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Bacterial transcription initiation requires σ factors for nucleation of the transcription bubble. The canonical housekeeping σ factor, σ 70 , nucleates DNA melting via recognition of conserved bases of the promoter −10 motif, which are unstacked and captured in pockets of σ 70 . By contrast, the mechanism of transcription bubble nucleation and formation during the unrelated σ N -mediated transcription initiation is poorly understood. Herein, we combine structural and biochemical approaches to establish that σ N , like σ 70 , captures a flipped, unstacked base in a pocket formed between its N-terminal region I (RI) and extra-long helix features. Strikingly, RI inserts into the nascent bubble to stabilize the nucleated bubble prior to engagement of the obligate ATPase activator. Our data suggest a general paradigm of transcription initiation that requires σ factors to nucleate an early melted intermediate prior to productive RNA synthesis.

In the global efforts to combat Covid-19, researchers have increasingly recognized the profound impacts of society lockdown on population mental health. However, the fine temporal evolution of negative psychological consequences induced by lockdowns remains poorly understood. Here we report a rapid and systematic increase in depression due to the Shanghai Covid lockdown in March 2022. Measured by Beck Depression Inventory-2, 10% of the participants experienced at least mild depression before the official citywide lockdown started, and two and four weeks later this number increased to 21% and 36 %, respectively. Regression analyses show that lockdown duration and physical restriction jointly contribute to worsening depression. Furthermore, the time of sleep and social communication during the lockdown are associated with the severity of depression symptoms. These results highlight the fast development of depression during lockdowns and call for special attention to early psychological interventions once a lockdown is initiated.

Accumulating clinical and epidemiological studies indicate that learning and memory impairment is more prevalent among people with diabetes mellitus (DM). PTP1B is a member of protein tyrosine phosphatase family and participates in a variety of pathophysiological effects including inflammatory, insulin signaling pathway, and learning and memory. This study was aimed to investigate the effects of CA, a specific inhibitor of PTP1B, on spatial learning and memory impairment in diabetic mice caused by high-fat diet and injection of streptozotocin. We found that the protein expressions of PTP1B increased in hippocampal CA1, CA3, and PFC regions of diabetic mice. Network pharmacology results showed that PTP1B might be one of the key targets between diabetes and cognitive dysfunction, and CA might alleviate DM-induced cognitive dysfunction. Animal experiments showed that CA ameliorated DM-induced spatial learning and memory impairment, and improved glucose and lipid metabolic disorders. Moreover, administration of CA alleviated hippocampal structure damage and enhanced the expressions of synaptic proteins, including PSD-95, SYN-1, and SYP in diabetic mice. Furthermore, CA treatment not only significantly down-regulated the expressions of PTP1B and NLRP3 inflammatory related proteins (NLRP3, ASC, Caspase-1, COX-2, IL-1β, and TNF-α), but also significantly up-regulated the expressions of insulin signaling pathway-related proteins (p-IRS1, p-PI3K, p-AKT, and p-GSK-3β) in diabetic mice. Taken together, these results suggested that PTP1B might be a targeted strategy to rescue learning and memory deficits in DM, possibly through inhibition of NLRP3 inflammasome and regulation of insulin signaling pathway.

Basic mesoporous zeolite ETS-10 (ETS-10-M) with high surface area (366 m2·g−1) and large mesopores volume (0.21 cm3·g−1) is synthesized by templated with an organosilan surfactant. After loading of Ni species and calcination, the obtained Ni/ETS-10-M as a bi-functional catalyst shows high activity and good product selectivity in the fluorination of N-aryl amides with N-fluorobenzenesulfonimide (NFSI). The Ni2+ species in Ni/ETS-10-M facilitate the formation of fluorine radical from NFSI, and the basic sites in Ni/ETS-10-M favour N-aryl amide transformation into corresponding carbon-radical, and reacted with fluorine radical to form the desired product. Ni/ETS-10-M catalyst exhibits good catalytic activity even it reused seven times.

