sheet wrinkling produced by dimensional mismatch between reacted and nonreacted sheet regions, sheet planarity is regained when the reaction is complete.

Improving Bond Dissociations of Reactive Machine Learning Potentials through Physics-Constrained Data Augmentation.

In the field of computational chemistry, predicting bond dissociation energies (BDEs) presents well-known challenges, particularly due to the multireference character of reactive systems. Many chemical reactions involve configurations where single-reference methods fall short, as the electronic structure can significantly change during bond breaking. As generating training data for partially broken bonds is a challenging task, even state-of-the-art reactive machine learning interatomic potentials (MLIPs) often fail to predict reliable BDEs and smooth dissociation curves.

Fentanyl and Fentanyl Analog Screening Using ASAP-MS With LiveID Confirmation.

Rationale: Fentanyl and fentanyl analogs continue to pose a serious threat to the public health. The vast number of fentanyl analogs emerging on the black-market call for optimized analytical methods for the detection, analysis, and characterization of these extremely dangerous drugs.

Methods: Atmospheric pressure solids analysis probe (ASAP) mass spectrometry was used for the rapid analysis of 250 synthetic opioid standards, including 211 fentanyl analogs, 32 non-fentanyl related opioids, and 8 fentanyl precursors.

Facet-controlled electrosynthesis of nanoparticles by combinatorial screening in scanning electrochemical cell microscopy.

Controlled synthesis of faceted nanoparticles on surfaces without explicit use of ligands has gained attention due to their promising applications in electrocatalysis and chemical sensing. Electrodeposition is a desirable method; however, precise control over their size, spatial distribution, and morphology requires extensive optimization. Here, we report the spatially resolved synthesis of shape-controlled Pt nanoparticles and fast screening of synthesis conditions in scanning electrochemical cell microscopy (SECCM) with pulse potentials.

P-P Coupling and Terminal Metal-Phosphorus Intermediates.

Terminal metal-phosphorus (M-P) complexes are of significant contemporary interest as potential platforms for P-atom transfer (PAT) chemistry. Decarbonylation of metal-phosphaethynolate (M-PCO) complexes has emerged as a general synthetic approach to terminal M-P complexes. M-P complexes that are stabilized by strong M-P multiple bonds are kinetically persistent and isolable.

Vitamin B2 Operates by Dual Thermodynamic and Kinetic Mechanisms to Selectively Tailor Urate Crystallization.

Here we demonstrate how a biologically relevant molecule, riboflavin (vitamin B2), operates by a dual mode of action to effectively control crystallization of ammonium urate (NHHU), which is associated with cetacean kidney stones. In situ microfluidics and atomic force microscopy experiments confirm a strong interaction between riboflavin and NHHU crystal surfaces that substantially inhibits layer nucleation and spreading by kinetic mechanisms of step pinning and kink blocking. Riboflavin does not alter the distribution of tautomeric urate isomers, but its adsorption on NHHU crystal surfaces does interfere with the effects of minor urate tautomer by limiting its ability to induce NHHU crystal defects while also suppressing NHHU nucleation and inhibiting crystal growth by 80% at an uncharacteristically low modifier concentration.