Polyadenylic acid in Visna virus RNA

Visna virus 70S RNA contains long stretches of polyadenylic acid [poly(A)]. The homogeneity in length of poly(4) regions is observed in 70S RNA from visna virus and all RNA tumor viruses tested, and not with other types of RNA. By this criterion visna virus resembles RNA tumor viruses.     

Polyinosinic acid--polycytidylic acid: inhibition of DNA synthesis stimulated by isoproterenol

Polyinosinic acid * polycytidylic acid (poly I * poly C) inhibits isoproterenol-stimulated DNA synthesis in salivary glands of mice. A single intraperitoneal injection of 250 micrograms of poly I * poly C inhibits the stimulation of DNA synthesis when given 10 minutes before isoproterenol or at any time during the 20-hour lag period between the injection of isoproterenol and the subsequent DNA synthesis. The inhibition caused by poly I * poly C is not due to a generalized toxic action but seems to be exerted through a relatively selective mechanism. Polyuridylic acid and diethylaminoethyl dextran are less effective in inhibiting isoproterenol-stimulated DNA synthesis.     

Direct measurement of energy thresholds to conformational isomerization in tryptamine

Stimulated emission pumping (SEP)-hole filling spectroscopy and SEP-induced population transfer spectroscopy have been used to place narrow bounds on the energy thresholds for isomerization between individual reactant-product isomer pairs involving the seven conformational minima of tryptamine. The thresholds for isomerizing conformer A to all six other conformations divided into three groups at 750 wavenumbers (cm-1)(A-->B, F), 1000 cm-1 [A-->C(2)], and 1280 to 1320 cm-1 [A-->D, E, and C(1)]. The appearance of the first band and the absence of the band below it were used to place upper and lower bounds to the barrier heights for each process. The thresholds for A-->B and B-->A isomerizations were also combined to determine the relative energies of these two lowest energy minima. The combined data from all X-->Y isomerizations identify important isomerization pathways on the potential energy surface linking the minima.     

Synthesis of RNA-polyadenylic acid by isolated brain nuclei

Nuclei, isolated from mouse brain tissue at various stages of postnatal development and incubated under cell-free conditions, synthesized RNA molecules that were associated with polyadenylic acid [poly(A)]. The RNA synthesized by these nuclei was similar to the poly(A)-associated products described for intact eukaryotic cells. The brain nuclei synthesized a similar proportion of RNA-poly(A) in the presence either of Mg(2+) or of Mn(2+) with (NH(4))(2)So(4). The RNA from neonatal brain nuclei appeared to have a greater proportion of poly(A)-containing RNA than nuclear products obtained from more mature neural tissue.     

High-Tc Molecular-Based Magnets: Ferrimagnetic Mixed-Valence Chromium(III)-Chromium(II) Cyanides with Tc at 240 and 190 Kelvin

Molecular-based magnets with high magnetic-ordering temperatures, T(c), can be obtained by mild chemistry methods by focusing on the bimetallic and mixed-valence transition metal micro-cyanide of the Prussian blue family. A simple orbital model was used to predict the electronic structure of the metal ions required to achieve a high ordering temperature. The synthesis and magnetic properties of two compounds, [Cr(5)(CN)(12)].10H(2)O and Cs(0.75) [Cr(2.125)(CN)(6)].5H(2)O, which exhibited magnetic-ordering temperatures of 240 and 190 kelvin, respectively, are reported, together with the strategy for further work.     

On the nature of a defect in cells from individuals with ataxia-telangiectasia

The cells and tissues of patients with ataxia-telangiectasia (A-T), an inherited disease characterized by a high degree of proneness to cancer, are abnormally sensitive to ionizing radiation. Noncycling cultures of normal human and A-T fibroblasts were exposed to x-rays so that the breakage and rejoining of prematurely condensed chromosomes in the G1 phase could be compared. After a dose of 6.0 grays, both cell types had the same initial frequency of breaks and the same rate for rejoining of the breaks, but the fraction of breaks that did not rejoin was five to six times greater for the A-T cells. The results also show that progression of cells into the S phase is not a prerequisite for the increased frequency of chromosome fragments that appear in mitosis after A-T cells are irradiated in the G1 or G0 phase.     

