Developing a PAM-Flexible CRISPR-Mediated Dual-Deaminase Base Editor to Regulate Extracellular Electron Transport in Shewanella oneidensis.

Shewanella oneidensis MR-1 is a promising electroactive microorganism in environmental bioremediation, bioenergy generation, and bioproduct synthesis. Accelerating the extracellular electron transfer (EET) pathway that enables efficient electron exchange between microbes and extracellular substances is critical for improving its electrochemical properties. However, the potential genomic engineering strategies for enhancing EET capabilities are still limited. Here, we developed a clustered regularly interspaced short palindromic repeats (CRISPR)-mediated dual-deaminase base editing system, named in situ protospacer-adjacent motif (PAM)-flexible dual base editing regulatory system (iSpider), for precise and high-throughput genomic manipulation. The iSpider enabled simultaneous C-to-T and A-to-G conversions with high diversity and efficiency in S. oneidensis. By weakening DNA glycosylase-based repair pathway and tethering two copies of adenosine deaminase, the A-to-G editing efficiency was obviously improved. As a proof-of-concept study, the iSpider was adapted to achieve multiplexed base editing for the regulation of the riboflavin biosynthesis pathway, and the optimized strain showed an approximately three-fold increase in riboflavin production. Moreover, the iSpider was also applied to evolve the performance of an inner membrane component CymA implicated in EET, and one beneficial mutant facilitating electron transfer could be rapidly identified. Taken together, our study demonstrates that the iSpider allows efficient base editing in a PAM-flexible manner, providing insights into the design of novel genomic tools for Shewanella engineering.

Facilitating the Carrier Transport Kinetics at the CsPbBr3/Carbon Interface through SbX3 (X = Cl, Br, I) Passivation.

The nonradiative carrier recombination at the perovskite/carrier selective layer (CSL) interface was accounted for the inferior power conversion efficiency (PCE) of perovskite solar cells (PSCs), especially rigid all-inorganic perovskite (CsPbI3 and CsPbBr3). In this study, targeting the poor interface, we introduce SbX3 (X = Cl, Br, I) surface passivation at the CsPbBr3/carbon interface. Smoothed compressive strain, reduced defect density, and enhanced energy-level alignment were achieved simultaneously, facilitating carrier extraction at the selective interface. With the simple aqueous solution-based two-step process, the PCE of our SbI3 passivated carbon-based CsPbBr3 PSCs has increased from 7.81% (without passivation) to 9.69%, a ∼25% enhancement. Specifically, Voc (1.657 V) of the SbI3-passivated cells was much higher than that of the control ones (1.488 V), confirming the ameliorated interface. Finally, our unencapsulated SbI3 passivated devices maintain 90% of their initial PCEs while left in the air for 30 days with a relative humidity of 60%. To conclude, we present an interfacial carrier extraction-enhanced strategy for preparing high-performance and stable CsPbBr3-based PSCs.

Tuning Redox Potential of Anthraquinone-2-Sulfonate (AQS) by Chemical Modification to Facilitate Electron Transfer From Electrodes in Shewanella oneidensis.

Bioelectrochemical systems (BESs) are emerging as attractive routes for sustainable energy generation, environmental remediation, bio-based chemical production and beyond. Electron shuttles (ESs) can be reversibly oxidized and reduced among multiple redox reactions, thereby assisting extracellular electron transfer (EET) process in BESs. Here, we explored the effects of 14 ESs on EET in Shewanella oneidensis MR-1, and found that anthraquinone-2-sulfonate (AQS) led to the highest cathodic current density, total charge production and reduction product formation. Subsequently, we showed that the introduction of -OH or -NH2 group into AQS at position one obviously affected redox potentials. The AQS-1-NH2 exhibited a lower redox potential and a higher Coulombic efficiency compared to AQS, revealing that the ESs with a more negative potential are conducive to minimize energy losses and improve the reduction of electron acceptor. Additionally, the cytochromes MtrA and MtrB were required for optimal AQS-mediated EET of S. oneidensis MR-1. This study will provide new clues for rational design of efficient ESs in microbial electrosynthesis.

Biomaterial Cues Regulated Differentiation of Neural Stem Cells into GABAergic Neurons through Ca2+/c-Jun/TLX3 Signaling Promoted by Hydroxyapatite Nanorods.

