Assessing bacterial magnetotactic behavior by using permanent magnet blocks

Assessing the movement of magnetotactic bacteria （MTB） under magnetic fields is a key to exploring the function of the magnetotaxis. In this study, a simple method was used to analyze the behavior of MTB, which was based on the accumulation of cells on the walls of a test tube when two permanent magnet blocks were applied on the tube. Experimental results showed a significant difference among the movements of the polar MTB, axial MTB, and ferrofluid. The polar magnetotactic cells aggregated as spots above or below the two magnet blocks besides the aggregated spots underneath the magnet blocks. By contrast, the axial magnetotactic cells aggregated only as two round spots underneath the magnet blocks, and more cells aggregated in the center than all around of the spot. For the ferrofluid, two spots were also formed underneath the magnet blocks, and the aggregated particles formed a ring shape. Magnetic calculation by finite element method was used to analyze the phenomenon, and the findings werereasonably explained by the MTB features and magnetic field theory. A scheme that differentiates polar MTB, axial MTB, and magnetic impurity could be developed, which would be beneficial to fieldworks involving MTB in the future.     

树突状细胞在抗结核分枝杆菌感染中的作用

树突状细胞（Dendritic cells,DCs）是最有效的抗原呈递细胞.DCs能够摄取外来物质,包括结核分枝杆菌（Mycobacterium tuberculosis,MTB）,并将其呈递给效应性淋巴细胞,激发宿主对抗病原微生物感染的免疫反应.因此,树突状细胞与结核分枝杆菌的相互作用在感染初期机体发动免疫应答中十分重要.研究树突状细胞和结核分枝杆菌间的相互作用,有利于从根本上了解细菌-宿主作用机理,为阐明结核分枝杆菌逃避免疫的机制提供依据.     

分枝杆菌细胞壁脂质PDIM致病机制研究进展

 结核分枝杆菌(Mycobacterium Tuberculosis,MTB)是导致人和动物结核病的病原体。MTB细胞壁成分复杂,功能多样,不但帮助分枝杆菌抵御外界不良的生活环境,同时在细菌逃逸宿主免疫攻击和致病过程中也发挥重要作用。脂质占细胞壁干重的60%以上,其高含量与细菌毒力密切相关。MTB不含内毒素,也不产生外毒素和侵袭性酶类,其致病性主要与占细胞壁干重60%以上的脂质成分密切相关。PDIM(phthiocerol dimycocerosate)作为细胞壁组分中独特而重要的结构,在维持细菌正常结构上发挥重要作用。由于PDIM在细胞壁分布的广泛性,研究发现PDIM在病原体-宿主的相互作用过程中也扮演重要角色,尤其是在细菌的早期侵染及进入巨噬细胞环节中发挥积极作用。对PDIM重要致病和毒力损伤机制研究,不仅加深对病原体-宿主互作网络中的理解,还有望为结核病的治疗带来新的希望与突破。     

结核分枝杆菌分泌蛋白调控巨噬细胞自噬诱导持续性感染

巨噬细胞的自噬作用能够保护宿主抵抗结核分枝杆菌的感染;而持续性感染的MTB(Mycobacterium tuberculosis)可以从自噬体中逃逸或抑制自噬的发生,从而在宿主体内长期存活。尽管相关机制不明确,但胞内存活的MTB分泌蛋白在持续性感染时发挥了重要作用。它可以通过抑制巨噬细胞自噬维持蛋白质稳定性和在胞内长期存活,导致LTBI(latent TB infection)的发生。综述了MTB的四种分泌蛋白(Eis、Pkn G、Sap M和Hsp16. 3)在持续性感染中调节巨噬细胞自噬的作用,可能为发现LTBI新的生物标志物和药物新靶点提供有效思路。     

甲基百里酚蓝-钕(Ⅲ)配合物与DNA作用研究

应用UV-Vis光谱法研究了pH=8.25的缓冲溶液中甲基百里酚蓝(MTB)-Nd(Ⅲ)配合物与鲱鱼精DNA的相互作用.发现MTB-Nd(Ⅲ)-DNA的最大吸收波长为610 nm,比MTB和MTB-DNA红移5 nm.DNA对MTB-Nd(Ⅲ)有增色效应.通过双波长物质的量比法、平衡透析物质的量比法研究,测得MTB-Nd(Ⅲ)-DNA三元复合物的结合比为n(MTB)∶n(Nd(Ⅲ))∶n(DNA)=10∶40∶1,MTB-Nd(Ⅲ)配合物与DNA作用的表观结合常数K=5.38×106.     

