ATP-binding cassette transporter A7 enhances phagocytosis of apoptotic cells and associated ERK signaling in macrophages

The mammalian ATP-binding cassette transporters A1 and A7 (ABCA1 and -A7) show sequence similarity to CED-7, a Caenorhabditis elegans gene that mediates the clearance of apoptotic cells. Using RNA interference or gene targeting, we show that knock down of macrophage ABCA7 but not -A1 results in defective engulfment of apoptotic cells. In response to apoptotic cells, ABCA7 moves to the macrophage cell surface and colocalizes with the low-density lipoprotein receptor–related protein 1 (LRP1) in phagocytic cups. The cell surface localization of ABCA7 and LRP1 is defective in ABCA7-deficient cells. C1q is an opsonin of apoptotic cells that acts via phagocyte LRP1 to induce extracellular signal–regulated kinase (ERK) signaling. We show that ERK signaling is required for phagocytosis of apoptotic cells and that ERK phosphorylation in response to apoptotic cells or C1q is defective in ABCA7-deficient cells. These studies reveal a major role of ABCA7 and not -A1 in the clearance of apoptotic cells and therefore suggest that ABCA7 is an authentic orthologue of CED-7

Status and Prospect of Ecological Environment in the Belt and Road Initiative Regions

With the widespread recognition and in-depth implementation of the Belt and Road Initiative (BRI), especially in the context of global climate change, the ecological environment of Belt and Road Initiative regions might be confronted with pressures and challenges with rapid socioeconomic development. In response to those potential environmental challenges, China has put forward Green BRI and enriched the new Silk Road with more environmental connotations, aiming to reduce the conflict between economic development and eco-environmental protection. Currently, there is a lack of systematic and holistic research on eco-environmental issues in BRI regions. In addition, feasible solutions to enhance BRI’s contribution to the eco-environment remain insufficient. Having systematically reviewed the relevant literature on the eco-environment in BRI regions, we found that most regions along the BRI routes are in sensitive zones of climate and geological change, with fragile eco-environments and strong vulnerability to climate change, natural disasters and human activities. The main eco-environment status of the BRI regions is as follows: (1) The total water resources in BRI regions account for only 36% of the global total, with uneven distribution and complex spatial precipitation, posing higher pressure on water security. (2) Vegetation varies significantly from region to region. The vegetation in South Asia is the richest, with its mean annual NDVI exceeding 0.7. The NDVI in East Europe, Russia and South China are between 0.4 and 0.7, and that in Central Asia and West Asia are below 0.2. (3) The BRI regions are abundantly blessed with natural resources, with the total recoverable oil reserves, natural gas reserves and the total mining area reaching 66%, 65.5% and 42.31% of the world’s total, respectively, but severe overexploitation and overconsumption of those resources degrade their eco-environment. Accordingly, future research directions, such as target on integrated, interdisciplinary and coordinated studies on eco-environmental issues in BRI regions, are proposed in this paper to achieve optimization of BRI’s contribution to eco-environment protection in BRI regions

Obtaining high-energy responses of nonlinear piezoelectric energy harvester by voltage impulse perturbations

Nonlinear energy harvesters have attracted wide research attentions to achieve broadband performances in recent years. Nonlinear structures have multiple solutions in certain frequency region that contains high-energy and low-energy orbits. It is effectively the frequency region of capturing a high-energy orbit that determines the broadband performance. Thus, maintaining large-amplitude high-energy-orbit oscillations is highly desired. In this paper, a voltage impulse perturbation approach based on negative resistance is applied to trigger high-energy-orbit responses of piezoelectric nonlinear energy harvesters. First, the mechanism of the voltage impulse perturbation and the implementation of the synthetic negative resistance circuit are discussed in detail. Subsequently, numerical simulation and experiment are conducted and the results demonstrate that the high-energy-orbit oscillations can be triggered by the voltage impulse perturbation method for both monostable and bistable configurations given various scenarios. It is revealed that the perturbation levels required to trigger and maintain high-energy-orbit oscillations are different for various excitation frequencies in the region where multiple solutions exist. The higher gain in voltage output when high-energy-orbit oscillations are captured is accompanied with the demand of a higher voltage impulse perturbation level

Double Knockouts of Phospholipases Dζ1 and Dζ2 in Arabidopsis Affect Root Elongation during Phosphate-Limited Growth But Do Not Affect Root Hair Patterning

Root elongation and root hair formation are important in nutrient absorption. We found that two Arabidopsis (Arabidopsis thaliana) phospholipase Ds (PLDs), PLDζ1 and PLDζ2, were involved in root elongation during phosphate limitation. PLDζ1 and PLDζ2 are structurally different from the majority of plant PLDs by having phox and pleckstrin homology domains. Both PLDζs were expressed more in roots than in other tissues. It was reported previously that inducible suppression or inducible overexpression of PLDζ1 affected root hair patterning. However, gene knockouts of PLDζ1, PLDζ2, or the double knockout of PLDζ1 and PLDζ2 showed no effect on root hair formation. The expression of PLDζs increased in response to phosphate limitation. The elongation of primary roots in PLDζ1 and PLDζ2 double knockout mutants was slower than that of wild type and single knockout mutants. The loss of PLDζ2, but not PLDζ1, led to a decreased accumulation of phosphatidic acid in roots under phosphate-limited conditions. These results indicate that PLDζ1 and PLDζ2 play a role in regulating root development in response to nutrient limitation

