糖蛋白生物活性研究综述

糖蛋白是生物体内重要的生物大分子之一，它广泛存在于动物、植物和某些微生物中，甚至还存在于单细胞有机体和病毒中糖蛋白可分别以可溶性和不溶性形式存在干细胞外液和细胞间质中几乎所有合成蛋白质的细胞都会合成糖蛋白，随着糖生物学研究的迅速发展，使长期被忽视的糖蛋白已成为生物化学研究的中心，它吸引着许多学科，包括化学、生物学、生物化学、兔疫学、细胞生物学、医药学以及食品科学的工作者从事这一领域的研究。     

Platelet membrane glycoprotein IIb/IIIa: member of a family of Arg-Gly-Asp--specific adhesion receptors

Adhesive interactions of the platelet surface with plasma proteins such as fibrinogen and fibronectin play an important role in thrombosis and hemostasis. The binding of both of these proteins to platelets is inhibited by synthetic peptides containing the sequence Arg-Gly-Asp, which corresponds to the cell adhesion site in fibronectin and is also present in the alpha chain of fibrinogen. An affinity matrix made of an insolubilized heptapeptide containing the Arg-Gly-Asp sequence selectively binds the platelet membrane glycoprotein IIb/IIIa from detergent extracts of platelets. When incorporated into liposome membranes, the isolated protein confers to the liposomes the ability to bind to surfaces coated with fibrinogen, fibronectin, and vitronectin but not to surfaces coated with thrombospondin or albumin. This platelet receptor is related to the previously identified fibronectin and vitronectin receptors in that it recognizes an Arg-Gly-Asp sequence but differs from the other receptors in its wider specificity toward various adhesive proteins. These results establish the existence of a family of adhesion receptors that recognize the sequence Arg-Gly-Asp.     

血管内皮生长因子研究进展

血管内皮生长因子(Vascular Endothelial Growth Factor, VEGF)是一种由各种正常细胞或肿瘤细胞合成和分泌的糖蛋白。人类医学研究证明,VEGF有两种受体——KDR/FLK-1和FLT-1。VEGF与受体结合,具有促进血管内皮细胞的增生和提高微血管对大分子物质的通透性作用。人的VEGF 基因由8个外显子构成,主要有VEGF121、VEGF145、VEGF165、VEGF189和VEGF206等5个同型异构体。等电点的差异和肝素亲合力的差异可能是造成VEGF 生物活性差异的主要原因。     

Growth cone guidance in insects: fasciclin II is a member of the immunoglobulin superfamily

The cellular cues that guide neuronal growth cones toward their targets are highly conserved in such diverse organisms as insects and vertebrates. Evidence presented here suggests that the molecular mechanisms underlying these events may be equally conserved. This article describes the structure and function of fasciclin II, a glycoprotein expressed on a subset of fasciculating axons in the grasshopper embryo. Antibody perturbation experiments suggest that fasciclin II functions in mediating one form of neuronal recognition: selective fasciculation. Fasciclin II is a member of the immunoglobulin gene superfamily and is homologous in structure and function to the neural cell adhesion molecule N-CAM and to several other vertebrate cell adhesion molecules.     

Expression of myelin-associated glycoprotein by small neurons of the dorsal root ganglion in chickens

Biochemical and immunocytochemical investigations have shown that myelin-associated glycoprotein (MAG) is exclusively related to myelin and myelin-forming cells in mammals. In the present study it was found that dorsal root ganglia in young chickens display MAG-immunoreactive material in most small sensory neurons. The presence of MAG at the surface of small sensory neurons raises the question of whether this glycoprotein acts as a cell adhesion molecule in lower vertebrates.     

An inducible endothelial cell surface glycoprotein mediates melanoma adhesion

Hematogenous metastasis requires the arrest and extravasation of blood-borne tumor cells, possibly involving direct adhesive interactions with vascular endothelium. Cytokine activation of cultured human endothelium increases adhesion of melanoma and carcinoma cell lines. An inducible 110-kD endothelial cell surface glycoprotein, designated INCAM-110, appears to mediate adhesion of melanoma cells. In addition, an inducible endothelial receptor for neutrophils, ELAM-1, supports the adhesion of a human colon carcinoma cell line. Thus, activation of vascular endothelium in vivo that results in increased expression of INCAM-110 and ELAM-1 may promote tumor cell adhesion and affect the incidence and distribution of metastases.     

