Demonstration by monoclonal antibodies that carbohydrate structures of glycoproteins and glycolipids are onco-developmental antigens

The hope that hybridoma antibodies would reveal unique cell surface antigens during embryogenesis, differentiation and oncogenesis has been replaced by the realization that such antigens are mainly carbohydrate structures of glycoproteins and glycolipids occurring in many cell types. These findings either may reflect limitations in the methods of selection of hybridoma antibodies or may point to important roles for the diverse carbohydrate structures as receptors for regulators of cell growth and differentiation.     

Neural adhesion molecule L1 as a member of the immunoglobulin superfamily with binding domains similar to fibronectin

Diverse glycoproteins of cell surfaces and extracellular matrices operationally termed 'adhesion molecules' are important in the specification of cell interactions during development, maintenance and regeneration of the nervous system. These adhesion molecules have distinct functions involving different cells at different developmental stages, but may cooperate when expressed together. Families of adhesion molecules which share common carbohydrate domains do exist, despite the structural and functional diversity of these glycoproteins. These include the Ca2+-independent neural adhesion molecules: N-CAM, myelin associated glycoprotein (MAG) and L1. L1 is involved in neuron-neuron adhesion, neurite fasciculation, outgrowth of neurites, cerebellar granule cell migration, neurite outgrowth on Schwann cells and interactions among epithelial cells of intestinal crypts. We show here that in addition to sharing carbohydrate epitopes with N-CAM and MAG, L1 is also a member of the immunoglobulin superfamily. It contains six C2 domains and also shares three type III domains with the extracellular matrix adhesion molecule fibronectin.     

Photoreceptor-specific degeneration caused by tunicamycin

The antibiotic tunicamycin inhibits the biosynthesis of N-acetylglucosaminylpyrophosphoryl polyisoprenol, a key intermediate in the formation of the asparagine-linked oligosaccharides of glycoproteins. The effects of tunicamycin have been studied in various biological systems, primarily with the aim of elucidating the role of the carbohydrate moieties in the cellular function of glycoproteins. Rhodopsin, the visual pigment of retinal rod photoreceptor cells, is a membrane glycoprotein which consists of a single polypeptide chain (opsin) to which a chromophoric prosthetic group (II-cis-retinaldehyde) and two asparagine-linked oligosaccharide chains are covalently attached. The glycosylation of opsin can be blocked with tunicamycin in vitro in conditions where polypeptide synthesis is only slightly decreased. We have reported that tunicamycin can disrupt the normal assembly of rod outer segment membranes in vitro without significantly inhibiting the biosynthesis or intracellular transport of opsin. Here we report that intraocular injection of tunicamycin produces a photoreceptor-specific degeneration characterized by progressive shortening of rod outer segment, decreased membrane assembly, and eventual photoreceptor cell death.     

Structural organization of the rat thy-1 gene

Thy-1 is a differentiation marker expressed predominantly on thymocytes, T cells and brain tissue. Its presence on murine peripheral T cells but not B cells has long been used to distinguish between these two populations of lymphocytes. Although analogues of Thy-1 have been described in several mammalian species, its tissue distribution in different species varies widely, precluding its use as T-cell-specific marker. The Thy-1 molecule is a cell-surface glycoprotein of relative molecular mass 18,000, one-third of which represents carbohydrate; the protein moieties of the rat and murine Thy-1 molecules have been sequenced and found to consist of 111 and 112 amino acids, respectively. An unusual aspect of Thy-1 is the apparent absence of a hydrophobic segment comparable to that observed in other membrane glycoproteins which would allow integration of Thy-1 within the membrane lipid bilayer. This has prompted speculation that Thy-1 is anchored to the cell surface by some other hydrophobic component such as glycolipid. Here we report the structure of thy-1 complementary DNA and genomic clones and describe the exon-intron organization of the gene. More importantly, our data indicate that Thy-1 is initially synthesized as a molecule of 142 amino acids, 31 amino acids longer at the carboxyl end than the Thy-1 molecule isolated and characterized by Campbell et al. An extremely hydrophobic region of 20 amino acids lies within this 31-amino acid stretch and may represent the transmembrane segment responsible for anchoring Thy-1 to the cell membrane.     

