Selective Recruitment of TAFs by Yeast Upstream Activating Sequences Implications for Eukaryotic Promoter Structure

AbstractThe general transcription factor TFIID is composed of the TATA box binding protein (TBP) and multiple TBP-associated factors (TAFs) [1–3]. In yeast, promoters can be grouped into two classes based on the involvement of TAFs [4, 5]. TAF-dependent (TAFdep) promoters require TAFs for transcription, and TBP and TAFs are present at comparable levels on these promoters. TAF-independent (TAFind) promoters do not require TAFs for activity, and TAFs are either absent or present at levels far below those of TBP on these promoters. Here, we demonstrate that the upstream activating sequence (UAS) mediates the selective recruitment of TAFs to TAFdep promoters. A TAFind UAS fails to recruit TAFs and to direct efficient transcription when inserted upstream of a TAFdep core promoter. This transcriptional defect can be overcome by a potent activator, indicating that a strong activation domain can compensate for the absence of TAFs on a TAFdep core promoter. Our results reveal a requirement for compatibility between the UAS and core promoter and thus help explain previous reports that only certain yeast UAS-core promoter combinations and mammalian enhancer-promoter combinations are efficiently transcribed [6–11]. The differential recruitment of TAFs by UASs provides strong evidence for the proposal that in vivo TAFs are the targets of some, but not all, activators

Study of interfacial transition zones between magnesium phosphate cement and Portland cement concrete pavement

The Portland cement concrete pavement (PCCP) often suffers from different environmental distresses and vehicle load failure, resulting in slab corner fractures, potholes, and other diseases. Rapid repair has become one of the effective ways to open traffic rapidly. In this study, a novel type of rapid repair material, basalt fiber reinforced polymer modified magnesium phosphate cement (BFPMPC), is used to rapidly repair PCCP. Notably, the mechanical properties and characteristics of the repair interfaces which are named interfacial transition zones (ITZs) formed by BFPMPC and cement concrete are focused on as a decisive factor for the performance of the rapid repair. The changing trend of the elastic moduli was studied by nanoindentation experiments in the ITZs with the deconvolution analysis that the elastic moduli of certain kinds of substances can be determined. The experimental results show that the elastic modulus of ITZ-1 with a width of about 20 μm can be regarded as 0.098 times of the aggregate, and 0.51 times of the ordinary Portland cement (OPC) mortar. The BFPMPC-OPC mortar ITZ has roughly the same mechanical properties as the ITZ between aggregate and BFPMPC. A multi-scale representative two-dimensional model was established by random aggregate and a two-dimensional extended finite element method (XFEM) to study the mechanical properties of the repair interface. The simulation results show that the ITZ formed by the interface of BFPMPC and OPC mortar and basalt aggregate is the most vulnerable to failure, which is consistent with the nano-indentation experimental results

Flexural Properties of Steel-Bamboo Composite Slabs in Different Connection Methods

This paper presents a study aimed to estimate the flexural performance of profiled steel sheet-bamboo plywood composite slabs as a first step to evaluate its potential application as structural components. Nine specimens were tested to investigate the stability of steel-bamboo composite structure. According to different connection methods, three types of composite slabs were discussed, including pure bonding slabs (PBSs), composite bonding slabs (CBSs), and reinforced composite bonding slabs (RCBS). The result showed that specimens employed multiple composite methods (RCBS) exhibited excellent flexural bearing capacity and stiffness compared with PBS. The increase of bamboo plywood thickness could improve bearing capacity and flexural stiffness of composite slabs, while the reduction of screw spacing could enhance the bearing capacity and ductility of composite slabs. The RCBS, which can provide higher bearing capacity and stiffness and possess excellent deformation capability, are well worth of research and practical application

