Structural elucidation and immunological activity of a polysaccharide from the fruiting body of Armillaria mellea

The water-soluble polysaccharide (AMP), with a molecular mass of 7.8 × 10³ Da as determined by high-performance size-exclusion chromatography (HPSEC), was obtained from the fruiting body of Armillaria mellea. Methylation, Smith degradation, acetolysis, ¹H and ¹³C NMR spectroscopy and acid hydrolysis studies were conducted to elucidate its structure. The results indicated that AMP consisted of a backbone composed of (1→6)-linked-α-d-glucopyranosyl, (1→2,6)-linked-α-d-glucopyranosyl and (1→6)-linked-α-d-galactopyranosyl residues in the ratio of 3:1:1, and terminated with one single terminal (1→)-β-d-glucopyranosyl at the O-2 position of (1→2,6)-linked-α-d-glucopyranosyl, on average, along the main chain. Preliminary tests in vitro showed that AMP has stimulating effects on murine lymphocyte proliferation induced by concanavalin A or lipopolysaccharide in a dose-dependent manner. It is a possible potential immunopotentiating agent for use in health-care food or medicine.     

Pyridopyrimidine based cannabinoid-1 receptor inverse agonists: Synthesis and biological evaluation

The synthesis, SAR and binding affinities are described for cannabinoid-1 receptor (CB1R) specific inverse agonists based on pyridopyrimidine and heterotricyclic scaffolds. Food intake and pharmacokinetic evaluation of several of these compounds indicate that they are effective orally active modulators of CB1R.     

Discovery of spirocyclic secondary amine-derived tertiary ureas as highly potent,selective and bioavailable soluble epoxide hydrolase inhibitors

Spirocyclic secondary amine-derived trisubstituted ureas were identified as highly potent, bioavailable and selective soluble epoxide hydrolase (sEH) inhibitors. Despite good oral exposure and excellent ex vivo target engagement in blood, one such compound, rac-1a, failed to lower blood pressure acutely in spontaneously hypertensive rats (SHRs). This study posed the question as to whether sEH inhibition provides a robust mechanism leading to a significant antihypertensive effect.     

车八岭山地常绿阔叶林冰灾后土壤节肢动物群落的多样性

2008年初车八岭山地常绿阔叶林受到中国南方80年一遇的冰灾的重创。为了揭示灾后林冠开度的梯度对土壤节肢动物多样性与分布的影响, 在受冰灾影响的车八岭山地常绿阔叶林设置2 ha固定样地, 按照冠层受损程度选取17个20 m×20 m的样方, 用半球面影像技术获取林冠开度, 并分凋落物层、0–10 cm和10–20 cm的矿质土层采集凋落物及土壤样品, 分析土壤节肢动物多样性。利用双向聚类分析(two-way cluster analysis)对凋落物层的土壤节肢动物和样地进行聚类, 以典范对应分析(canonical correspondence analysis)研究冠层开度、土壤有机质、电导率以及自然含水量与0–10 cm表土层土壤节肢动物的关系。结果表明土壤节肢动物的多度、丰富度和多样性随土壤层的加深而下降, 具有明显的表聚性; 林冠开度与凋落物层的土壤节肢动物类群数量呈负相关; 甲螨亚目、中气门亚目和前气门亚目动物对光照的适应范围广; 膜翅目、鞘翅目幼虫、综合纲和伪蝎目动物具有明显的避光性; 土壤节肢动物类群的分布与林冠开度、土壤自然含水量、电导率和有机质关系密切。因此可以推论, 冰灾对车八岭山地常绿阔叶林冠层的破坏及土壤因子的变化会进一步影响土壤节肢动物群落的组成和分布。本项研究还表明, 土壤节肢动物群落能有效地表征它们所栖息的生态系统的特点, 可用于监测冰灾后森林恢复和演替动态。而双向聚类分析和典范对应分析对于揭示土壤节肢动物的空间异质性及其与环境因子的相互关系具有理想的效果。     