A flexible, modular and versatile functional part assembly toolkit for gene cluster engineering in Streptomyces

Streptomyces has enormous potential to produce novel natural products (NPs) as it harbors a huge reservoir of uncharacterized and silent natural product biosynthetic gene clusters (BGCs). However, the lack of efficient gene cluster engineering strategies has hampered the pace of new drug discovery. Here, we developed an easy-to-use, highly flexible DNA assembly toolkit for gene cluster engineering. The DNA assembly toolkit is compatible with various DNA assembling approaches including Biobrick, Golden Gate, CATCH, yeast homologous recombination-based DNA assembly and homing endonuclease-mediated assembly. This compatibility offers great flexibility in handling multiple genetic parts or refactoring large gene clusters. To demonstrate the utility of this toolkit, we quantified a library of modular regulatory parts, and engineered a gene cluster (act) using characterized promoters that led to increased production. Overall, this work provides a powerful part assembly toolkit that can be used for natural product discovery and optimization in Streptomyces

Investigations into the Microstructure and Texture Evolution of Inertia-Friction-Welded Dissimilar Titanium Alloys

The welded joint of a dissimilar titanium alloy was obtained via inertial friction welding technology. The characteristics of the bonding interface and the microstructure of the welded joint were investigated via optical microscopy, scanning electron microscopy and electron backscattered diffraction. The results show that fine, equiaxed grains and interdiffusion bands of the elements Mo and Sn were formed in the weld zone under the high temperature and plastic deformation of the inertial friction welding. The weld zone and thermo-mechanically affected zone formed ⟨1¯21¯0⟩ α texture and ⟨111⟩ β texture, respectively

Jointing Achievement and Performance Evaluation of Bogie Crossmember Ring Joint Welded via Inertia Friction Welding

As a major load-bearing component of trains, the weld quality of the bogie beam is critical to the safety of railway operations. This study specifically investigates the inertia friction welding process of S355 bogie crosshead tubes, with the aim of improving the weld quality and achieving one-time formation of the crosshead tube and tube seat. The microstructural features and mechanical properties of S355 inertia-welded joints were also compared with the base metal. Research indicates that inertia friction welds have no visible defects, and that the microstructure of the welding seam (WS) consists of granular bainite, acicular ferrite and little pearlite. The thermo-mechanically affected zone (TMAZ) consists of granular bainite bands and ferrite + pearlite bands. The hot work strengthening mechanism of inertia friction welding results in a higher level of hardness for both WS and TMAZ. The tensile property of the welded joints can be compared to the base metal. The yield strength, tensile strength and elongation of the welded joints, respectively, reach 87.5%, 100% and 79.5% of S355. However, the impact toughness of the welds at room temperature is lower than that of the base material, particularly in the TMAZ zone. Conversely, in an environment with a temperature of −40 °C, WS’s impact toughness surpasses that of the parent material

Construction of an Ecological Security Pattern in an Urban–Lake Symbiosis Area: A Case Study of Hefei Metropolitan Area

In the context of rapid urbanization, building an ecological security pattern that takes into account both ecological protection and economic growth is of great significance for guiding high-quality regional development. Taking the Hefei metropolitan area as an example, we identified the ecological source from three aspects—the importance of ecosystem services, ecological sensitivity, and landscape connectivity—by using NPP-VIIRS night light data, impervious surfaces, and the topographical index to the rest of the landscape resistance surface, and the least cumulative resistance model to identify ecological corridors and ecological buffer zones. We then constructed a comprehensive regional ecological security pattern. The results show the following: (1) The ecological source area of the Hefei metropolitan area is 15,538.74 km2, accounting for 24.5% of the total study area. It is mainly composed of the Dabie Mountains, the Yangtze River, the Huai River, and Chaohu Lake. (2) The area of an ecological buffer zone, ecological transition zone, and development and construction zone account for 21.8%, 39.7%, and 38.5%, respectively. Among them, the ecological buffer zone serves as a protective barrier for the ecological source area; therefore, development and construction activities should be restricted. The ecological transition zone should be constructed with low development intensity, and the development and construction zone can be carried out with greater development intensity. (3) The total length of the ecological corridor is 2816.89 km, with the mainland of the corridor being cultivated land. Identified by superposition of the land use, the area of conflict of urban expansion is 305.23 km2, mainly distributed along the Yangtze River and around Chao Lake. The results may provide decision support for the construction of ecological security in the study area