Clinical and epidemiological studies indicate that diabetic cognitive impairment often occurs in diabetes mellitus patients. Matrine (Mat), an active component of Sophora flavescens Ait root extracts, has widely pharmacological activities including anti-tumor, anti-diabetes, cardioprotective and neuroprotective effects. The present study was designed to elucidate the possibly neuroprotective effects of Mat against diabetic spatial learning and memory impairment caused by high-fat diet and streptozotocin injection in mice. The results showed that Mat treatment significantly ameliorated fasting blood glucose level, impaired glucose tolerance, and lipid metabolism disorder in diabetic mice. In addition, diabetic mice exhibited spatial learning and memory impairment in the Morris water maze test, which could be attenuated by Mat treatment. Moreover, administration of Mat remarkably alleviated histological damage in diabetic hippocampus. Also, further investigations showed that Mat treatment abated endoplasmic reticulum stress induced hippocampal ultra-structure injury as evidenced by increasing the numbers of rough endoplasmic reticulum and mitochondria, as well as down-regulating endoplasmic reticulum stress related protein levels (GRP78, CHOP, ATF6 and Caspase-12). Furthermore, administration of Mat enhanced hippocampal protein expressions of PK2, PKR1 and PKR2, which decreased significantly in diabetic mice. Collectively, these findings suggested that Mat could ameliorate diabetes-induced spatial learning and memory impairment, possibly by alleviating ER stress, and partly through modulation of PK2/PKRs pathway.

Over the past decade, technical and methodological improvements in cryogenic electron microscopy (cryo-EM) single-particle analysis have enabled routine high-resolution structural analyses of biological macromolecules, resulting in a flood of new molecular insights into protracted biological questions. However, despite the tremendous progress and success of the field in recent years, opportunities for improvement remain in various aspects of the cryo-EM single-particle analysis workflow (e.g., sample preparation, image acquisition and processing, and structure validation). Here, we review recent advances that have contributed to the principal methods in cryo-EM and identify persisting challenges and bottlenecks that will require further methodological and hardware development.

For decades, high-resolution structural studies of biological macromolecules with masses of

This study identifies general characteristics of methods to estimate the absolute range between an acoustic transmitter and a receiver in the deep ocean. The data are from three days of the PhilSea10 experiment with a single fixed transmitter depth (∼998 m) and 150 receiver depths (∼210–5388 m) of known location, and a great-circle transmitter-receiver distance of ∼510 km. The proposed ranging methods compare observed acoustic records with synthetic records computed through the HYCOM (hybrid coordinate ocean model) model. More than 8900 transmissions over 3 days characterize the statistical variation of range errors. Reliable ranging methods de-emphasize the parts of the data records least likely to be reproduced by the synthetics, which include arrival amplitudes, the later parts of the acoustic records composed of nearly horizontally launched rays (i.e., the finale), and waves that sample a narrow span of ocean depths. The ranging methods proposed normalize amplitudes, measure travel times, or reject parts of the waveforms beyond a critical time. All deliver reliable range estimates based on the time and path-averaged HYCOM model, although the final method performs best. The principles behind these methods are transportable and expected to provide reliable range estimates in different deep water settings.This study identifies general characteristics of methods to estimate the absolute range between an acoustic transmitter and a receiver in the deep ocean. The data are from three days of the PhilSea10 experiment with a single fixed transmitter depth (∼998 m) and 150 receiver depths (∼210–5388 m) of known location, and a great-circle transmitter-receiver distance of ∼510 km. The proposed ranging methods compare observed acoustic records with synthetic records computed through the HYCOM (hybrid coordinate ocean model) model. More than 8900 transmissions over 3 days characterize the statistical variation of range errors. Reliable ranging methods de-emphasize the parts of the data records least likely to be reproduced by the synthetics, which include arrival amplitudes, the later parts of the acoustic records composed of nearly horizontally launched rays (i.e., the finale), and waves that sample a narrow span of ocean depths. The ranging methods proposed normalize amplitudes, measure travel times, or reject pa...