覆盆子糖蛋白提取工艺的研究

[目的]研究中药覆盆子糖蛋白的最佳提取工艺。[方法]采用热水提取法提取覆盆子糖蛋白，考察了料液比、提取温度、提取时间和提取次数对覆盆子糖蛋白得率的影响。在此基础上，考察了超声波辅助热水提取各因素对糖蛋白得率的影响。[结果]结果表明，在料液比1：15、提取温度为50℃、提取时间4h、提取次数2次的条件下，覆盆子糖蛋白得率最高。经超声波处理后覆盆子糖蛋白得率明显增加，超声波处理频率60kHz，功率140W，超声时间为20min，糖蛋白得率最高。[结论]超声波辅助提取法工艺操作简单，成本较低，提取率较高，适于大规模生产，也可将此法提取到的糖蛋白进一步地纯化以用于后续试验研究。     

淀山湖生态示范区附着藻类季节动态变化研究

于2010年在淀山湖生态修复示范区分0.1、0.5、1.0、1.5 m 4个水层挂片,进行附着藻类群落结构的季节调查,以期探索其时空变化特征,为淀山湖生态修复积累基本资料。结果显示,共检出附着藻类139种,隶属7门50属;其中硅藻门最多,为19属89种;附着藻类的种类数在不同水层的分布具有季节特性,优势种具有明显的季节性和垂直性特性;该水域附着藻类密度在春季0.1 m水层最高,为12.73×104cell·cm-2;在冬季1.5 m水层最低,为367 cell·cm-2。除秋季0.5 m水层密度高于0.1 m水层外,其他3季藻类密度均随水深的增加而递减;二因素方差分析显示,附着藻类密度春季显著高于其他3季(P<0.05),秋季显著高于夏季和冬季(P<0.05);0.1 m水层密度与0.5 m水层密度之间无显著差异(P>0.05),但此两水层藻类密度均显著高于1.0 m和1.5 m(P<0.05)。附着藻类Shannon-weaver多样性指数(H′)为1.29～4.32,春季显著高于其他3个季节(P<0.05);1.5 m水层显著低于其他各水层(P<0.05)。表层水体(0.1 m)附着藻类密度和多样性易受降雨、风浪等因素干扰。     

Biological bulldozers and the evolution of marine benthic communities

During the Phanerozoic, the diversity of immobile suspension feeders living on the surface of soft substrata (ISOSS) declined significantly. Immobile taxa on hard surfaces and mobile taxa diversified. Extinction rates of ISOSS were significantly greater than in other benthos. These changes in the structure of benthic communities are attributed to increased biological disturbance of the sediment (bioturbation) by diversifying deposit feeders.     

Molecular aspects of specific cell contact

Complementary macromolecules were isolated from yeasts of opposite mating type. These cell-surface molecules neutralize each other as do antibodies and antigens. Both yeast factors are glycoproteins of low molecular weight. Other specific cell associations may be due to the interaction of such complementary macromolecules.     

Cell guidance by alterations in monomolecular films

Monolayers of stearic and behenic acids were transferred to quartz slides by the Blodgett technique. Troughs of different depths were cut into these multilayers (substrata), and additional monolayers were superimposed. When cultured and fresh embryonic cells were grown on these substrata, the cells were entrapped within troughs whose depths were as small as 60 angstroms. The results demonstrate cellular responses to molecular changes in contact surfaces.     

猴头菌栽培基质最佳配方的数学模型研究

采用比率设计与正交旋转组合设计方法,通过建立数学模型,研究了猴头菌人工栽培中6种常用基质的用量及其交互作用与产量的定量关系。结果表明:各基质之间的最佳组合可以大幅度提高猴头菌的产量,得出了各种基质在生产中实用的比率范围及最佳栽培配方,即麸皮19.3％,玉米粉1.43％,黄豆饼粉2.86％,过磷酸钙2.86％,生石膏2.14％,棉子壳71.4％。其生物学效率可达180％。     

The convergence of synthetic organic and polymer chemistries

Several recent conceptual advances, which take advantage of the design criteria and practical techniques of molecular-level control in organic chemistry, allow preparation of well-defined polymers and nanostructured materials. Two trends are clear: the realization that synthesis of complex macromolecules poses major challenges and opportunities and the expectation that such materials will exhibit distinctive properties and functions. Polymer synthesis methods now being developed will yield well-defined synthetic macromolecules that are capable of mimicking many of the features of proteins (for example, three-dimensional folded structure) and other natural materials. These macromolecules have far-reaching potential for the study of molecular-level behavior at interfaces, in thin films, and in solution, while also enabling the development of encapsulation, drug-delivery, and nanoscale-patterning technologies.     

