Differential requirement of protein tyrosine kinase and protein kinase C in the generation of IL-2-induced LAK cell and αCD3-induced CD3-AK cell responses

This study examined the role of protein tyrosine kinase (PTK) and protein kinase C (PKC) in the signal transduction pathways for lymphocyte activation through IL-2R to generate LAK cells and through TCR—CD3 to generate CD3-AK cells. Two PTK inhibitors [herbimycin A and genistein (PTK-I)] and two PKC inhibitors [calphositin C and staurosporine (PKC-I)] were used in the experiments. It was found that the primary activation pathway through IL-2R was PTK-dependent; that is, generation of both the IL-2-induced proliferative and the cytotoxic responses was completely abrogated by PTK-I and not by PKC-I. Quite different results were obtained with the αCD3-induced CD3-AK cell response. First, the αCD3-induced proliferation was only partially inhibited by PTK-I or PKC-I alone. Second, generation of CD3-AK cytotoxic response was primarily PKC-dependent; that is, only PKC-I induced significant inhibition. Genistein was found to reduce protein tyrosine phosphorylation in both LAK cells and CD3-AK cells, indicating that CD3-AK cells were also susceptible to PTK-I treatment. Further studies showed that PTK-I and not PKC-I suppressed perforin mRNA expression and N-2-benzyoxycarbonyl-l-lysine thiobeneylester esterase production in LAK cells, and the opposite was true for CD3-AK cells. These results indicate that different pathways were employed in lymphocyte activation through IL-2R and TCR—CD3. The former pathway is primarily PTK-dependent. Activation through TCR—CD3 is a more complex event. Induction of a proliferative response can employ either a PTK- or a PKC-dependent pathway, whereas induction of a cytotoxic response is primarily PKC-dependent. Furthermore, it appears that a PTK-independent pathway exists for the induction of a CD3-AK response and thus suggests that activation of the second messenger PKC may not necessarily be preceded by PTK activation.     

外消旋薄荷醇对映选择性酶促酯化中酸酐与羧酸的比较研究

利用脂肪酶在有机溶剂中催化对映选择性酯化反应对外消旋薄荷醇进行了有效的光学拆分。对分别使用酸酐和相应的游离羧酸作酰基给体时的反应性能进行了比较。发现酸酐的反应性远高于对应的游离羧酸,但在酶的催化作用下酸酐易水解成为游离羧酸;在微水系统中使用过高浓度的酸酐会导致酶缺水而失活,同时会促进手性醇的非选择性酯化,从而降低产物的光学纯度。然而,在连续流加丙酸酐的半批式反应系统中,所有这些缺点均可有效地克服。与使用游离丙酸的批式反应系统相比,ｄｌ-薄荷醇的反应时间缩短了一半,酶的稳定性大幅度提高,而产物ｌ薄荷醇酯的光学纯度不相上下（＞９８％ｅ）。     

腺苷酸激酶基因在大肠杆菌中的可溶性高表达

报道了鸡肌腺苷酸激酶基因的克隆和在温控启动子P_RP_L调控下在大肠杆菌中的可溶性高效表达.SDS-PAGE分析表明,鸡肌腺苷酸激酶的含量可占大肠杆菌细胞总蛋白含量的38％.利用Johnson等的干冰/乙醇-冰水浴反复冻融法,可将此重组蛋白进行富集,纯度可达85％以上.鸡肌腺苷酸激酶可与抗兔肌腺苷酸激酶单克隆抗体产生强的交叉反应.     

Enzyme-linked immunosorbent assay (ELISA) using a glycolipid antigen for the serodiagnosis of melioidosis

Abstract The serodiagnosis of melioidosis is commonly performed with tests using protein or polysaccharide as antigen. However, due to the low sensitivity, specificity and difficulty in the preparation of the antigens, more simple, precise and reproducible diagnostic tests were required. A purified glycolipid antigen (GL) which is a specific lipid component of Burkholderia pseudomallei has been used in an ELISA. With this antigen, specific immunoglobulin G (IgG) was detected in 49 out of 50 melioidosis sera. IgG was also detected in 2 out of 185 (Japanese) and 16 out of 181 (Vietnamese) control sera. Thus, the sensitivity was 98.0%, and specificity was 98.9% and 91.1% in the Japanese and Vietnamese sera, respectively. When the ELISA and indirect haemagglutination (IHA) tests were combined, a sensitivity of 100% and specificity of 97.8% were achieved. The advantages of the glycolipid antigen are ease of preparation, stability, high sensitivity and specificity.     