Transient receptor potential vanilloid channel 3 (TRPV3), a member of the thermosensitive TRP (thermoTRPV) channels, is activated by warm temperatures and serves as a key regulator of normal skin physiology through the release of pro-inflammatory messengers. Mutations in trpv3 have been identified as the cause of the congenital skin disorder, Olmsted syndrome. Unlike other members of the thermoTRPV channel family, TRPV3 sensitizes upon repeated stimulation, yet a lack of structural information about the channel precludes a molecular-level understanding of TRPV3 sensitization and gating. Here, we present the cryo-electron microscopy structures of apo and sensitized human TRPV3, as well as several structures of TRPV3 in the presence of the common thermoTRPV agonist 2-aminoethoxydiphenyl borate (2-APB). Our results show α-to-π-helix transitions in the S6 during sensitization, and suggest a critical role for the S4-S5 linker π-helix during ligand-dependent gating., Transient receptor potential vanilloid channel 3 (TRPV3) responds to temperature and sensitizes upon repeated stimulation with either heat or agonists. Here authors present the cryo-EM structures of apo and sensitized human TRPV3 and describe the structural basis of sensitization.

A channel for calcium Maintaining the correct balance of calcium concentrations between the cytosol and the mitochondria is essential for cellular physiology. A calcium-selective channel called the mitochondrial calcium uniporter (MCU) mediates calcium entry into mitochondria. Yoo et al. report the high-resolution structure of MCU from Neurospora crassa. The channel is formed by four MCU protomers with differing symmetry between the soluble and membrane domains. The structure, together with mutagenesis, suggests that two acidic rings inside the channel provide the selectivity for calcium. Science , this issue p. 506

Architecture of the TRPM subfamily Transient receptor potential melastatin (TRPM) ion channels constitute the largest TRP subfamily and are involved in many physiological processes. TRPM8 is the primary cold and menthol sensor, and TRPM4 is associated with cardiovascular disorders. Yin et al. and Autzen et al. shed light on the general architecture of the TRPM subfamily by solving the structures of TRPM8 and TRPM4, respectively (see the Perspective by Bae et al. ). The three-layered architecture of the TRPM8 channel provides the framework for understanding the mechanisms of cold and menthol sensing. The two distinct closed states of TRPM4, with and without calcium, reveal a calcium-binding site and calcium-binding-induced conformational changes. Science , this issue p. 237 , p. 228 ; see also p. 160

the fundamental objective of this study was to quantitatively examine the influence of entrepreneurial orientation on financial performance under Small and Medium Enterprises (SMEs) in Ghana. This study centred on the SMEs in the manufacturing subsector of the Ghanaian economy. The study employed a quantitative research approach because there was a need to generate numerical evidence and data sets that depict the current situation and trend of the SMEs operations in Ghana. Research data sample of two hundred and sixty-seven (246) SMEs owners and managers in the manufacturing subsector were used in the study. Data collected was coded using Statistical Package for Social Sciences (SPSS V22.0) and Structural Equation Modelling (SEM) was used to evaluate the proposed model for a clear understanding of the relationships that exist among SMEs and its constructs. The study found out that, there is statistically a significant relationship between entrepreneurial orientation and SME financial performance quantitatively. Specifically, the result highlights SME innovativeness, autonomy, proactiveness and competitive aggressiveness as the dimensions of entrepreneurial orientation that have a significant positive effect on SME financial performance in Ghana’s economy. The study seeks to discover how the dimensions of entrepreneurial orientation result in SME financial performance of manufacturing firms in Ghana. The manufacturing companies selected for this study are based in the capital of Ghana, Accra. These manufacturing companies were selected due to proximity and most importantly Accra seems to be the host of many small and medium enterprises (SMEs) in Ghana. &nbsp

Although the advent of direct electron detectors (DEDs) and software developments have enabled the routine use of single-particle cryogenic electron microscopy (cryo-EM) for structure determination of well-behaved specimens to high-resolution, there nonetheless remains a discrepancy between the resolutions attained for biological specimens and the information limits of modern transmission electron microscopes (TEMs). Instruments operating at 300 kV equipped with DEDs are the current paradigm for high-resolution single-particle cryo-EM, while 200 kV TEMs remain comparatively underutilized for purposes beyond sample screening. Here, we expand upon our prior work and demonstrate that one such 200 kV microscope, the Talos Arctica, equipped with a K2 DED is capable of determining structures of macromolecules to as high as ∼1.7 Å resolution. At this resolution, ordered water molecules are readily assigned and holes in aromatic residues can be clearly distinguished in the reconstructions. This work emphasizes the utility of 200 keV for high-resolution single-particle cryo-EM and applications such as structure-based drug design.

