Hydrological regulation drives regime shifts: evidence from paleolimnology and ecosystem modeling of a large shallow Chinese lake

Quantitative evidence of sudden shifts in ecological structure and function in large shallow lakes is rare, even though they provide essential benefits to society. Such ‘regime shifts’ can be driven by human activities which degrade ecological stability including water level control (WLC) and nutrient loading. Interactions between WLC and nutrient loading on the long‐term dynamics of shallow lake ecosystems are, however, often overlooked and largely underestimated, which has hampered the effectiveness of lake management. Here, we focus on a large shallow lake (Lake Chaohu) located in one of the most densely populated areas in China, the lower Yangtze River floodplain, which has undergone both WLC and increasing nutrient loading over the last several decades. We applied a novel methodology that combines consistent evidence from both paleolimnological records and ecosystem modeling to overcome the hurdle of data insufficiency and to unravel the drivers and underlying mechanisms in ecosystem dynamics. We identified the occurrence of two regime shifts: one in 1963, characterized by the abrupt disappearance of submerged vegetation, and another around 1980, with strong algal blooms being observed thereafter. Using model scenarios, we further disentangled the roles of WLC and nutrient loading, showing that the 1963 shift was predominantly triggered by WLC, whereas the shift ca. 1980 was attributed to aggravated nutrient loading. Our analysis also shows interactions between these two stressors. Compared to the dynamics driven by nutrient loading alone, WLC reduced the critical P loading and resulted in earlier disappearance of submerged vegetation and emergence of algal blooms by approximately 26 and 10 years, respectively. Overall, our study reveals the significant role of hydrological regulation in driving shallow lake ecosystem dynamics, and it highlights the urgency of using multi‐objective management criteria that includes ecological sustainability perspectives when implementing hydrological regulation for aquatic ecosystems around the globe.     

Electrochemistry and electrocatalysis with heme proteins in chitosan biopolymer films

Protein-chitosan (CS) films were made by casting a solution of proteins and CS on pyrolytic graphite electrodes. Myoglobin (Mb), hemoglobin (Hb), and horseradish peroxidase (HRP) incorporated in CS films gave a pair of stable, well-defined, and quasi-reversible cyclic voltammetric peaks at about -0.33V vs saturated calomel electrode in pH 7 buffers, respectively, while catalase (Ct) in CS films showed a peak pair at about -0.46V which was not stable. All these peaks are located at the potentials characteristic of heme Fe(III)/Fe(II) redox couples of the proteins. The electrochemical parameters such as formal potentials (E degrees (')) and apparent heterogeneous electron-transfer rate constants (k(s)) were estimated by square-wave voltammetry with nonlinear regression analysis. Chitosan films contained considerable water and formed hydrogel in aqueous solution. Positions of the Soret absorbance band suggest that Mb and Hb in CS films keep their secondary structure similar to the native states in the medium pH range, while HRP and Ct retain their native conformation at least in the dry CS films. Scanning electron microscopy of the films demonstrated that interaction between the proteins and CS would make the morphology of dry protein-CS films very different from the CS films alone. Oxygen, trichloroacetic acid, nitrite, and hydrogen peroxide were catalytically reduced by all four proteins in CS films.     

Viruses and interferon: a fight for supremacy

The action of interferons (IFNs) on virus-infected cells and surrounding tissues elicits an antiviral state that is characterized by the expression and antiviral activity of IFN-stimulated genes. In turn, viruses encode mechanisms to counteract the host response and support efficient viral replication, thereby minimizing the therapeutic antiviral power of IFNs. In this review, we discuss the interplay between the IFN system and four medically important and challenging viruses -- influenza, hepatitis C, herpes simplex and vaccinia -- to highlight the diversity of viral strategies. Understanding the complex network of cellular antiviral processes and virus-host interactions should aid in identifying new and common targets for the therapeutic intervention of virus infection. This effort must take advantage of the recent developments in functional genomics, bioinformatics and other emerging technologies.     