利用微藻规模化生产EPA的最佳条件探讨

[目的]探讨微藻规模化生产二十碳五烯酸(EPA)的最佳条件。[方法]研究了温度对ENN1001A生长及EPA产量的影响,分析了液位对温度的影响,阐述了EPA的规模化生产工艺。[结果]5月和9月EPA产量最高,分别达到738和786 mg/(m2·d),全年平均产量为666 mg/(m2·d),远高于文献报道的516 g/(m2·d)。全养殖季EPA与藻液平均温度变化相一致,整体上呈先下降后上升的变化趋势。[结论]研究结果可为EPA的规模化生产奠定基础。     

徐州市三环南路土壤Cd的形态特征及影响因素研究

[目的]探讨重金属的形态分布特征,揭示重金属污染对土壤环境的影响程度,阐明重金属形态与理化性质之间的相关性。[方法]采用Tissier的同步提取法测定Cd形态含量,利用SPSS对Cd形态和理化性质作Pearson相关分析,并且对Cd形态与其主要影响因子作线性回归模拟。[结果]土壤Cd以残渣态、可交换态和碳酸盐结合态为主,三者含量之和占总量的91.40%;Cd活性态含量较高,占总量的40.09%。[结论]土壤Cd具有一定的生物有效性和潜在危害性,在土地利用时应给予关注;pH是影响土壤Cd形态含量的主要因素;此外,CEC和有机质含量对Cd形态含量也有一定程度的影响。     

The DNA-binding properties of the major regulatory protein alpha 4 of herpes simplex viruses

The transition from the expression of alpha, the first set of five herpes simplex virus genes expressed after infection, to beta and gamma genes, expressed later in infection, requires the participation of infected cell protein 4 (alpha 4), the major viral regulatory protein. The alpha 4 protein is present in complexes formed by proteins extracted from infected cells and viral DNA fragments derived from promoter domains. This report shows that the alpha 4 protein forms specific complexes with DNA fragments derived from 5' transcribed noncoding domains of late (gamma 2) genes whose expression requires viral DNA synthesis as well as functional alpha 4 protein. Some of the DNA fragments to which alpha 4 binds do not contain homologs of the previously reported DNA binding site consensus sequence, suggesting that alpha 4 may recognize and interact with more than one type of DNA binding site. The alpha 4 proteins can bind to DNA directly. A posttranslationally modified form of the alpha 4 protein designated alpha 4c differs from the alpha 4a and alpha 4b forms with respect to its affinity for DNA fragments differing in the nucleotide sequences of the binding sites.     

有机负荷对餐厨垃圾单相厌氧发酵的影响

[目的]为实现餐厨垃圾资源化利用提供依据。[方法]在中试规模条件下,以餐厨垃圾为底物,研究有机负荷对餐厨垃圾单相厌氧发酵的影响。[结果]低有机负荷[0.75~1.25 g/（L.d）]时,发酵过程的pH、氨氮、可溶性化学需氧量SCOD维持相对稳定,提高有机负荷有利于提高沼气产量和产率,而当有机负荷达到一定高度[1.50 g/（L.d）]时,发酵过程的pH下降,氨氮和SCOD含量上升,说明单相厌氧发酵工艺对餐厨垃圾的处理能力较低。餐厨垃圾中的氮含量高,发酵前应调节碳氮比。沼气中甲烷浓度都在50%~75%,不受有机负荷影响。[结论]低有机负荷[0.75~1.25 g/（L.d）]有利于餐厨垃圾单相厌氧发酵。     

罹病光肩星天牛幼虫分离菌株的16S rDNA系统发育分析(英文)