The transient receptor potential melastatin 2 (TRPM2) channel plays a key role in redox sensation in many cell types. Channel activation requires binding of both ADP-ribose (ADPR) and Ca2+. The recently published TRPM2 structures from Danio rerio in the ligand-free and the ADPR/Ca2+-bound conditions represent the channel in closed and open states, which uncovered substantial tertiary and quaternary conformational rearrangements. However, it is unclear how these rearrangements are achieved within the tetrameric channel during channel gating. Here we report the cryo-electron microscopy structures of Danio rerio TRPM2 in the absence of ligands, in complex with Ca2+ alone, and with both ADPR and Ca2+, resolved to ~4.3 Å, ~3.8 Å, and ~4.2 Å, respectively. In contrast to the published results, our studies capture ligand-bound TRPM2 structures in two-fold symmetric intermediate states, offering a glimpse of the structural transitions that bridge the closed and open conformations., The transient receptor potential channel member 2 (TRPM2) ion channel has a function in redox-dependent signaling. Here the authors present the cryo-EM structures of zebrafish TRPM2 in the ligand-free form, with Ca2+ and both ADP-ribose/Ca2+ and observe two-fold symmetric quaternary structure rearrangements in the ligand-bound structures that likely represent intermediate gating states.

the aim of this paper was to find out the impact of managerial practices on the performance of Small and Medium-sized Enterprise’s (SME’s) in Ghana. The growth and development of SME’s are predominantly dependent on the efficient managerial practices of SME’s and subsequently the need to examine its influence on the performance of SME’s as well. Data were collected through self-administered questionnaires from 200 registered SMEs operating within the three major cities in Ghana. The Cronbach's Alpha was used to check the reliability of the data which indicated high levels of consistencies. The empirical analysis was conducted using the multiple linear regression model. The results of the study indicated that there was a positive relationship between training practice and SME performance, performance appraisal, and SME performance and between incentive compensation and SME performance. This, therefore, implies that for the effective development of SME’s in Ghana, the owners should pay more attention to employees’ incentive motivation, capacity building of employees and the performance appraisal of employees

The most common way of transportation for refined oil is long-distance pipeline. Pipeline accidents occur frequently due to corrosion, equipment failure, external forces destruction. Aiming at predicting the contaminated area in soil caused by products pipeline accidents, this experimental study was conducted to examine the relationship between the light non-aqueous phase liquids (LNAPL) accumulative infiltrate volume and the time of infiltration process in homogeneous and layered soils. The soil’s hydraulic parameters were obtained by basic experiments and RETC software. Compared with traditional infiltration mathematical model, Green-Ampt model is the most common mathematical model to calculate the infiltration process in the unsaturated soil. In this study, a modified Green-Ampt model was developed to describe water and diesel infiltration through a 100-cm-long and layered soil column. In the modified Green-Ampt model, an infiltration reduction ratio was introduced to describe the effect of the hydraulic conductivity of the layered position. To evaluate the proposed method in the effect of the layers position infiltration permeability, eight constant water head layered column infiltration experiment were conducted to record the different infiltration fluid and different constant water head infiltration process. Compared the experiment results with traditional mathematical traditional Green-Ampt model (average R2 = 0.976) and Hydrus-1D software (average R2 = 0.988) The modified Green-Ampt model had relatively higher precision in accumulative infiltrate volume (average R2 = 0.992) and the wetting front velocity in infiltration process (average R2 = 0.997). Thus, the modified mathematical model was applied an effective upscaling scheme in layered formations. The experimental result also demonstrated that soil layering affected the infiltration process. With the increase of soil depth and density, the infiltration speed of the layered soil column decreased. Additionally, the infiltrate speed of wetting front decreases slowly at the layered surface. The experiment’s fitting results showed that the modified mathematical model about infiltrate time and liquid contaminant accumulative infiltrate volume, wetting front infiltrate velocity can highly effective approach to simulate water and light non-aqueous phase liquids (LNAPL) infiltration process in layered soils.

