不同蔬菜防癌抗促活性的比较研究

本研究采用EBV-EA诱导抑制实验的方法,对40种蔬菜,60个品种,共150个样品的防癌抗促作用效果进行了筛选与比较,其中具有中等以上抑制活性的样品117个,占样品总数的78％,尤其以非洲野苋菜、辣椒、羽衣甘蓝、山药芋头、苦瓜及紫苏、罗勒等一些芳香莱的效果较好。不同品种、不同植株部位、不同提取方法以及不同产地,对蔬菜的抗促活性也有影响,值得进一步研究。     

良种茶树芽叶中氨基酸研究

本文报导利用日立－ＥＧ型氨基酸自动分析仪测定的六个茶树良种芽叶中十九种氨基酸组成情况,并以此为依据对良好的品质风格进行了探讨。     

甜玉米籽实含糖量的配合力分析

采用不完全双列杂交设计研究了 6个母本3个父本甜玉米自交系籽实含糖量的配合力效应。结果表明,父母本一般配合力和特殊配合力效应均方都显著。根据各亲本的表现把亲本5033归为一般配合力高而特殊配合力方差大的最理想类型;亲本5012和5011属一般配合力高而特殊配合力方差小的类型;亲本5018、5034、5028和5024为一般配合力低,但特殊配合力方差高的类型; 亲本5023和5009属一般配合力效应和特殊配合力方差都低的类型,最缺少实用价值。     

GI双突变体GIK253RA198C的构建及其性质分析

以双引物法对葡萄糖异构酶（GI）基因进行定点突变,将突变体基因于大肠杆菌中表达,获得了GI双点突变体GIK253RA198C.研究K253R和A198C双点突变对GI的结构和性质的作用,结果表明GIK253RA198C的热稳定性明显下降,最适反应温度降低5℃.文章从结构和机制上解释了为何同是K253R突变,对SM33 GI和密苏里游动放线菌GI的热稳定性产生不同的影响,认为这是由于Lys253在两种GI结构的位置上存在微小差异,从而使引入的Arg对亚基间的相互作用产生了相反效应所引起.     

Mutations in the X-linked E1 alpha subunit of pyruvate dehydrogenase: exon skipping, insertion of duplicate sequence, and missense mutations leading to the deficiency of the pyruvate dehydrogenase complex.

Human pyruvate dehydrogenase (PDH)-complex deficiency is an inborn error of metabolism that is extremely heterogeneous in its presentation and clinical course. In a study of 14 patients (7 females and 7 males), we have found a mutation in the coding region of the E1 alpha gene in all 14 patients. Two female patients had the same 7-bp deletion at nt 927; another female patient had a 3-bp deletion at nt 931. Another female patient was found to have a deletion of exon 6 in her cDNA. Two other female patients were found to have insertions, one of 13 bp at nt 981 and one of 46 bp at nucleotide 1078. Two male patients were found to have a 4-bp insertion at nucleotide 1163. The remaining six patients all had missense mutations. A male patient and a female patient both had an A1133G mutation. The other missense mutations were C214T, C615A, and C787G (two patients). Five of these mutations are novel mutations, five have been previously reported in other patients, and two were published observations in other patients in an E1 alpha-mutation summary. In the four cases where parent DNA was available, only one mother was found to be a carrier of the same mutation as her child.     

Yersinia pseudotuberculosis in China

Thirty strains of Yersinia pseudotuberculosis were isolated from rabbits (17 strains), wild rats (9 strains) and house rats (4 strains) in China between 1990 and 1993. The biochemical properties of these isolates were identical with those of Y. pseudotuberculosis and no special characteristics were found in these strains. Serologically, serogroups 4b and 5b were identical to isolates found in Japan, and a new serogroup 1c and unclassified strains have also been detected. The existence of virulence-associated properties were different among strains. The pYV plasmid was detected from 6 strains of 30 isolates. This report documents the presence of Y. pseudotuberculosis in China, providing important epidemiological information.     

