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Quorum sensing (QS) is a conserved cell–cell communication mechanism widely distributed in bacteria, and is oftentimes tightly correlated with pathogen virulence. Quorum quenching enzymes, which interfere with QS through degrading the QS signaling molecules, could attenuate virulence instead of killing the pathogens, and thus are less likely to induce drug resistance. Many Gram-negative bacteria produce N-acyl homoserine lactones (AHLs) for interspecies communication. In this study, we isolated and identified a bacterial strain, Mesoflavibacter zeaxanthinifaciens XY-85, from an Onchidium sp. collected from the intertidal zone of Dapeng Reserve in Shenzhen, China, and found it had strong AHL degradative activity. Whole genome sequencing and blast analysis revealed that XY-85 harbors an AHL lactonase (designated MzmL), which is predicted to have an N-terminal signal peptide and share the “HXHXDH” motif with known AHL lactonases belonging to the Metallo-β-lactamase superfamily. Phylogenetic studies showed MzmL was closest to marine lactonase cluster members, MomL and Aii20J, instead of the AiiA type lactonases. Ultra performance liquid chromatography-mass spectrometry analysis confirmed that MzmL functions as an AHL lactonase catalyzing AHL degradation through lactone hydrolysis. MzmL could degrade both short- and long-chain AHLs with or without a substitution of oxo-group at the C-3 position, and retained full bioactivity under a wide range of temperatures (28–100°C) and pHs (4–11). Furthermore, MzmL significantly reduced Pectobacterium carotovorum subsp. carotovorum virulence factor production in vitro, such as biofilm formation and plant cell wall degrading enzyme production, and inhibited soft rot development on potato slices. These results demonstrated that MzmL may be a novel type of AHL lactonase with good environmental stability, and has great potential to be developed into a novel biological control agent for bacterial disease management.

Summary: Experimental studies have shown that neuropathic pain impairs hippocampal synaptic plasticity. Here, we sought to determine the underlying mechanisms responsible for synaptic changes in neuropathic painful mouse hippocampal neurons. Beyond demonstrating proof-of-concept for the location of DExH-box helicase 9 (DHX9) in the nucleus, we found that it did exist in the cytoplasm and DHX9 depletion resulted in structural and functional changes at synapses in the hippocampus. A decrease of DHX9 was observed in the hippocampus after peripheral nerve injury; overexpression of DHX9 in the hippocampus significantly alleviated the nociceptive responses and improved anxiety behaviors. Mimicking DHX9 decrease evoked spontaneous pain behavioral symptoms and anxiety emotion in naïve mice. Mechanistically, we found that DHX9 bound to dendrin (Ddn) mRNA, which may have altered the level of synaptic- and dendritic-associated proteins. The data suggest that DHX9 contributes to synapses in hippocampal neurons and may modulate neuropathic pain and its comorbidity aversive emotion.

This study investigates the potential of natural products derived from two mangrove soil bacteria, GP521A and GP3R5, in anthracnose management in oil tea. Based on 16s rDNA sequencing, GP521A and GP3R5 were identified as Bacillus velezensis and Pseudoalteromonas caenipelagi, respectively. Both bacteria showed strong antagonistic effects towards multiple fungal pathogens on dual cultural plates. The ethyl acetate extracts of fermentation cultures of GP521A (FEGP5) and GP3R5 (FEGP3) significantly inhibited mycelial growth of both Colletotrichum camelliae MC171, C. fructicola CF-1 and Pyricularia oryzae P131 at 100 and 200 μg/mL, respectively. Furthermore, FEGP5 and FEGP3 significantly inhibited conidiation, conidial germination and appressorial formation in C. camelliae MC171 at 50 μg/mL, with stronger inhibitory effects observed in the latter. On detached oil tea leaves, 100 μg/mL of FEGP5 and FEGP3 resulted in ~ 98.0% and 97.5% reduction in diseased areas, respectively, when applied before MC171 inoculation, whereas the reduction was approximately 55.0% and 77.6%, respectively, in the curative treatments. In fresh fruits, both extracts also significantly inhibited disease development, either in preventative or curative treatments. Moreover, FEGP5 and FEGP3 demonstrated significantly lower aquatic toxicity than prochloraz at the same concentrations towards a commonly used bioindicator, Artemia salina. In conclusion, this study demonstrates the potential of marine microbes derived natural products in development of environmentally compatible biopesticides to control anthracnose in oil tea.