Determining high-resolution structures of biological macromolecules amassing less than 100 kilodaltons (kDa) has been a longstanding goal of the cryo-electron microscopy (cryo-EM) community. While the Volta phase plate has enabled visualization of specimens in this size range, this instrumentation is not yet fully automated and can present technical challenges. Here, we show that conventional defocus-based cryo-EM methodologies can be used to determine high-resolution structures of specimens amassing less than 100 kDa using a transmission electron microscope operating at 200 keV coupled with a direct electron detector. Our ~2.7 Å structure of alcohol dehydrogenase (82 kDa) proves that bound ligands can be resolved with high fidelity to enable investigation of drug-target interactions. Our ~2.8 Å and ~3.2 Å structures of methemoglobin demonstrate that distinct conformational states can be identified within a dataset for proteins as small as 64 kDa. Furthermore, we provide the sub-nanometer cryo-EM structure of a sub-50 kDa protein., Despite many recent advances in cryo-EM, imaging smaller macromolecules (below 100 kDa) has remained a challenge. Here the authors show that biological specimens amassing

Two kinds of silicon carbide (SiC) powders with median diameters of 0.60μm and 2.04μm were selected as raw materials, and uniformly dispersed SiC coating film solutions were prepared through different particle grading. The effects of gradation ratio and dispersant tetramethylammonium hydroxide (TMAH) on the dispersibility and rheology of SiC coating films were studied, and the effect of dispersant content on the film forming properties of the slurry was discussed. When the fine powder and coarse powder grading mass ratio is 3:7, the particle size distribution of the mixed powder is closest to the theoretical distribution of the Dinger model. At this time, the slurry has good rheology and high particle bulk density. When 0.4% TMAH is added, the viscosity of the slurry is the lowest. When TMAH is added in an amount of 0.1 to 0.2%, the slurry has good film-forming properties.

The silicon carbide (SiC) powder is covered with polycarbosilane (PCS), N-Methyl pyrrolidone (NMP) is a solvent, polyethersulfone (PES) is a bonding aid, using phase-phase and solid-phase sintering process combined with a step-by-step molding to prepare a symmetrical structure of silicon carbide hollow fibers, and determine the membrane’s perforation and purification and purity of the water distribution and the circumference of the membrane. The results show that the SiC membrane tube is a finger-hole structure layer-spongy structure layer-finger-hole structure structure, the optimal sintering temperature is at 1200 °C, the size of the prepared ceramic membrane aperture is concentrated in about 0.9 μm, and the pure water flux is 2.832m3 / (m2⋅h).

Technical and methodological advances in single-particle cryo-electron microscopy (cryo-EM) have expanded the technique into a resolution regime that was previously only attainable by X-ray crystallography. Although single-particle cryo-EM has proven to be a useful technique for determining the structures of biomedically relevant molecules at near-atomic resolution, nearly 98% of the structures resolved to better than 4 Å resolution have been determined using 300 keV transmission electron microscopes (TEMs). We demonstrate that it is possible to obtain cryo-EM reconstructions of macromolecular complexes at a range of sizes to better than 3 Å resolution using a 200 keV TEM. These structures are of sufficient quality to unambiguously assign amino acid rotameric conformations and identify ordered water molecules, features previously thought only to be resolvable using TEMs operating at 300 keV.

The accidental leakage of long-distance pressurized oil pipelines is a major area of risk, capable of causing extensive damage to human health and environment. However, the complexity of the leaking process, with its complex boundary conditions, leads to difficulty in calculating the leakage volume. In this study, the leaking process is divided into 4 stages based on the strength of transient pressure. 3 models are established to calculate the leaking flowrate and volume. First, a negative pressure wave propagation attenuation model is applied to calculate the sizes of orifices. Second, a transient oil leaking model, consisting of continuity, momentum conservation, energy conservation and orifice flow equations, is built to calculate the leakage volume. Third, a steady-state oil leaking model is employed to calculate the leakage after valves and pumps shut down. Moreover, sensitive factors that affect the leak coefficient of orifices and volume are analyzed respectively to determine the most influential one. To validate the numerical simulation, two types of leakage test with different sizes of leakage holes were conducted from Sinopec product pipelines. More validations were carried out by applying commercial software to supplement the experimental insufficiency. Thus, the leaking process under different leaking conditions are described and analyzed.