Directed differentiation enables the production of a specific cell type by manipulating signals in development. However, there is a lack of effective means to accelerate the regeneration of neurons of particular subtypes for pathogenesis and clinical therapy. In this study, we find that hydroxyapatite (HAp) nanorods promote neural differentiation of neural stem cells due to their chemical compositions. Lysosome-mediated degradation of HAp nanorods elevates intracellular calcium concentrations and accelerates GABAergic neurogenesis. As a mechanism, the enhanced activity of a Ca2+ peak initiated by HAp nanorods leads to the activation of c-Jun and thus suppresses the expression of GABAergic/glutamatergic selection gene TLX3. We demonstrate the capability of HAp nanorods in promoting the differentiation into GABAergic neurons at both molecular and cellular function levels. Given that GABAergic neurons are responsible for various physiological and pathological processes, our findings open up enormous opportunities in efficient and precise stem cell therapy of neurodegenerative diseases.

Na2 FePO4 F/Biocarbon Nanocomposite Hollow Microspheres Derived from Biological Cell Template as High-Performance Cathode Material for Sodium-Ion Batteries.

We have successfully synthesized Na2 FePO4 F/biocarbon nanocomposite hollow microspheres from FeIII precursor as cathodes for sodium-ion batteries through self-assembly of yeast cell biotemplate and sol-gel technology. The carbon coating on the nanoparticle surface with a mesoporous structure enhances electron diffusion into Na2 FePO4 F crystal particles. The improved electrochemical performance of Na2 FePO4 F/biocarbon nanocomposites is attributed to the larger electrode-electrolyte contact area and more active sites for Na+ on the surface of hollow microspheres compared with those of Na2 FePO4 F/C. The Na2 FePO4 F/biocarbon nanocomposite exhibits a high initial discharge capacity of 114.3 mAh g-1 at 0.1 C, long-cycle stability with a capacity retention of 74.3 % after 500 cycles at 5 C, and excellent rate capability (70.2 mAh g-1 at 5 C) compared with Na2 FePO4 F/C. This novel nanocomposite hollow microsphere structure is suitable for improving the property of other cathode materials for high-power batteries.

[Thrombolytic effects of recombinant staphylokinase on coronary thrombosis in miniature pigs].

OBJECTIVE: To evaluate the thrombolytic effects of recombinant staphylokinase and compare it with those of recombinant streptokinase. METHODS: Thirty Chinese experimental miniature pigs were divided into five groups, namely, solvent control group, positive drug control group and three recombinant staphylokinase groups, six in each group. The thrombus of coronary artery was formed by surgical thoracotomy and direct current stimulation in anesthetized animals. Intravenous administration was started after the thrombus of coronary artery was formed for 30 minutes, and the method of first injection and then constant speed infusion by peristaltic pump was used. The solvent control group was injected intravenously with solvent, the positive drug control group was given recombinant streptokinase 4 mg·kg-1 intravenously, and the three recombinant staphylokinase groups were given recombinant staphylokinase at the doses of 4, 2 and 1 mg.kg-1 intravenously. The volume of intravenous injection was 5 ml, which was completed within 1 min, the speed of infusion was 0.5 ml·min-1, which was completed within 60 min, and the animals were sacrificed 120 minutes later. Before and 30, 60 and 120 min after administration, the venous blood samples were collected. At the end of the experiment, the coronary artery segments of the thrombosis site were taken, and the euglobulin dissolution time (ELT), blood fibrinogen content (FBG), fibrinogen degradation product (FDP) and wound bleeding volume were measured respectively. The coronary thrombolysis rate, myocardial ischemia degree and ischemia range were measured. RESULTS: Compared with the solvent control group, ELT in the experimental group was significantly shortened (P＜0.05 or P＜0.01), FBG degradation in a few experimental animals was more than 20%, FDP was significantly increased (P＜0.05 or P＜0.01), and there was no significant effect on blood pressure and heart rate of small pigs. Compared with the control group, the maximum thrombus area was decreased by 34.3% and 15.4% (P＜0.05) in the high and middle dose groups of the experimental group. Compared with the same dose of recombinant streptokinase, recombinant staphylokinase had stronger thrombolytic effect (P＜0.05 or P＜0.01) on the coronary thrombus caused by electrical stimulation, less bleeding side effects and the same effect on the degree and range of myocardial infarction as recombinant streptokinase. CONCLUSION: Compared with recombinant streptokinase, recombinant staphylokinase has faster thrombolysis speed, higher fibrin specificity and less bleeding side effects. In general, 2 mg.kg-1 recombinant staphylokinase has better efficacy and safety.

The moss flavone synthase I positively regulates the tolerance of plants to drought stress and UV-B radiation.

