Streptococcus suis biofilm: regulation,drug-resistance mechanisms,and disinfection strategies

Streptococcus suis (S. suis) is a major swine pathogen and an important zoonotic agent. Like most pathogens, the ability of S. suis to form biofilms plays a significant role in its virulence and drug resistance. A better understanding of the mechanisms involved in biofilm formation by S. suis as well as of the methods to efficiently remove and kill biofilm-embedded bacteria can be of high interest for the prevention and treatment of S. suis infections. The aim of this literature review is to update our current knowledge of S. suis biofilm formation, regulatory mechanisms, drug-resistance mechanisms, and disinfection strategies.

     

Interpenetrating Triphase Cobalt‐Based Nanocomposites as Efficient Bifunctional Oxygen Electrocatalysts for Long‐Lasting Rechargeable Zn–Air Batteries

Rational construction of atomic‐scale interfaces in multiphase nanocomposites is an intriguing and challenging approach to developing advanced catalysts for both oxygen reduction (ORR) and evolution reactions (OER). Herein, a hybrid of interpenetrating metallic Co and spinel Co₃O₄ “Janus” nanoparticles stitched in porous graphitized shells (Co/Co₃O₄@PGS) is synthesized via ionic exchange and redox between Co²⁺ and 2D metal–organic‐framework nanosheets. This strategy is proven to effectively establish highways for the transfer of electrons and reactants within the hybrid through interfacial engineering. Specifically, the phase interpenetration of mixed Co species and encapsulating porous graphitized shells provides an optimal charge/mass transport environment. Furthermore, the defect‐rich interfaces act as atomic‐traps to achieve exceptional adsorption capability for oxygen reactants. Finally, robust coupling between Co and N through intimate covalent bonds prohibits the detachment of nanoparticles. As a result, Co/Co₃O₄@PGS outperforms state‐of‐the‐art noble‐metal catalysts with a positive half‐wave potential of 0.89 V for ORR and a low potential of 1.58 V at 10 mA cm^?2 for OER. In a practical demonstration, ultrastable cyclability with a record lifetime of over 800 h at 10 mA cm^?2 is achieved by Zn–air batteries with Co/Co₃O₄@PGS within the rechargeable air electrode.     

Strong effects of hydrologic environment and weak effects of elevated CO<Subscript>2</Subscript> on the invasive weed <Emphasis Type="Italic">Alternanthera philoxeroides</Emphasis> and the biocontrol beetle <Emphasis Type="Italic">Agasicles hygrophila</Emphasis>

Global change, such as elevated CO₂, may alter interactions between invasive plants and biocontrol agents, impacting biocontrol efficacy. Here, we conducted four experiments in Texas, USA to test how elevated CO₂ influences an invasive plant (Alternanthera philoxeroides) and its interactions with an introduced biocontrol beetle (Agasicles hygrophila) in terrestrial (well-watered) and flooded environments. We grew plants for 9 months in ambient or elevated CO₂ (800 ppm) chambers in continuously flooded or well-watered conditions. In no-choice trials, flooding increased leaf toughness and decreased beetle consumption but beetles only oviposited on ambient CO₂ leaves. In choice trials, beetles preferred to feed and oviposit on terrestrial plants but were also less likely to damage elevated CO₂ leaves. Caged beetle populations were larger in terrestrial conditions than aquatic conditions for a second set of plants grown in the chambers. With a third set of plants grown in the ambient or elevated CO₂ chambers, damage for plants placed in the field (aquatic setting) was higher for plants grown in terrestrial conditions vs. flooded conditions at ambient CO₂. Our results suggest that elevated CO₂ will have minor effects on the efficacy of this biocontrol agent by decreasing oviposition and number of leaves damaged, and hydrologic environment may affect invasive plant performance by altering herbivore oviposition and feeding preferences. A broader understanding of the effects of global change on biocontrol will help prevent and manage future spread of invasive plants.     

Novel γ-lactone derivatives from Trigonostemon heterophyllus with their potential antiproliferative activities

Two novel γ-lactone derivatives, trigoheterophines A (1) and B (2), together with four known furan derivatives (3–6), were isolated from the stems and leaves of Trigonostemon heterophyllus. The structures of 1 and 2 were elucidated by extensive spectroscopic methods and the known compounds were identified by comparing with the data reported in literature. Among them, trigoheterophines A (1) and B (2) represent an unusual type of γ-lactone derivatives, possessing 21 carbon atoms on the carbon skeleton, and known compouds (3–6) are rare furan derivatives in the plant kingdom with diverse long-chain hydrocarbyl groups as substituents at C-4. All isolated compounds were evaluated for their antiproliferative activities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Compounds 1–6 showed significant antiproliferative effects against various human cancer cell lines with IC₅₀ values ranging from 0.28 to 12.06 μM. These findings suggest that the discoveries of these novel γ-lactone derivatives and furan derivatives with significant antiproliferative activities isolated from T. heterophyllus could be of great importance to the development of new anticancer agents.     

Design,synthesis and evaluation of pterostilbene β-amino alcohol derivatives as multifunctional agents for Alzheimer's disease treatment

A series of pterostilbene β-amino alcohol derivatives were designed, synthesized and evaluated as multifunctional agents for the treatment of Alzheimer’s disease (AD). In vitro assays demonstrated that most of the derivatives were selective acetylacholinesterase (AChE) inhibitors with moderate multifunctional properties. Among them, compound 5f exhibited the best inhibitory activity for EeAChE (IC₅₀ = 24.04 μM), that was better than pterostilbene under our experimental condition. In addition, compound 5f displayed reasonable antioxidant activity and could confer significant neuroprotective effect against H₂O₂-induced PC-12 cell injury. Moreover, 5f also showed self-induced Aβ_1-42 aggregation inhibitory potency and displayed high BBB permeability in vitro. These multifunctional properties highlight 5f as a promising candidate for further studies directed to the development of novel drugs against AD.     

烟草赤星病菌拮抗性大豆根瘤内生菌的筛选及抑制作用

以烟草赤星病菌为供试病原菌,采用对峙法、代谢液培养法对分离自大豆根瘤的内生细菌进行抑菌筛选,对筛选菌株作用的病原菌菌丝进行显微观察,研究筛选菌株细胞培养特征及生理生化特性、16S rDNA测序序列、系统发育,以及进行温室接种防病试验.结果表明: 大豆根瘤内生菌经初筛、复筛,对烟草赤星病菌抑菌率42%以上的有7株菌,分别属于芽孢杆菌属、假单胞菌属、中华根瘤菌属和寡养单胞菌属.显微观察表明,在拮抗性内生菌作用下病原菌菌丝末端出现明显畸形,呈珊瑚状分枝、球状膨大等;代谢液试验表明,内生菌对病原菌的抑制作用主要是内生菌代谢产生的胞外物质在发挥作用;对峙试验表明,芽孢杆菌可迅速形成生物薄膜,有效阻碍病原菌丝生长和延伸.盆栽防病试验表明,拮抗性内生菌处理下烟草病情指数显著低于对照,表明筛选菌株可作为烟草赤星病的生防菌株资源.