The induction of acetylcholine synthesis in primary cultures of dissociated rat sympathetic neurons : II. Developmental aspects

Dissociated sympathetic neurons from the neonatal rat, grown in cell culture in the virtual absence of other cell types, can develop many of the properties expected of differentiated adrenergic neurons including the ability to synthesize and accumulate catecholamines (CA)². However, in the presence of high concentrations of appropriately conditioned medium (CM), the cultures develop the ability to synthesize and accumulate acetylcholine (ACh); correspondingly, their ability to synthesize CA decreases. In this paper several developmental aspects of the CM effect are described. The time course of development of cultures grown with or without CM was followed using synthesis and accumulation of [³H]CA from [³H]tyrosine and production of [³H]ACh from [³H]choline as assays for adrenergic and cholinergic differentiation. The ability to produce CA or ACh developed along parallel time courses in the two sets of cultures, rising primarily during the second week in vitro and reaching a plateau during the fourth week. When CM was used as a cholinergic developmental signal, the sympathetic neurons showed a decreasing response to addition of CM as they matured adrenergically; addition of CM during the third or fourth 10 days in vitro was not as effective in inducing ACh production as addition during the first or second 10 days. Similarly, removal of CM at various times from cultures previously grown in CM showed that the cholinergic induction caused by CM was not easily reversible in older cultures. Thus, as with the adrenergic decision, the cholinergic decision becomes less reversible as the phenotype becomes fully expressed.     

Baked-Bean Waste: a Potential Substrate for Producing Fungal Amylases

Baked-bean waste was found to be a favorable substrate for amylase production by Aspergillus foetidus NRRL 337. Under optimum conditions, the yields of α-amylase (EC 3.2.1.1) and glucoamylase (EC 3.2.1.3) were 47 and 226 U, respectively, per ml of the waste fermented.     

Concanavalin A Receptors Associated with Rat Brain Synaptic Junctions Are High Mannose-Type Oligosaccharides

Abstract: Glycoproteins were isolated from a rat brain synaptic junction fraction by affinity chromatography on Concanavalin A-agarose. The isolated glycoproteins were digested with pronase and radiolabeled with ¹²⁵I-Bolton Hunter reagent, and ¹²⁵I-Concanavalin A-binding glycopeptides were isolated by chromatography on Concanavalin A-agarose. Treatment of the ¹²⁵I-Concanavalin A-binding glycopeptides with either α-mannosidase or endo-β- N -acetylglucosaminidase-C₁₁ abolished their interaction with Concanavalin A. The pronase digest was reacted with endo-β-N-acetylglucosaminidase-C₁₁ and released oligosaccharides were reduced with NaB³H₄. Following affinity chromatography on Concanavalin A-agarose, Concanavalin A-binding [³H]oligosaccharides were chromatographed on Biogel P₄. Two major oligosaccharides corresponding to standard carbohydrates containing eight and five mannose residues were identified. Treatment of these oligosaccharides with α-mannosidase converted them to smaller saccharides having a mobility on Biogel P₄ columns equal to the standard disaccharide mannose-β-1-4- N '-acetylglucosamine. These results demonstrate that the Concanavalin A receptor activity associated with CNS synaptic junctions resides in asparaginelinked oligosaccharides of the high-mannose type.     

Scanning molecular sieve chromatography of interacting protein systems. IV. The difference profile method as applied to the Gibbs-Duhem expression in the analysis of the dimer-tetramer equilibria of oxyhemoglobin A

The recently-developed large zone difference profile method in scanning molecular sieve chromatography is applied to the analysis of the Gibbs-Duhem expression in the tetramer-dimer equilibrium of human oxyhemoglobin A. The preferential binding term and solvation parameters of the Hofmeister anion phosphate are examined. Results indicate that as the concentration of phosphate ions increase, a hydrated phosphate is formed which enhances the association by perturbing the solvation layer of the hemoglobin molecules. The standard free energy change at a given Hofmeister anion activity of InA(x) = -3.2476 is 9.4 +/- 0.2 kcal mole . DeltaG degrees at InA(x) = -1.2711 is 10.90 +/- 0.05 kcal mole , suggesting that approximately 11 kcal are required to dissociate one mole of tetramer into dimer.