The synthesis of 2-pyrimidinone nucleosides and their incorporation into oligodeoxynucleotides.

The synthesis of 1-(beta-D-2'-deoxyribosyl)-2-pyrimidinone (dK) and its 5-methyl derivative (d5) from 2'-deoxycytidine or 2'-deoxythymidine, respectively, via silver oxide oxidation of 4-hydrazinopyrimidines is described. The necessary hydrazine substituted pyrimidine nucleosides have been prepared by transamination of a protected cytidine derivative or by addition/elimination reactions to an O4-sulfonated thymidine derivative. Oxidation of the 4-hydrazino pyrimidines was complicated by a competing hydrolytic reaction which generated 2'-deoxyuridine or 2'-deoxythymidine. However, in the presence of an organic base such as triethylamine, oxidation became the predominant reaction. After suitable protection and formation of the 3'-phosphoramidite derivatives, these modified nucleosides were incorporated into seven self-complementary oligodeoxynucleotides by chemical synthesis using phosphite triester methodology. Oligodeoxynucleotides were prepared such that dA-dT and dG-dC base pairs were substituted by dA-d5 or dG-dK base pairs, respectively. Both circular dichroism spectra and thermal denaturation studies were used to characterize the modified oligodeoxynucleotides.     

酪氨酸对人离体滋养层细胞孕酮与hCG分泌的影响

本文观察三种剂量(2×10~(-5)mol/L,2×10~(-4)mol/L和2×10~(-3)mol/L)的酪氮酸对离体培养的滋养层细胞孕酮及hCG分泌的影响,并对其抑制效应的机理作了初步探讨。实验结果表明,三种剂量的酪氨酸均可抑制滋养层细胞孕酮分泌(P<0.01),但是,在孕酮分泌受酪氨酸抑制的同时,未见对hCG分泌发生影响(P>0.05),进一步观察了酪氨酸对滋养层细胞3β-羟甾脱氢酶活性的影响,结果表明,酪氨酸能显著抑制3β-羟甾脱氢酶活性,提示酪氨酸对滋养层细胞孕酮生成的抑制作用与抑制3β-羟甾脱氢酶活性有关。     

胄蝗属一新种及其染色体组型与带型分析(直翅目:蝗总科)

胄蝗属(Stolzia Willemse)的种类,已知分布于菲律宾、印度尼西亚、马来西亚及我国等地区。在我国已知仅一种,即海南胄蝗Stolzia hainanensis(Tinkham).作者等于1985年9月,在海南省尖峰岭地区采集时,采得胄蝗属一新种,我们同时对该种蝗虫的染色体组型和带型进行了观察,现记述如下。 模式标本保存于陕西师范大学生物系蝗虫研究室。 尖峰胄蝗Stolzia jianfengensis新种 雄性:体中小型,密具皱纹和刻点。头顶近平,狭三角形,突出于触角基节之前,眼间距极狭,其最狭处狭于触角基节的宽度;颜面侧观倾斜,在触角基部之间的下方略凹曲,颜     

Transposon mutagenesis and complementation of the fructokinase gene in Rhizobium leguminosarum biovar trifolii

Transposon Tn5 was used to generate a fructokinase mutation in Rhizobium leguminosarum biovar trifolii BAL. The section of the genome containing Tn5 was cloned into the EcoRI site of the vector pHC79 and isolated by direct selection on medium containing kanamycin and tetracycline. Total EcoRI digestion was used to obtain a single fragment containing Tn5 and flanking DNA sequences. The flanking DNA was used as a probe to isolate an intact fructokinase gene from a pLAFR1 cosmid clone bank of the parental strain. A cosmid showing homology to the probe was tri-parentally conjugated into the fructokinase-negative strain, complementing the mutation. The complemented mutant exhibited the wild-type phenotype, with an increase in fructokinase production presumably due to multiple copies of the gene.     

Reactivity of anti-human milk fat globule antibodies with synthetic peptides

The nucleotide sequence of partial cDNA clones coding for the core protein of a human polymorphic epithelial mucin has recently been obtained, this mucin consists of a highly conserved 60 bp tandem repeat and the amino acids commonly found are PDTRPAPGSTAPPAHGVTSA. We synthesized three peptides, 1) P1.24 containing the 20 amino acids and four amino acids (PDTR) of the adjoining repeat; 2) P1.15 consisting of the first fifteen (PDTRPAPGSTAPPAH) and P1.09 the second nine amino acids (GVTSAPDTR) of peptide P1.24. The reactivities of the synthetic peptides with mAb known to react with breast cancer (BC1, BC2, BC3, HMFG-1, 3E1.2, and RCC-1) were studied. The synthetic peptide, P1.24, corresponding to the antigenic sequence predicted from the tandem repeat reacted with antibodies BC1, BC2, and BC3 (known to react with human milk mucin and mucin expressed in breast cancer) and the antibody HMFG-1 which was used to select the cDNA clones. In addition, the epitopes recognized by BC1, BC2, and BC3 appear to be in the same region of the molecule represented by their reactions with the nine amino acids in peptide P1.09 (GVTSAPDTR). By contrast, other antibodies such as 3E1.2 which reacts only weakly with components of human milk, and RCC-1 that detects a low Mr component (95 kDa) in breast cancer, had no specific reaction with the synthetic peptides, indicating that their epitopes are distinct from those of BC1, BC2, BC3, and HMFG-1. Inasmuch as the antibodies HMFG-1, BC1, BC2, and BC3 react with the fully processed milk mucin, it is likely that some of the peptide is exposed, even in the fully glycosylated molecule. Identification of the different epitopes could lead to the development of "second generation" mAb with enhanced specificity for breast carcinoma using the appropriate synthetic peptides as immunogens.     