The J1 glycoprotein--a novel nervous system cell adhesion molecule of the L2/HNK-1 family

The neural cell adhesion molecules L1 and N-CAM share a common carbohydrate epitope that is recognized by the monoclonal antibodies L2 and HNK-1. The L2/HNK-1 epitope is also present on the myelin-associated glycoprotein (MAG) which is thought to mediate surface interactions between the axon and myelinating cell. Other, as yet unidentified, cell-surface glycoproteins are recognized by the two antibodies and are believed to belong to a family of neural cell adhesion molecules. To test this hypothesis, we have prepared polyclonal antibodies to a prominent member of the L2/HNK-1 family, the 160K (relative molecular mass (Mr)160,000) glycoprotein. Here we report that these antibodies, designated J1 antibodies, react with astrocytes and oligodendrocytes and interfere with neurone-astrocyte adhesion, but not with neurone-neurone or astrocyte-astrocyte adhesion. This result suggests the involvement of the J1 antigen in cell-cell interactions.     

A T3-like protein complex associated with the antigen receptor on murine T cells

Antigen recognition by human T lymphocytes and initiation of T-cell activation are mediated by a group of integral membrane proteins, the T-cell antigen receptor (TCR) and the T3 complex. The polypeptides which comprise T3 (a gamma-chain of relative molecular mass (Mr) 25,000 (25K), and delta and epsilon chains of 20K each) are physically associated with the TCR chains. Surface expression of the complex requires the presence of all the component T3 and TCR proteins. In contrast to the human system, murine T3 has not been identified using antibodies. Here we describe a murine T3-like protein complex. It appears to be more complicated than human T3, containing three monomeric glycoproteins (21-28K), two of which have N-linked carbohydrate side chains and a novel family of TCR-associated homo- and heterodimers. The 28K protein is identified as the murine T3 delta-chain. The 21K protein is phosphorylated on cell activation with concanavalin A (Con A).     

鱼抗冻糖蛋白AFGP7－8的热滞研究

分析了鱼抗冻糖蛋白（ＡＦＧＰ７－８）的结构特点及在溶液中的特性，计算了ＡＦＧＰ７－８溶液的热滞，理论结果与实验数据较好地符合．     

极区鱼的抗冷冻机理

鱼抗冷冻蛋白和抗冷冻糖蛋白有抗冻功能，本文阐述并讨论了各种抗冻机理学说。本文在预测了ＡＦＰⅠ、ＡＦＰⅡ和ＡＦＰⅢ的二级结构并分析了ＡＦＰ三级结构的特点基础上，计算了抗冷冻蛋白的热滞，得出了与实验相符结论．     

黑蚂蚁的食性与生态习性的研究

对黑蚂蚁的食性与生态习性进行了研究.结果表明,黑蚂蚁的食性很广,属杂食性昆虫.但在不同季节,黑蚂蚁对各种食物的喜好程度稍有不同.黑蚂蚁在冬季以糖类和水果类食物最多,在春季则以糖类和动物性食物最多.黑蚂蚁的食物组成与生活环境中的动物和植物种类有一定的相关性.黑蚂蚁出巢摄食时间有一定的规律性,冬季,黑蚂蚁每天摄食的高峰时间为上午10点以后到下午4点以前;春季,黑蚂蚁每天出巢摄食一般有两个高峰时间,即上午8~10时和下午4~7时.     

Chemical glycosylation in the synthesis of glycoconjugate antitumour vaccines

Therapeutic vaccines derived from carbohydrate antigen-adjuvant combinations are a promising approach for cancer immunotherapy. One of the critical limitations in this area is access to sufficient quantities of tumour-associated carbohydrate antigens and glycoconjugate adjuvants. At present, availability of the complex oligosaccharide constructs that are needed for the systematic design and evaluation of novel vaccine formulations relies on de novo chemical synthesis. The use of both state-of-the-art and emerging glycosylation technologies has led to significant advances in this field, allowing the clinical exploration of carbohydrate-based antigens in the treatment of cancer.     

