Concanavalin A reaction with human normal immunoglobulin G and myeloma immunoglobulin G

Concanavalin A precipitated less than 5 percent of immunoglobulin G from human serum. It reacted with all of 42 myeloma serums of the immunoglobulin G type tested, but no more than approximately 50 percent of the total myeloma protein was ever precipitated. The fact that not all of the protein was precipitated and that the amounts precipitated varied from serum to serum may be interpreted as demonstrating heterogeneity of the carbohydrate in these myeloma proteins. Other glycoproteins precipitated by concanavalin A were identified, and subsequently separated from concanavalin A by chromatography.     

Assembly of a functional immunoglobulin Fv fragment in Escherichia coli

An expression system was developed that allows the production of a completely functional antigen-binding fragment of an antibody in Escherichia coli. The variable domains of the phosphorylcholine-binding antibody McPC603 were secreted together into the periplasmic space, where protein folding as well as heterodimer association occurred correctly. Thus, the assembly pathway for the Fv fragment in E. coli is similar to that of a whole antibody in the eukaryotic cell. The Fv fragment of McPC603 was purified to homogeneity with an antigen-affinity column in a single step. The correct processing of both signal sequences was confirmed by amino-terminal protein sequencing. The functionality of the recombinant Fv fragment was demonstrated by equilibrium dialysis. These experiments showed that the affinity constant of the Fv fragment is identical to that of the native antibody McPC603, that there is one binding site for phosphorylcholine in the Fv fragment, and that there is no inactive protein in the preparation. This expression system should facilitate future protein engineering experiments on antibodies.     

Genetic factors and polypeptide chain subclasses of human immunoglobulin G detected in chimpanzee serums

The Gm and Inv genetic factors, characteristic antigens of human immunoglobulin G, were detected in chimpanzee serums. All animals tested were Gm(a+, x-, b(l)-, b(2)-, b(3)+, b(4)+). Polymorphism was demonstrated for factors Gm(c), Inv(l), and Inv(b). Three of the subclasses of heavy polypeptide chains and both types of light polypeptide chains that are present in human immunoglobulin G were identified in chimpanzee serums.     

Molecular defects in a human immunoglobulin kappa chain deficiency

The molecular basis of a human immunoglobulin deficiency characterized by the complete absence of kappa chains has been investigated by nucleotide sequence analyses of a patient's kappa constant region (C kappa) genes. Both of his C kappa genes had a single point mutation, resulting in the loss of the invariant tryptophan from one allele and of an invariant cysteine from the other allele. These results indicate that neither of the patient's C kappa alleles encoded a kappa chain that could form a stable intradomain disulfide bond, although peculiarities in the expression of kappa chains in the patient's family suggest that other factors may be involved.     

Interleukin-1 immunoreactive innervation of the human hypothalamus

Interleukin-1 (IL-1) is a cytokine that mediates the acute phase reaction. Many of the actions of IL-1 involve direct effects on the central nervous system. However, IL-1 has not previously been identified as an intrinsic component within the brain, except in glial cells. An antiserum directed against human IL-1 beta was used to stain the human brain immunohistochemically for IL-1 beta-like immunoreactive neural elements. IL-1 beta-immunoreactive fibers were found innervating the key endocrine and autonomic cell groups that control the central components of the acute phase reaction. These results indicate that IL-1 may be an intrinsic neuromodulator in central nervous system pathways that mediate various metabolic functions of the acute phase reaction, including the body temperature changes that produce the febrile response.     

Anti-inflammatory activity of immunoglobulin G resulting from Fc sialylation

Immunoglobulin G (IgG) mediates pro- and anti-inflammatory activities through the engagement of its Fc fragment (Fc) with distinct Fcg receptors (FcgRs). One class of Fc-FcgR interactions generates pro-inflammatory effects of immune complexes and cytotoxic antibodies. In contrast, therapeutic intravenous gamma globulin and its Fc fragments are anti-inflammatory. We show here that these distinct properties of the IgG Fc result from differential sialylation of the Fc core polysaccharide. IgG acquires anti-inflammatory properties upon Fc sialylation, which is reduced upon the induction of an antigen-specific immune response. This differential sialylation may provide a switch from innate anti-inflammatory activity in the steady state to generating adaptive pro-inflammatory effects upon antigenic challenge.     

山西小麦品种(系)的高分子谷蛋白亚基遗传变异分析

应用SDS -PAGE技术 ,对来源于山西的 39份小麦品种 (系 ) ,其中 2 6个为已审定的被大面积推广的高产品种 ,1 3个为新近育成的优良品系 ,分析了它们的高分子谷蛋白亚基组成。同时按照Payne等的谷蛋白亚基评分标准 ,进行了品质评分。结果表明 ,山西小麦育成品系的高分子谷蛋白亚基的组成较差 ,主要表现在 :Glu -A1位点上主要为Null或 1亚基 ,2 较少 ;在Glu -B1上为 7+8、7+9或 2 0亚基 ;而在Glu -D1上主要为 2 +1 2亚基 ,优质的5 +1 0亚基组合较少。这也可能部分解释了山西小麦的烘烤品质较差的原因。因此 ,可以加强引进具有优质谷蛋白亚基的小麦种质资源 ,综合利用SDS -PAGE等技术将它们引入小麦品种中 ,丰富小麦品种中谷蛋白亚基组成的遗传基础 ,从而进一步提高山西小麦的品质育种的水平。另外 ,其中的 5个含优质亚基、兼抗条锈病的品种 (系 )可以作为四川小麦育种的种质资源     