生物炭配合有机物料对水稻育秧基质的影响

[目的]以水稻品种"龙稻11号"为供试品种,采用生物炭配合有机物料玉米秸秆和稻壳,同时添加有机肥、草炭、沸石、细河沙、耕层土等按一定的体积比混合,进行新基质的水稻育秧试验,研究生物炭配合有机物料新基质的理化性质及其对秧苗生长状况的影响。[方法]采用大棚育苗,随机区组试验。[结果]生物炭配合有机物料玉米秸秆和稻壳的基质能够提高基质的最大持水量,降低基质的容重,改善基质的pH缓冲性,对基质的碱解氮和速效钾含量影响较大,并且能够提高秧苗的发根数和充实度。[结论]生物炭配合有机物料玉米秸秆和稻壳的基质（处理 HC）为最优基质。     

香菇渣在韭菜基质栽培中的应用效果

采用盆栽试验,研究了香菇渣对基质栽培韭菜生长发育及产量的影响。试验结果表明：不同用量的香菇渣对韭菜生长发育影响显著,株高以T2处理最高,叶宽、茎粗和分蘖数等指标以T3处理最大;对韭菜产量的影响以T2处理最高;对叶绿素和类胡萝h素含量呈现先增加后降低的趋势,但各处理组均大于对照组;香菇渣比例在16．00％-50．00％之间对韭菜生长的效果均高于单独运用草炭的对照组,以他处理（香菇渣：草炭：珍珠岩=2：4：3）韭菜的生长发育及产量表现最优,香菇渣对草炭最适宜的替代率为33．33％。     

胡椒木扦插繁殖研究

通过不同扦插基质、扦插季节、插条部位和生根剂种类及其不同浓度处理的比较试验,进行了胡椒木扦插繁殖的研究。结果表明:不同处理对胡椒木扦插生根和生长存在影响,其中效果最佳的处理组合为:秋季扦插+中部枝条扦插+IBA(200mg/L处理2h)+50%椰糠+50%红壌,生根率可达92.21%,平均最长根长达13.56cm。     

进化论的进化——达尔文主义、现代达尔文主义和非达尔文主义

<正> 达尔文主义的贡献1859年达尔文(Darwin,C.)(1809—1882)的名著《物种起源》的出版,标志着生物进化论——达尔文主义的诞生。一百多年来进化论的发展经历了达尔文主义、现代达尔文主义和非达尔文主义三个发展阶段。达尔文认为:生物繁殖以几何级数增加,表现繁殖过剩;为了争夺空间和食物,生物之间必然存在着生存斗争;在生存斗争中,有利的变异得到保存并传给后代,有害的变异受到淘汰,通过自然选择的历史过程,微小的变异逐渐累积成     

Solution structure of kistrin, a potent platelet aggregation inhibitor and GP IIb-IIIa antagonist.

The structure of kistrin, which is a member of a homologous family of glycoprotein IIb-IIIa (GP IIb-IIIa) antagonists and potent protein inhibitors of platelet aggregation, has been determined by two-dimensional nuclear magnetic resonance (NMR) spectroscopy. The 68-residue protein consists of a series of tightly packed loops held together by six disulfide bonds and has almost no regular secondary structure. Kistrin has an Arg-Gly-Asp (RGD) adhesion site recognition sequence important for binding to GP IIb-IIIa that is located at the apex of a long loop across the surface of the protein.     

Structurally homologous ligand binding of integrin Mac-1 and viral glycoprotein C receptors

Three spatially distant surface loops were found to mediate the interaction of the coagulation protein factor X with the leukocyte integrin Mac-1. This interacting region, which by computational modeling defines a three-dimensional macromotif in the catalytic domain, was also recognized by glycoprotein C (gC), a factor X receptor expressed on herpes simplex virus (HSV)-infected endothelial cells. Peptidyl mimicry of each loop inhibited factor X binding to Mac-1 and gC, blocked monocyte generation of thrombin, and prevented monocyte adhesion to HSV-infected endothelium. These data link the ligand recognition of Mac-1 to established mechanisms of receptor-mediated vascular injury.