Symmetry of Pyridine Derivatives Controlled Two-Dimensional Nanostructural Diversity by Co-Assembly with Aromatic Carboxylic Acids.

The self-assembly behaviors of aromatic carboxylic acids are commonly investigated at the liquid/solid interfaces because of their rigid skeletons and both hydrogen-bond donors and receptors. However, self-assemblies of aromatic carboxylic acids with low symmetry and interactions between carboxylic acid and pyridine derivatives are worth exploring. In this work, the self-assembled structural transitions of a kind of low-symmetric aromatic carboxylic acid (H4QDA) are regulated by the coadsorption of two pyridine derivatives (DPE and T4PT) with different symmetry, which are investigated by scanning tunneling microscopy under ambient conditions. For the H4QDA/DPE system, the grid structure appears. For the H4QDA/T4PT system, the coassembled morphologies display an obvious concentration dependence. With the increase of solution concentration of T4PT, three coassembled patterns (network structure, chiral linear structure, and brick-like structure) are observed. Corresponding structural models suggest that the O-H···N hydrogen bonds have great contributions to stabilizing these coassembled structures. Our studies will help to explore the complexity, diversity, and functionality of multiple component systems and are conducive to further understanding the underlying mechanisms in the assembly process.

Genome-wide identification and transcriptome profiling expression analysis of the U-box E3 ubiquitin ligase gene family related to abiotic stress in maize (Zea mays L.).

BACKGROUND: The U-box gene family encodes E3 ubiquitin ligases involved in plant hormone signaling pathways and abiotic stress responses. However, there has yet to be a comprehensive analysis of the U-box gene family in maize (Zea mays L.) and its responses to abiotic stress. RESULTS: In this study, 85 U-box family proteins were identified in maize and were classified into four subfamilies based on phylogenetic analysis. In addition to the conserved U-box domain, we identified additional functional domains, including Pkinase, ARM, KAP and Tyr domains, by analyzing the conserved motifs and gene structures. Chromosomal localization and collinearity analysis revealed that gene duplications may have contributed to the expansion and evolution of the U-box gene family. GO annotation and KEGG pathway enrichment analysis identified a total of 105 GO terms and 21 KEGG pathways that were notably enriched, including ubiquitin-protein transferase activity, ubiquitin conjugating enzyme activity and ubiquitin-mediated proteolysis pathway. Tissue expression analysis showed that some ZmPUB genes were specifically expressed in certain tissues and that this could be due to their functions. In addition, RNA-seq data for maize seedlings under salt stress revealed 16 stress-inducible plant U-box genes, of which 10 genes were upregulated and 6 genes were downregulated. The qRT-PCR results for genes responding to abiotic stress were consistent with the transcriptome analysis. Among them, ZmPUB13, ZmPUB18, ZmPUB19 and ZmPUB68 were upregulated under all three abiotic stress conditions. Subcellular localization analysis showed that ZmPUB19 and ZmPUB59 were located in the nucleus. CONCLUSIONS: Overall, our study provides a comprehensive analysis of the U-box gene family in maize and its responses to abiotic stress, suggesting that U-box genes play an important role in the stress response and providing insights into the regulatory mechanisms underlying the response to abiotic stress in maize.

Terminal Group Effect on Two-Dimensional Self-Assembly of Fluorenone-Based Liquid Crystals at the Solid/Liquid Interface.

Self-assemblies of two fluorenone-based derivatives (FE and FEC) consisting of a central 2,7-diphenyl-9-fluorenone polar moiety but differing in the flexible terminal groups were investigated by scanning tunneling microscopy (STM) at the 1-octanoic acid/HOPG interface under different concentrations and density functional theory calculation (DFT). STM results reveal a concentration-dependent polymorphic self-assembly behavior for FE, but without the presence of co-adsorbed solvents. As the concentration decreases, the dimer, bracket-like, and ribbon-like self-assembled structures were observed. On the contrary, FEC molecules assemble into only a type of oval-shaped morphology by the intermolecular N···H-O hydrogen bonds with the solvent molecules. Combined with DFT calculations, it can be deduced that the intermolecular van der Waals forces, dipole-dipole interactions, and hydrogen bonding are the main driving forces to stabilize the molecular packing of fluorenone-based polycatenars with strong polarity. Our work is of significance at the molecular level to further clarify the intermolecular interactions and conformational effects on the formation of molecular packing structures with liquid crystal property.