Flavonoids are extensively distributed secondary metabolites in land plants. They play a critical role in plant evolution from aquatic to terrestrial and plant adaption to ultraviolet radiation. However, the downstream branching pathway of flavonoids and its regulatory mechanism in bryophytes, which are the most ancient of terrestrial plants, remain unclear. Here, a type I flavone synthase (PnFNSI) was characterized from the Antarctic moss Pohlia nutans. PnFNSI was primarily distributed in the cytoplasm, as detected by subcellular localization. PnFNSI could catalyze the conversion of naringenin to apigenin with an optimal temperature between 15 and 20 °C in vitro. Overexpression of PnFNSI in Arabidopsis alleviated the growth restriction caused by naringenin and accumulated apigenin product. PnFNSI-overexpressing plants showed enhanced plant tolerance to drought stress and UV-B radiation. PnFNSI also increased the enzyme activities and gene transcription levels of reactive oxygen species (ROS) scavengers, protecting plants against oxidative stress. Moreover, overexpression of PnFNSI enhanced the flavone biosynthesis pathway in Arabidopsis. Therefore, this moss FNSI-type enzyme participates in flavone metabolism, conferring protection against drought stress and UV-B radiation.

Na3V2(PO4)3/Porous Carbon Skeleton Embellished with ZIF-67 for Sodium-Ion Storage.

Sodium super ionic conductor (NASICON) Na3V2(PO4)3 (NVP) is a type of promising cathode material for sodium-ion batteries (SIBs) with superior structural integrity, high energy density, and fast diffusion of sodium ions. However, NVP suffers from intrinsically low electrical conductivity, which results in poor rate performance. Herein, we report on the outstanding cathode performance of Na3V2(PO4)3 (NVP@C-ZIF67) wrapped by the ZIF-67-derived carbon, which was prepared by sol-gel method and solid-phase method. Electrochemical measurements show an initial discharge-specific capacity of 135 mA h g-1 at 1 C, and the discharge capacity maintains 82 mA h g-1 after 1000 cycles at 10 C. The results indicate the improvement in electrical conductivity and electrochemical performance due to the Co doping from ZIF-67. Moreover, we calculate the diffusion coefficient of sodium ions by the cyclic voltammetry (CV, DNa+ = 1.521 × 10-11 and 2.3484 × 10-11 cm2 s-1 for charging and discharging, respectively) and the galvanostatic intermittent titration technique (GITT, DNa+ ranges from 10-11-10-15 cm2 s-1). The exceptional performance is ascribed to the excellent structural stability and outstanding electrical conductivity of NVP modified by porous carbon skeleton and ZIF-67-derived carbon.

Overexpression of Grapevine VvIAA18 Gene Enhanced Salt Tolerance in Tobacco.

In plants, auxin/indoleacetic acid (Aux/IAA) proteins are transcriptional regulators that regulate developmental process and responses to phytohormones and stress treatments. However, the regulatory functions of the Vitis vinifera L. (grapevine) Aux/IAA transcription factor gene VvIAA18 have not been reported. In this study, the VvIAA18 gene was successfully cloned from grapevine. Subcellular localization analysis in onion epidermal cells indicated that VvIAA18 was localized to the nucleus. Expression analysis in yeast showed that the full length of VvIAA18 exhibited transcriptional activation. Salt tolerance in transgenic tobacco plants and Escherichia. coli was significantly enhanced by VvIAA18 overexpression. Real-time quantitative PCR analysis showed that overexpression of VvIAA18 up-regulated the salt stress-responsive genes, including pyrroline-5-carboxylate synthase (NtP5CS), late embryogenesis abundant protein (NtLEA5), superoxide dismutase (NtSOD), and peroxidase (NtPOD) genes, under salt stress. Enzymatic analyses found that the transgenic plants had higher SOD and POD activities under salt stress. Meanwhile, component analysis showed that the content of proline in transgenic plants increased significantly, while the content of hydrogen peroxide (H2O2) and malondialdehyde (MDA) decreased significantly. Based on the above results, the VvIAA18 gene is related to improving the salt tolerance of transgenic tobacco plants. The VvIAA18 gene has the potential to be applied to enhance plant tolerance to abiotic stress.

Mulberry-like heterostructure (Fe-O-Ti): a novel sensing material for ethanol gas sensors.

The gas sensors have been widely used in various fields, to protect the safety of life and property. A novel heterostructure of Fe-O-Ti nanoparticles is fabricated by hydrothermal and wet chemical deposition methods. The Fe-O-Ti nanoparticles with a large number of pores possess high surface area, which is in favour of high-performance gas sensors. Compared with pure Fe2O3 and TiO2, the Fe-O-Ti composite exhibits obviously enhanced sensing characteristics, such as faster response-recovery time (T res = 6 s, T rec = 48 s), higher sensing response (response = 35.6) and better selectivity. The results show that the special morphology and large specific surface area of mulberry-like Fe-O-Ti heterostructures provided a large contact area for gas reactions.

