Bacterial Strains Isolated from Different Niches Can Exhibit Different Patterns of Adhesion to Substrata

Various mechanisms have been demonstrated to be operative in bacterial adhesion to surfaces, but whether bacterial adhesion to surfaces can ever be captured in one generally valid mechanism is open to question. Although many papers in the literature make an attempt to generalize their conclusions, the majority of studies of bacterial adhesion comprise only two or fewer strains. Here we demonstrate that three strains isolated from a medical environment have a decreasing affinity for substrata with increasing surface free energy, whereas three strains from a marine environment have an increasing affinity for substrata with increasing surface free energy. Furthermore, adhesion of the marine strains related positively with substratum elasticity, but such a relation was absent in the strains from the medical environment. This study makes it clear that strains isolated from a given niche, whether medical or marine, utilize different mechanisms in adherence, which hampers the development of a generalized theory for bacterial adhesion to surfaces.     

HL-60细胞内DNA甲基化作用与RNA聚合酶活力的关系

以 S-腺苷酰 - L-甲硫氨酸 ( SAM)为诱导物 ,在 1 0 μmol/L最佳浓度下可诱导 HL- 60细胞分化达 1 6%左右 .HPLC测定结果证明 ,诱导物处理后 HL- 60细胞 DNA甲基化水平升高 .通过 3 H-UTP同位素参入法 ,测定了不同处理时间和不同浓度 SAM对 HL- 60细胞 DNA模板体外转录活性的影响 ,发现体外活力下降 .比较了不同浓度α-鹅膏蕈碱存在下 RNA聚合酶活力的变化 ,结果表明 SAM处理后细胞中不同 RNA转录产物所占份额改变     

Characterization of RNA-dependent RNA Polymerases in Healthy and Tobacco Mosaic Virus-infected Tomato Plants

Healthy tomato plants were shown to contain high levels of RNA-dependentRNA polymerase activity, mainly in a ‘soluble’ form,but also partly in a ‘ bound’ form. The ‘bound’enzyme was solublized by EDTA treatment. Both forms of enzymewere partially purified and characterized. The ion and pH optimaof the two forms were identical at all stages of purification.Both enzymes exhibited uridylyl transferase activity, whichmade up 35 per cent of total incorporation. Infection with tobacco mosaic virus (TMV) increased activityof ‘soluble’ enzyme by twofold, and of solubilized‘bound’ enzyme by less than twofold. Uridylyl transferaseactivity was also increased by infection. General propertiesof the enzymes were unaltered by infection with one exception:in the presence of TMV RNA as added template, the ‘soluble’enzyme from infected plants incorporated ³H-UTP into productswith the electrophoretic properties and RNase sensitivitiesexpected for replicative form and replicative intermediate ofTMV. ‘Soluble’ enzyme from healthy plants, and solublized‘ bound’ enzyme from either healthy or infectedplants did not synthesize these products. The ‘soluble’ and solubilized ‘bound’enzymes behaved differently on ion-exchange chromatography.Under the conditions used, ‘soluble’ enzyme didnot bind to the column, whereas solublized ‘bound’enzyme did. No differences in chromatographic behaviour werefound between enzymes from healthy or infected plants. Withboth ‘soluble’ and solublized ‘bound’enzymes, the uridylyl transferase activity co-chromatographedwith the polymerase activity. Tomato, Lycopersicon esculentum, RNA-dependent RNA polymerase, tobacco mosaic virus, tobacco mosaic virus replicase     

Purification and Characterization of DNA-dependent RNA Polymerases from Cauliflower Nuclei

DNA-dependent RNA polymerases were solubilized from nuclei of cauliflower inflorescences and purified by agarose A-1.5m, DEAE-cellulose, DEAE-Sephadex, and phosphocellulose chromatography and sucrose density gradient centrifugation. RNA polymerases I + III were separated from II by DEAE-cellulose chromatography. Subsequent chromatography on DEAE-Sephadex resolved RNA polymerase I from III. RNA polymerases I and II were further purified to high specific activity by phosphocellulose chromatography and sucrose density gradient centrifugation. RNA polymerase I was refractory to α-amanitin at 2 mg/ml. RNA polymerase II was 50% inhibited at 0.05 μg/ml, and RNA polymerase III was 50% inhibited at 1 to 2 mg/ml of α-amanitin. The enzymes were characterized with respect to divalent cation optima, ionic strength optima, and abilities to transcribe cauliflower, synthetic, and cauliflower mosaic virus DNA templates.     