Binding of basic peptides to acidic lipids in membranes: effects of inserting alanine(s) between the basic residues.

We studied the binding of peptides containing five basic residues to membranes containing acidic lipids. The peptides have five arginine or lysine residues and zero, one, or two alanines between the basic groups. The vesicles were formed from mixtures of a zwitterionic lipid, phosphatidylcholine, and an acidic lipid, either phosphatidylserine or phosphatidylglycerol. Measuring the binding using equilibrium dialysis, ultrafiltration, and electrophoretic mobility techniques, we found that all peptides bind to the membranes with a sigmoidal dependence on the mole fraction of acidic lipid. The sigmoidal dependence (Hill coefficient greater than 1 or apparent cooperativity) is due to both electrostatics and reduction of dimensionality and can be described by a simple model that combines Gouy-Chapman-Stern theory with mass action formalism. The adjustable parameter in this model is the microscopic association constant k between a basic residue and an acidic lipid (1 less than k less than 10 M-1). The addition of alanine residues decreases the affinity of the peptides for the membranes; two alanines inserted between the basic residues reduces k 2-fold. Equivalently, the affinity of the peptide for the membrane decreases 10-fold, probably due to a combination of local electrostatic effects and the increased loss of entropy that may occur when the more massive alanine-containing peptides bind to the membrane. The arginine peptides bind more strongly than the lysine peptides: k for an arginine residue is 2-fold higher than for a lysine residue. Our results imply that a cluster of arginine and lysine residues with interspersed electrically neutral amino acids can bind a significant fraction of a cytoplasmic protein to the plasma membrane if the cluster contains more than five basic residues.     

内蒙古自治区螽亚目(Tettigoniodea,Orthoptera)昆虫区系及地带性分布的研究

内蒙古自治区目前共知螽亚目昆虫5科、26属、58种(表1)。其中螽斯占总种数的74.2％,蟋蟀占17.3％,其余的占7.5％。其区系组成以古北种为主体,特别是东北中国种、东西伯利亚——蒙古种和欧洲——西伯利亚种是区系组成的核心(表2)。特有种占有一定的比例(10.3％),主要分布于该区东北部的森林草原亚带和西部的荒漠带。中部地区有部分华北种的渗入。在本区东部的草原带中,螽斯亚科昆虫最为丰富;西部的荒漠带中,硕螽亚科昆虫是最突出的代表种,并有中亚种的分布(表4)。从总的种类分布来看,东北部的森林带和草原带的昆虫种类明显比西部荒漠带要丰富,中部的干草原亚带则是上述两者的过渡区域。 文中还根据螽亚目昆虫在不同植被地区的分布情况,采用Sφgrensen系数比较了各地带之间昆虫区系的相似性(表3)。用聚类分析的方法将10个植被地带或亚带划分成6个大的地带区:森林区、草原区、荒漠区、暖温型森林草原区、暖温型典型草原区和暖温型荒漠草原区(图2)。作者详细地叙述了各个地带区中昆虫区系的组成特点和分布规律。并就前人对该区昆虫区划工作提出了若干修订意见。     

Construction and packaging of pseudotype retrovirus containing human N—ras cDNA antisense sequence and its biological effects on human hepatoma cells

N-ras is one of the transforming genes in human hepatic cancer cells.It has been found that N-ras was overexpressed at the mRNA and protein level in hepatoma cells.In order to explore the biological roles of N-ras in human hepatic carcinogenesis and the potential application in control of cancer cell growth,a preudotype retrovirus containing antisense sequence of human N-ras was constructed and packaged.A recombinant retrovirus vector containing antisense or sense sequences of N-ras cDNA was constructed by pZIP-NeoSV(X)1.The pseudotype virus was packaged ang rescued by transfection and infection in PA317 and ψ 2 helper cells.It has been demonstrated that the pseudotype retrovirus containing antisense N-ras sequence did inhibit the growth of human PLC/PRF/5 hepatoma cells accompanied with inhibition of p21 expression,while the retrovirus containing sense sequence had none.The pseudotype virus had no effect on human diploid fibroblasts.     

吉林省寄螨亚科三新种(啤螨目:寄螨科)

本文记述寄螨亚科(Parasitinae)三新种。模式标本保存于吉林省地方病第一防治研究所。文内测量单位为微米,括号内为测量平均值。     

腐霉属分类性状评价及其中国的种

本文对腐霉属Pythium Pringsheim的研究历史作了简单的回顾,对该属的分类性状和系统进行了论述和评价,最后对中国已发现的55种腐霉,以检索表的方式进行了分类、检索。