13C-NMR of double and triple bond carbon atoms of unsaturated fatty acid methyl esters

The carbon magnetic resonance spectra of many fatty acid methyl esters with cis and trans double bonds and triple bonds at various positions and in many different combinations have been investigated.The influence of the ester group on double and triple bonds in the fatty acid chain depends strongly on the positions of these bonds. For a given position the influence is constant, even if one or more other double or triple bonds are present.Together with the evaluated chemical shift parameters for the effects of double and triple bonds on each other, complete assignments are possible and spectra of various types of unsaturated esters can be predicted with high accuracy (±0.1 ppm).     

Production of Glucose Isomerase by Streptomyces flavogriseus

A microorganism that produces glucose isomerase was isolated from soil and identified as a strain of Streptomyces flavogriseus. The organism produced a large quantity of glucose isomerase when grown on straw hemicellulose, xylan, xylose, and H₂SO₄ hydrolysate of ryegrass straw. The organism produced glucose isomerase both intra- and extra-cellularly. The highest level of intracellular glucose isomerase (3.5 U/ml) was obtained in about 36 h by a culture grown on straw hemicellulose; the extracellular enzyme (1.5 U/ml) appeared in cultures grown for about 72 h. About equal levels of enzyme were produced in cultures grown on straw hemicellulose, xylan, xylose, and H₂SO₄ hydrolysate of straw, but production of the enzyme was drastically reduced when the organism was grown on other carbon sources. As a nitrogen source, corn steep liquor produced the best results. Soy flour extract, yeast extract, and various peptones also were adequate substrates for glucose isomerase production. Addition of Mg²⁺, Mn²⁺, or Fe²⁺ to the growth medium significantly enhanced enzyme production. The organism, however, did not require Co²⁺, which is commonly required by microorganisms used in the production of glucose isomerase.     

Some cellular immune reactions in infants. MIF,E-rosette formation and changes in nucleolar morphology

The cellular immune response (MIF, E-rosette formation and changes in nucleolar morphology of lymphocytes) was followed as related to age and antigenic stimulation. MIF in healthy infants increased from the 2nd to the 12th week of life as compared with the first week, probably due to BCG vaccination. The total and active E-rosette formation did not change during the whole period of investigation. Ring-shaped nucleoli increased gradually from the second week of life. Active nucleoli increased up to the 4th week,i.e. after BCG vaccination and then slowly decreased. Micronucleoli being high in the first week, decreased during 24 weeks of life. After artificial colonization of the intestine the production of MIF was slightly lower in colonized infants than in controls from the 2nd to the 12th week. The other parameters followed were not influenced by colonization.     

大刍草稀有等位基因促进玉米密植高产

密植是提高作物单位面积产量、促进粮食增产的重要途径之一。叶夹角是影响玉米(Zea mays)密植的关键因子。中国农业大学田丰课题组最近克隆了2个调控玉米叶夹角的数量性状位点(QTL)——UPA1和UPA2, 揭示了这2个位点的功能基因(brd1和ZmRAVL1)通过油菜素内酯(BR)信号通路调控叶夹角。UPA2位于ZmRAVL1上游9.5 kb, 可与DRL1蛋白结合。另一个影响玉米叶夹角的蛋白LG1可以激活ZmRAVL1的表达; DRL1蛋白与LG1蛋白直接互作抑制LG1对ZmRAVL1的激活表达。玉米祖先种大刍草(teosinte)的UPA2位点序列与DRL1蛋白结合能力更强, 导致大刍草ZmRAVL1的表达受到更强的抑制, 下调表达的ZmRAVL1进一步使下游基因brd1的表达下调, 进而降低叶环区的内源BR水平, 导致叶夹角变小。将大刍草的UPA2等位基因导入到玉米中或对玉米中ZmRAVL1进行基因编辑, 在密植条件下均可显著提高玉米产量。上述发现为高产玉米品种的分子育种改良提供了重要理论基础和基因资源。