Point mutations in the catalytic domain disrupt cellulose synthase (CESA6) vesicle trafficking and protein dynamics.

Cellulose, the main component of the plant cell wall, is synthesized by the multimeric cellulose synthase (CESA) complex (CSC). In plant cells, CSCs are assembled in the endoplasmic reticulum or Golgi and transported through the endomembrane system to the plasma membrane (PM). However, how CESA catalytic activity or conserved motifs around the catalytic core influence vesicle trafficking or protein dynamics is not well understood. Here, we used yellow fluorescent protein (YFP)-tagged AtCESA6 and created 18 mutants in key motifs of the catalytic domain to analyze how they affected seedling growth, cellulose biosynthesis, complex formation, and CSC dynamics and trafficking in Arabidopsis thaliana. Seedling growth and cellulose content were reduced by nearly all mutations. Moreover, mutations in most conserved motifs slowed CSC movement in the PM as well as delivery of CSCs to the PM. Interestingly, mutations in the DDG and QXXRW motifs affected YFP-CESA6 abundance in the Golgi. These mutations also perturbed post-Golgi trafficking of CSCs. The 18 mutations were divided into 2 groups based on their phenotypes; we propose that Group I mutations cause CSC trafficking defects, whereas Group II mutations, especially in the QXXRW motif, affect protein folding and/or CSC rosette formation. Collectively, our results demonstrate that the CESA6 catalytic domain is essential for cellulose biosynthesis as well as CSC formation, protein folding and dynamics, and vesicle trafficking.

Endosidin20 Targets the Cellulose Synthase Catalytic Domain to Inhibit Cellulose Biosynthesis.

Plant cellulose is synthesized by rosette-structured cellulose synthase (CESA) complexes (CSCs). Each CSC is composed of multiple subunits of CESAs representing three different isoforms. Individual CESA proteins contain conserved catalytic domains for catalyzing cellulose synthesis, other domains such as plant-conserved sequences, and class-specific regions that are thought to facilitate complex assembly and CSC trafficking. Because of the current lack of atomic-resolution structures for plant CSCs or CESAs, the molecular mechanism through which CESA catalyzes cellulose synthesis and whether its catalytic activity influences efficient CSC transport at the subcellular level remain unknown. Here, by performing chemical genetic analyses, biochemical assays, structural modeling, and molecular docking, we demonstrate that Endosidin20 (ES20) targets the catalytic site of CESA6 in Arabidopsis (Arabidopsis thaliana). Chemical genetic analysis revealed important amino acids that potentially participate in the catalytic activity of plant CESA6, in addition to previously identified conserved motifs across kingdoms. Using high spatiotemporal resolution live cell imaging, we found that inhibiting the catalytic activity of CESA6 by ES20 treatment reduced the efficiency of CSC transport to the plasma membrane. Our results demonstrate that ES20 is a chemical inhibitor of CESA activity and trafficking that represents a powerful tool for studying cellulose synthesis in plants.

Fabrication of Silane-Grafted Cellulose Nanocrystals and Their Effects on the Structural, Thermal, Mechanical, and Hysteretic Behavior of Thermoplastic Polyurethane.

Reinforcement of polymer nanocomposites can be achieved by the selection of the appropriate fabrication method, surface modification, and orientation of the filler. Herein, we present a nonsolvent-induced phase separation method with ternary solvents to prepare thermoplastic polyurethane (TPU) composite films with excellent mechanical properties using 3-Glycidyloxypropyltrimethoxysilane-modified cellulose nanocrystals (GLCNCs). ATR-IR and SEM analyses of the GLCNCs confirmed that GL was successfully coated on the surface of the nanocrystals. The incorporation of GLCNCs in TPU resulted in the enhancement of the tensile strain and toughness of pure TPU owing to the enhanced interfacial interactions between them. The GLCNC-TPU composite film had tensile strain and toughness values of 1740.42% and 90.01 MJ/m3, respectively. Additionally, GLCNC-TPU exhibited a good elastic recovery rate. CNCs were readily aligned along the fiber axis after the spinning and drawing of the composites into fibers, which further improved the mechanical properties of the composites. The stress, strain, and toughness of the GLCNC-TPU composite fiber increased by 72.60%, 10.25%, and 103.61%, respectively, compared to those of the pure TPU film. This study demonstrates a facile and effective strategy for fabricating mechanically enhanced TPU composites.

