堤坝砂土地基液化的数值模拟

基于足立－岗循环弹塑性模型和固液两相介质耦合的有效应力反应分析方法,数值模拟分析了模型试验中的堤坝及其砂土地基,揭示了幅值为0.1g和0.2g正弦波动荷载下提坝的动力反应过程,并与振动模型试验的结果进行了比较分析。结果表明,该反应分析方法能够合理求得土体中孔隙水压力,有效应力,加速度变化过程以及堤坝的沉降变形。     

亮氨酸拉链结构蛋白基因表达载体选择

以ZG1( )、ZG1(-)、ZG2( )、ZG2(-)、ZG3( )、ZG3(-)寡聚核苷酸片段为材料，合成了含有GCN4亮氨酸拉链蛋白基区结合DNA必需的35个氨基酸的折叠片段，将此片段分别克隆到pET3b质粒和pBLZ质粒中．酶切后用2％琼脂糖电泳检测证明两者克隆成功．将这2种重组质粒分别转化到E.coli DH5a中．发现pET3b重组体在E．coli DH5a中表达成功．而pBLZ质粒重组体在E．coli DH5a中不能成功表达；从转化子中分离得到重组质粒pET3b,酶切和序到分析都证明插入序列为合成的亮氨酸拉链蛋白基因．     

b-nucleic acid,and the initial step of deoxyribonucleic acid-degradation by deoxyribonuclease I

Zusammenfassung Feulgen fand, dass die Degradation der Desoxyribonukleinsäure durch Pankreatin keine Mononucleotide bildete, jedoch auf der Stufe der Oligonucleotide (b-Nukleinsäure) blieb. In dieser Mitteilung wird die b-Säure mit dem ersten Degradationsprodukt identifiziert, welches aus Nukleinsäure unter Einwirkung von DNase 1 gebildet wird, und der Verlauf der Nukleinsäure-Degradation wird ausführlich verfolgt.     

The course of depolymerization of DNA by DNase I

Zusammenfassung Es wird beobachtet, dass während der Depolymerisation von DNA mit DN-ase I zur kleinmolekularen DNA (b-Nukleinsäure), ein bemerkenswertes Zwischenprodukt mit physico-chemischen Eigenschaften der b-Nukleinsäure mit doppelter Helix auftritt.     

Frequent somatic mutations in PTEN and TP53 are mutually exclusive in the stroma of breast carcinomas

We have recently shown that loss of heterozygosity of specific markers, including those at 10q23, 17p13-p15 and 16q24, can occur in the stromal and epithelial compartments of primary invasive breast carcinomas. Here, we demonstrate high frequencies of somatic mutations in TP53 (encoding tumor protein p53) and PTEN (encoding phosphate and tensin homolog) in breast neoplastic epithelium and stroma. Mutations in TP53 and PTEN are mutually exclusive in either compartment. In contrast, mutations in WFDC1 (16q24, encoding WAP four-disulfide core domain 1) occur with low frequency in the stroma.     

Molecular cloning and sequencing of a human hepatitis delta (delta) virus RNA

Human hepatitis delta (delta) virus (HDV) is a form of defective virus, which infects humans only in the presence of a co-infecting hepatitis B virus (HBV). HDV superinfection in a chronic HBV carrier often results in severe chronic hepatitis and cirrhosis, whereas acute HDV and HBV co-infection is frequently associated with fulminant hepatitis. HDV consists of a 36-nm particle, which contains an envelope with HBV surface antigen, and a nucleocapsid containing the hepatitis delta-antigen (HDAg) and an RNA genome of 1.75 kilobases (kb). Recently, the genomic RNA from an HDV serially passaged in chimpanzees has been cloned and sequenced in a study which showed that the HDV RNA is a single-stranded circular molecule with properties similar to those of viroid or virusoid. However, it is not known whether serial passages in chimpanzees had altered the properties of human HDV. Here we report the cloning and sequencing of an HDV RNA isolated directly from a patient with acute delta-hepatitis. The sequence showed considerable divergence (11%) from that of the chimpanzee-adapted HDV. Five open reading frames (ORFs) of more than 100 amino acids in both genomic and anti-genomic sense were found. The largest ORF in antigenomic sense, which can code for 214 amino acids, may correspond to the HDAg.     

A rat mutant unable to synthesize vitamin C

A colony of Wistar rats with a hereditary defect in L-ascorbic acid-synthesizing ability was established. This rat, like primates and guinea pigs, lacks L-gulonolactone oxidase (EC 1.1.3.8) which catalyzes the last step of L-ascorbic acid biosynthesis. When L-ascorbic acid was added to their drinking water, the rats grew almost normally and were fertile. These mutant rats should be useful not only for nutritional and pharmacological studies on vitamin C, but also for genetic studies on the lack of this enzyme.     

基于离子注入技术的GaMnN室温铁磁半导体制备及其表征

通过离子注入技术制备出GaMnN三元磁性半导体材料．Raman光谱，x射线衍射和光致发光谱(PL)揭示了Mn在材料中的晶体结构与电子结构．这些基本表征结果表明注入的Mn占据了晶格位置，且多数形成了GaMnN三元相．超导量子干涉仪的测量结果表明合成的材料在室温下仍有铁磁性．磁化强度随温度的变化曲线表明材料中存在着不同的铁磁机制．     

Structure of the DNA deaminase domain of the HIV-1 restriction factor APOBEC3G

The human APOBEC3G (apolipoprotein B messenger-RNA-editing enzyme, catalytic polypeptide-like 3G) protein is a single-strand DNA deaminase that inhibits the replication of human immunodeficiency virus-1 (HIV-1), other retroviruses and retrotransposons. APOBEC3G anti-viral activity is circumvented by most retroelements, such as through degradation by HIV-1 Vif. APOBEC3G is a member of a family of polynucleotide cytosine deaminases, several of which also target distinct physiological substrates. For instance, APOBEC1 edits APOB mRNA and AID deaminates antibody gene DNA. Although structures of other family members exist, none of these proteins has elicited polynucleotide cytosine deaminase or anti-viral activity. Here we report a solution structure of the human APOBEC3G catalytic domain. Five alpha-helices, including two that form the zinc-coordinating active site, are arranged over a hydrophobic platform consisting of five beta-strands. NMR DNA titration experiments, computational modelling, phylogenetic conservation and Escherichia coli-based activity assays combine to suggest a DNA-binding model in which a brim of positively charged residues positions the target cytosine for catalysis. The structure of the APOBEC3G catalytic domain will help us to understand functions of other family members and interactions that occur with pathogenic proteins such as HIV-1 Vif.