[Objective] Study on the phylogenetic analysis of the 16S rDNA and insecticidal characteristics of strain BH-1 isolated from diseased larva of Anoplophora glabripennis(Motsch.) [Method] The strain was identified by routine method and inoculated onto healthy Anoplophora glabripennis(Motsch.) for observing insecticidal effect,further 16S DNA was amplified by the specific primers for sequencing and homology analysis. [Result] The mortality of second instar of Anoplophora glabripennis(Motsch.) reached 72.7% 8 d after 1010 cfu/ml BH-1 was inoculated. The homology of 16S DNA sequences between BH-1 and Serratia marcescens accessed in GenBank reached 99.5%. Combined with the results of routine identification,BH-1 was identified as S. marcescens. [Conclusion] BH-1 could be used for biological control of Anoplophora glabripennis (Motsch.).     

Phylogenetic Analysis of the 16S rDNA of a Strain Isolated from Diseased Larva of Anoplophora glabripennis (Motsch.)

[Objective] Study on the phylogenetic analysis of the 16S rDNA and insecticidal characteristics of strain BH-1 isolated from diseased larva of Anoplophora glabripennis (Motsch.) [Method] The strain was identified by routine method and inoculated onto healthy Anoplophora glabripennis (Motsch.) for observing insecticidal effect, further 16S DNA was amplified by the specific primers for sequencing and homology analysis. [Result] The mortality of second instar of Anoplophora glabripennis(Motsch.) reached 72.7% 8 d after 1010 cfu/ml BH-1 was inoculated. The homology of 16S DNA se- quences between BH-1 and Serratia marcescens accessed in GenBank reached 99.5%. Combined with the results of routine identification, BH-1 was identi-fied as S. marcescens. [Conclusion] BH-1 could be used for biological control ofAnoplophora glabripenais (Motsch.).     

Genetic expression in the developing brain

The adult mouse brain contains complex populations of polyadenylated [poly(A)+] and nonpolyadenylated [poly(A)-] messenger RNA's (mRNA's). These mRNA's are separate sequence populations, similar in complexity, and in combination are equivalent to approximately 150,000 different mRNA sequences, of average length. Essentially all of the "adult" poly(A)+ mRNA's are present in the brain at birth. In contrast, most of the poly(A)- mRNA's are absent. Brain poly(A)- mRNA's begin to appear soon after birth, but the full adult complement is not reached until young adulthood. This suggests that these poly(A)- mRNA's specify proteins required for the biological capabilities of the brain that emerge during the course of postnatal development.     

罹病光肩星天牛幼虫分离菌株的16 S rDNA系统发育分析

BH-1是在北京大必区一片旱柳树林的光肩星天牛刻槽中分离所得的细菌,室内杀虫生测试验表明其对天牛低龄幼虫有显著的致死作用。笔者通过16S rDNA序列分析和生化指标测定,对BH-1菌株进行丁鉴定。     

白藜芦醇对动脉粥样硬化大鼠核转录因子NF-кB的影响

[目的]研究白藜芦醇（Res）对动脉粥样硬化（AS）大鼠血脂水平和NF-κB的影响,探讨抗AS的部分机制。[方法]制成AS大鼠模型后,设4个组：①模型对照组（高脂饲料）;②低剂量给药组[高脂饲料＋Res30mg/（kg·d）];③中剂量给药组[高脂饲料＋Res60mg/（kg·d）];④高剂量给药组[高脂饲料＋Res120mg/（kg·d）],连续灌胃给药5周后,测定各组血脂和血管壁组织NF-кB阳性细胞表达率。[结果]各给药组TG、TC和LDL-C均较对照组有不同程度的降低,HDL-C较对照组有所升高;免疫组化和蛋白印迹分析均显示各给药组NF-кB阳性细胞表达率明显低于对照组。[结论]白藜芦醇可调节AS大鼠血脂,降低AS大鼠主动脉壁NF-κB的表达,从而抑制AS的形成。     

