一株新的α-淀粉酶抑制剂生产菌株ZG0656及其产物的发酵、分离、性质与应用

从土壤中分离并筛选得到了一株α-淀粉酶抑制剂生产菌,编号ZG0656.根据形态特征,培养特征、生理生化特征、细胞壁化学组成特征和16S rDNA全序列相似性比较分析等多相分类方法,确认菌株ZG0656为天蓝黄链霉菌的新变种,命名为天蓝黄链霉菌南开变种(Streptomyces coelicoflavus var.nankaiensis).该菌经10 L发酵罐水平发酵,发酵液中可积累一定量的α-淀粉酶抑制荆.采用浓缩,树脂吸附,凝胶过滤,减压干燥等方法得到α-淀粉酶抑制剂混合物.该α-淀粉酶抑制剂为含氮的拟低聚糖类物质.能强烈抑制哺乳动物来源的α-淀粉酶,对餐后高血糖的形成有明显改善作用.可用于制备治疗糖尿病,肥胖症的药物或功能性食品.     

戊型肝炎病毒荧光定量RT-PCR快速检测技术的建立和初步应用

利用DNAMAN软件对GenBank登录的戊型肝炎病毒四个主要基因型代表株的序列进行分析, 选择其高度保守的ORF2区域设计合成引物和探针, 并用包含有扩增区域的核苷酸片段进行体外转录制备标准品cRNA。在对荧光定量RT-PCR的反应条件优化的基础上, 建立了适用于戊型肝炎病毒主要基因型检测的荧光定量RT-PCR检测技术。该检测技术可以有效检测I型和IV型戊型肝炎阳性病料, 而对猪的其它几种疫病阳性病料则为阴性结果, 证实本技术的特异性强、可靠性好。对阳性标准品的检测结果表明, 所建立的TaqMan荧光定量RT-PCR灵敏度可达2.0×101拷贝/反应, 相比于巢式RT-PCR方法, 其灵敏度高10~100倍以上。在对54份临床样品的检测中, 进一步证实了该方法快速、灵敏且重复性好, 可满足戊型肝炎病毒早期快速诊断的需要。     

拉萨河谷上段江孜沙棘Hippophea gyantsensis(Rousi)Lian种群的海拔梯度性变异

江孜沙棘[Hippophea gyantsensis(Rousi)Lian]是青藏高原特有的一种广生态幅的小乔木,在拉萨河谷地区的海拔3500～4200 m范围内均有分布.前人工作多集中在江孜沙棘果实的开发利用方面,对其基础生态学研究较少.本研究旨在探讨江孜沙棘沿海拔梯度的群落组成和表型变异的规律.为此,在拉萨河谷上段沿海拔梯度由东向西设置了4个样带:3850 m、3950 m、4050 m和4200 m,每个样带设置2至3个10 m×10 m的样方进行研究.首先,详细记录了每个样方内林下维管植物的物种组成、样方内的沙棘盖度、海拔、样方与河岸的实际距离,并用DCA [detrended correspondence analysis (去势对应分析)] 排序方法对群落及其组成物种进行排序分析.随机抽取了每个样方内的20个江孜沙棘植株个体,测定其胸径、基径、株高和叶片长度,用回归分析法分析这些变量和海拔之间的关系.研究结果表明,江孜沙棘在拉萨河谷内的主要生境分为4种类型,即:河边砾石滩地、河阶草滩、河边草甸和河边林缘, 样方排序结果主要受海拔的影响;同时,江孜沙棘植株的基径、胸径和高度都随着海拔的升高而显著减小,而叶片长度与海拔之间无显著相关.本文研究结果表明,对江孜沙棘而言,海拔所代表的综合环境因子对其分布和表型有显著的影响,而局部光照可能也是影响其表型特征的重要生态因子.     