抗冻糖蛋白(AFGP1-5)溶液中自由生长条件下冰晶生长激活能的计算

根据冰晶生长速率理论，计算了抗冻糖蛋白（ＡＦＧＰ１－５）溶液中自由生长条件下冰晶生长的激活能．这种定量计算对研究抗冻糖蛋白溶液中冰晶生长习性有重要意义．     

烯效唑应用于小麦生态雄性不育系的效应研究

用不同浓度的烯效唑进行浸种处理，探讨其对生态雄性不育系小麦的生物学效应。测定了不同处理的植株的生物学性状和可溶性糖、淀粉、蛋白质、叶绿素、游离氨基酸总量等生理生化指标。结果表明：适当浓度的烯效唑能促进发芽，矮化植株，增加生理量，提高可溶性糖，淀粉，叶绿素的含量，降低可溶性蛋白和游离氨基酸的含量。     

镉对集胞藻PCC6803生长的影响

以集胞藻为研究材料,研究不同浓度的Cd2 处理对集胞藻生长的影响.研究发现:低浓度的Cd2 处理(0~0.1 m g/L),能够促进集胞藻的生长,表现为叶绿素、可溶性糖、蛋白质含量随着浓度的增大而增大;当Cd2 浓度进一步增加时,Cd2 开始抑制集胞藻的生长,表现为叶绿素、可溶性糖、蛋白质含量减小,Cd2 浓度达到1.0 m g/L则完全抑制集胞藻的生长,无任何产物累积.     

增加投喂频率改善彭泽鲫对饲料糖的利用

用分别含20%（低）、40%（高）葡萄糖和糊精的4种等氮（粗蛋白为35.5%）、等能(16.8 kJ·g-1)饲料饲养平均尾重为3.7±0.3 g彭泽鲫16周,投饲率为4%左右,研究投喂频率分别为每天2次和每天6次时鲫鱼对糖利用性的差异.结果显示,鲫鱼的增重率、饲料效率和蛋白质效率都随投喂频率增加而显著提高 (〖WTBX〗P〖WTBZ〗<0.001).投喂频率为每天2次时,增重率表现为高糖组显著低于低糖组 (〖WTBX〗P〖WTBZ〗=0.003),葡萄糖组显著低于糊精组(〖WTBX〗P〖WTBZ〗=0.003),蛋白质沉积率表现为糊精组显著高于葡萄糖组(〖WTBX〗P〖WTBZ〗<0.05);投喂频率为每天6次时,增重率无显著差异,糖源和糖水平对蛋白质沉积率的影响均无显著差异.脂肪和能量沉积率也有相似的趋势,且高糖组脂肪沉积率接近或大于100%,提示有大量糖类转化为体脂.投喂频率增加,体脂含量显著增加 (〖WTBX〗P〖WTBZ〗<0.001).投喂频率为每天6次时,高葡萄糖组体脂含量显著低于其它各组.鱼体粗蛋白、粗灰分及水分含量受饲料糖种类、水平及投喂频率的影响不明显.高糖组糖化血红蛋白含量显著高于低糖组(〖WTBX〗P〖WTBZ〗<0.001),血浆甘油三酯及胆固醇各组无显著差异.上述结果提示增加投喂频率显著改善鲫鱼对饲料糖的利用,其原因可能与削弱或消除代谢通量迁移有关.     

中华盒形藻三类大小细胞的生化组成

用ｆ／２培养液培养的中华盒形藻的三类不同大小细胞进行生化组成分析，结果表明，蛋白质、氨基酸、核酸、糖类和叶绿素等在细胞中的含量随细胞的缩小而减少，其中，糖类减少的比例最小，在小型细胞中糖类相应于蛋白质增加１３．５％。三类细胞中的Ｃ／Ｎ比值分别为３．８，４．３和４．７，反映该藻细胞在缩小期间碳水化合物比含氮化物更多的积累。这显示，硅藻细胞从营养生长期过滤到生殖生长期过程，除了细胞大小参数外，细胞中的     

Novel mannosidase inhibitor blocking conversion of high mannose to complex oligosaccharides