结核分枝杆菌Hsp16．3对感染巨噬细胞凋亡的影响

为研究结核分枝杆菌Hsp16．3对感染巨噬细胞凋亡的影响。分别用结核分枝杆菌国际标准强毒株H37Rv株（H37Rv）、结核分枝杆菌国际标准强毒株H37Rv株Hsp16．3基因缺失突变株（△H37Rv）、卡介苗（BCG）和卡介苗Hsp16．3基因缺失突变株（△BCG）感染RAW264．7巨噬细胞株,使用流式细胞技术于感染1、3、6及12h检测各组感染巨噬细胞的凋亡率,并分析其变化。结果显示,巨噬细胞感染结核分枝杆菌后凋亡率升高,其中在感染1、3、12h,BCG组与H37Rv组比较差异具有统计学意义（P〈O．05）;在感染1、3h,△BCG组与AH37Rv组比较差异具有统计学意义（P〈0．05）;在感染3、6、12h,△H37Rv组与H37Rv组比较差异具有统计学意义（P〈0．05）,△BCG组与BCG组比较差异具有统计学意义（P〈0．05）。由此可知,结核分枝杆菌Hspl6．3可抑制感染巨噬细胞的凋亡。     

微好氧MTB吸附Cr3+的研究

研究了趋磁性细菌吸附Cr^3 的主要影响因素。在室温范围内，温度对吸附几乎无影响，而体系的pH值和吸附时间等的影响较为重要。运用Langmuir和Freundlich等模型对实验数据进行了拟合，获得了各种模型参数，验证计算表明Langmuir模型拟合结果与实验数据较好。     

小鼠结核分枝杆菌感染模型用于评价重组HBHA疫苗免疫效果的实验研究

目的通过复制小鼠结核病模型评价重组HBHA疫苗的免疫效果。方法将重组肝素结合血凝素(HBHA)疫苗接种BALB/c小鼠,观察其诱导的细胞免疫应答水平,并以MTB H37Rv毒株攻击免疫小鼠,研究重组疫苗诱导的保护力。结果重组HBHA免疫BALB/c小鼠后可诱发细胞毒作用,将体内MTB裂解。重组疫苗不仅能刺激CD4+T,CD8+T增殖、活化,还可诱导脾细胞分泌IFN-γ、IL-2等细胞因子。H37Rv毒株攻击后,被免疫小鼠的组织病理学症状减轻。结论本研究通过检测小鼠体内细胞免疫应答和肺脏组织病理学改变等指标,客观的反映了重组疫苗免疫小鼠结核模型的保护效果。     

钙─镁混合体系的光度分析研究及其应用

研究了以甲基百里香酚兰络合剂（ＭＩＢ）为显色剂，用分光光度法测定水硬度的最佳试验条件，导出了朗伯─比尔定律在Ｃａ—ＭＴＢ与Ｍｇ—ＭＴＢ二元混合体系中的具体形式。     

尘肺结核患者Mycobacterium tuberculosis耐药基因突变研究

研究尘肺结核患者结核分枝杆菌(Mycobacterium tuberculosis,MTB)耐药基因突变与耐药性的关系。在97例尘肺结核患者痰中检出MTB菌株28株,采用PCR-SSCP法检测katG、rpoB和rpsL基因突变,并与采用常规药敏试验(AST)法检测的耐药结果进行对比分析。采用PCR-SSCP法检测katG、rpoB和rpsL基因,突变率分别为42.86%(12/28)、42.86%(12/28)和32.14%(9/28),采用AST法检测INH、RFP和SM,耐药率分别为64.23%(18/28)、60.71%(17/28)和53.57%(15/28),两者之间差异均无显著性(P>0.05)。其中多耐药株20例(71.43%),包括耐三种药物12例(42.86%),耐两种药8例(28.57%),单耐药株6例(21.43%),敏感株2例,耐药率92.86%。PCR-SSCP法检出3个基因联合突变8株,与AST法符合率为66.67%(8/12);2个基因突变5株,符合率为62.50%(5/8);单基因突变2株,符合率为33.33%(2/6)。结果表明:PCR-SSCP技术适用于MTB katG、rpoB和rpsL耐药基因突变的筛选,对指导尘肺结核患者临床用药上具有重要意义。     