Boron Nitride/Polyurethane Composites with Good Thermal Conductivity and Flexibility.

Thermal insulating composites are indispensable in electronic applications; however, their poor thermal conductivity and flexibility have become bottlenecks for improving device operations. Hexagonal boron nitride (BN) has excellent thermal conductivity and insulating properties and is an ideal filler for preparing thermally insulating polymer composites. In this study, we report a method to fabricate BN/polyurethane (PU) composites using an improved nonsolvent-induced phase separation method with binary solvents to improve the thermal performance and flexibility of PU. The stress and strain of BN60/PU are 7.52 ± 0.87 MPa and 707.34 ± 38.34%, respectively. As prepared, BN60/PU composites with unordered BN exhibited high thermal conductivity and a volume resistivity of 0.653 W/(m·K) and 23.9 × 1012 Ω·cm, which are 218.71 and 39.77% higher than that of pure PU, respectively. Moreover, these composite films demonstrated a thermal diffusion ability and maintained good integrity after 1000 bending cycles, demonstrating good mechanical and thermal reliability for practical use. Our findings provide a practical route for the production of flexible materials for efficient thermal management.

Endosidin20-1 is more potent than endosidin20 in inhibiting plant cellulose biosynthesis and molecular docking analysis of cellulose biosynthesis inhibitors on modeled cellulose synthase structure.

Endosidin20 (ES20) is a recently identified cellulose biosynthesis inhibitor (CBI) that targets the catalytic site of plant cellulose synthase (CESA). Here, we screened over 600 ES20 analogs and identified nine active analogs named ES20-1 to ES20-9. Among these, endosidin20-1 (ES20-1) had stronger inhibitory effects on plant growth and cellulose biosynthesis than ES20. At the biochemical level, we demonstrated that ES20-1, like ES20, directly interacts with CESA6. At the cellular level, this molecule, like ES20, induced the accumulation of cellulose synthase complexes at the Golgi apparatus and inhibited their secretion to the plasma membrane. Like ES20, ES20-1 likely targets the catalytic site of CESA. However, through molecular docking analysis using a modeled structure of full-length CESA6, we found that both ES20 and ES20-1 might have another target site at the transmembrane regions of CESA6. Besides ES20, other CBIs such as isoxaben, C17, and flupoxam are widely used tools to dissect the mechanism of cellulose biosynthesis and are also valuable resources for the development of herbicides. Here, based on mutant genetic analysis and molecular docking analysis, we have identified the potential target sites of these CBIs on a modeled CESA structure. Some bacteria also produce cellulose, and both ES20 and ES20-1 inhibited bacterial cellulose biosynthesis. Therefore, we conclude that ES20-1 is a more potent analog of ES20 that inhibits intrinsic cellulose biosynthesis in plants, and both ES20 and ES20-1 show an inhibitory effect on bacterial growth and cellulose synthesis, making them excellent tools for exploring the mechanisms of cellulose biosynthesis across kingdoms.

Metal-Organic Frameworks Meet Metallic Oxide on Carbon Fiber: Synergistic Effect for Enhanced Photodegradation of Antibiotic Pollutant.

Photodegradation shows a potential strategy for alleviating the excessive antibiotics crisis. The synergistic effect of various metal compounds immobilized on conductive substrates has been considered for wastewater treatment. However, developing a facile and universal approach for rational design and enhancing photocatalytic properties has endured extreme challenges. Herein, we develop a strategy to facilitate the photocatalytic reactions by designing a composite architecture of ZIF-8 ligand binding to the in-situ synthesis ZnO seed layer on carbon fiber. In this architecture, the dissolution and release of the seed layer in the excessive 2-Methylimidazole methanol solution were used as the binder to enhance the interplay between organic ligand and substrate. As an evaluated system for antibiotic contaminants, the photodegradation of tetracycline hydrochloride was performed with a removal efficiency of 88.47% (TC = 50 mg/L, pH = 4, 0.08 g of photocatalyst, illumination within 100 min). Moreover, the photocatalyst exhibited a steady photocatalytic activity (75.0%) after five cycles. The present work demonstrated a strategy for enhancing the photocatalytic performances of carbon fiber and accordingly provided useful perception into the design of the synergistic structure.