生石膏对致热原作用下猫PO／AH温敏神经元放电的影响

目的:研究中药生石膏解热作用的中枢机制.方法:复制发热模型后,静脉注射生石膏,应用微电极细胞外记录技术记录视前区-下丘脑前部(PO/AH) 温敏神经元单位放电的变化情况.结果:给予致热原后,PO/AH 区热敏神经元放电频率显著减少(P<0.01 ),冷敏神经元放电频率明显增加(P<0.05); 静脉注射生石膏后,可反转致热原对PO/AH区温敏神经元的上述作用,与给药前相比,热敏神经元放电频率明显回升(P<0.01 ),冷敏神经元放电频率明显回降(P<0.05).结论:提示生石膏是通过影响致热原作用下PO/AH区温敏神经元的放电活动,在中枢神经元水平上发挥解热作用的.     

Structure-activity relationship and pharmacokinetic profile of 5-ketopyrazole factor Xa inhibitors

Efforts to further optimize the clinical candidate razaxaban have led to a new series of pyrazole-based factor Xa (fXa) inhibitors. Designed to prevent the potential formation of primary aniline metabolites in vivo, the nitrogen of the carboxamido linker between the pyrazole and proximal phenyl moiety of the razaxaban scaffold was replaced with a methylene group. The resulting ketones demonstrated excellent potency and selectivity for fXa but initially had poor oral bioavailability. Optimization by conversion from a P1 aminobenzisoxazole to a P1 p-methoxyphenyl residue, replacing the 3-trifluoromethylpyrazole with a 3-amidopyrazole, and employing a pyridone P4 group provided a fXa inhibitor with a potency and pharmacokinetic profile equivalent to that of razaxaban and improved selectivity over thrombin.     

Novel analogs of D-e-MAPP and B13. Part 2: signature effects on bioactive sphingolipids

Novel isosteric analogs of the ceramidase inhibitors (1S,2R)-N-myristoylamino-phenylpropanol-1 (d-e-MAPP) and (1R,2R)-N-myristoylamino-4'-nitro-phenylpropandiol-1,3 (B13) with modified targeting and physicochemical properties were developed and evaluated for their effects on endogenous bioactive sphingolipids: ceramide, sphingosine, and sphingosine 1-phosphate (Cer, Sph, and S1P) in MCF7 cells as determined by high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS). Time- and dose-response studies on the effects of these compounds on Cer species and Sph levels, combined with structure-activity relationship (SAR) data, revealed 4 distinct classes of analogs which were predominantly defined by modifications of the N-acyl-hydrophobic interfaces: N-acyl-analogs (class A), urea-analogs (class B), N-alkyl-analogs (class C), and omega-cationic-N-acyl analogs (class D). Signature patterns recognized for two of the classes correspond to the cellular compartment of action of the new analogs, with class D acting as mitochondriotropic agents and class C compounds acting as lysosomotropic agents. The neutral agents, classes A and B, do not have this compartmental preference. Moreover, we observed a close correlation between the selective increase of C(16)-, C(14)-, and C(18)-Cers and inhibitory effects on MCF7 cell growth. The results are discussed in the context of compartmentally targeted regulators of Sph, Cer species, and S1P in cancer cell death, emphasizing the role of C(16)-Cer. These novel analogs should be useful in cell-based studies as specific regulators of Cer-Sph-S1P inter-metabolism, in vitro enzymatic studies, and for therapeutic development.     

NMR evaluation of adipocyte fatty acid binding protein (aP2) with R- and S-ibuprofen

We have examined global chemical shift perturbations for aP2 ligand complexes and compared these with amide temperature coefficients. Hydrogen bond potential was monitored by amide chemical shift's temperature coefficient. Based on this information, we propose that the binding energy contribution can be spread out to multiple distant residues. For aP2, the ability of the receptor protein to change its hydrogen bond interactions in the beta-strands to accommodate different ligand scaffolds seems to make this receptor difficult for structure based drug design. While stabilization energy differential on hydrogen bonds is likely to be small for individual residues, the accumulative effect on multiple hydrogen bonds may have a dramatic impact on ligand affinity.     

