Isolation and Characterization of Two Novel Antibacterial Cyclic Hexapeptides from Streptomyces alboflavus 313

Two novel cyclic hexapeptides, designated NW-G08 (1) and NW-G09 (2), were isolated from the fermentation broth of Streptomyces alboflavus 313. Their structures were elucidated on the basis of extensive spectroscopic analysis, MS experiments, and chemical analysis. Their antibacterial activities against several strains of bacteria were evaluated by micro-broth dilution method. NW-G08 (1) and NW-G09 (2) were highly antibacterial against Gram-positive but not active against Gram-negative bactaria. The minimum inhibitory concentrations (MICs) of 1 against Bacillus cereus, Bacillus subtilis, and Staphylococcus aureus were 6.25, 6.25, and 1.56?μg/ml, respectively. It is worth noting that 1 and 2 exhibited much higher activities against methicillin-resistant Staphylococcus aureus (MRSA) than ampicillin, which implies that they might be potential candidates for the development of novel drugs against resistant pathogenic bacteria.     

JAK-STAT signaling mediates the senescence of cartilage-derived stem/progenitor cells

Journal of Molecular Histology - Aging is a major risk factor for degenerative joint diseases, such as osteoarthritis (OA). Previous studies have confirmed the link between senescent mesenchymal...     

The accumulation of pigment in fiber related to proanthocyanidins synthesis for brown cotton

Brown cotton is a kind of naturally colored cotton. Because of less processing and little dying, it is more friendlier to environment than white cotton. For brown cotton, pigment accumulation in fiber is one of the most important characteristics. In this study, we selected a brown fiber line and a white fiber cultivar to determine the factor that affects the pigmentation in brown fiber. Accordingly, fibers were collected to verify the presence of PAs by p-dimethylaminocinnamaldehyde (DMACA) and toluidine blue O (TBO) staining. The PAs content and related genes expressions were determined. As a result, there were obvious differences on the aspect of PAs synthesis in fiber between white cotton and brown cotton. For white fiber, the PAs content reached maximum at 5 DPA, and then gradually decreased to zero. But for brown fiber, the PAs content was increased from 5 to 15 DPA stage, and reached the maximum at the 15 DPA stage, then gradually decreased from 15 to 40 DPA stage. On the contrary, in white cotton, PAs were synthesized in the whole developmental stage from 5 to 40 DPA. And PAs content in brown fiber were far more than that in white fiber, which may be the reason why the brown pigment accumulated in brown fiber.     

Spontaneous mutations in FgSAD1 suppress the growth defect of the Fgprp4 mutant by affecting tri-snRNP stability and its docking in Fusarium graminearum

FgPrp4, the only kinase in the spliceosome, is not essential for viability, but is important for splicing efficiency in Fusarium graminearum. The Fgprp4 deletion mutant had severe growth defects but often produced spontaneous suppressors with faster growth rate. To better understand the suppression mechanism, we identified and characterized spontaneous mutations in the tri-snRNP-specific protein, FgSad1, which suppressed the growth defects of Fgprp4. The L512P mutation was verified for its suppressive effects on Fgprp4, suggesting that mutations in FgSad1 may have effects involving FgPrp4 phosphorylation on FgSad1. Phosphoproteomics analysis showed that FgSad1 may not be the direct substrate of FgPrp4 kinase. Furthermore, truncation analysis showed that the N-terminal, extra RS-rich region of FgSad1 is critical for its function and is post-translationally modified. The P258S or S269P mutations in FgSad1 increased its interactions with the U5 protein FgPrp8 and the U4/U6 protein FgPrp31, which may result in tri-snRNP stabilization. Additionally, the D76N mutation increased the association of FgSad1 with the U2 snRNP. These data indicate that suppressor mutations in FgSad1 increase the stability of the tri-snRNP and/or the affinity of FgSad1 with U2 snRNP and therefore potentially facilitate the docking of tri-snRNP into the spliceosome.     

Vacancy in Ultrathin 2D Nanomaterials toward Sustainable Energy Application

The unique physicochemical properties of (2D) nanomaterials make them well‐suited for use in sustainable energy applications. Many of these materials can be further improved with vacancy engineering. This review details recent progress in the vacancy engineering of ultrathin 2D nanomaterials. For clarity, it mainly focuses on various ultrathin 2D materials in three categories: X_a&X_aY_b‐, M_aX_b‐, or M_aX_bY_c‐structured materials. Recently developed vacancies in different types of ultrathin 2D materials, as well as their preparation and characterization, are described. Emphasis is placed on the potential electrochemical energy storage and conversion applications of these materials. This review considers the relationship between vacancy properties and material categories of various ultrathin 2D materials in terms of application requirements, preparation, and characterization techniques. The challenges and future outlook of this promising field are summarized.     

Boosting Polysulfide Redox Kinetics by Graphene‐Supported Ni Nanoparticles with Carbon Coating

Lithium–sulfur batteries have attracted extensive attention because of their high energy density. However, their application is still impeded by the inherent sluggish kinetics and solubility of intermediate products (i.e., polysulfides) of the sulfur cathode. Herein, graphene‐supported Ni nanoparticles with a carbon coating are fabricated by directly carbonizing a metal–organic framework/graphene oxide composite, which is then dispersed on a commercial glass fiber membrane to form a separator with electrocatalytic activity. In situ analysis and electrochemical investigation demonstrate that this modified separator can effectively suppress the shuttle effect and regulate the catalytic conversion of intercepted polysulfides, which is also confirmed by density functional theory calculations. It is found that Ni–C sites can chemically interact with polysulfides and stabilize the radical S₃^?? through Ni? S bonds to enable fast dynamic equilibrium with S₆^2?, while Ni nanoparticles reduce the oxidation barrier of Li₂S and accelerate ion/electron transport. As a result, the corresponding lithium–sulfur battery shows a high cycle stability (88% capacity retention over 100 cycles) even with a high sulfur mass loading of 8 mg cm^?2 and lean electrolyte (6.25 µ L mg^?1). Surprisingly, benefitting from the improved kinetics, the battery can work well at ?50 °C, which is rarely achieved by conventional Li–S batteries.     

鼠伤寒沙门菌入侵宿主细胞机制研究进展*

鼠伤寒沙门菌(Salmonella typhimurium)是一种人畜共患的肠道病原菌,可引起肠道炎症。该病原菌主要通过其致病岛(SPIs)编码的III型分泌系统(T3SS)分泌效应因子,包括促炎因子和抗炎因子。其在入侵肠上皮细胞时会释放促炎因子引发炎症反应,同时,为防止促炎因子过度破坏宿主细胞影响菌体的生存和繁殖,鼠伤寒沙门菌会产生一系列抗炎因子来调节细胞内信号通路,与宿主共同繁殖并最终全身扩散造成严重感染。旨在对鼠伤寒沙门菌利用T3SS效应因子入侵并调节宿主细胞信号通路机制进行概述。