一种与核黄素合酶α亚基具有结构相似性的板蓝根多肽的分离纯化与表征

利用离子交换色谱SP-5PW和疏水色谱POROS HP2从板蓝根鲜根水相抽提物中分离纯化多肽组分,并对其进行生化表征.获得一种达到电泳纯的多肽RIP2,其相对分子质量约为6.87 ku,等电点约为7.73,N端氨基酸序列依次为QIGEFATAPF.经数据库搜索比对,发现该多肽与核黄素合酶α亚基具有一定的同源性.细胞毒性实验表明该多肽具有一定抗病毒作用.     

基于不同安全车距策略的自适应巡航控制稳定性研究

在自适应巡航控制系统的基础上,建立了固定车距和固定时距两种策略下的车辆跟随安全车距模型。针对固定车距策略,研究了在有、无领车的情况下车队的稳定性;针对固定时距策略,研究了其在理想情况下和引入机械延迟、通信延迟的情况下车队的稳定性。并且从车辆跟随误差的传递函数角度出发,给出了能够保障车队稳定的参数关系。最后,通过Matlab数值仿真,结果表明当各参数满足车队稳定性条件时,能保证整个车队的稳定行驶。     

Direct observation of the clockwise light-driven rotation of F<Subscript>0</Subscript>F<Subscript>1</Subscript>-ATP synthase complex

The purified thermophilic bacterium PS3 F₁ β _10×His-tag is inserted into the F_oF₁-ATP synthases of chro-matophores isolated from photosynthetic bacteria Rhodo-spirillum rubrum. The studies of biochemical properties of the hybrid chromatophores show that they have both protons-driving capability and photophosphorylation. The fluorescent actin filaments, as a marker of its orientation by video-microscopic experiment, are connected via Maleimido-C₃-NTA to the reconstituted β_10×His-tag of F_oF₁-ATP synthases. The clockwise rotation of F_oF₁-ATP synthases driven by light is observed directly when viewed from the F_o side to F₁. This system should be valuable for further studying the coupling property of F_oF₁-ATP synthase.     

Regulation between nitric oxide and MAPK signal transduction in mammals

Nitric oxide (NO) is an important biological messenger in the regulation of tissue homeostasis. It exhibits a wide range of effects during physiological and pathophysiological processes. Typical beneficial properties of NO include the regulation of vascular tone,the protection of cells against apoptosis, the modulation of immune responses, and the killing of microbial pathogens. On the other hand,NO may cause severe vasodilation and myocardial depression during bacterial sepsis or act as a cytotoxic and tissue-damaging molecule in autoimmune diseases. Mitogen-activated protein kinase (MAPK) is a family of serine/threonine protein kinases that are widely distributed in mammalian cells. MAPK cascade plays pivotal roles in gene expression, cell proliferation, differentiation, neuronal survival and programmed cell death under a variety of experimental conditions. MAPKs transduce the signal for the cellular response to extracellular stresses or stimuli. The relation between them, however, has never been reviewed. Based on our researches and other reports in the field, we review their reciprocal regulatory functions.     

河套蜜瓜ACC氧化酶基因cDNA部分片段的克隆和序列分析

以河套蜜瓜(Cucumis melo L．ev Hetao)成熟果实为材料，用硫氰酸胍法提取总RNA，以oligo(dT)15为引物，反转录合成cDNA，利用一对甜瓜ACC氧化酶(1-aminocyclopropane-1-earboxylate oxidase，ACO)基因cDNA的特异性引物进行聚合酶链式反应(PCR)扩增。获得了预期大小的cDNA片段．将此片段克隆于pUCl9质粒中，进行DNA序列分析．序列分析结果表明该片段为545bp，编码甜瓜ACO的第126至第306个氨基酸．该河套蜜瓜ACO基因cDNA序列与Andes甜瓜、Cantaloup charentais甜瓜和哈密瓜的相应序列进行比较，其核苷酸序列与Andes甜瓜的同源性为99．4％；与Cantaloup charentais甜瓜和哈密瓜的同源性均为99．6％。与其对应的氨基酸序列的同源性均为99．4％．     

瓜类蔬菜昆虫群落(包括蛛形纲和软体动物)的研究Ⅲ.群落的数量动态

本报道了瓜类昆虫群落(包括蛛形纲和软体动物门中的一些有害生物及天敌)的数量动态之二，从两个方面进行了分析描述．①采用最优分割分析各瓜类昆虫群落的发展阶段；②采用主分量分析方法探讨各昆虫种群对群落特征的作用．     

Cloning and enzymology analysis of farnesyl pyrophosphate synthase gene from a superior strain of<Emphasis Type="Italic">Artemisia annua</Emphasis> L.