The Mode of Action of Endosidin20 Differs from That of Other Cellulose Biosynthesis Inhibitors.

Endosidin20 (ES20) was recently identified as a cellulose biosynthesis inhibitor (CBI) that targets the catalytic domain of CELLULOSE SYNTHASE 6 (CESA6) and thus inhibits the growth of Arabidopsis thaliana. Here, we characterized the effects of ES20 on the growth of other plant species and found that ES20 is a broad-spectrum plant growth inhibitor. We tested the inhibitory effects of previously characterized CBIs (isoxaben, indaziflam and C17) on the growth of Arabidopsis cesa6 mutants that have reduced sensitivity to ES20. We found that most of these mutants are sensitive to isoxaben, indaziflam and C17, indicating that these tested CBIs have a different mode of action than ES20. ES20 also has a synergistic inhibitory effect on plant growth when jointly applied with other CBIs, further confirming that ES20 has a different mode of action than isoxaben, indaziflam and C17. We demonstrated that plants carrying two missense mutations conferring resistance to ES20 and isoxaben can tolerate the dual inhibitory effects of these CBIs when combined. ES20 inhibits Arabidopsis growth in growth medium and in soil following direct spraying. Therefore, our results pave the way for using ES20 as a broad-spectrum herbicide, and for the use of gene-editing technologies to produce ES20-resistant crop plants.

Sorption and transformation of arsenic by extracellular polymeric substances extracted from Synechocystis sp. PCC6803.

Cyanobacteria widely distribute in the aqueous ecosystem and produce abundant extracellular polymeric substances (EPS), yet little is known about how the quantity and composition of cyanobacterial EPS change upon As exposure, and what are functions of these complex biopolymers in the As sorption and transformation processes. Here we extracted the EPS from Synechocystis sp. PCC6803, characterized their properties, quantified their components upon exposure to arsenite (As(III))/arsenate (As(V)) treatments, and investigated As binding and speciation as affected by the levels of EPS and solution pH. The total binding sites, zeta potential and reducing power of EPS were 17.47 mmol g-1, -19.72 mV and 1.71. The amounts of EPS increased by 22-65.3% and 13.8-39% when the cells were treated with 10-500 µM As(III) and As(V) respectively. The As removal was influenced by the EPS doses and solution pH, with 52.8% at pH 8.5 for As(III) and 49.5% at pH 4.5 for As(V) at 300 mg L-1 EPS. In addition, As speciation was transformed with the addition of EPS. As(V) and As(III) respectively accounted for 4.9-20.3% and 6.5-26.7% of the total dissolved As after the EPS were added (100-300 mg L-1) to the As(III) and As(V) solutions. Fourier transform infrared spectroscopy (FTIR) and three-dimensional excitation-emission fluorescence spectra (3D-EEM) revealed that As was bound to functional groups such as C═O, ─NH, and ─OH in the EPS via surface complexation/hydrophobic interactions. Taken together, this study demonstrated that the EPS extracted from Synechocystis were capable to bind and transform As and could be potentially applied to remove or detoxify As in solutions.

Single-step synthesis of monolithic comb-like CdS nanostructures with tunable waveguide properties.

Using a simple in situ seeding chemical vapor deposition (CVD) process, comb-like (branched) monolithic CdS micro/nanostructures were grown. Efficient optical coupling between the backbone and the teeth of the branched architecture is demonstrated by distributing light from an UV-laser-excited spot at one end of the backbone to all branch tips. By varying the deposition conditions, the orientation of the branches with respect to the backbone, their size and density can be tuned as well as the size of the backbone. This in situ seeding CVD method has the potential for a low-cost single-step fabrication of high-quality, micro/nanointegrated photonic devices, with tunable complex waveguiding possibilities.