Many secretory and membrane proteins are glycoproteins carrying asparagine-linked (N-linked) oligosaccharides. There are two types of N-linked glycans, referred to as high-mannose and complex type, respectively. Biosynthesis of N-linked glycans of the complex type proceeds via a high-mannose intermediate. After the initial transfer of a high-mannose oligosaccharide with the composition (Glc)3(Man)9(GlcNAc)2 from a lipid carrier to the nascent polypeptide chain, trimming reactions take place. Trimming glucosidases remove the glucose residues quantitatively and mannosidases IA/B and II can remove all but three mannose residues. After trimming, terminal sugars such as N-acetylglucosamine, galactose, sialic acid and fucose may be added and result in the conversion to a glycan of the complex type. Because suitable inhibitors were lacking, it was difficult to assess the importance of the trimming reactions for proper intracellular traffic, modification reactions other than the addition of terminal sugars, or as regulatory steps in glycoprotein processing. Here we describe the action of 1-deoxymannojirimycin (1,5-dideoxy-1,5-imino-D-mannitol, dMM; Fig. 1) on the biosynthesis of IgM and IgD. dMM is the mannose analogue of 1-deoxynojirimycin (dNM; Fig. 1), itself a glucosidase inhibitor. We present evidence that dMM is a mannosidase inhibitor. In vivo dMM inhibits the equivalent of the mannosidase IA/B activities and blocks conversion of high-mannose to complex oligosaccharides. It is the first such inhibitor to be reported. Interference with the biosynthetic pathway of N-linked glycans could prove to be a powerful way to manipulate carbohydrate structure in vivo.     

不同糖源对南美白对虾Penaeus vannamei生长、成活率和虾体组成的影响

在饲料中分别添加w=20%的葡萄糖、小麦淀粉、玉米淀粉、马铃薯淀粉、蔗糖、糊精,饲养初始质量为(0.78±0.01)g的南美白对虾,经过56 d的生长试验,观察不同糖源对于南美白对虾的生长、成活率、机体营养组成的影响.实验结果表明,南美白对虾对不同糖源的利用表现出差异性,蔗糖组的成活率、特定生长率、饲料效率均最高;其他各组差异不显著.不同糖源对南美白对虾生长的影响依次为蔗糖>玉米淀粉>小麦淀粉>糊精>葡萄糖>马铃薯淀粉;对南美白对虾成活率的影响依次为蔗糖>马铃薯淀粉>玉米淀粉>小麦淀粉>糊精>葡萄糖.不同糖源对南美白对虾全虾蛋白质含量和水分含量的影响差异不大,但是糊精和马铃薯淀粉组的全虾脂肪含量明显低于其他各组,蔗糖组的全虾灰分与其他各组都没有显著性差异,葡萄糖组最高,糊精组最低.     

不同刈割强度下冷蒿再生生长与可溶性碳水化合物的相关分析

在不同刈割强度、不同资源空间下，对冷蒿再生生长指标与可溶性碳水化合物含量、可溶性碳水化合物库进行相关分析．结果表明：在不同刈割强度下，冷蒿可溶性碳水化合物含量与再生生长不相关，而可溶性碳水化合物库与再生生长显著相关，并且轻度刈割可溶性碳水化合物库与再生生长相关水平高于不刈割，重度刈割低于不刈割．在不同的资源与空间，相同年龄的冷蒿可溶性碳水化合物库与再生生长的相关水平在资源空间充足的情况下高于资源空间缺乏的情况．在相同的资源与空间，幼龄冷蒿比多年龄冷蒿的再生生长与可溶性碳水化合物库的相关水平高．说明可溶性碳水化合物含量不能表征再生生长能力，而可溶性碳水化合物库是再生生长能力的度量；适度的刈割有利于碳水化合物的积累，促进冷蒿的再生；冷蒿的再生在不受(或较少受)分生组织限制时，它受可溶性碳水化合物的影响；冷蒿的再生首先要有活跃的分生组织，其次是碳水化合物贮藏．     

糖类油田化学品中多糖的定量分析

为定量分析糖类油田化学品中多糖的含量,采用苯酚-硫酸比色法进行测量,探讨波长、显色温度、显色时间、溶液稀释倍数等因素对检测结果的影响,分析线性区域并评价此方法的稳定性、精确度与重现性,并与蒽酮比色法进行对比.实验结果表明:采用苯酚-硫酸比色法,杂多糖苷KD-03溶液质量浓度在20～200mg/L之间、显色时间30min、波长为485nm时,吸光度与质量浓度呈良好的线性关系,稳定性好,精确度与重现性实验RSD值分别为0.76%和2.42%.对比蒽酮比色法,苯酚-硫酸比色法精确度与重现性分别提高了1.19%和3.04%.为油气田定量分析糖类材料中多糖含量找到一种新方法.