用体外免疫法建立人—人抗流行性乙型脑炎病毒杂交瘤细胞株

利用单克隆抗体(McAb)进行病毒病的治疗是人们所关心的一个重大课题。 流行性乙型脑炎(乙脑)是一种严重威胁人民健康的急性传染病,病死率高,后遗症严重。国内外目前尚无特效疗法。陈伯权等用乙脑病毒皮下或腹腔感染3周龄小白鼠24、48小时及5天后,分别用乙脑病毒51-8McAb进行治疗,平均治愈率分别为78％、73％及22％。     

银额果蝇的B染色体研究 2.昆明群体的生活力和B染色体的关系

本文分析了钮额果蝇的生活力和B染色体的关系。结果表明,银额果蝇的B染色体在其生长和发育过程中具双重性调节作用。一方面,B染色体以单一的形式存在于单雌系核型中,即1B或2Bs,可刺激生长、发育,增强生活力。另一方面,在单雌系的细胞中存在多条B染色体,并形成核型多态性,这似乎对生长和发育又有一定的抑制作用而减弱其生活力。     

Nucleotide and deduced amino acid sequence of bovine adrenal medulla chromogranin B (secretogranin I)

1. A novel 1745-dalton pyroglutamyl peptide (BAM-1745)6 was recently isolated and characterized from bovine adrenal medulla chromaffin granules. Its amino acid sequence was found to be 93% identical to residues 580-593 of human chromogranin B (secretogranin I). 2. Based on this sequence a degenerate oligonucleotide probe was synthesized and used to identify a 2.4-kb bovine adrenal medulla chromogranin B cDNA. 3. The deduced polypeptide is 647 amino acids long and begins with a putative signal sequence of 20 residues as in the human, rat, and mouse proteins. Also conserved in the bovine protein is a tyrosine residue which may be sulfated, two N-terminal cysteines, and many paired basic amino acids which may serve as sites of posttranslational processing. The peptide BAM-1745 is flanked by paired basic amino acids and therefore is most likely a product of posttranslational processing. Bovine chromogranin B is 67, 58, and 58% identical to the human, rat, and mouse chromogranin B proteins, respectively. 4. The carboxyl terminus of bovine chromogranin B, including BAM-1745, was found to be the most conserved region of the polypeptide and may identify it as an important functional domain.     

Separation and analysis of the glycoform populations of ribonuclease B using capillary electrophoresis

The development of methods to separate, analyse and monitor changes in glycoform populations is essential if a more detailed understanding of the structure, function and processing of glycoproteins is to emerge. In this study, intact ribonuclease B was resolved by borate capillary electrophoresis into five populations according to the particular oligomnnose structure associated with each glycoform. The relative proportions of these populations are correlated with the percentages obtained indirectly by analysis of the hydrazine released oligosaccharides using Bio-Gel P-4 gel filtration, matrix assisted laser desorption mass spectrometry and high performance anion exchange chromatography. Alterations in the composition of the glycoform populations during digestion of ribonuclease B withA. saitoi (1–2)mannosidase were monitored by capillary electrophoresis (CE). Digestion of the free oligosaccharides under the same conditions, monitored by anion exchange chromatography, revealed a difference in rate, allowing some insight into the role of the protein during oligosaccharide processing. In conjunction with other methods, this novel application of CE may prove a useful addition to the techniques available for the study of glycoform populations.     

Characterization of a glucuronyltransferase: neolactotetraosylceramide glucuronyltransferase from rat brain

The properties of a rat brain glucuronyltransferase, which is presumed to be associated with the biosynthesis of the HNK-1 epitope on sulfoglucuronyl glycolipids, are described. The enzyme required divalent cations for reaction, with maximal activity at 10mm Mn²⁺, and exhibited a dual optimum at pH 4–5 and pH 6 depending upon the buffer used, with the highest activity at pH 4.5 in MES buffer. This enzyme strictly recognized the Gal1-4GlcNAc terminal structure, and was highly specific for neolacto (type 2) glycolipids as acceptor. The enzyme was localized specifically in the brain, and was barely detected in other issues, including the thymus, spleen, liver, kidney, lung, and sciatic nerve fibres. Phosphatidylinositol and phosphatidylserine increased the enzymatic reaction 4.4- and 2.3-fold, respectively, whereas phosphatidylcholine slightly decreased the rate.Abbreviations GlcA glucuronic acid - Lc-PA₁₄ lactotetraose-phenyl-C₁₄H₂₉ - nLc-PA₁₄ neolactotetraose-phenyl-C₁₄H₂₉ - nLcOse₄-Cer neolactotetraosylceramide - NP-40 Nonidet P-40 - PC phosphatidylcholine - PE phosphatidylethanolamine - PI phosphatidylinositol - PS phosphatidylserine - SGGL sulfoglucuronyl glycolipid     