Impaired bisecting GlcNAc reprogrammed M1 polarization of macrophage.

The functions of macrophages are governed by distinct polarization phenotypes, which can be categorized as either anti-tumor/M1 type or pro-tumor/M2 type. Glycosylation is known to play a crucial role in various cellular processes, but its influence on macrophage polarization is not well-studied. In this study, we observed a significant decrease in bisecting GlcNAc during M0-M1 polarization, and impaired bisecting GlcNAc was found to drive M0-M1 polarization. Using a glycoproteomics strategy, we identified Lgals3bp as a specific glycoprotein carrying bisecting GlcNAc. A high level of bisecting GlcNAc modification facilitated the degradation of Lgals3bp, while a low level of bisecting GlcNAc stabilized Lgals3bp. Elevated levels of Lgals3bp promoted M1 polarization through the activation of the NF-кB pathway. Conversely, the activated NF-кB pathway significantly repressed the transcription of MGAT3, leading to reduced levels of bisecting GlcNAc modification on Lgals3bp. Overall, our study highlights the impact of glycosylation on macrophage polarization and suggests the potential of engineered macrophages via glycosylated modification. Video Abstract.

Knockdown of USF2 inhibits pyroptosis of podocytes and attenuates kidney injury in lupus nephritis.

As an essential factor in the prognosis of Systemic lupus erythematosus (SLE), lupus nephritis (LN) can accelerate the rate at which patients with SLE can transition to chronic kidney disease or even end-stage renal disease (ESRD). Proteinuria due to decreased glomerular filtration rate following podocyte injury is LN's most common clinical manifestation. Podocyte pyroptosis and related inflammatory factors in its process can promote lupus to involve kidney cells and worsen the occurrence and progression of LN, but its regulatory mechanism remains unknown. Accumulating evidence has shown that upstream stimulatory factor 2 (USF2) plays a vital role in the pathophysiology of kidney diseases. In this research, multiple experiments were performed to investigate the role of USF2 in the process of LN. USF2 was abnormally highly expressed in MRL/lpr mice kidney tissues. Renal function impairment and USF2 mRNA levels were positively correlated. Silencing of USF2 in MRL/lpr serum-stimulated cells significantly reduced serum-induced podocyte pyroptosis. USF2 enhanced NLRP3 expression at the transcriptional level. Silencing of USF2 in vivo attenuated kidney injury in MRL/lpr mice, which suggests that USF2 is important for LN development and occurrence.

F···Br and F···S Heterohalogen-Bond-Directed 2D Self-Assemblies of a Benzothiadiazole Derivative.

Halogen bonding (XB) is of great importance in fabricating a two-dimensional (2D) self-assembly for its adaptive directionality. However, the XBs involving fluorine (F) have barely been studied due to the absence of an σ-hole on F. Here, 2D self-assemblies of a F-substituted 4,7-bis(5-bromo-4-dodecylthiophen-2-yl)-5,6-difluorobenzo[c][1,2,5]thiadiazole (BTZ-BrF) molecule on graphite were investigated using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. STM experiments revealed that the 2D patterns of BTZ-BrF had a clear solvent and concentration dependence, showing a frame-like pattern in aliphatic acid and aliphatic hydrocarbon solvents at high concentrations. At lower concentrations, a bamboo-like and a wave-like pattern were observed in aliphatic acid, whereas small frame-like and large ladder-like domains at high solution concentrations in aliphatic hydrocarbon were observed. As the concentration further decreased, two linear patterns were observed. DFT calculations suggested that the hetero-XBs of F···Br, F···S, Br···S, and Br···N, the homo-XBs of type-II Br···Br, and the S···S interactions synergistically directed and stabilized the polymorphic 2D architectures. This understanding of intermolecular XBs during the molecular assembly at the molecular level may shed light on the ongoing efforts of regulating nanostructures of multifunctional organics.

[C21 inhibits cytokine secretion in rat renal tubular epithelial cells stimulated by advanced glycation end products].