Stable and Reversible Lithium Storage with High Pseudocapacitance in GaN Nanowires.

In this work, gallium nitride (GaN) nanowires (NWs) were synthesized by chemical vapor deposition (CVD) process. The hybrid electrode showed the capacity up to 486 mAh g-1 after 400 cycles at 0.1 A g-1. Even at 10 A g-1, the reversible capacity can stabilize at 75 mAh g-1 (after 1000 cycles). Pseudocapacitive capacity was defined by kinetics analysis. The dynamics analysis and electrochemical reaction mechanism of GaN with Li+ was also analyzed by ex situ XRD, HRTEM, and XPS results. These results not only cast new light on pseudocapacitance enhanced high-rate energy storage devices by self-assembled nanoengineering but also extend the application range of traditional binary III/V semiconductors.

Graphene-Oxide-Assisted Synthesis of GaN Nanosheets as a New Anode Material for Lithium-Ion Battery.

As the most-studied III-nitride, theoretical researches have predicted the presence of gallium nitride (GaN) nanosheets (NSs). Herein, a facile synthesis approach is reported to prepare GaN NSs using graphene oxide (GO) as sacrificial template. As a new anode material of Li-ion battery (LIBs), GaN NSs anodes deliver the reversible discharge capacity above 600 mA h g-1 at 1.0 A g-1 after 1000 cycles, and excellent rate performance at current rates from 0.1 to 10 A g-1. These results not only extend the family of 2D materials but also facilitate their use in energy storage and other applications.

PnLRR-RLK27, a novel leucine-rich repeats receptor-like protein kinase from the Antarctic moss Pohlia nutans, positively regulates salinity and oxidation-stress tolerance.

Leucine-rich repeats receptor-like kinases (LRR-RLKs) play important roles in plant growth and development as well as stress responses. Here, 56 LRR-RLK genes were identified in the Antarctic moss Pohlia nutans transcriptome, which were further classified into 11 subgroups based on their extracellular domain. Of them, PnLRR-RLK27 belongs to the LRR II subgroup and its expression was significantly induced by abiotic stresses. Subcellular localization analysis showed that PnLRR-RLK27 was a plasma membrane protein. The overexpression of PnLRR-RLK27 in Physcomitrella significantly enhanced the salinity and ABA tolerance in their gametophyte growth. Similarly, PnLRR-RLK27 heterologous expression in Arabidopsis increased the salinity and ABA tolerance in their seed germination and early root growth as well as the tolerance to oxidative stress. PnLRR-RLK27 overproduction in these transgenic plants increased the expression of salt stress/ABA-related genes. Furthermore, PnLRR-RLK27 increased the activities of reactive oxygen species (ROS) scavengers and reduced the levels of malondialdehyde (MDA) and ROS. Taken together, these results suggested that PnLRR-RLK27 as a signaling regulator confer abiotic stress response associated with the regulation of the stress- and ABA-mediated signaling network.

A Novel Mild Phase-Transition to Prepare Black Phosphorus Nanosheets with Excellent Energy Applications.

Based on the phase transformation of phosphorus and Gibbs free energy theory, a new mild method to fabricate black phosphorus nanosheets from their red phosphorus microsphere counterparts is proposed. Interestingly, the as-prepared black phosphorus nanosheets, as a kind of novel metal-free photocatalyst, exhibit excellent photocatalytic H2 production performance owing to their intrinsic layered polycrystalline structure. Besides, the nanosheet is also a kind of potential anode material in lithium-ion batteries and shows good electrochemical performance.

Fabrication of two-dimensional nanosheets via water freezing expansion exfoliation.

Layered materials, if exfoliated effectively, will exhibit several unique properties, offering great potential for diverse applications. To this end, in this study, we develop a novel, universal, and environmentally friendly method named as 'water freezing expansion exfoliation' for producing two-dimensional nanosheets. This method exploits the expansion in the volume of water upon freezing. When the water freezing expansion condition is reproduced in layered materials, the layers exfoliate to overcome the van der Waals force between them. The expansion process is performed by repeated cycling between 4 °C and -20 °C to effectively exfoliate layered materials of graphite, hexagonal boron nitride (h-BN), MoS2 and WS2. Systematic characterization of the samples thus obtained using electron microscopy and optical studies substantiate the formation of thin flakes (graphene, h-BN, MoS2, and WS2 nanosheets). The method demonstrated in this study is cost-effective and does not demand sophisticated equipment and stringent high temperature conditions. Given this general applicability, this method holds great promise for exfoliating layered materials that are sensitive to elevated temperature.