林可链霉菌黑色素生物合成基因的克隆与表达

以pIJ702的melCl－C2基因为探针杂交林可链霉菌（Streptomyceslincolnensis）78－11染色体DNA,呈现出3．2kb的BamHI片段和2．6kb的SphI片段等一系列阳性条带。构建了含3．0～3．5kbBamHI片段的林可链霉菌78-11基因文库,从中分离克隆了黑色素生物合成基因melCl和melC2,并测定了含有mel基因的重组子pRSB336插入片段的全部DNA顺序。3152bpBamHI片段含有5个开放阅读框架,其中melCl和melC2与链霉菌属三个种的相应基因具有较高的同源性。此外,林可链霉菌78－11的melC2基因产物与人和鼠的酪氨酸酶轻微同源,分别为17．3％和24．5％。种种迹象表明,melCl、melC2和orf3组成黑色素生物合成操纵子结构。为了进一步鉴定上述克隆的林可链霉菌78-11黑色素生物合成基因,构建了分别含有新霉素抗性基因启动子和正反方向mel基因的重组质粒pPZ518和pPZ519,并转化变铅青链霉菌TK23。随机挑选的12个pPZ518转化子在R2YE培养基上均能分泌淡褐色色素,而所有的pPZ519和pES1转化子则都呈白色。     

宁虫素对蔬菜、水稻害虫的毒力及药效特性研究

本研究了复方生物农药宁虫素对蔬菜、水稻害虫的毒力及药效特性,结果表明,该药集速效性、特效性于一体,对蚜虫、褐飞虱的毒力分别为：0.63ppm和2.00ppm。田间试验表明,宁虫素可有效地控制蔬菜蚜虫、小菜蛾、菜青虫、稻飞虱等的危害,防效显。田间使用宁虫素后,平均蛛虱比明显优于噻嗪酮和吡虫啉,生态安全性好。     

Increased invasiveness of osteosarcoma mesenchymal stem cells induced by bone-morphogenetic protein-2

To evaluate the different traits of mesenchymal stem cell (MSC) isolated from osteosarcoma (OS) and normal bone marrow (BM) induced by bone-morphogenetic protein-2 (BMP-2). MSCs from implanted osteosarcoma or femur bone marrow were isolated and cultured. Differentiation potency was verified and phenotypes were evaluated by flow cytometry. Increased or decreased expressions of BMP-2 were delivered by adenovirus and lentivirus vector, respectively. Expressions of VEGF, EMMPRIN, and MMP-9 were examined. Cell cycle, apoptosis, invasiveness, and proliferation assays were performed between the transfected groups and controls. Increased BMP-2 induced over-expression of VEGF, EMMPRIN, and MMP-9 in OS- and BM-MSCs both intra- and extra-cellularly. Decreased BMP-2 expression induced inhibition of the factors. Increased BMP-2 also induced less population of cells at G1 phase, more apoptotic cells, more cells that invade through Transwell membrane, and faster proliferation in OSMSC compared to those in BMMSC. BMP-2 induced higher expression of tumorigenic factors, which could be responsible for promoting the proliferation and aggressiveness of OSMSC over BMMSC.     

Marine Sediment Bacteria Harbor Antibiotic Resistance Genes Highly Similar to Those Found in Human Pathogens

The ocean is a natural habitat for antibiotic-producing bacteria, and marine aquaculture introduces antibiotics into the ocean to treat infections and improve aquaculture production. Studies have shown that the ocean is an important reservoir of antibiotic resistance genes. However, there is a lack of understanding and knowledge about the clinical importance of the ocean resistome. We investigated the relationship between the ocean bacterial resistome and pathogenic resistome. We applied high-throughput sequencing and metagenomic analyses to explore the resistance genes in bacterial plasmids from marine sediments. Numerous putative resistance determinants were detected among the resistance genes in the sediment bacteria. We also found that several contigs shared high identity with transposons or plasmids from human pathogens, indicating that the sediment bacteria recently contributed or acquired resistance genes from pathogens. Marine sediment bacteria could play an important role in the global exchange of antibiotic resistance.     

透射电子显微镜(TEM)技术在大孢子化石超微结构研究中的应用

透射电子显微镜(TEM)具有优异的纳米尺度显微成像性能,因此被广泛应用于材料科学、物理学和生物学等学科的超微结构研究领域。文中根据应用TEM技术研究大孢子化石壁超微结构的实践体会,系统归纳和总结了大孢子化石TEM样品制备的前处理过程,主要步骤包括:材料选取、梯度脱水、包埋剂配比、梯度渗透、包埋、聚合、超薄切片和染色。运用上述TEM实验技术,文中以云南省曲靖市沾益区龙华山剖面中泥盆统吉维特阶上双河组分散拟网龙华山大孢(Longhuashanispora reticuloides Lu and Ouyang, 1978)的壁层超微结构为研究案例,揭示了这类孢子壁主要由三层薄壁组成,包括内部基底层、中部疏松层和外部致密层,其射线唇基底层下部具有近平行排列的多细纹带结构。此类大孢子的多细纹带结构与从加拿大新不伦瑞克省下泥盆统埃姆斯阶Campbellton组同孢植物化石Leclercqia complexa Banks et al., 1972中发现的原位小孢子射线唇基底层下部的多细纹带结构特征非常相似。此外,两者都具有相似的完全弓形脊和远极表面刺瘤状二型纹饰。因此综合外壁超微结构和纹饰形态特征...     