Objective To investigate the effect and mechanism of compound 21(C21), an agonist of angiotensin II-2 receptor (AT2R) on the cytokine levels of NRK-52E cells stimulated by advanced glycation end products bovine serum albumin (AGE-BSA). Methods NRK-52E cells were divided into control and (25, 50, 100, 200)mg/L AGE-BSA groups and cultured for 48 hours. The mRNA and protein expression levels of leukin-6 (IL-6) and tumor necrosis factor α (TNF-α) were detected by real-time quantitative PCR and ELISA. The NRK-52E cells stimulated by AGE-BSA(25 mg/L) for 48 hours were then treated with (0.01, 0.05, 0.1)mmol/L C21 for 24 hours. The mRNA and protein expression levels of protein kinase C (PKC), nuclear factor κB p65 (NF-κB p65) and transforming growth factor ß1 (TGF-ß1) were detected by qRT-PCR and Western blot analysis. Results The mRNA expression levels of IL-6 and TNF-α significantly increased in NRK-52E cells stimulated by AGE-BSA at different doses, with the greatest increase in the 25 mg/L AGE-BSA group. The mRNA and protein expression levels of PKC, NF-κB p65 and TGF-ß1 in AGE-BSA-induced NRK-52E cells significantly decreased by (0.01, 0.05, 0.1)mmol/L C21. Conclusion AGE-BSA promotes the expression of IL-6, TNF-α, PKC, NF-κB p65 and TGF-ß1 in NRK-52E cells, while C21 inhibits the effect of AGE-BSA on NRK-52E cells.

Different Stepwise Growth Mechanism of AIE-Active Tetraphenylethylene-Functionalized Metal-Organic Frameworks on Au(111) and Cu(111) Surfaces.

Fabricating tetraphenylethylene (TPE)-functionalized metal-organic frameworks (MOFs) with aggregation- induced emission on surfaces and understanding the growth mechanism have not yet been pursued. Herein, MOFs constructed via the Ullmann-type reaction of a C2-symmetry TPE derivative (p-BrTBE) on Au(111) and Cu(111) surfaces were thoroughly investigated using scanning tunneling microscopy. On a Au(111) surface, p-BrTBE molecules formed the self-assembled pattern at 298 K. Stepwise annealing led to a progressive evolution process, in which the stepwise debromination reaction led to organometallic intermediates, and surface-stabilized radicals and metal-organic networks were formed. By contrast, the relatively ordered MOFs were obtained by replacing the underlying substrate with the more catalytically active Cu(111) at 298 K. Density functional theory calculations demonstrated that the formation of different networks on Au(111) and Cu(111) was determined by the different conformations of the TBE unit on the different substrates due to the different adsorption energy.

Genesis of Superlow Friction in Strengthening Si-DLC/PLC Nanostructured Multilayer Films for Robust Superlubricity at Ultrahigh Contact Stress.

Diamond-like carbon (DLC) films have significant potential to provide solutions for the friction reduction and the lubricity problem of mechanical moving friction pairs. However, the realization of excellent lubrication or even superlubricity and long lifetime under heavy loading conditions is still a great challenge, which is crucial for the applications of DLC in harsh environments. Here, we construct a group of property-strengthening Si-DLC/PLC multilayer films that could withstand ultrahigh contact stresses and achieve robust superlubricity. Under a peak Hertz contact stress of up to 2.37 GPa, the setup of a bilayer thickness of 324 nm enables the multilayered film (an overall film thickness of 1.53 µm) to achieve a superlow coefficient of friction toward 0.001 and an ultralow wear rate of 3.13 × 10-9 mm3/Nm. An alternating load reciprocating friction test emphasizes that this strengthening nanostructured Si-DLC/PLC multilayer possesses a kind of load self-adaptation because of its in situ nanoclustering transformation and local ordering of sp2-C phases at the sliding interface. The genesis of self-adaptation to the applied load is evaluated comprehensively to reveal its strengthening and toughening structural characteristics and robustness of the near-zero friction and wear features. The findings provide a significant design criterion for carbon-based solid lubricants applicable to harsh loading environments.

Fabrication of robust superhydrophobic magnetic multifunctional coatings and liquid marbles.