Facile preparation of biocompatible and antibacterial water-soluble films using polyvinyl alcohol/carboxymethyl chitosan blend fibers via centrifugal spinning.

Water-soluble polyvinyl alcohol/carboxymethyl chitosan (PVA/CMCS) blend fiber films were successfully prepared using a plane-collection centrifugal spinning machine. The addition of CMCS significantly increased the shear viscosity of the PVA/CMCS blend solution. The effects of spinning temperature on the shear viscosity and the centrifugal spinnability of PVA/CMCS blend solution were discussed. The PVA/CMCS blend fibers were uniform, and their average diameters ranged from 1.23 µm to 29.01 µm. It was found that the CMCS was distributed evenly in the PVA matrix and increased the crystallinity of PVA/CMCS blend fiber films. The hydrogen bonds between the hydroxyl group of PVA and the carboxymethyl group of CMCS were also detected. An in vitro cell study of human skin fibroblast cells on the PVA/CMCS blend fiber films confirmed biocompatibility. The maximum tensile strength and elongation at break of PVA/CMCS blend fiber films could reach 3.28 MPa and 29.52 %, respectively. The colony-plate-count tests indicated that the PVA16-CMCS2 presented 72.05 % and 21.36 % antibacterial rates against Staphylococcus aureus (104 CFU/mL) and Escherichia coli (103 CFU/mL), respectively. These values indicated that the newly prepared PVA/CMCS blend fiber films are promising materials for cosmetic and dermatological applications.

A Flexible and Weavable Lignocellulose-Based Photocatalyst Supported by Natural Three-Dimensional Porous Juncus effusus for Highly Efficient Degradation of Environmental Contaminants.

Lignocellulosic biomass is a potential biotemplate for disposing the burden of the uncontrollable accumulation of environmental contaminants disrupting the hydrophytic ecosystems. Herein, an efficient solar-driven catalyst was prepared using a natural three-dimensional (3D) porous lignocellulose-based Juncus effusus (JE) fiber for wastewater treatment. Owing to the exquisite 3D microstructure and abundant hydroxyl groups, the two-dimensional lamellar graphitic carbon nitride/graphene oxide (g-C3N4/GO) nanocomposites were successfully synthesized and decorated on the carboxymethylated JE fiber via the electrostatic self-assembly method. The as-prepared g-C3N4/GO-JE (CNG-JE) photocatalyst exhibits excellent light absorption efficiency and a superior ability to accelerate photogenerated electron migration. The outstanding adsorption performance toward pollutants also contributes to the photodegradation property of CNG-JE, showing highly efficient degradation of C.I. Reactive Red 120 (99.8%), C.I. Acid Yellow 11 (99.8%), methylene blue (99.4%), Cr(VI) (98.8%), and tetracycline (87.2%). Most importantly, the lignocellulose-based CNG-JE fibers could be fabricated into a photocatalyst textile due to their flexible and weavable properties. In actual application, the CNG-JE textile can be reused for at least five cycles under the sun, demonstrating that the flexible CNG-JE textile is practical and recyclable. This study may provide a platform for constructing efficient, flexible, and weavable biomass-based porous materials for cost-effective and sustainable catalytic applications.

Fabrication of a High-Toughness Polyurethane/Fibroin Composite without Interfacial Treatment and Its Toughening Mechanism.