抗结核化合物的设计与合成

针对日益突出的结核病(TB)药物耐药性问题,对抗结核药物进行了合理的修饰,以增强其结核病治疗的效果.以异烟肼(INH)为原料,与不同的异氰酸酯反应,成功制备了9种新型的不对称取代脲类化合物,这类脲桥结构对结核分枝杆菌(MTB)中的半胱氨酸合酶具有抑制作用,合成的产物经质谱(MS)、氢核磁共振谱(~1H NMR)等方法进行了分析表征.     

Mineral magnetic properties of surface sediments at Bei’anhe, Beijing, and its environmental significance

A multiparameter investigation of surface sediments from the Bei＇anhe section （Beijing） has been conducted using environmental magnetic approaches. The studied sedimentary sequence consists of pluvial and lacustrine silts and clay of the Holocene age. Magnetite, hematite and pyrrhotite were identiffed as the dominant magnetic minerals. The mineral magnetic characteristics are considered to reflect the Holocene paleoenvironmental processes of the studied area, which are different from the mineral magnetic properties of typical polluted sections reported in the Beijing area. The low-field magnetic susceptibility and saturated isothermal remanence magnetization of the section decrease gradually with increasing depth. This indicates that the concentration of magnetic minerals in the strata decreases down the section. Values of interparametric ratios, such as ARM/SIRM, XARM/Xand SIRM/X, gradually increase with increasing depth, which indicates a down-section decreasing trend in the magnetic grain size of the sediments. Pyrrhotite occurs below the depth of 22 cm, suggesting the existence of redox interface. The magnetic variations of the Bei＇anhe surface sediments might be controlled by two geological processes： reductive diagenesis and pedogenesis. Our findings may have provided a reference point for magnetic investigation of polluted surface sediments in the Beijing area.     

Magnetic Properties of Soils of the Ljubljana Basin Chronosequence, Slovenia

Pedogenic processes can explain the trends in magnetic susceptibility and soil magnetic mineralogy of the Ljubljana Basin chronosequence. The chronosequence formed in predominantly carbonate sandy gravel outwash terraces ranging from 5 to 1800 ka. Magnetic susceptibility enhancement can be attributed to the formation of secondary superparamagnetic (SP) and single domain (SD) ferrimagnetic minerals in eluvial horizons. Magnetic minerals that form in illuvial horizons are predominantly antiferromagnetic. Downward migration of pedogenic iron compounds with clay (formation of ferri-argillans) causes thickening of the enhanced zone with soil age. In contrast to other published soil chronosequence studies, magnetic susceptibility values do not increase with soil-age (duration of pedogenesis). Nevertheless, frequency dependence of magnetic susceptibility (FD%) and indices such as maximum eluvial magnetic susceptibility (MS) divided by minimum illuvial MS (Max. E / Min. IX_(lf) and maximum eluvial MS minus minimum illuvial MS (Max. E -Min. IX_(lf)) increase with the logarithm of soil age suggesting that the magnetic mineral transformations continue with time, but that their rate decreases. These indices are useful for comparisons, and may be useful for age correlations. Hypothesis that magnetic susceptibility enhancement and precipitation have a positive correlation seems to be valid until the precipitation exceeds the critical value of 100-150 cm/year. The critical value in different settings may depend on the temperature regime and on the yearly distribution of precipitation.     

结核分枝杆菌的抗逆性与致病性研究进展

结核病是由结核分枝杆菌(Mycobacterium tuberculosis,MTB)复合群感染导致的人畜共患传染病,在新型冠状病毒感染暴发前是全球死亡人数最多的单一传染病。结核病致死率高,主要原因是其致病菌结核分枝杆菌具有极强的毒力且可以抵御多种外界环境胁迫因子。本文主要介绍结核分枝杆菌对理化胁迫的耐受性,以及结核分枝杆菌的耐药性、致病性与免疫性,为深入研究结核病的发病机制和研发新型的抗结核药物提供理论指导。     