无籽八月橘授粉受精的观察

通过设置2个授粉组合(无籽八月橘×无籽八月橘、无籽八月橘×有籽八月橘),对无籽八月橘自交和异交后花粉管的行为及授粉受精结果进行观察.结果表明,无籽八月橘自交和异交授粉后,花粉管在柱头、花柱和子房中均能正常生长,最后经珠孔进入珠心;对授粉受精果实种子数进行分析,其杂交果平均单果种子数在15粒以上.本研究表明无籽八月橘自交是可亲和的,其无籽的原因不是由自交不亲和所引起.     

水稻斑点叶突变体W1764的遗传分析及初步定位

从籼稻品种“明恢86”转基因后代中发现1个非T-DNA插入的叶斑突变体W1764.突变体在分蘖后期最先从基部叶叶尖处开始出现褐色斑点,随着植株的生长,斑点逐渐从叶尖扩展到整个叶片,同时从下到上叶片依次出现表型,至成熟时几乎遍布整个植株.遗传学分析表明,该突变体表型受单个隐性核基因控制.以突变体W1764和粳稻品种024...     

Transition from B to Z DNA: contribution of internal fluctuations to the configurational entropy difference

The internal motions of the double-stranded DNA oligomer (dCdG)3 (dC, deoxycytidylate; dG, deoxyguanylate) in the B and Z forms have been calculated in the harmonic approximation. A complete vibrational analysis has been made, and the resulting normal mode frequencies have been used to evaluate the vibrational entropy of B and Z DNA. The greater flexibility of the B DNA hexamer leads to an entropic stabilization relative to the stiffer Z DNA hexamer of 22 calories per mole per kelvin at 300 K. The calculated value is of the same order as that (21 to 27 calories per mole per kelvin) obtained from nuclear magnetic resonance measurements on the methylated duplexes (m5dCdG)3 and (dCdGm5dCdGdCdG). This result demonstrates the importance of internal motions, which have been neglected in earlier studies of the transition from B to Z DNA, in the stability of different nucleic acid conformers.     

Proapoptotic BAX and BAK modulate the unfolded protein response by a direct interaction with IRE1alpha

Accumulation of misfolded protein in the endoplasmic reticulum (ER) triggers an adaptive stress response-termed the unfolded protein response (UPR)-mediated by the ER transmembrane protein kinase and endoribonuclease inositol-requiring enzyme-1alpha (IRE1alpha). We investigated UPR signaling events in mice in the absence of the proapoptotic BCL-2 family members BAX and BAK [double knockout (DKO)]. DKO mice responded abnormally to tunicamycin-induced ER stress in the liver, with extensive tissue damage and decreased expression of the IRE1 substrate X-box-binding protein 1 and its target genes. ER-stressed DKO cells showed deficient IRE1alpha signaling. BAX and BAK formed a protein complex with the cytosolic domain of IRE1alpha that was essential for IRE1alpha activation. Thus, BAX and BAK function at the ER membrane to activate IRE1alpha signaling and to provide a physical link between members of the core apoptotic pathway and the UPR.     

Design and application of electron-transporting organic materials

Operating lifetime is the main problem that complicates the use of polymeric light-emitting diodes (LEDs). A class of electron transport (ET) polymers [poly(aryl acrylate) and poly(aryl ether)s] is reported in which moieties with high electron affinities are covalently attached to stable polymer backbones. Devices based on poly(p-phenylenevinylene) (PPV) prepared with these materials exhibited a 30-fold improvement in stability and, in one case, dramatically lower (10 volts versus about 30 volts) operating voltage relative to those having conventional ET layers. The current-carrying capacity of indium tin oxide-PPV-polymeric ET layer-aluminum LEDs was also increased by a factor of 30. These improvements lead to an enhancement in power efficiency of nearly an order of magnitude. Choosing polymers with high glass transition temperatures increases device lifetime.