Controlling the assembly modes of polymer chains and the interfacial interactions between the filler and polymer matrix is vital for improving the mechanical properties of the composites. Herein, we report an approach for significantly enhancing the toughness of unmodified silk fibroin (SF) powder from silk waste-incorporated polyurethane (PU) composite films via nonsolvent-induced phase separation (NIPS) using binary solvents. The incorporation of 50 wt % SF into the PU3 film (NIPS, binary solvents) resulted in a toughness value of 54.9 ± 0.4 MJ·m-3, exhibiting 1670.9 and 6000.0% increments compared to those of PU1-50% SF (NIPS, one solvent) and PU2-50% SF (solvent evaporation, one solvent), respectively. The toughness enhancement in the PU3-50% SF composite film benefits from the good interfacial interaction between SF and PU and the unique structure of the compacted "fishing net" with reinforced connections, which can transfer stress under loading effectively. Furthermore, the PU-SF composites with good mechanical properties may have potential applications in silklike fibers and biomimetic materials.

Juncus effusus fiber-based cellulose cigarette filter with 3D hierarchically porous structure for removal of PAHs from mainstream smoke.

Polycyclic aromatic hydrocarbons (PAHs) from cigarettes are one of the main pollutants affecting public health. Herein, a cellulose cigarette filter with three-dimensional (3D) hierarchically porous structure was fabricated using a natural cellulose Juncus effusus (JE) fiber, whose pore size was well controlled by biocompatible polyvinylpyrrolidone (PVP) using a simple dip-dry method. The adsorption capacity and mechanism of the PVP-JE filter tips (PJF) against PAHs were investigated in detail. Compared with conventional cellulose acetate filter tips (CAF), the cellulose PJF were superior at filtering and adsorbing of PAHs from mainstream smoke with the removal efficiency of 61.79 %, which was 22.57 % higher than that of CAF (39.22 %). The ternary structures including polymer filter membrane, 3D network, and interconnected channels were demonstrated as the main roles for highly effective removal of PAHs. The JE-based cellulose cigarette filter can be a promising candidature to broaden the application range of polysaccharide in pollutant elimination.

A reference substance free diagnostic fragment ion-based approach for rapid identification of non-target components in Pudilan Xiaoyan oral liquid by high resolution mass spectrometry.

Rapid and reliable identification of non-target components in herbal preparations remains a primary challenge, especially when corresponding reference substances are inaccessible. In this work, an efficient post-experiment data processing methodology, named reference substance free diagnostic fragment ion (RSFDFI), was developed based on ultra-high-performance liquid chromatography coupled with linear ion trap-Orbitrap tandem mass spectrometry (UHPLC/LTQ-Orbitrap). The first step of this approach was to cluster the components that share common fragment ions into several groups. After querying the database using a predicted chemical formula, the component with the fewest primary hits was preferentially deduced based on its MS/MS spectrum. Once the structure was characterized, its common fragment ions could be used as the prior structural information to select the possible candidates that would facilitate the subsequent identification for each group. Taking Pudilan Xiaoyan oral liquid (PDL) as a model herbal preparation, which has been extensively used for the treatment of epidemic parotitis and children with hand-foot-mouth diseases, this strategy enables a nearly eight-fold narrowing of the database hits, with fifty-two components, including lignans, flavonoids, alkaloids and steroids, being rapidly identified. In conclusion, our work clearly demonstrates that integrating RSFDFI with high-resolution mass spectrometry is a powerful methodology for rapid identification of non-target components from herbal prescriptions and may open new avenues for chemical analysis in other complex mixtures.

An analytical model for volatile organic compound transport through a composite liner consisting of a geomembrane, a GCL, and a soil liner.

An analytical model for volatile organic compounds (VOCs) transport through a composite liner consisting of a geomembrane (GM), a geosynthetic clay liner (GCL), and a soil liner (SL) was developed for the assessment of the performance of this triple liner system. Both advection through the defects of GM and diffusion in the intact GM were considered in the model, and dimensionless analytical solution was obtained. The soil concentration profiles obtained by the proposed analytical solution have a good agreement with those obtained by the finite-layer-based software POLLUTE v7. The effects of leachate head, length of the connected wrinkles, and the interface transmissivity of GM/GCL on the breakthrough curves of the liner system were then investigated. Results show that the 30-year base flux of the liner system for the case with leachate head = 10 m and length of the connected wrinkles = 1,000 m can be over 60 times greater than that of the pure diffusion case. The length of the connected wrinkles of the GM has greater influence on the base flux of the liner system than on the base concentration. The interface transmissivity has negligible effect on the solute breakthrough curves of the liner system for relatively low values of the length of the connected wrinkles (e.g., <100 m). The groundwater protection level achieved by GM/CCL is more effective than that by GM/GCL/SL in the earlier times. However, the steady state base flux for GM/GCL/SL can be seven to eight times lower than that for GM/CCL. The analytical solution can also be used for experimental data fitting, verification of complicated numerical models, and preliminary design of composite liners.

