Diseases cause a significant loss in both yield and quality of spinach. The cell cycle signalling pathway plays a central role in balancing development and immunity of plants. Cyclin-Dependent Kinase ...Inhibitor (CKI) is a core cell cycle regulator. It has been found that two Arabidopsis CKIs, SIAMESE (SIM) and SMR1 (SIAMESE-Related 1), function redundantly not only as negative regulators of cell proliferation but also as positive regulators of plant immunity. In the spinach genome, we identified a homologue of Arabidopsis SIM, referred to as Spinacia oleracea SIAMESE (SoSIM). To investigate the function of SoSIM, we introduced the 35S promoter-driven SoSIM (35S:SoSIM) into Arabidopsis sim smr1 double mutants. Over-expression of SoSIM phenocopied RNA interference of Cyclin-Dependent Kinase A1 (CDKA1) which exhibited dwarf and serrated leaves, confirming that SIM is a CDK inhibitor. Arabidopsis wild-type trichomes are single and unicellular, whereas sim smr1 mutant trichomes are clustered and multicellular. SoSIM restored wild-type trichome phenotype of sim smr1 mutant. The sim smr1 mutants were susceptible to the avirulent pathogen Pseudomonas syringae pv. maculicola as compared with wild-type plants. Our data showed that the resistance of 35S:SoSIM-transgenic sim smr1 lines to the pathogen was fully restored, indicating that SoSIM activates plant immunity. These data verify that SoSIM functions as its Arabidopsis counterpart in inhibition of plant development and activation of plant immunity. Therefore, SoSIM can be explored to control the balance between development and immunity in spinach.
The phenomenon of granular flows appears frequently in industrial and daily life. The particle-particle interaction plays an important role in granular flows, which makes the flows have some strong ...nonlinear characteristics and so different from the normal materials, either solids or liquids. Discrete element method (DEM) is a powerful tool to catch this interaction in meso-scopic scale. A brief review of DEM is presented, including some of our new works in this area. DEM can also be coupled with other CFD methods for simulations of solid-liquid suspension flow. An example of such coupling is presented in this article as well.
A differentiated path availability (DPA) protection approach in WDM ring networks was introduced. This approach can minimize the total wavelength mileage of ring, while guaranteeing the required path ...availability degree of each connection. The simulation result shows that in the uniform traffic study the used wavelength mileage decreases and the reused wavelength mileage increases, as the required availability degree of connection becomes lower. This rule fits in different traffic proportion scenarios.
Graphene has been recognized as an excellent lubrication material owing to its two-dimensional structure and weak interlayer interactions. However, most extant works concerning superlubricity ...involving graphene oxide have been limited to nanoscale or microscale dimensions (of the order of 1–10 μm). In present work, realization of a robust macroscale superlubricity state (μ = 0.0037), by taking advantage of the synergy effect of graphene-oxide nanoflakes (GONFs) and ethanediol (EDO) at Si3N4–SiO2 interfaces is reported. GONFs have been observed as being adsorbed on friction surfaces, thereby preventing direct contact between surface asperities. The extremely low shear stresses developed between these asperities contribute toward enhanced superlubricity and the resulting super-low wear. Meanwhile, the formation of partial-slip hydrodynamic boundary condition at the GONFs–EDO interface along with the formation of hydrated GONFs–EDO networks through hydrogen-bond interactions contribute to the generation of extremely low shear stresses of the liquid lubricating film. Such macroscale superlubricity provides a new approach toward realization of extremely low friction in GONFs through the synergy effect with liquids.
Several ionic liquids (ILs) are formed in situ with monovalent metal salts and ethylene glycol (EG). The macroscale superlubricity and antiwear properties of the ILs were studied between ceramic ...materials. Superlow coefficients of friction of less than 0.01 could be obtained for all ILs at silicon nitride (Si3N4) interfaces induced by tribochemical reactions. Notably, the IL (Li(EG)PF6) formed with LiPF6 and EG exhibited the greatest superlubricity and antiwear properties. The results of film thickness calculations and surface analysis showed that the lubrication regime during the superlubricity period was the mixed lubrication, and a composite tribochemical layer (composed of phosphates, fluorides, silica (SiO2), and ammonia-containing compounds), hydration layer, and fluid film contributed to superlubricity and wear protection. It was found that the small size of metal cations was beneficial for alleviating wear, and PF6 – anions exhibited the smallest friction and best antiwear performance at Si3N4 interfaces. This work studied the lubricity and antiwear properties of ILs with different cations and anions, enriching the range of alternative ILs for macroscale superlubricity and low wear, and is of importance to engineering applications.
The robust liquid superlubricity of a room-temperature ionic liquid induced by tribochemical reactions is explored in this study. Here, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ...(EMIMTFS) could realize stable superlubricity (μ < 0.01) with water at the interfaces of Si3N4/SiO2. A superlow and steady friction coefficient of 0.002–0.004 could be achieved under neutral conditions (pH of 6.9 ± 0.1) after 600 s of running-in process. Various factors that could affect superlubricity were explored, including concentration of EMIMTFS, sliding speed, applied load, and volume of the lubricant. The results reveal that superlubricity can be achieved with EMIMTFS aqueous solution under a broad scope of conditions. The results of surface analysis show that a steady composite tribochemical layer comprising EMIMTFS, silica, ammonia-containing compounds, and sulfides was formed by tribochemical reactions between EMIMTFS and Si3N4 during the running-in period. The film thickness calculation reveals that the achieved superlubricity is in a mixed lubrication regime that comprises boundary lubrication and thin film lubrication. The superlubricity state is governed by a firm composite tribochemical layer, a molecular adsorption layer (electric double layer of EMIMTFS), and a fluid layer. The liquid superlubricity achieved by the ionic liquid is helpful for the development of new ionic liquids with superlubricity characteristics and is of great significance for scientific understanding as well as engineering applications.
Polycomb repressive complex 2 (PRC2) consists of three core subunits, EZH2, EED and SUZ12, and plays pivotal roles in transcriptional regulation. The catalytic subunit EZH2 methylates histone H3 ...lysine 27 (H3K27), and its activity is further enhanced by the binding of EED to trimethylated H3K27 (H3K27me3). Small-molecule inhibitors that compete with the cofactor S-adenosylmethionine (SAM) have been reported. Here we report the discovery of EED226, a potent and selective PRC2 inhibitor that directly binds to the H3K27me3 binding pocket of EED. EED226 induces a conformational change upon binding EED, leading to loss of PRC2 activity. EED226 shows similar activity to SAM-competitive inhibitors in blocking H3K27 methylation of PRC2 target genes and inducing regression of human lymphoma xenograft tumors. Interestingly, EED226 also effectively inhibits PRC2 containing a mutant EZH2 protein resistant to SAM-competitive inhibitors. Together, we show that EED226 inhibits PRC2 activity via an allosteric mechanism and offers an opportunity for treatment of PRC2-dependent cancers.
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