To obtain durable and multi-function superhydrophobic surfaces, we reported a facial method to prepare a multifunctional suspension (γ-Fe2O3@SiO2@PDMS suspension) named as FSP suspension, in which γ-Fe2O3 was coated by the silica shell and PDMS was used as the outer layer. Superhydrophobic magnetic polyurethane (SMPU) sponge was prepared by immersing the polyurethane (PU) sponge into the FSP suspension, exhibiting the superior ability to absorb oil. In addition, it could also move directionally by the attraction of magnets and absorb the oil along the fixed path. The heated superhydrophobic magnetic stainless steel (H-SMSS) mesh was acquired by spraying FSP suspension onto the stainless steel mesh and then heating at 400 °C, which demonstrated superior superhydrophobicity and resistance to abrasion and chemical corrosion. Besides, the H-SMSS mesh displayed excellent flux and efficiency to separate the oil/water mixture. Rolling droplets on FSP particles, the superhydrophobic magnetic liquid marbles (SMLMs) were fabricated, in which liquids with different volumes were encapsulated and transported directionally. Further, it was convenient to inject liquid into the SMLM and withdraw liquid from it. Thus, the prepared FSP suspension has promising applications in constructing large-area, robust, and multifunctional surfaces and microreactors.

Chain-Length- and Concentration-Dependent Isomerization of Bithiophenyl-Based Diaminotriazine Derivatives in Two-Dimensional Polymorphic Self-Assembly§.

Bithiophenyl-based diaminotriazine derivatives (2TDT-n, n = 10, 12, 16, and 18) with different chain lengths display colhex/p6mm mesophases. Their supramolecular self-assembled mechanism is investigated using scanning tunneling microscopy (STM) at the 1-octanoic acid/graphite interface at various concentrations. The chain length effect on the two-dimensional adlayers is observed in this system, and 2TDT-n molecules show a structural phase transition from the four-leaf arrangement to the two-row linear nanostructure accompanied by the emergence of molecular isomerization with the increase of the side-chain length. The self-assembled structure of 2TDT-10 is composed of a four-leaf pattern with uniform s-cis conformers. In 2TDT-12, three kinds of nanostructures (bamboo-like, two-row linear pattern-I, and flower-like) are observed. These nanostructures are randomly constituted by cis and trans conformers, and the ratios of the s-cis conformer in three kinds of patterns are 55.7, 42.3, and 62.5%, respectively. Furthermore, when n = 16 and 18, the ratio of the s-cis conformer further decreases to 19.0 and 4.3%, respectively. Those molecules mainly form linear nanostructures consisting of s-trans conformers. Therefore, it is reasonable to conclude that the side-chain length has a great effect on the self-assembled patterns and the molecular conformation of bithiophenyl-based diaminotriazine derivatives. Density functional theory calculations are applied to optimize molecular conformers and assess their single-point energies, showing that the s-cis conformation has higher energy than the s-trans conformer. We speculate that the ratio of two conformers in nanostructures might be similar to that of the liquid crystalline phase.

Coronene and Phthalocyanine Trapping Efficiency of a Two-Dimensional Kagomé Host-Nanoarchitecture.

The trapping of coronene and zinc phthalocyanine (ZnPc) molecules at low concentration by a two-dimensional self-assembled nanoarchitecture of a push-pull dye is investigated using scanning tunneling microscopy (STM) at the liquid-solid interface. The push-pull molecules adopt an L-shaped conformation and self-assemble on a graphite surface into a hydrogen-bonded Kagomé network with porous hexagonal cavities. This porous host-structure is used to trap coronene and ZnPc guest molecules. STM images reveal that only 11% of the Kagomé network cavities are filled with coronene molecules. In addition, these guest molecules are not locked in the host-network and are desorbing from the surface. In contrast, STM results reveal that the occupancy of the Kagomé cavities by ZnPc evolves linearly with time until 95% are occupied and that the host structure cavities are all occupied after few hours.

Odd-Even Effect on Supramolecular Co-Assemblies: Control over the Two-Dimensional Self-Assemblies of a Fluorenone Derivative with Asymmetrically Substituted Alkyl Chains.