Detection of smoking-related covalent DNA adducts in human placenta

The presence of covalent DNA chemical addition products (adducts) in human term placentas was investigated by recently developed immunologic and 32P-postlabeling assays. DNA from placental specimens of smokers showed a small but not statistically significant increase in adduct levels when tested by antibodies to DNA modified with a benzo[a]pyrene dihydrodiol epoxide (BPDE-I), the ultimate carcinogenic derivative of benzo[a]pyrene. The postlabeling assay detected several modified nucleotides, one of which (adduct 1) strongly related to maternal smoking during pregnancy. This adduct was present in placental tissue from 16 of 17 smokers, but only 3 of 14 nonsmokers. Among smokers, levels of adduct 1 in general were only weakly related to questionnaire and biochemical measures of the intensity of smoking exposures, which suggests modulation by individual susceptibility factors. The adduct seemed to be derived from an aromatic carcinogen, but it may not result from several of the most intensely studied polycyclic aromatic hydrocarbons or aromatic amines in tobacco smoke. The data show the association of cigarette smoking with covalent damage to human DNA in vivo.     

Subclasses of human immunoglobulin a based on differences in the alpha polypeptide chains

Antiserum from goats immunized with heavy polypeptide chains from a gammaA-type myeloma globulin was absorbed with serum from patients with selective absence of immunoglobulin A (gammaA). The resulting reagents could be used for the classification of 58 gammaA-myeloma proteins into two distinct antigenic types, respectively called subclasses He and Le. These differences were shown to be related to the heavy (alpha) polypeptide chains and independent of the integrity of interchain disulfide bridges. The gammaA-immunoglobulin from normal serum appears to consist, for the most part, of molecules with Le subclass specificity.     

Antigenic heterogeneity of human immunoglobulin A proteins

Two types of human IgA myeloma proteins were distinguished by immunochemical tests. Seven of 51 IgA-myeloma proteins contained an an tigenic determinant that was not de tected in the other 44 proteins. The distinctive antigenic site was not dem onstrated on either the heavy or light polypeptide chains.     

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.     

Structural heterogeneity and functional domains of murine immunoglobulin G Fc receptors

Binding of antibodies to effector cells by way of receptors to their constant regions (Fc receptors) is central to the pathway that leads to clearance of antigens by the immune system. The structure and function of this important class of receptors on immune cells is addressed through the molecular characterization of Fc receptors (FcR) specific for the murine immunoglobulin G isotype. Structural diversity is encoded by two genes that by alternative splicing result in expression of molecules with highly conserved extracellular domains and different transmembrane and intracytoplasmic domains. The proteins encoded by these genes are members of the immunoglobulin supergene family, most homologous to the major histocompatibility complex molecule E beta. Functional reconstitution of ligand binding by transfection of individual FcR genes demonstrates that the requirements for ligand binding are encoded in a single gene. These studies demonstrate the molecular basis for the functional heterogeneity of FcR's, accounting for the possible transduction of different signals in response to a single ligand.     

用CODEHOP法设计简并引物克隆草鱼多聚免疫球蛋白受体基因片段

为克隆草鱼Ctenopharyngodon idellus多聚免疫球蛋白受体p IgR基因,本研究中借助于NCBI、Blast等数据库及Primer Premier 5.0、DNAMAN等生物软件,利用CODEHOP法设计了简并引物,并对克隆基因进行同源性比较和系统发生分析。结果表明:用CODEHOP法设计的简并引物特异性强,试验成功率高;草鱼p IgR基因属于整个脊椎动物的p IgR基因群,与鲤Cyprinus carpio同源性最高,为84%。     

Complete amino acid sequence of the Mu heavy chain of a human IgM immunoglobulin

The amino acid sequence of the micro, chain of a human IgM immunoglobulin, including the location of all disulfide bridges and oligosaccharides, has been determined. The homology of the constant regions of immunoglobulin micro, gamma, alpha, and epsilon heavy chains reveals evolutionary relationships and suggests that two genes code for each heavy chain.     

人胎盘TRAIL基因的cDNA克隆及序列测定

根据GeneBank(U37518)中TRAIL(肿瘤坏死因子相关的凋亡诱导配体)的cDNA序列,设计扩增引物。采用RT-PCR从人胎盘中扩增出TRAIL基因的全长cDNA。产物纯化后连至pGEM-TEasy载体,转化大肠杆菌DH5α。筛选阳性克隆菌,酶切鉴定并进行序列测定。结果表明,本试验成功地克隆了TRAIL基因的1039bp全长cDNA。     

野生大麦与青稞高分子量谷蛋白亚基遗传变异研究

通过SDS-PAGE方法对33份青稞I组和5份野生大麦H组染色体编码的高分子量谷蛋白亚基(HMW-GS)的多态性进行了研究。结果表明I组和H组染色体编码的HMW-GS亚基之间存在带型差异,I组高分子量谷蛋白亚基存在两种带型,一种接近7亚基上部,一种接近7亚基下部,H组内部只有一种带型,靠近10亚基。因此,要改进青稞的面筋品质现状,应在青稞中引入新的优质HMW-GS亚基的变异类型。