Efficient Organic Solar Cell with 16.88% Efficiency Enabled by Refined Acceptor Crystallization and Morphology with Improved Charge Transfer and Transport Properties

Single‐layered organic solar cells (OSCs) using nonfullerene acceptors have reached 16% efficiency. Such a breakthrough has inspired new sparks for the development of the next generation of OSC materials. In addition to the optimization of electronic structure, it is important to investigate the essential solid‐state structure that guides the high efficiency of bulk heterojunction blends, which provides insight in understanding how to pair an efficient donor–acceptor mixture and refine film morphology. In this study, a thorough analysis is executed to reveal morphology details, and the results demonstrate that Y6 can form a unique 2D packing with a polymer‐like conjugated backbone oriented normal to the substrate, controlled by the processing solvent and thermal annealing conditions. Such morphology provides improved carrier transport and ultrafast hole and electron transfer, leading to improved device performance, and the best optimized device shows a power conversion efficiency of 16.88% (16.4% certified). This work reveals the importance of film morphology and the mechanism by which it affects device performance. A full set of analytical methods and processing conditions are executed to achieve high efficiency solar cells from materials design to device optimization, which will be useful in future OSC technology development.     

中国主要农产品虚拟要素贸易网络结构特征分析

据虚拟水概念定义虚拟要素,并将其划分为虚拟资源要素和虚拟生态要素两类,选取虚拟资源要素中的耕地要素和虚拟生态要素中的化肥/农药要素为研究对象,定量分析2002—2016年以粮食贸易为载体的虚拟耕地、虚拟化肥/农药要素的贸易量,构建虚拟要素贸易网络,通过复杂网络的研究方法,结果表明:2002—2016年我国主要农产品虚拟耕地、化肥/农药要素的贸易总量呈下降趋势,降幅分别约25.51%、8.01%;虚拟耕地要素网络节点入度较大的为长江中下游、华南、西南地区,出度较大的为黄淮海和东北地区,虚拟化肥/农药要素网络与之相反;地区间节点强度的差异性大,虚拟耕地要素差值最大可达1459.56万hm²,虚拟化肥/农药要素达61.38万t;二者网络节点度和强度的累积分布均符合幂律分布规律,其尾部的"重尾"现象揭示了节点度和强度的高可变性以及网络结构的脆弱性;虚拟耕地要素的输入区网络同配,输出区网络异配,揭示了地区间耕地要素的流动既呈集聚又有分散的态势,虚拟化肥/农药要素网络节点相关性皆为减函数,网络异配,揭示了虚拟化肥/农药要素在八大区域间联通的状况。网络结构特征分析为研究网络抗毁...     

Suppressing Voltage Fading of Li‐Rich Oxide Cathode via Building a Well‐Protected and Partially‐Protonated Surface by Polyacrylic Acid Binder for Cycle‐Stable Li‐Ion Batteries

Li‐rich manganese based oxides (LRMOs) are considered an attractive high‐capacity cathode for advanced Li‐ion batteries; however, their poor cyclability and gradual voltage fading have hindered their practical applications. Herein, an efficient and facile strategy is proposed to stabilize the lattice structure of LRMOs by surface modification of polyacrylic acid (PAA). The PAA‐coated LRMO electrode exhibits only 104 mV of the voltage fading after 100 cycles and 88% capacity retention over 500 cycles. The structural stability is attributed to the carboxyl groups in PAA chains reacting with oxygen species on the surface of LRMO to form a uniform and tightly coated film, which significantly suppresses the dissolution of transition metal elements from the cathode materials into the electrolyte. Importantly, a H⁺/Li⁺ exchange reaction takes place between the LRMO and PAA, generating a proton‐doped surface layer. Density functional theory calculations and experimental evidence demonstrates that the H⁺ ions in the surface lattice efficiently inhibit the migration of transition metal ions, leading to a stabilized lattice structure. This surface modification approach may provide a new route to building a stable Li‐rich oxide cathode with high capacity retention and low voltage fading for practical Li‐ion battery applications.     

Expression of Nemo-Like Kinase (NLK) in the Brain in a Rat Experimental Subarachnoid Hemorrhage Model

This study aimed to investigate the expression of the Nemo-like kinase (NLK) in the brain after experimental subarachnoid hemorrhage (SAH) in rats. A total of 90 rats were randomly divided into six groups: control group, day 1, day 3, day 5, day 7, and day 14. Day 1, day 3, day 5, day 7, and day 14 groups were all SAH groups in which the rats were killed on days 1, 3, 5, 7, and 14, respectively. In SAH groups, autologous arterial blood was injected into cisterna magna once on day 0. Cross-sectional area of basilar artery was measured by H&E staining. Immunostaining and immunoblotting experiments were performed to detect the expression of NLK protein. Real-time polymerase chain reaction was used to analyze the presence and quantity of NLK mRNA. The level of oxidative stress in the artery was also measured. The basilar arteries exhibited vasospasm after SAH and became the most severe on day 3. The expressions of NLK protein and mRNA were decreased remarkably in SAH groups compared with the control group. The down-regulated expression of NLK was detected after SAH and the low ebb was on day 3, which was oppositely the peak time of oxidative stress. The expression of NLK was present mainly in the neurons in the brain and smooth muscle cells in the basilar artery. NLK is decreasingly expressed in an opposite time-course to the development of cerebral vasospasm (CVS) and SAH-induced brain injury in this rat experimental model of SAH and these findings might have important implications during the administration of specific NLK agonist to prevent or reduce CVS or neuronal apoptosis caused by SAH.