正交设计优化缩叶藓属植物的ISSR-PCR反应体系

目的：建立缩叶藓属（Ptychomitrium）植物ISSR-PCR反应的最佳体系。方法：利用正交设计实验的方法,采用引物562,10号材料Ptychomitrium gardneri为模板对缩叶藓属植物的ISSR-PCR反应体系中的5种主要因素（Mg2＋d、NTPs、引物、模板量、Taq酶量）在4个水平上进行体系优化。结果：确定了缩叶藓属（Ptychomitrium）植物ISSR-PCR反应的最佳体系（25μl）为：Mg2＋浓度为3.2mmol/L、dNTPs浓度为0.96mmol/L、引物浓度为1.04μmol/L、模板量10ng、Taq酶量1.5U。利用该体系,采用引物564在16个材料中能有效扩增。结论：这一优化体系的建立为以后缩叶藓属植物的ISSR遗传多样性的分析奠定了基础。     

天山北部拟南芥生存群落特征及其与环境的关系

为了解拟南芥在天山北部的分布状况及环境依赖特点, 分析拟南芥的自然选择特征, 本文对天山北部分布的13个拟南芥(Arabidopsis thaliana)生存群落结构、组成及其与环境关系进行了研究, 并分析了拟南芥与群落主要物种的种间联结性。结果表明: 拟南芥生存的群落结构简单, 其中天山北坡中段的石河子、一四三团、沙湾、独山子地区的8个群落均为草本类型, 优势种相似, 而与伊犁果子沟、额敏和阿勒泰的5个群落差别较大。属的区系成分分析表明世界分布、北温带分布以及地中海、西亚至中亚分布型成分占大多数, 具有典型的地中海旱生植物区系分布特征, 体现了本地拟南芥分布及演化的干旱、半干旱的地理环境特点。采用双向指示种分析(TWINSPAN)将13个群落分为新疆绢蒿–猪毛菜–角果毛茛(Seriphidium kaschgaricum–Salsola collina–Ceratocephalus testiculatus)、新疆绢蒿–猪毛菜(S. kaschgaricum–S. collina)、新疆绢蒿–狭果鹤虱(S. kaschgaricum–Lappula semiglabra)、新疆绢蒿–旱麦草(S. kaschgaricum–Eremopyrum triticeum)、勿忘草–草原苔草(Myosotis sylvatica–Carex liparocarpos)5个群落类型。去势典范对应分析(DCCA)表明纬度、坡向、土壤有机质及pH值是决定天山北部拟南芥种群分布的主导因子。拟南芥分布与群落内其他物种有极强的依赖关系, 与13个群落62个主要物种的种间联结性分析表明, 共有119个正关联性种对, 明显高于72个负关联性种对, 与各群落优势种呈显著正关联。拟南芥种群分布数量在群落间差异较大, 分布于降雨较少的天山中部浅山地带拟南芥种群数量均高于降雨较丰富的天山西部伊犁果子沟地区, 是否发生适应性分化需要深入研究。     

乳酸杆菌发酵滤液对人宫颈癌细胞株Hela细胞的抑制作用

目的观察乳酸杆菌DM9811发酵滤液及其主要成分对宫颈癌细胞株Hela细胞的体外增殖的影响,探索乳酸杆菌发酵滤液对宫颈癌细胞是否有抑制作用及解析作用的有效成分。方法用MTr法研究不同浓度乳酸杆菌DM9811发酵滤液在不同时间对Hela细胞的抑制作用,在此基础上研究脂肪酸、菌体核酸在不同时间对Hela细胞的抑制作用。结果不同浓度乳酸杆菌DM9811发酵滤液及相关物质在不同时间对Hela细胞的抑制作用显示：（1）乳酸杆菌DM9811发酵滤液各浓度组对Hela细胞的生长均有抑制作用,且这种抑制作用呈剂量-时间依赖方式。24、48、72h达到半数抑制率的发酵滤液浓度分别为8．9％、5．3％、3．8％。（2）乳酸杆菌DM9811发酵滤液脂肪酸对Hela细胞的生长有一定抑制作用,抑制率在7．0％～34．0％。（3）乳酸杆菌DM9811菌体核酸对Hela细胞的生长有抑制作用,抑制率为9．7％-53．4％,呈剂量一时间依赖方式。72h达到半数抑制率核酸的浓度为5．5μg/ml。结论乳酸杆菌DM9811发酵滤液对Hela细胞的生长具有显著的抑制作用,其中脂肪酸组分是有效成分之一。     