新型冠状病毒感染与复制的进展

冠状病毒是一类具有囊膜包裹的线性单股正链RNA病毒,在自然界广泛存在,可引起不同程度的呼吸性传染病。新型冠状病毒是一种新发突发病毒,对各类人群均易感。截止目前,该病已经在世界范围内广泛流行,对公共卫生安全构成极大的威胁。文中从冠状病毒及新型冠状病毒的基因组特征、关键蛋白、对宿主的感染和复制的角度加以综述,旨在为获得病毒侵染宿主细胞致病机制的探究提供理论依据,也为特异的抗病毒药物的研发提供基础支持。     

Total Flavonoids of Engelhardia roxburghiana Wall. Leaves Alleviated Foam Cells Formation through AKT/mTOR-Mediated Autophagy in the Progression of Atherosclerosis

Engelhardia roxburghiana Wall. is a traditional Chinese medicine used for treating cardiovascular diseases. Our previous study has implicated potential effects of total flavonoids of Engelhardia roxburghiana Wall. (TFER) against hyperlipidemia. The aim of the study is to uncover the effects and underlying mechanisms of TFER on foam cells formation after atherosclerosis. We used high fat diet (HFD) induced Apoe-/- mice and oxidized density lipoprotein (ox-LDL) induced THP-1 cells to mimic process of atherosclerosis in vivo and in vitro, respectively. Lipid accumulation, inflammation response, autophagosomes formation and expressions of autophagy related target genes were assessed. Our present study demonstrated TFER (500 mg/kg) alleviated macrophage infiltration and lipid accumulation in thoracic aortas of HFD-treated mice. In ox-LDL-treated THP-1 cells, MDC staining and Western blot analysis all indicated that the TFER (200 μg/ml) reduced foam cells formation and IL-1β releasing, activated autophagy through suppressing AKT/mTOR signaling, significantly regulating expressions of AKT, p-AKT, mTOR, p-mTOR, Beclin 1, LC3-II, p62. It is suggested that TFER alleviated atherosclerosis progression in vivo and in vitro through reducing foam cells formation and inflammatory responses, and the possible mechanism may be due to the activation of macrophage autophagy by inhibiting AKT and mTOR phosphorylation.     

Phytochemical Constituents and Biological Activities of Plants from the Genus Cissampelos

Cissampelos is a significant genus comprising of approximately 21 species of the medicinal plants (Menispermaceae). The plants of this genus are used in traditional medicine for the treatment of various ailments such as asthma, arthritis, dysentery, hyperglycemia, cardiopathy, hypertension and other related problems. These plants are rich in bioactive dibenzylisoquinoline and aborphine as well as small amounts of other ingredients. In recent years, the chemical constituents and pharmacological activities of Cissampelos genus have been paid more and more attention due to their diversity. Herein, we compile the chemical constituents and biological activities on this genus, and summarize the ¹³C-NMR data of the main bioactive ingredients. All information comes from scientific databases such as Google Scholar, PubMed, Sci-Finder, ScienceDirect, Web of Science and CNKI. It provides valuable data for the future research and development of Cissampelos genus.     

Simvastatin augments the efficacy of therapeutic angiogenesis induced by bone marrow-derived mesenchymal stem cells in a murine model of hindlimb ischemia