Highly Anti-UV Properties of Silk Fiber with Uniform and Conformal Nanoscale TiO2 Coatings via Atomic Layer Deposition.

In this study, silk fiber was successfully modified via the application of a nanoscale titania coating using atomic layer deposition (ALD), with titanium tetraisopropoxide (TIP) and water as precursors at 100 °C. Scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscope, and field emission scanning electron microscope results demonstrated that uniform and conformal titania coatings were deposited onto the silk fiber. The thermal and mechanical properties of the TiO2 silk fiber were then investigated. The results showed that the thermal stability and mechanical properties of this material were superior to those of the uncoated substance. Furthermore, the titania ALD process provided the silk fiber with excellent protection against UV radiation. Specifically, the TiO2-coated silk fibers exhibited significant increases in UV absorbance, considerably less yellowing, and greatly enhanced mechanical properties compared with the uncoated silk fiber after UV exposure.

Seasonal and clonal variation in cellulose microfibril orientation during cell wall formation of tracheids in Cryptomeria japonica.

To investigate the biological mechanism by which trees control the changes in microfibril (MF) orientation among secondary cell wall layers of conifer tracheids, we studied seasonal variation in the orientation of newly deposited MFs during tracheid cell wall development in Japanese cedar (Cryptomeria japonica D. Don) trees growing in Central Japan (36°36'N, 140°39'E). Sample blocks were repeatedly collected from four 16-year-old clones of different origins during the growing season of 2010 to investigate the hypotheses that changes in cellulose MF orientation between wall layers exhibited seasonal and clonal differences. The progressive change in the orientation of newly deposited MFs on the primary and secondary cell wall layers of tracheids was detected by field-emission-scanning electron microscopy. Tracheid production and differentiation was studied by light microscopy. We observed a decreasing trend in the orientation of deposited MFs from earlywood to latewood in the S2 and S1 layers, where MFs appeared in a Z-helix. In contrast, no seasonal pattern in the orientation of the MFs in the S-helix was observed. Minor clonal variation was observed in the phenology of tracheid production and differentiation. We concluded that a seasonal decreasing trend in the orientation of the MFs in the Z-helix in S1 and S2 was present, whereas the MFs in other layers exhibited minor random variations. Thus, the orientation of the MFs in S2 was affected by seasonal factors, whereas the MFs in other layers were more intrinsically controlled. The within-ring variations in the MF orientation and thus the resulting average MF angle might also be related to genotypic differences in the tracheid production and differentiation rate. However, our results do not exclude other intrinsic and environmental regulations in the change in MF orientation, which remains a topic for future studies.

[Effect of extra-cellular polymeric substances on filtration of modified non-woven fabric in membrane bio-reactor].

The effect of extra-cellular polymeric substances (EPS) on filtration of polyvinyl alcohol modified polypropylene non-woven in submerged membrane bioreactor (SMBR) was investigated by statistical method. The results show that soluble extra-cellular polymeric substances (EPSs) of activated sludge on the non-woven modules surface, components (protein/carbohydrate, P/C) of EPSs and relative hydrophobicity (RH) have a significant influence on filtration performance of module B, the Pearson's correlation coefficient (r(p)) related to membrane fouling resistance are 0.868, 0.840, 0.890, respectively. Modified module can effectively restrict the adsorption of EPSs, can reduce the ratio of P/C in EPSs and can decrease the accumulation of activated sludge. After hydrophilic modification of non-woven, the filtration performance is improved obviously and the un-fouling performance is increased.