Study of the Lytic Activities of Actinomycetes Isolated from Different Soils in Georgia

The lytic activities of 310 cultures from the Collection of Actinomycetes of the Institute of Biochemistry and Biotechnology, National Academy of Sciences of Georgia, were studied; 18% of these strains appeared capable of lysing yeast cell wall. The active producer of the enzyme was selected. This culture was isolated from chestnut soil in Gardabani raion (Central Georgia). Its cultural–morphological, biochemical, and antagonistic properties allowed the culture to be ascribed to the species Geodermatophilus obseurusLuedemann, 1968. The maximal lytic activity under submerged cultivation conditions, exceeding the activity of Actinomyces griseinusby twofold, was observed during the logarithmic growth phase.     

Characterization of Avian Paramyxoviruses Isolated from Feral Ducks in Northern Japan: The Presence of Three Distinct Viruses in Nature

Seventy-eight strains of avian paramyxoviruses (PMV) were isolated from cloacal and/or tracheal swabs taken from 1,342 feral ducks, comprised of spot-bill ducks, mallards, pintails, teals, falcated teals, wigeons and buffie-heads, in Wakuya-cho, Miyagi Prefecture, Japan, between 1976 and 1979. Five and a half percent of the ducks were positive for virus. Serological and structural characterization indicated that three different avian paramyxoviruses arc prevalent in the Japanese feral duck population. The first group of PMV was Newcastle disease virus (NDV), and in vivo pathogenecity tests in embryonated chicken eggs and 1-day-old chicks revealed that all the NDV strains isolated were avirulent. The second and most prevalent strain was closely related to PMV-4, duck/Hong Kong/D3/75 strain. The viruses of the third group were recovered only from pintails. They cross-reacted antigenically with PMV-3 when antisera to the PMV-3 reference strains, turkey/Wisconsin/68 and parakeet/Netherlands/449/75, were employed. However, no cross-reaction was observed when antiserum to pintail/ Wakuya/20/78, the prototype of this group, was used. The viruses of the third group also differed in viral polypeptide profile from the reference strains of PMV-3.     

Purification, Characterization, and Comparison of the DNA Polymerases from Two Primate RNA Tumor Viruses

The DNA polymerase from the Mason-Pfizer monkey virus (M-PMV), an RNA tumor virus not typical type-C or type-B, has been purified a thousand-fold over the original crude viral suspension. This purified enzyme is compared to a similarly purified DNA polymerase from the primate woolly monkey virus, a type-C virus. The two enzymes have similar template specificities but differ in their requirements for optimum activity. Both DNA polymerases have a pH optimum of 7.3 in Tris buffer. M-PMV enzyme has maximum activity with 5 mM Mg(2+) and 40 mM potassium chloride, whereas the woolly monkey virus optima are 100 mM potassium chloride with 0.8 mM Mn(2+). The apparent molecular weight of the M-PMV enzyme is approximately 110,000, whereas the woolly monkey virus polymerase is approximately 70,000. The biochemical properties of these two enzymes were also compared to a similarly purified enzyme from a type-C virus from a lower mammal (Rauscher murine leukemia virus). The results show that more similarity exists between the DNA polymerases from viruses of the same type (type-C), than between the polymerases from viruses of different types but from closely related species.     

云南五个不同地区烟草花叶病毒外壳蛋白基因的序列比较

烟草花叶病毒(Tobacco mosaic virus,TMV)是烟草花叶病毒属(Tobamovirus)中的典型成员,具有极广的寄主范围,可以侵染30个科的310多种植物,为单组份正链ssRNA病毒,TMV基因组RNA由6395个核苷酸组成,共有4个ORF,分别编码183kDa、126 kDa、30 kDa和17.5 kDa蛋白[1,2].     