Rice blast, caused by the filamentous fungus Pyricularia oryzae, has long been one of the major threats to almost all rice-growing areas worldwide. Metconazole, 5-(4-chlorobenzyl)-2, 2-dimethyl-1-(1H-1, 2, 4-triazol-1-ylmethyl) cyclopentanol, is a lipophilic, highly active triazole fungicide that has been applied in the control of various fungal pathogens of crops (cereals, barley, wheat), such as the Fusarium and Alternaria species. However, the antifungal activity of metconazole against P. oryzae is unknown. In this study, metconazole exhibited broad spectrum antifungal activities against seven P. oryzae strains collected from rice paddy fields and the wild type strain P131. Scanning electron microscopic analysis and fluorescein diacetate staining assays revealed that metconazole treatment damaged the cell wall integrity, cell membrane permeability and even cell viability of P. oryzae, resulting in deformed and shrunken hyphae. The supplementation of metconazole in vitro increased fungal sensitivity to different stresses, such as sodium dodecyl sulfate, congo red, sodium chloride, sorbitol and oxidative stress (H2O2). Metconazole could inhibit key virulence processes of P. oryzae, including conidial germination, germ tube elongation and appressorium formation. Furthermore, this chemical prevented P. oryzae from infecting barley epidermal cells by disturbing appressorium penetration and subsequent invasive hyphae development. Pathogenicity assays indicated a reduction of over 75% in the length of blast lesions in both barley and rice leaves when 10 μg/mL of metconazole was applied. This study provides evidence to understand the antifungal effects of metconazole against P. oryzae and demonstrates its potential in rice blast management.

The hair follicle (HF) is the fundamental unit for fleece and cashmere production in cashmere goats and is crucial in determining cashmere yield and quality. The mechanisms regulating HF development in cashmere goats during the embryonic period remain unclear. Growing evidence suggests that HF development involves complex developmental stages and critical events, and identifying the underlying factors can improve our understanding of HF development. In this study, samples were collected from embryonic day 75 (E75) to E125, the major HF developmental stages. The embryonic HFs of cashmere goats were subjected to proteomic and metabolomic analyses, which revealed dynamic changes in the key factors and signalling pathways controlling HF development at the protein and metabolic levels. Gene ontology and the Kyoto Encyclopaedia of Genes and Genomes were used to functionally annotate 1784 significantly differentially expressed proteins and 454 significantly differentially expressed metabolites enriched in different HF developmental stages. A joint analysis revealed that the oxytocin signalling pathway plays a sustained role in embryonic HF development by activating the MAPK and Ca2+ signalling pathways, and a related regulatory network map was constructed. This study provides a global perspective on the mechanism of HF development in cashmere goats and enriches our understanding of embryonic HF development.

Insufficient oxygen supply at the tumor site and hypoxia caused during tumor treatment lead to a poor therapeutic effect and poor prognosis. Therefore, effectively overcoming the problem of hypoxia in tumors and avoiding hypoxia that compromises the efficacy of the treatment could improve the anti-tumor therapeutic effect. Thus, this study reports the ability of W18O49@EP nanoparticles to release reactive oxygen species (ROS) during the combined tumor radiotherapy (RT) and photodynamic therapy (PDT). The release of ROS by the nanoparticles during near infrared light (NIR) irradiation was demonstrated by in vitro and in vivo experiments, realizing an effective PDT without inducing hypoxia. Indeed, the ROS did not derive from the oxygen in the tumor microenvironment but they were released by the nanoparticles. Thus, ROS could improve the therapeutic effect of RT avoiding the problem of hypoxia after RT. Hence, W18O49@EP nanoparticles greatly improved the anti-tumor effect due to their effectiveness despite the insufficient oxygen supply and hypoxia caused by traditional RT and PDT.

Failure in the epigenetic reprogramming of somatic cells is considered the main reason for lower cloned embryo development efficiency. Lysine crotonylation (Kcr) occupies an important position in epigenetic modification, while its effects on somatic cell reprogramming have not been reported. In this study, we detected the influence of sodium crotonate (NaCr) on the Kcr levels in three types of somatic cells (muscle-derived satellite cells, MDSCs; fetal fibroblast cells, FFCs; and ear tip fibroblast cells, EFCs). The three types of somatic cells were treated with NaCr for cloned embryo construction, and the cleavage rates and Kcr, H3K9cr, and H3K18cr levels in the cloned embryos were analyzed. The results showed that the abnormal levels of Kcr, H3K9cr, and H3K18cr were corrected in the treatment groups. Although there was no significant difference in the cloned embryo cleavage rate in the FFC treatment group, the cleavage rates of the cloned embryos in the MDSCs and EFCs treatment groups were increased. These findings demonstrated that the Kcr level was increased with NaCr treatment in somatic cells from Cashmere goat, which contributed to proper reprogramming. The reprogramming of somatic cells can be promoted and cloned embryo development can be improved through the treatment of somatic cells with NaCr.

