兰州唐古特白刺根际微生物分离鉴定

【目的】从兰州唐古特白刺根际分离得到对植物有潜在促生效果的功能微生物，为研发相关菌种制剂的研究奠定基础。【方法】通过平板划线法从其根际分离纯化出6株细菌，并对菌株进行形态特征观察、革兰氏染色等一系列生理生化试验。用藜麦检测各菌株的促生功能，并对具有优良促生作用的1个菌株16S rRNA基因进行分子鉴定及基因草图绘制。【结果】根据生化鉴定结果，6株细菌分别属于不动杆菌属(Acinetobacter)、土壤杆菌属(Agrobacterium)、类芽孢杆菌属(Paenibacillus)、芽孢杆菌属(Bacillus)、鞘氨醇单胞菌属(Sphingomonas)和假单胞菌属(Pseudomonas)。其中，16S rRNA基因鉴定BC4属于肠杆菌属(Enterobacter)，具有较好的促生效果。【结论】BC4具有较好的促生效果，为兰州唐古特白刺菌种资源的开发和利用提供了一定的理论依据。     

阿拉善高原2种荒漠植物根系构型及生态适应性特征

根系构型决定了植物对资源的吸收方式，根系构型的变化是植物对环境的生态适应和有效生存策略。在阿拉善高原西南缘红砂（Reaumuria soongarica）-珍珠猪毛菜（Salsola passerina）混生群落采用传统挖掘法收集两种植物根系，基于量化的根系形态指标，利用几何拓扑学及分形理论分析了根系构型特征，探讨了该地区2种植物对干旱生境的生态适应策略。结果表明：红砂和珍珠猪毛菜根系均以水平分布占优，根系浅层化分布明显，混生的两种植物占据不同的生态位；2种荒漠植物均具有较大的比根长（SRL）和比表面积（SRA），红砂SRL=21.3 cm/g，SRA=7.6 cm²/g，珍珠SRL=22.4 cm/g，SRA=6.5 cm²/g，有利于水分和养分的获取；红砂根系拓扑指数（TI）、修正拓扑参数（q_a和q_b）分别为0.86、0.52、0.49，珍珠猪毛菜对应参数分别为0.93、0.76、0.73，表明2种植物根系均趋向于鱼尾形分支结构；根系分形维数值（FD_红=1.488、FD_珍=1.422）较小，而分形丰度值（lgK_红=1.855、lgK_珍=1.774）较大，表明2种植物分支相对简单，但空间拓展能力强，有利于对营养空间的占有。上述特征可能是阿拉善西南缘红砂-珍珠猪毛菜群落2种荒漠植物植物对干旱贫瘠生境的重要生态适应策略。     

不同修复措施对黄河源退化高寒草甸植物群落与土壤养分的影响

为了揭示退化高寒草甸逆向转变的驱动因子，通过野外调查和室内分析相结合的方法探究了黄河源不同修复措施（施有机肥F、免耕补播N、施有机肥+免耕补播FN）处理高寒草甸植物群落特征、土壤理化性质和两者相关性的变化规律，阐明不同修复措施对黄河源退化高寒草甸植物群落与土壤养分的影响。结果表明：免耕补播显著增加草甸物种丰富度指数（P<0.05）；施有机肥+免耕补播显著增加草甸植物盖度、总生物量、Shannon Wiener多样性指数和Pielous均匀度指数（P<0.05）。不同人工修复后草甸植物功能群地上、地下生物量变化趋势基本一致（除豆科）。和对照相比，莎草科，杂类草地上和地下生物量含量在N、FN处理分别降低83.04%、73.86%、30.43%、92.37%和96.51%、84.09%、85.68%、95.36%；禾本科地上和地下生物量含量在F、N和FN处理分别增加7.29%、23.45%、17.93%和6.04%、4.03%、10.52%；豆科地上生物量含量基本保持不变，地下生物量含量在F、N和FN处理分别降低24.43%、82.19%和42.61%。F显著增加土壤有机碳含量（P=0.033）；N显著降低土壤NO₃^--N含量（P=0.009）；FN显著降低土壤pH和增加土壤速效磷含量（P=0.024）；F和FN显著增加土壤含水量（P=0.000），N则显著降低土壤含水量（P=0.000）；F显著降低土壤容重（P=0.018）。相关性分析表明植物Shannon Wiener多样性和Pielous均匀度与土壤速效磷含量呈显著正相关（P=0.037；P=0.033），土壤有机碳和含水量与总生物量呈显著正相关（P=0.027；P=0.032），pH与盖度呈显著负相关（P=0.049）。冗余度分析结果表明土壤有机碳含量和含水量显著影响了植物群落结构特征，解释率分别为30.3%和19.7%。研究结果表明，因地制宜进行退化高寒草甸施有机肥+免耕补播修复措施，能够明显提高草地生产力，改善草甸植物群落及其土壤养分和水分环境。     