孕激素诱导cyclin G1在小鼠子宫内膜上皮细胞的表达及其对细胞增殖的影响

本文在体外培养条件下研究卵巢激素诱导小鼠子宫内膜上皮细胞cyclin G1的表达及细胞增殖和细胞周期进程的变化,以探讨孕激素依赖的细胞周期调控因子cyclin G1对子宫内膜上皮细胞增殖的负调控作用.原代培养小鼠子宫内膜上皮细胞,待其生长汇合后分为4组:对照组(C组)、雌激素组(E组)、孕激素组(P组)、雌、孕激素共同作用组(EP组).加入相应激素作用24 h后,用细胞免疫化学方法检测各组细胞cyclin G1的表达水平:四甲基偶氮唑蓝(MTT)比色法检测各组细胞活力,间接观察子宫内膜上皮细胞的增殖情况;用流式细胞仪检测分布在细胞周期各时相的子宫内膜上皮细胞所占百分数.细胞免疫化学结果显示,cyclin G1在C组和E组子宫内膜上皮细胞上无明显表达,而在P组和EP组子宫内膜上皮细胞中表达明显,且定位于细胞核内.MTT法结果显示,与C组相比,E组细胞活力明显增高,而P组和EP组的细胞活力均明显下降,表明雌激素能促进子宫内膜上皮细胞增殖,而孕激素则具有抑制子宫内膜上皮细胞增殖的作用.流式细胞术检测显示,与C组相比,E组中处于S期的子宫内膜上皮细胞百分数增多;P组与EP组中处于S期的子宫内膜上皮细胞百分数明显减少,而处于G1期的细胞百分数和G2/M期的细胞百分数则明显增加.上述结果提示,孕激素依赖的cyclin G1可能通过阻滞细胞周期进程来参与孕激素对子宫内膜上皮细胞增殖的负调控作用.     

Seasonal Dynamics in Resource Partitioning to Growth and Storage in Response to Drought in a Perennial Rhizomatous Grass, <Emphasis Type="Italic">Leymus chinensis</Emphasis>

A natural grassland in northeastern China dominated by Leymus chinensis (Trin.) was subject to drought treatments to determine the seasonal dynamics in resource partitioning to shoot and storage organs in response to drought. The growing season was divided into six stages according to the phenology of L. chinensis. Plant samples of L. chinensis were collected at each stage to determine biomass, gross calorific value, relative water content, and key mineral contents of plant parts, including rhizomes, roots, leaves, and stems. Resource partitioning to shoot and storage organs as measured by biomass, gross calorific value, and N, K⁺, and Na⁺ contents varied significantly among phenologic stages. Drought treatment (natural precipitation, 50–60 % of field capacity) significantly reduced biomass, gross calorific value, relative water content of shoot, and N and K⁺ contents in both shoot and storage organs, but it enhanced rhizome : shoot ratio and Na⁺ content. A negative correlation in biomass, gross calorific value, and K⁺ and Na⁺ contents between shoot and storage organs was found throughout the growing season, which may have been accentuated by drought when soil moisture was limited. Our results indicate that resource partitioning to storage plays an important role in regulating plant growth of L. chinensis, especially under drought conditions.     

Dynamic property is a key determinant for protein-protein interactions

Dynamic property is highly correlated with the biological functions of macromolecules, such as the activity and specificity of enzymes and the allosteric regulation in the signal transduction process. Applications of the dynamic property to protein function researches have been discussed and encouraging progresses have been achieved, for example, in enzyme activity and protein-protein docking studies. However, how the global dynamic property contributes to protein-protein interaction was still unclear. We have studied the dynamic property in protein-protein interactions based on Gaussian Network Model and applied it to classify biological and nonbiological protein-protein complexes in crystal structures. The global motion correlation between residues from the two protomers was found to be remarkably different for biological and nonbiological complexes. This correlation has been used to discriminate biological and nonbiological complexes in crystal and gave a classification rate of 86.9% in the cross-validation test. The innovation of this feature is that it is a global dynamic property which does not rely directly on the interfacial properties of the complex. In addition, the correlation of the global motions was found to be weakly correlated with the dissociation rate constant of protein complexes. We suggest that the dynamic property is a key determinant for protein-protein interaction, which can be used to discriminate native and crystal complexes and potentially be applied in protein-protein dynamic rate constants estimations.