外延生长在GaAs(001)表面的磁性薄膜

采用多种实验技术研究外延生长在GaAs(001)表面的Mn,Co和FeMn合金等磁性金属薄膜，研究结果表明外延生长的磁性薄膜的晶体结构和磁学性质与体材料相比有明显的判别，在一些情况下，外延薄膜和衬底之间的界面结构对于磁性薄膜的晶体结构和磁学性质起着决定性的作用。     

导电聚合物/磁性纳米复合材料的制备及其结构与性能

导电聚合物/磁性纳米复合材料的研究是开发同时具有电、磁性能的功能材料的最佳选择之一,是制备电磁屏蔽材料,电磁波吸收剂等功能材料的重要途径。导电聚合物与磁性纳米粒子复合,既可实现电、磁性能的复合,又可通过调节各组元的组成和结构实现对材料电、磁性能的调节。对目前导电聚合物/磁性纳米复合材料的制备原理、方法,复合材料的结构及控制,材料的性能与应用进行了评述。     

Spatial and temporal variation in magnetic properties of street dust in Lanzhou City, China

Urban environmental problems are of increasing concern. Lanzhou is a large industrial city in Northwest China. Street dust samples representing different temporal and spatial scales were collected for magnetic properties study. Magnetic measurements indicate a high concentration of magnetic minerals in Lanzhou street dust, dominated by pseudo-single domain （PSD） magnetite. The concentration of magnetic materials is distinctly high in winter and spring, low in autumn. Similarly, higher concentrations associated with heavy industry, concentrated residential development, and vehicular traffic suggest mixed contributions of magnetic material from both anthropogenic and natural sources. XIf and SOFT% are effective magnetic parameters that denote seasonal differences among magnetic properties in street dust, convenient and economical methods for monitoring street dust pollution.     

基于生物信息学的结核杆菌候选药靶基因的分析筛选

结核分支杆菌(Mycobacterium tuberculosis,MTB)是结核病的致病菌,MTB基因组和蛋白质组的研究为筛选新的抗MTB药物提供了可能．鉴于前人所做的工作,目前比较一致的意见是：与MTB细胞壁的合成相关的酶类,尤其是与脂肪酸合成和降解相关的酶类,是筛选抗结核杆菌药物的理想靶标．选取与脂肪酸合成、分解、转运相关的187个基因,分析blast结果,剔除与人和其他生物(如大肠杆菌等)蛋白序列相似性大于60％的基因．利用相关生物软件挑选出至少有一个糖基位点且具有溶剂可及性的抗原基因9个．本研究为以后分析药靶基因编码蛋白质的三维结构、利用现有的生物技术和有关的化合物对候选药靶进行功能研究、在细胞水平加以验证打下基础．     

全球稀土市场分析及未来的发展和需求

原有稀土市场主要受稀土永磁材料对镨、钕、铽及镝需求的影响.随着国际形势的不断变化,传统工业、军事工业及民用工业对稀土的需求量逐渐增大,稀土市场的总体格局也随之改变.未来全球稀土市场将更加开放,更加相融发展,对稀土的需求将不会局限于稀土永磁材料的原料,而是面向更多领域、更加广泛的产业链发展.     

A review of recent studies on coronal dynamics: Streamers, coronal mass ejections, and their interactions

In this article I present a review of recent studies on coronal dynamics, including research progresses on the physics of coronal streamers that are the largest structure in the corona, physics of coronal mass ejections (CMEs) that may cause a global disturbance to the corona, as well as physics of CME-streamer interactions. The following topics will be discussed in depth: (1) acceleration of the slow wind flowing around the streamer considering the effect of magnetic flux tube curvature; (2) physical mechanism accounting for persistent releases of streamer blobs and diagnostic results on the temporal variability of the slow wind speed with such events; (3) force balance analysis and energy release mechanism of CMEs with a flux rope magnetohydrodynamic model; (4) statistical studies on magnetic islands along the coronal-ray structure behind a CME and the first observation of magnetic island coalescence with associated electron acceleration; and (5) white light and radio manifestations of CME-streamer interactions. These studies shed new light on the physics of coronal streamers, the acceleration of the slow wind, the physics of solar eruptions, the physics of magnetic reconnection and associated electron acceleration, the large-scale coronal wave phenomenon, as well as the physics accounting for CME shock-induced type II radio bursts.