格网尺度下典型旅游城市生态服务价值估算和时空分异特征——以三亚为例

以典型旅游城市三亚市为案例地，利用2006-2018年4期Landsat遥感影像数据，借助ENVI、ArcGIS平台定量识别土地利用演变特征，在1km×1km格网尺度下估算旅游地生态系统服务价值，并结合空间探索性数据分析揭示生态系统服务价值时空分异特征及其与旅游地发展的时空耦合关系。结果表明：（1）2006-2018年间，三亚市生态系统服务价值总量呈逐年下降趋势，由6.73×10⁹元降至5.76×10⁹元，累计减少9.78×10⁸元；（2）空间格局上，三亚市呈"南低北高"空间分异格局，2006-2018年增值区域连片分布于崖州区、天涯区、吉阳区南部区域，且呈逐年减少趋势，减值区域集聚于天涯区东北部、海棠区；（3）空间集聚上，生态系统服务价值截面各年份均呈显著空间正相关且相关性先降后增。高高集聚区位于天涯区北部区域，低低集聚区分布于沿海、海湾地区；（4）旅游发展与生态系统服务价值时空演化特征关联性较强。三亚市天涯区北部林地生态环境良好，生态系统服务价值略有下降但绝对数值稳定，是生态系统服务价值主要来源；旅游发展较为迅速的三亚湾、崖州湾以及海棠湾，相对增值区域较多，但绝对生态系统服务价值损失显著，严重滞后于其他区域。     

A cross-talk between epithelium and endothelium mediates human alveolar–capillary injury during SARS-CoV-2 infection

COVID-19, caused by SARS-CoV-2, is an acute and rapidly developing pandemic, which leads to a global health crisis. SARS-CoV-2 primarily attacks human alveoli and causes severe lung infection and damage. To better understand the molecular basis of this disease, we sought to characterize the responses of alveolar epithelium and its adjacent microvascular endothelium to viral infection under a co-culture system. SARS-CoV-2 infection caused massive virus replication and dramatic organelles remodeling in alveolar epithelial cells, alone. While, viral infection affected endothelial cells in an indirect manner, which was mediated by infected alveolar epithelium. Proteomics analysis and TEM examinations showed viral infection caused global proteomic modulations and marked ultrastructural changes in both epithelial cells and endothelial cells under the co-culture system. In particular, viral infection elicited global protein changes and structural reorganizations across many sub-cellular compartments in epithelial cells. Among the affected organelles, mitochondrion seems to be a primary target organelle. Besides, according to EM and proteomic results, we identified Daurisoline, a potent autophagy inhibitor, could inhibit virus replication effectively in host cells. Collectively, our study revealed an unrecognized cross-talk between epithelium and endothelium, which contributed to alveolar–capillary injury during SARS-CoV-2 infection. These new findings will expand our understanding of COVID-19 and may also be helpful for targeted drug development.Subject terms: Mechanisms of disease, Viral infection     

<Emphasis Type="Italic">In vitro</Emphasis> Enhancement of Lactate Esters on the Percutaneous Penetration of Drugs with Different Lipophilicity

Lactate esters are widely used as food additives, perfume materials, medicine additives, and personal care products. The objective of this work was to investigate the effect of a series of lactate esters as penetration enhancers on the in vitro skin permeation of four drugs with different physicochemical properties, including ibuprofen, salicylic acid, dexamethasone and 5-fluorouracil. The saturated donor solutions of the evaluated drugs in propylene glycol were used in order to keep a constant driving force with maximum thermodynamic activity. The permeability coefficient (K _p), skin concentration of drugs (SC), and lag time (T), as well as the enhancement ratios for K _p and SC were recorded. All results indicated that lactate esters can exert a significant influence on the transdermal delivery of the model drugs and there is a structure-activity relationship between the tested lactate esters and their enhancement effects. The results also suggested that the lactate esters with the chain length of fatty alcohol moieties of 10–12 are more effective enhancers. Furthermore, the enhancement effect of lactate esters increases with a decrease of the drug lipophilicity, which suggests that they may be more efficient at enhancing the penetration of hydrophilic drugs than lipophilic drugs. The influence of the concentration of lactate esters was evaluated and the optimal concentration is in the range of 5∼10 wt.%. In sum, lactate esters as a penetration enhancer for some drugs are of interest for transdermal administration when the safety of penetration enhancers is a prime consideration.     

Computational and Experimental Investigation of the Antimicrobial Peptide Cecropin XJ and its Ligands as the Impact Factors of Antibacterial Activity

Cecropin XJ, as a heat stable antimicrobial peptide (AMP), displayed broad bacteriostatic activities, effectively inhibited proliferation of cancer cells and induced cell apoptosis in vitro. However, it exhibited little hemolytic activity and very low cytotoxicity to erythrocytes and normal cells. Although exerts multiple remarkable bioactivities, the refined molecular conformation of native Cecropin XJ remains unsolved. The aim of the present study is to comprehensively investigate the physicochemical characteristics and structure-function relationship of this antimicrobial peptide by using a series of bioinformatics and experimental approaches. In this study, we revealed that the mature Cecropin XJ consists of 41 amino acids, containing two α-helical structures from Lys⁷ to Lys²⁵ and from Ala²⁹ to Ile³⁹. The phylogenetic tree indicated that Cecropin XJ belongs to the Class I AMPs of cecropin family. Hydrophobic analysis showed Cecropin XJ is a typical amphiphilic molecule. The surface of Cecropin XJ was found to have a much wide range of electrostatic potential from ?83.243 to +83.243. The amphipathicity and surface potential of Cecropin XJ partially supported the AMP pore-forming hypothesis. Scanning electron microscopy experimentally confirmed the damages of Cecropin XJ to microbial membrane. Four predicted docking sites respectively for magnesium ion (Mg²⁺), adenosine diphosphate (ADP), bacteriopheophytin (BPH), and guanosine triphosphate (GTP) were found on the surface of Cecropin XJ. Thereinto, Mg²⁺ was experimentally proved to suppress the antibacterial activity of Cecropin XJ; both GTP and ADP enhanced the bactericidal activities to varying degrees. The present study provides a foundation for further investigation of molecular evolution, structural modification, and functional mechanisms of Cecropin XJ.