云南五个不同地区烟草花叶病毒外壳蛋白基因的序列比较

Five Tobacco mosaic virus isolates, obtained from tobacco leaves showing typical symptom in Qujing, Honghe, Dali, Chuxiong and Yuxi in Yunnan province, were selected and studied from 637 TMV samples. Using a pair of primers specific for TMV-U1 strain, a specific fragment of 530bp including the TMV coat protein gene was amplified using IC-PCR. The products of PCR were cloned and sequenced. The nucleotide and amino acid sequences of the coat protein of the five isolates were found to be very similar each other and have more than 90% sequence identity with TMV-U1, TMV-B,TMV-P, TMV-FUJIAN, although minor differences existed among them. The results showed that the five isolates from Yunnan province belong toTMV-U1 strain.     

Distinct Immunomodulation of Bone Marrow-Derived Dendritic Cell Responses to Lactobacillus plantarum WCFS1 by Two Different Polysaccharides Isolated from Lactobacillus rhamnosus LOCK 0900

The structures of polysaccharides (PS) isolated from Lactobacillus rhamnosus LOCK 0900 and results from stimulation of mouse bone marrow-derived dendritic cells (BM-DC) and human embryonal kidney (HEK293) cells stably transfected with Toll-like receptors (TLR) upon exposure to these antigens were studied. L. rhamnosus LOCK 0900 produces PS that differ greatly in their structure. The polymer L900/2, with a high average molecular mass of 830 kDa, is a branched heteropolysaccharide with a unique repeating unit consisting of seven sugar residues and pyruvic acid, whereas L900/3 has a low average molecular mass of 18 kDa and contains a pentasaccharide repeating unit and phosphorus. Furthermore, we found that both described PS neither induce cytokine production and maturation of mouse BM-DC nor induce signaling through TLR2/TLR4 receptors. However, they differ profoundly in their abilities to modulate the BM-DC immune response to the well-characterized human isolate Lactobacillus plantarum WCFS1. Exposure to L900/2 enhanced interleukin-10 (IL-10) production induced by L. plantarum WCFS1, while in contrast, L900/3 enhanced the production of IL-12p70. We conclude that PS, probably due to their chemical features, are able to modulate the immune responses to third-party antigens. The ability to induce regulatory IL-10 by L900/2 opens up the possibility to use this PS in therapy of inflammatory conditions, such as inflammatory bowel disease, whereas L900/3 might be useful in reverting the antigen-dependent Th2-skewed immune responses in allergies.     

从滑桃树种壳中分离到具抗细菌活性的新木脂素

从滑桃树(Trewia nudiflora L.)的种壳中分离到5个木脂素,其中4个是新木脂素,它们的结构分别鉴定为:9'-nethyl americanol A(1)、9'-nethyl isoamericanol A(2)、9'-nethyl americanol A(3)、9'-nethyl americanol A(4)和americanin(5);并制备了化合物5的两个乙酰化产物3,4-diacetyl americanin(5a)和3,4,9-triacetyl americanin(5b).以羧苄青霉素钠盐、硫酸链霉素和利福平为阳性对照,对这7个化合物进行了抗细菌的活性检测:化合物4和5对革兰氏阳性菌金黄色葡萄球菌(Staphylococcus aureus)和革兰氏阴性菌结核分枝杆菌(Mycobacterium tubercrlosis)有明显的抑制菌作用,其中化合物4对两种菌的最低抑制浓度均为40μg/Ml,化合物5对两种菌的最低抑制浓度为100μg/Ml,但是化合物5的两个乙酰化产物在每纸片200μg的剂量下没有表现出抑菌活性.     

光质对烤烟成熟过程中碳水化合物和部分酶活性及其生长的影响

以烤烟品种‘K326’为材料,在盆栽条件下研究了不同光质对烤烟成熟过程中碳水化合物和部分酶活性及植株生长状况的影响。结果表明,与对照(中性无色膜处理)相比,红膜处理烟叶转化酶活性下降,淀粉酶活性升高,淀粉和还原糖含量增加;蓝膜处理烟叶转化酶和淀粉酶活性较低,淀粉和总糖含量较高;绿膜处理烟叶转化酶活性增强,淀粉酶活性减弱,淀粉、总糖和还原糖含量降低。植株生长状况表现为红膜处理较好,绿膜最差,对照和蓝膜处理差异不大。研究发现,红膜处理更能改善烟株的生长环境,明显调节烟叶转化酶和淀粉酶活性,促进淀粉和还原糖累积,有利于烟株更好地生长。