Terpyridine-Based, Coordination-Driven, 2D and 3D Supramolecular Architectures

Utilization of \u3c tpy-MII-tpy \u3e (tpy = 2,2\u27:6\u27,2 -terpyridine; M = metal) connectivity to construct specific shaped supramolecular architectures has been recently well-developed. Many transition metals can readily coordinate to terpyridine providing a wide range of bonding strength and properties. A large number of stoichiometrically self-assembled, terpyridine-based, supramolecular architectures have been achieved by using ZnII and CdII ions, which are known as the labile-bonded metals in the \u3c tpy-MII-tpy \u3e connectivity family. In recent years, a series of supramolecular polygons, utilizing \u3c tpy-MII-tpy \u3e connectivity, as the edges, and bisterpyridine ligands, as the vertices, have been synthesized. To explore the formation of higher-ordered 2D- and 3D-supramolecular architectures, multitopic terpyridine ligands must be considered, since each vertex contains at least three branching arms. Multitopic terpyridine ligands, such as tristerpyridine and hexakisterpyridine possessing 60° or 120° directionality, have been successfully synthesized via Suzuki cross-coupling reaction. Various coordination-driven, supramolecular structures, from 2D-based centrally-bridged rhomboid and spoked wheel, to 3D-based tetrahedron and mandoline-shaped architecture, have been quantitatively formed via a facial stoichiometric self-assembly. These novel assemblies will be addressed and their related synthesis, characterization, and properties will also be considered

MSR405: Inhibiting Neuroinflammation after Spinal Cord Injury in Rats

The treatment of spinal cord injury (SCI) is often ineffective. Additionally, SCI-induced inflammation leads to secondary injury. Current anti-inflammatory hydrophilic drugs fail to reach the nerve injury site due to the blood–brain barrier. Here, we synthesized MSR405, a new lipophilic unsaturated fatty acid derivative of Radix Isatidis and investigated its therapeutic effect in SCI model rats. Furthermore, we systematically investigated its structure, toxicity, anti-inflammatory effect, and the underlying mechanism. MSR405 was injected into the abdominal cavity of the Sprague Dawley SCI model rats, and the effect on their behavioral scores and pathology was estimated to assess the status of neurological inflammation. Our data show that MSR405 treatment significantly improved the motor function of SCI rats, and markedly suppressed the associated neuroinflammation. Moreover, MSR405 could attenuate LPS-induced inflammatory response in BV2 cells (Mouse microglia cells) in vitro. Mechanistically, MSR405 inhibits proinflammatory cytokines, supporting the anti-inflammatory response. Additionally, MSR405 can significantly block the TLR4/NF-κB signaling pathway and nitric oxide production. In summary, MSR405 reduces inflammation in SCI rats through the TLR4/NF-κB signal cascade and can inhibit neuroinflammation after spinal cord injury

Combustion Characteristics of a Supersonic Combustor with a Large Cavity Length-to-Depth Ratio

The combustion characteristics of a hydrogen-fueled supersonic combustor featuring a large cavity length-to-depth ratio (i.e., 11) were examined by performing experimental trials while varying the fuel injector positions and equivalence ratios. During these trials, flame chemiluminescence images were acquired simultaneously from the side and bottom of the combustor under Mach 2.0 inflow conditions. The flame was observed to stabilize inside the cavity under all conditions. Proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) analyses of sequential flame chemiluminescence images demonstrated the important effects of oblique shocks induced by fuel injection and heat release on flame stabilization. Because fluctuations in the locations of the flame and of the intense heat release zone were not observed and no dominant frequency was identified in POD and DMD analyses, the present configuration was evidently able to suppress combustion instability. The present research provides preliminary guidance for exploring the feasibility of using cavity combustors with large length-to-depth ratios in scramjet engines

Effect of Graphene on Modified Asphalt Microstructures Based on Atomic Force Microscopy

Atomic force microscopy (AFM) was used to explore the effects of graphene modifier on the microstructure of asphalt. The morphologies of the before- and after-aged base asphalt and modified asphalt were performed and compared with analysis. The formation mechanism of asphaltic “bee structures” and the influence mechanism of graphene on asphalt were discussed from the classical theory of material science (phase transformation theory and diffusion theory). The results show that graphene facilitates the nucleation of “bee structures”, resulting in an increasing number and decreasing volume of “bee structures” in modified asphalt. Additionally, the anti-aging performance of the modified asphalt improved significantly because of graphene incorporation