Therapeutic ophthalmic contact lenses with prolonged drug release and improved bioavailability have been developed to circumvent tedious eye drop instillation. In this work, zwitterionic nanogels based on poly(sulfobetaine methacrylate) (PSBMA) were easily fabricated by one-step reflux-precipitation polymerization, with the advantages of being surfactant-free and morphology controlled. Then, the ophthalmic drug levofloxacin (LEV) was encapsulated into the nanogels. A set of contact lenses with varied nanogel-loading content was fabricated by the cast molding method, with the drug-loaded nanogels dispersed in pre-monomer solutions composed of 2-hydroxyethyl methacrylate (HEMA) and N-vinyl-2-pyrrolidone (NVP). The structure, surface morphology, water contact angle (WCA), equilibrium water content (EWC), transmittance, and mechanical properties of the contact lenses were subsequently investigated, and in vitro drug release and biocompatibility were further evaluated. As a result, the optimized contact lens with nanogel-loading content of 8 wt% could sustainably deliver LEV for ten days, with critical lens properties within the range of recommended values for commercial contact lenses. Moreover, cell viability assays revealed that the prepared contact lenses were cytocompatible, suggesting their significant potential as an alternative to traditional eye drops or ointment formulations for long-term oculopathy treatment.

In this work, a spherical nano core-shell material was constructed by encapsulating Fe3O4 microsphere into conductive polymer-metal composite shell. The Fe3O4 microspheres were fabricated by assembling large amounts of Fe3O4 nano-crystals, which endowed the microspheres with super-paramagnetic property and high saturation magnetization. The polymer-metal composite shell was constructed by inserting Pt nano-particles (NPs) into the conductive polymer polypyrrole (PPy). As size and dispersion of the Pt NPs has an important influence on their surface area and surface energy, it was effective to enlarge the interface area between PPy and Pt NPs, enhance the electron transfer efficiency of PPy/Pt composite shell, and reinforced the shell’s structural stability just by tuning the size and dispersion of Pt NPs. Moreover, core-shell structure of the materials made it convenient to investigate the PPy/Pt shell’s shielding effect on the Fe3O4 core’s magnetic response to external magnetic fields. It was found that the saturation magnetization of Fe3O4/PPy/Pt core-shell material could be reduced by 20.5% by regulating the conductivity of the PPy/Pt shell. Keywords: Super-paramagnetic, Conductivity, Magnetic shielding, Structural stability

Xylella fastidiosa is a xylem-limited bacterium in plant hosts and causes Pierce's disease (PD) of grapevines, which differ in susceptibility according to the Vitis species (spp.). In this work we compared X. fastidiosa biofilm formation and population dynamics when cultured in xylem saps from PD-susceptible and -resistant Vitis spp. under different conditions. Behaviors in a closed-culture system were compared to those in different sap-renewal cultures that would more closely mimic the physicochemical environment encountered in planta. Significant differences in biofilm formation and growth in saps from PD-susceptible and -resistant spp. were only observed using sap renewal culture. Compared to saps from susceptible V. vinifera, those from PD-resistant V. aestivalis supported lower titers of X. fastidiosa and less biofilm and V. champinii suppressed both growth and biofilm formation, behaviors which are correlated with disease susceptibility. Furthermore, in microfluidic chambers X. fastidiosa formed thick mature biofilm with three-dimensional (3-D) structures, such as pillars and mounds, in saps from all susceptible spp. In contrast, only small aggregates of various shapes were formed in saps from four out of five of the resistant spp.; sap from the resistant spp. V. mustangensis was an exception in that it also supported thick lawns of biofilm but not the above described 3-D structures typically seen in a mature biofilm from the susceptible saps. Our findings provide not only critical technical information for future bioassays, but also suggest further understanding of PD susceptibility.

Soft contact lenses can improve the bioavailability and prolong the residence time of drugs and, therefore, are ideal drug carriers for ophthalmic drug delivery. Hydrogels are the leading materials of soft contact lenses because of their biocompatibility and transparent characteristic. In order to increase the amount of load drug and to control their release at the expected intervals, many strategies are developed to modify the conventional contact lens as well as the novel hydrogel contact lenses that include (i) polymeric hydrogels with controlled hydrophilic/hydrophobic copolymer ratio; (ii) hydrogels for inclusion of drugs in a colloidal structure dispersed in the contact lenses; (iii) ligand-containing hydrogels; (iv) molecularly imprinted polymeric hydrogels; (v) hydrogel with the surface containing multilayer structure for drugs loading and releasing. The advantages and disadvantages of these strategies in modifying or designing hydrogel contact lenses for extended ophthalmic drug delivery are analyzed in this paper.