The precise control of two-dimensional supramolecular co-assemblies presents a research topic related to advance nanotechnology. Here, we report a scanning tunneling microscopy (STM) study of the mixture behavior of three fluorenone derivatives at the liquid-solid interface. The target molecule is F-C12C13 whose structure bears asymmetrical alkyls, whereas the regulating molecules, either F-C12C12 or F-C13C13, are structurally symmetric. By STM imaging of systematic mixtures with various volumes among the sample solutions, we found that the mixing ratio mainly determined the binary outcomes. Compared with F-C12C12, F-C13C13 shows a stronger ability to dominate the patterning, explained by the larger binding and adsorption energies calculated by the force field simulations. Moreover, the odd-even effect exists in the system. Overall, we acquired knowledge about the regulating ability of bi-component supramolecular assembling, especially for structurally asymmetric molecular systems.

Stepwise on-surface synthesis of thiophene-based polymeric ribbons by coupling reactions and the carbon-fluorine bond cleavage.

The rational synthesis of thiophene-based cross-coupled polymers on surfaces has been attracting more attention recently. Here, we report the stepwise activation of 5,5'-(2,3-difluoro-1,4-phenylene)bis(2-bromothiophene) as a precursor to synthesize thiophene-based polymeric ribbons on the Au(111) surface. Scanning tunneling microscopy studies showed that the precursor adopted different conformations in the self-assembled structure, organometallic species, and covalent polymers. On annealing the sample at a relatively low temperature (150 °C), the conversion of the organometallic structure into a covalent product with straight lines was observed, in which the Br adatoms arranged between the neighboring chains. On further annealing the sample at 270 °C, the detached Br adatoms played a key role in promoting the C-H bond activation. The cross-linked polymer was achieved by a combination of Ullmann and dehydrogenative coupling. When the annealing temperature was up to 390 °C, the C-F bond activation was triggered, which led to the formation of polymeric ribbons resulting from the cyclodehydrogenation of the fluorinated polymer. This study further supplements the reaction mechanism of thiophene-based dehalogenative, dehydrogenative and defluorinative coupling, and provides us a rational way for synthesizing cross-linked functional materials.

Modeling retinitis pigmentosa through patient-derived retinal organoids.

Human-induced pluripotent stem cells (hiPSCs) can be differentiated into well-structured retinal organoids. In this protocol, we successfully established 3D retinae from patient-derived hiPSCs and built the retinitis pigmentosa model in vitro. Moreover, mutation in the retinitis pigmentosa GTPase regulator (RPGR) gene was corrected by CRISPR-Cas9 gene editing, which rescued the structure and function of the 3D retinae. For complete details on the use and execution of this protocol, please refer to Deng et al. (2018).

Template-assisted 2D self-assembled chiral Kagomé network for selective adsorption of coronene.

Solvent molecules (n-tridecane and n-tetradecane) act as templates by coadsorption to direct the assembly of asymmetric 2-bisthienyl-4,6-diamino-1,3,5-triazine into chiral Kagomé networks. Furthermore, guest molecules (coronene) fill in the hexagonal voids by replacing the solvent molecules due to the selective and competitive adsorption behavior.

Altered m6 A modification is involved in up-regulated expression of FOXO3 in luteinized granulosa cells of non-obese polycystic ovary syndrome patients.

The pathophysiology of polycystic ovary syndrome (PCOS) is characterized by granulosa cell (GC) dysfunction. m6 A modification affects GC function in patients with premature ovarian insufficiency (POI), but the role of m6 A modification in PCOS is unknown. The purpose of the prospective comparative study was to analyse the m6 A profile of the luteinized GCs from normovulatory women and non-obese PCOS patients following controlled ovarian hyperstimulation. RNA m6 A methylation levels were measured by m6 A quantification assay in the luteinized GCs of the controls and PCOS patients. Then, m6 A profiles were analysed by methylated RNA immunoprecipitation sequencing (MeRIP-seq). We reported that the m6 A level was increased in the luteinized GCs of PCOS patients. Comparative analysis revealed differences between the m6 A profiles from the luteinized GC of the controls and PCOS patients. We identified FOXO3 mRNA with reduced m6 A modification in the luteinized GCs of PCOS patients. Selectively knocking down m6 A methyltransferases or demethylases altered expression of FOXO3 in the luteinized GCs from the controls, but did not in PCOS patients. These suggested an absence of m6 A-mediated transcription of FOXO3 in the luteinized GCs of PCOS patients. Furthermore, we demonstrated that the involvement of m6 A in the stability of the FOXO3 mRNA that is regulated via a putative methylation site in the 3'-UTR only in the luteinized GCs of the controls. In summary, our findings showed that altered m6 A modification was involved in up-regulated expression of FOXO3 mRNA in the luteinized GCs from non-obese PCOS patients following controlled ovarian hyperstimulation.