妈咪爱联合利巴韦林、思密达治疗婴幼儿轮状病毒肠炎的观察

目的观察妈咪爱联合利巴韦林、思密达治疗婴幼儿轮状病毒性肠炎的疗效。方法将轮状病毒性肠炎患儿58例按就诊先后顺序随机分为对照组29例,用利巴韦林、思密达治疗。治疗组29例,在对照组治疗的基础上加用妈咪爱治疗;利巴韦林用法：10mg/（kg·d）,分3次口服;思密达用法：1岁以下,1g/次,1岁以上,1．5g/次,3次／d;妈咪爱用法：1岁以下,0．5g／次,1岁以上,1g,／次,2次／d。结果治疗组的治愈率和总有效率分别为75．86％和96．55％,对照组的治愈率和总有效率分别为48．28％和75．86％,组间比较,其差异有显著性（P〈0．05）。结论妈咪爱联合利巴韦林、思密达治疗婴幼儿轮状病毒性肠炎疗效显著。     

Differential Roles of Blocking Ions in KirBac1.1 Tetramer Stability

Potassium channels are tetrameric proteins that mediate K⁺-selective transmembrane diffusion. For KcsA, tetramer stability depends on interactions between permeant ions and the channel pore. We have examined the role of pore blockers on the tetramer stability of KirBac1.1. In 150 mm KCl, purified KirBac1.1 protein migrates as a monomer (∼40 kDa) on SDS-PAGE. Addition of Ba²⁺ (K_1/2 ∼ 50 μm) prior to loading results in an additional tetramer band (∼160 kDa). Mutation A109C, at a residue located near the expected Ba²⁺-binding site, decreased tetramer stabilization by Ba²⁺ (K_1/2 ∼ 300 μm), whereas I131C, located nearby, stabilized tetramers in the absence of Ba²⁺. Neither mutation affected Ba²⁺ block of channel activity (using ⁸⁶Rb⁺ flux assay). In contrast to Ba²⁺, Mg²⁺ had no effect on tetramer stability (even though Mg²⁺ was a potent blocker). Many studies have shown Cd²⁺ block of K⁺ channels as a result of cysteine substitution of cavity-lining M2 (S6) residues, with the implicit interpretation that coordination of a single ion by cysteine side chains along the central axis effectively blocks the pore. We examined blocking and tetramer-stabilizing effects of Cd²⁺ on KirBac1.1 with cysteine substitutions in M2. Cd²⁺ block potency followed an α-helical pattern consistent with the crystal structure. Significantly, Cd²⁺ strongly stabilized tetramers of I138C, located in the center of the inner cavity. This stabilization was additive with the effect of Ba²⁺, consistent with both ions simultaneously occupying the channel: Ba²⁺ at the selectivity filter entrance and Cd²⁺ coordinated by I138C side chains in the inner cavity.Potassium channels are expressed in many cell types and are key players in a wide range of physiological processes. One subset of potassium channels, the inward-rectifying potassium (Kir) channels, are functionally blocked by cytosolic cations such as Mg²⁺ and polyamines and contribute to the regulation of membrane excitability, cardiac rhythm, vascular tone, insulin release, and salt flow across epithelia (1–3). There are seven subfamilies of eukaryotic Kir channel genes. Among them, Kir1 encodes weak rectifiers, whereas Kir2 and Kir5 encode strong rectifiers; Kir3 encodes G-protein-regulated channels; and Kir6 encodes ATP-sensitive channels (4). Recently, a related bacterial family of genes (KirBac) has been identified (5, 6), and in 2003, the first member (KirBac1.1) was crystallized (7), providing a structural model for eukaryotic channels.The crystal structure of KirBac1.1 revealed a tetrameric pore structure similar to that seen in KcsA and a novel cytoplasmic domain (7, 8). The selectivity filter of both KirBac1.1 and KcsA consists of an extremely conserved pore loop followed by a central cavity, forming a transmembrane ion-selective permeation pore (7, 8). The linear arrangement of five oxygen rings (four from carbonyl oxygens and one from a Thr side chain) in the selectivity filter coordinates with ions, compensating for the energy barrier caused by K⁺ dehydration, thereby facilitating the rapid diffusion of K⁺ across the membrane (8–12). Two-thirds of the KirBac1.1 amino acid residues constitute the cytosolic domain that is highly conserved among the Kir subfamilies and form the cytosolic vestibule (13–16), which, together with the transmembrane pore, generates an 88-Å-long ion conduction pore (7).The prototypic potassium channel KcsA exists very stably as a tetramer, even in the harsh conditions of SDS-PAGE (17). In addition to protein-protein interaction between monomers, protein-lipid and protein-ion interactions play important roles in stabilizing the KcsA tetramer (17–20). The selectivity filter of KcsA, coordinated with K⁺ ions, can serve as a bridge between the four monomers to maintain the structure of the selectivity filter and the tetrameric architecture of the channel as a whole (11, 21). Blocking ions, such as Ba²⁺, also act as strong stabilizers (17). In the crystal structure of KcsA, Ba²⁺ occupies a site equivalent to the S4 K⁺-binding site within the selectivity filter (22). Other permeant ions (Rb⁺, Cs⁺, Tl⁺, and NH⁺₄) and strong blockers (Sr²⁺) can also contribute to the thermostability of the KcsA tetramer in SDS-PAGE (17). In contrast, impermeant ions such as Na⁺ and Li⁺ or weak blockers such as Mg²⁺ tend to destabilize the KcsA tetramer (17, 19).Like KcsA, KirBac1.1 purified using decylmaltoside or tridecylmaltoside is active and presumably stable as a tetramer in mild detergent solutions. However, in SDS-PAGE, KirBac1.1 migrates exclusively as a monomer (23). Because KcsA and KirBac1.1 are structurally similar in the transmembrane region of the pore, we hypothesized that permeant and blocking ions would also affect KirBac1.1 tetramer stability in SDS-PAGE. In the present work, the effects of blocking ions such as Ba²⁺ and Mg²⁺ on KirBac1.1 tetramer stability were examined to provide insight to the physical nature of their interaction with KirBac1.1, particularly in the selectivity filter and TM2 cavity. The data reveal important differences in the nature of the interaction of Mg²⁺ and Ba²⁺ with the channel as well as provide previously unavailable evidence for the nature of Cd²⁺ coordination within the channel.     

天山北麓拟南芥表型特征的自然选择

本文研究了天山北麓干旱、湿润2种不同水分条件下拟南芥(Arabidopsis thaliana)光合生理、形态及发育特征的自然适应特点。结果表明：分枝数、株高、相对适合度（角果质量）、莲座叶面积等特征在不同水分下差异极显著;根质量与相对适合度、莲座叶面积、水分利用效率和光合速率之间表现了正相关,胞间二氧化碳浓度与光合速率、水分利用效率之间表现了负相关;选择梯度分析得出,干湿水分条件下分枝数、株高、莲座叶面积均表现定向选择;主成分分析发现,光合生理特征整合在处理间有一定的规律性,表现出拟南芥物种特征整体协调一致性较强,对环境响应具有较大的趋同性;通径分析发现,水分利用效率、枝质量、株高、角果数对相对适合度直接产生较大影响,因而在通径模型中设置为直接路径特征,将莲座叶面积通过分枝数、花期、角果数,花期通过角果数到达相对适合度的过程设置为间接路径,这些特征通过间接路径对相对适合度间接产生较大影响。