Purification of the Lewis blood-group gene associated α-3/4-fucosyltransferase from human milk: an enzyme transferring fucose primarily to Type 1 and lactose-based oligosaccharide chains

A soluble Lewis blood-group gene associated -3/4-L-fucosyltransferase has been purified from human milk by a series of steps involving hydrophobic chromatography on Phenyl Sepharose 4B, ion exchange chromatography on CM-Sephadex C-50, affinity chromatography on GDP-hexanolamine Sepharose 4B and gel filtration on Sephacryl S-200. The first step separated -3-L-fucosyltransferase activity directed towardsN-acetylglucosamine in Type 2 (Gal1-4GlcNAc-R) acceptors from an -3/4-fucosyltransferase fraction acting on both Type 1 (Gal1-3GlcNAc-R) and Type 2 acceptors. Further purification of this latter fraction on CM-Sephadex and GDP-hexanolamine Sepharose gave a single peak of fucosyltransferase activity that catalysed the addition of fucose toN-acetylglucosamine in both Type 1 and Type 2 acceptors and to theO-3 position of glucose in lactose-based oligosaccharides. The enzyme preparation at this stage resembled previously described -3/4-fucosyltransferase preparations purified from human milk. However, gel filtration of this preparation on Sephacryl S-200 or Sephadex G-150 separated further amounts of -3-fucosyltransferase activity acting solely on Type 2 acceptors and left a residual -3/4-fucosyltransferase that retained strong -4 activity with the Type 1 acceptor, lacto-N-biose 1, and -3 activity with 2-fucosyllactose, but had relatively little -3 activity withN-acetyllactosamine and virtually no capacity to transfer fucose to glycoproteins withN-linked oligosaccharide chains having unsubstituted terminal Type 2 structures.     

Enzyme-linked immunosorbent assays for the measurement of blood group A and B glycosyltransferase activities

ELISA assays have been developed for (1–3)N-acetylgalactosaminyltransferase (blood group A transferase) and (1–3)galactosyltransferase (blood group B transferase) activities. In these assays, microtitre plates coated with the bovine serum albumin conjugate of a synthetic Fuc1–2Gal-R acceptor substrate are incubated with the appropriate nucleotide donor (UDP-GalNAc or UDP-Gal) and human serum as the enzyme source. The resulting trisaccharide products Fuc1–2(GalNAc1–3)Gal-R-BSA or Fuc1–2(Gal1–3)Gal-R-BSA are detected and quantified with monoclonal antibodies selected not to cross-react with the substrate structure. With less than a microliter of human serum, product formation is proportional to enzyme concentration and to time of incubation of up to 90 min.     

Regulation of ACV synthetase activity in the beta-lactam biosynthetic pathway by carbon sources and their metabolites

The activity of -l--aminoadipyl)-l-cysteinyl-d-valine catalysis. Addition of l-cysteine to fermentation media increased -lactam production in both organisms and alleviated the negative carbon source regulation by glycerol in S. clavuligerus.     

Regulation of polyphosphate metabolism in Acinetobacter strain 210A grown in carbon- and phosphate-limited continuous cultures

The response of Acinetobacter strain 210A to low phosphate concentrations was investigated in P- or C-limited chemostat cultures. The organism accumulated poly--hydroxybutyric acid under P-deprivation, at phosphate concentrations ranging from 0.1 to 0.7 mM. The amount of biomass was proportional to the phosphate concentration in the medium and no polyphosphate was formed. When shifting a culture from P- to C-limitation phosphate was accumulated as polyphosphate. No poly--hydroxybutyrate could be detected in these cells. The amount of polyphosphate in the cell showed a hysteresis. When cultures were shifted from low to high phosphate concentrations, polyphosphate reached a maximum of about 60 mg P per gram of dry weight at about 3 times excess phosphate (ca. 2.5 mM P_i). It decreased to 45 mg P per gram dry weight at approximately 5 times the phosphate needed for growth (ca. 3.5 mM P_i). In the reverse case (high to low) polyphosphate did never exceed 45 mg P per gram dry weight. The specific activities of alkaline phosphatase and the phosphate uptake system were induced at residual P_i concentrations below the detection limit (<10 M). The specific uptake rate followed also a hysteresis. The specific activities of polyphosphatase and polyphosphate: AMP phosphotransferase increased when polyphosphate formation was possible.Abbreviations HPP High polymeric polyphosphates - PHB Poly--hydroxybutyric acid - PP_n Polyphosphate - PQQ Pyrrolo-quinoline quinone - U 1 mol product formed · min^-1