Many studies showed beneficial effects of either statin or bone marrow-derived mesenchymal stem cells (MSC) treatment in ischemic disease. In an attempt to further improve postischemic tissue repair, we investigated the effect of a local administration of MSC, in the presence or not of low-dose simvastatin, on angiogenesis and functional recovery in a mouse model of hindlimb ischemia. In vitro, the proliferation, migration, apoptosis, and tube formation of bone marrow MSC derived from transgenic mice expressing green fluorescent protein (GFP) were detected in the presence or not of 0.01 μmol/l simvastatin, respectively. In vivo, immediately after hindlimb ischemia, the mice were divided into four groups, namely control, MSC, statin, and statin-MSC, and received a single local injection of MSC (2 × 10⁶ cells) and/or a repeated gavages’ administration of simvastatin (0.2 mg/kg) for 21 days. The blood flow was measured by laser Doppler imaging, the capillary density was detected by alkaline phosphatase staining and, the MSC differentiation was assessed by immunofluorescent staining at 21 days after the ischemia. In vitro, the MSC proliferation rate, migration ability and tube formation number were increased significantly in simvastatin group relative to control group. Whereas, the H₂O₂ induced-apoptosis was inhibited significantly in simvastatin group relative to control group. In vivo, hindlimb blood reperfusion was significantly improved (MSC 0.55 ± 0.08, statin 0.57 ± 0.05, vs. control 0.47 ± 0.07, P < 0.05) and capillary density was obviously higher at day 21 post-ischemia by Laser Doppler Imaging in the MSC group and the Statin group when compared with control group. The combined use of statin and MSC further improved revascularization (perfusion ratio of 0.70 ± 0.09; P < 0.001 verse other groups) and resulted in the highest capillary density (P < 0.05 vs. all other groups). GFP-labeled transplanted cells were more frequently observed in the Statin-MSC group than in the MSC group (6.8 ± 0.5–3.1 ± 0.7, P < 0.05). Low-dose simvastatin could act in a synergistic way with MSC to potentiate the functional neovascularization in a mouse model of hind limb ischemia.     

Influence of Donor Polymer on the Molecular Ordering of Small Molecular Acceptors in Nonfullerene Polymer Solar Cells

Nonfullerene polymer solar cells (PSCs) based on polymer donors and nonfullerene small molecular acceptors (SMAs) have recently attracted considerable attention. Although much of the progress is driven by the development of novel SMAs, the donor polymer also plays an important role in achieving efficient nonfullerene PSCs. However, it is far from clear how the polymer donor choice influences the morphology and performance of the SMAs and the nonfullerene blends. In addition, it is challenging to carry out quantitative analysis of the morphology of polymer:SMA blends, due to the low material contrast and overlapping scattering features of the π–π stacking between the two organic components. Here, a series of nonfullerene blends is studied based on ITIC‐Th blended with five different donor polymers. Through quantitative morphology analysis, the (010) coherence length of the SMA is characterized and a positive correlation between the coherence length of the SMA and the device fill factor (FF) is established. The study reveals that the donor polymer can significantly change the molecular ordering of the SMA and thus improve the electron mobility and domain purity of the blend, which has an overall positive effect that leads to the enhanced device FF for nonfullerene PSCs.     

Sodium Ion Stabilized Vanadium Oxide Nanowire Cathode for High‐Performance Zinc‐Ion Batteries

Aqueous Zn‐ion batteries (ZIBs) have received incremental attention because of their cost‐effectiveness and the materials abundance. They are a promising choice for large‐scale energy storage applications. However, developing suitable cathode materials for ZIBs remains a great challenge. In this work, pioneering work on the designing and construction of aqueous Zn//Na_0.33V₂O₅ batteries is reported. The Na_0.33V₂O₅ (NVO) electrode delivers a high capacity of 367.1 mA h g^?1 at 0.1 A g^?1, and exhibits long‐term cyclic stability with a capacity retention over 93% for 1000 cycles. The improvement of electrical conductivity, resulting from the intercalation of sodium ions between the [V₄O₁₂]_n layers, is demonstrated by single nanowire device. Furthermore, the reversible intercalation reaction mechanism is confirmed by X‐ray diffraction, Raman, X‐ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy analysis. The outstanding performance can be attributed to the stable layered structure and high conductivity of NVO. This work also indicates that layered structural materials show great potential as the cathode of ZIBs, and the indigenous ions can act as pillars to stabilize the layered structure, thereby ensuring an enhanced cycling stability.