Conformation modification of terthiophene during the on-surface synthesis of pure polythiophene.

On-surface coupling under ultra-high vacuum is employed as a versatile approach to synthesize pure polythiophene from a 5,5''-dibromo-2,2':5',2''-terthiophene (DBTT) precursor and the corresponding temperature-dependent stepwise reaction mechanism is systematically studied by scanning tunneling microscopy (STM). After thermal deposition of the precursor onto a Au(111) surface that is kept at room temperature, a triangle-like pattern and a linear self-assembled pattern are formed with different molecular coverages through BrBrS halogen bonds and BrBr type-I contact bonds, respectively. In the self-assembled nanostructures, the thiophene units adopt trans-conformation. Mild annealing promotes the structural transition of both nanostructures into ordered zigzag organometallic linear chains with all-cis configured thiophene units connected through coordination bonds to the Au adatoms. Such conformational variety is easily recognized by STM, particularly in the case of DBTT-CH3 with the extra -CH3 signals. The covalently coupled products from the DBTT precursor are obtained by further annealing the organometallic intermediate at higher temperatures, which leads to the removal of Au atoms and the formation of ordered polymer chains and disordered polythiophene networks. Further characterization suggests that the reaction mechanism is associated with Ullmann-type coupling to form the ordered chains as well as Ullmann-type and dehydrogenative C-C coupling to fabricate cross-linked polymer networks. Compared with the on-surface synthesis process of DBTT on the Cu(111) surface, it can be confirmed that the Au adatoms are vital to synthesize polythiophene. These findings provide important insight into the reaction mechanism of on-surface synthesized pure polythiophene and on-surface coupling can potentially be applied to synthesize other functional conjugated polymers.

The Brπ halogen bond assisted self-assembly of an asymmetric molecule regulated by concentration.

The two-dimensional (2D) self-assembly behavior of an asymmetric thienophenanthrene derivative (M1) has been theoretically predicted and further probed via STM. The barely exploited Brπ halogen bonds play an assisting role in the structural formation, and a strong cooperative effect from the C-HBr bonds is shown. Such π-type halogen bond assisted self-assembly reveals self-adaption properties, which is of great interest for flexible light-emitting devices and self-healing materials.

Cloning and characterization of a glycosyltransferase from Catharanthus roseus for glycosylation of cardiotonic steroids and phenolic compounds.

OBJECTIVES: To characterize a glycosyltransferase (UGT74AN3) from Catharanthus roseus and investigate its specificity toward cardiotonic steroids and phenolic compounds. RESULTS: UGT74AN3, a novel permissive GT from C. roseus, displayed average high conversion rate (> 90%) toward eight structurally different cardiotonic steroids. Among them, resibufogenin, digitoxigenin, and uzarigenin gave 100% yield. Based on LC-MS, 1H-NMR and 13C-NMR analysis, structure elucidation of eight glycosides was consistent with 3-O-ß-D-glucosides. We further confirmed UGT74AN3 was permissive enough to glycosylate curcumin, resveratrol, and phloretin. The cDNA sequence of UGT74AN3 contained an ORF of 1,425 nucleotides encoding 474 amino acids. UGT74AN3 performed the maximum catalytic activity at 40 °C, pH 8.0, and was divalent cation-independent. Km values of UGT74AN3 toward resibufogenin, digitoxigenin, and uzarigenin were 7.0 µM, 12.3 µM, and 17.4 µM, respectively. CONCLUSIONS: UGT74AN3, a glycosyltransferase from a noncardenolide-producing plant, displayed catalytic efficiency toward cardiotonic steroids and phenolic compounds, which would make it feasible for glycosylation of bioactive molecules.