A cDNA(af1) encoding farnesyl pyrophosphate synthase AaFPS1(FPS,EC2.5.1.1/EC2.5.1.10) from a high yield Artemisia annua strain 025 has heen cloned from its cDNA library .Sequence analysis showed that the cDNA encoded a protein of 343 amino acid (aa) residues with molecular weight of 39 kD.Deduced aa sequence of the cDNA was similar to FPS from other plants,yeast and mammals,containing 5 conserved domains found in both prenyl trans-ferase and polyprenyl synthase,The expression of the cDNA in Escherichia coli showed measurable specific activity of FPS in vitro.The enzyme was purified by ion exchange chromatography and its kinetics was measured ,These results would further promote the molecular regulation of artemisnin biosynthesis.     

Abnormal expression of inducible nitric oxide synthase in Duchenne muscular dystrophy muscles

Duchenne muscular dystrophy (DMD) is a fatal genetic disease for the youth and children. 8 biopsies of DMD patients were determined and demonstrated that the membrane_binding nitric oxide synthase was enriched in normal skeletal muscles and was little in DMD muscles. The results from Western blot and immunohistochemistry showed that inducible nitric oxide synthase (iNOS) was overexpressed in DMD muscle fibers, while a small amount of highly localized iNOS can be found in normal fibers. Based on these findings, it is proposed that the mechanism of progressive injury in DMD muscle might be associated with the abnormal expression of iNOS.     

Study on structure-activity relationship of mutation-dependent herbicide resistance acetohydroxyacid synthase through 3D-QSAR and mutation

Seventy-four sulfonylureas were synthesized and tested for their inhibitory activity against the whole enzyme of E. coli acetohydroxyacid synthase (AHAS, EC 2.2.1.6) isoenzyme II, and 3D-QSAR analyses were performed based on these inhibitory activities. The binding conformation of chlorimuron-ethyl, a commercial herbicide of AHAS, in the crystal structure of AHAS complex was extracted and used as template to build the initial three-dimensional structure of other sulfonylureas, and then all structures were fully geometry optimized. After systematic optimization of the alignment rule, molecular orienta- tion, grid space and attenuation factor, two satisfactory models with excellent performances (CoMFA: q2 = 0.735, r2 = 0.954, n = 7, r 2 pred = 0.832; CoMSIA: q2 = 0.721, r2 = 0.913, n = 8, r 2pred = 0.844) were estab- lished. By mapping the 3D contour maps of CoMFA and CoMSIA models into the possible inhibitory active site in the crystal structure of catalytic subunit of yeast AHAS, a plausible binding model for AHAS, with best fit QSAR in the literature so far, was proposed. Moreover, the results of 3D-QSAR were further utilized to interpret resistance of site-directed mutants. A relative activity index (RAI) for AHAS enzyme mutant was defined for the first time to relate the 3D-QSAR and resistance of mutants. This study, for the first time, demonstrated that combination of 3D-QSAR and enzyme mutation can be used to decipher the molecular basis of ligand-receptor interaction mechanism. This study refined our understanding of the ligand-receptor interaction and resistance mechanism in AHAS-sulfonylurea system, and provided basis for designing new potent herbicides to combat the herbicide resistance.     

Effects of niacin on nitric oxide synthase expression in rat lungs exposed to silica

The aim of this study was to evaluate the effects of niacin in diet on the expression of nitric oxide synthase (NOS) in rat lungs of the animal model of silicosis established by direct tracheal instillation of silica particles into rat lungs surgically. The niacin concentration in serum was analyzed by high performance liquid chromatography (HPLC). The expression of inducible nitric oxide synthase (iNOS) protein in paraffin-embedded lung sections was determined by streptavidin/peroxidase (SP) staining. Quantitative analysis by Image-Pro Plus was also performed on the expression of iNOS. The results showed that niacin concentration in serum of the niacin-treated rats was significantly higher than that in the control and silica-treated rats. After 7 days of silica instillation, iNOS integrated optical density (IOD) in rat lungs and total NOS and iNOS activities in bronchoalveolar lavage fluid (BALF) in silica-treated rats rose by 273420.75, 2.61 units/mL and 1.89 units/mL respectively, when compared with those in the control rats. Niacin treatment significantly reduced silica-induced iNOS IOD in rat lung tissues and total NOS and iNOS activities in BALF supernatant by 248292.35, 1.50 units/mL and 0.91 units/mL, respectively, as compared with those in silica-treated rats. Therefore, niacin can effectively attenuate the pathological expression of NOS in rat lung tissues induced by silica particles.