Microorganism Capable of Decomposing N-Acetylglucosaminyl Ribitol Teichoic Acid of Staphylococcus aureus

Enzyme(s) capable of decomposing N-acetylglucosaminyl ribitol teichoic acid prepared from the cell wall of Staphylococcus aureus FDA 209 P was obtained from the culture supernatant of a gram-negative, rod-shaped, spore-forming soil bacterium. Properties of the bacterium were very similar to those of Bacillus circulans.     

Erythrocyte Sensitization by Blood Group-Specific Bacterial Antigens

Human and chicken erythrocytes are readily coated in vitro by blood group active protein-lipopolysaccharides and lipopolysaccharides from E. coli O₈₆ and E. coli O₁₂₈. Serum albumin, α₂- and β-lipoproteins inhibit this sensitization. Blood group B specific agglutination of erythrocytes with B or B-like antigens was obtained with antibodies purified by adsorption on and elution from B erythrocytes. Anti-blood group B and E. coli O₈₆-specific antibodies could be eluted from E. coli O₈₆-coated O erythrocytes. Eel anti-H(O) serum agglutinated O erythrocytes and only those A₁B red cells which were coated with blood group H(O) active E. coli products. Blood group active substances specifically inhibited agglutination of lipopolysaccharide-coated erythrocytes by anti-B and anti-H(O) agglutinins. Demonstrable amounts of lipopolysaccharide could only be removed from coated erythrocytes by washing them at elevated temperatures (58°C) in physiological solutions. Red cell sensitization with B active E. coli O₈₆ substances was achieved in vivo in a minority of severely diseased infants and in germ-free and ordinary chicks which were in tourniquet shock after treatment with cathartics. Therefore, a possible mode by which erythrocytes of patients with severe intestinal disorders acquire antigens is the fixation of bacterial substances to their surfaces, if there are not enough of the normally interfering plasma factors present.     

Major Group-Specific Protein of Rat Type C Viruses

The major internal protein of a rat type C virus pseudotype of murine sarcoma virus, MSV(RaLV), was purified by isoelectric focusing (pI = 8.6) and used to prepare antibody in guinea pigs. The protein was identified by its reaction with antisera reactive with the mammalian type C virus group-specific (gs) antigenic determinant, gs-3. The guinea pig antisera mainly contained species-specific (gs-1) antibody for reactions in gel diffusion with other type C viruses were limited to those of rat origin, whereas in complement fixation tests heterologous reactions could be eliminated by use of appropriate antiserum concentrations without affecting homologous reactions. Guinea pig antisera against mouse, hamster, or cat gs-1 determinants did not react with MSV(RaLV) purified gs protein or with any of several other rat type C viruses.     

Modified Radioimmunoassay for Murine Sarcoma-Leukemia Virus Group-Specific Antigen

Iodination of disrupted Moloney strain murine sarcoma-leukemia virus resulted in labeled group-specific (gs) protein which was subsequently purified on an isoelectrofocusing column. This iodinated purified gs antigen, prepared from a relatively small quantity of purified virus, was used in a radioimmunoassay. A radioimmunoassay inhibition method was developed so that antibody specific for mammalian C-type gs antigen could be measured in undiluted or low dilutions of test serum without altering the known reagents of the test. The gs antigen isolated from purified Moloney strain murine sarcoma-leukemia virus has an isoelectric point (pH 5.95) which is significantly lower than that reported for other murine leukemia viruses.     

Immunochemistry of the Group-Specific Polysaccharide of Nocardia brasiliensis.

Estrada-Parra, Sergio (Escuela Nacional de Ciencias Biológicas, México, D.F., México), Abel Zamora, and L. F. Bojalil. Immunochemistry of the group-specific polysaccharide of Nocardia brasiliensis. J. Bacteriol. 90:571-574. 1965.-The group-specific polysaccharide of Nocardia brasiliensis was further purified, yielding an amorphous white material with the following characteristics: [alpha](D) (20) = + 48; nitrogen, 0.5%; phosphorus, 0.1%; and ash as sodium, 0.8%. The polymer is made of d-arabinose and d-galactose in a molar ratio of 3:1, and no other sugars were detected. Mild hydrolysis liberates mainly arabinose. The polysaccharide consumes 3.46 mumoles of periodate per mg of polymer in 15 days at 4 C (this value remains constant after 4 more days). Oxidation results in destruction of two of the arabinose, with the formation of two glycerols after borohydride reduction and hydrolysis. The polysaccharide oxidized by periodate and reduced under mild acid hydrolysis at 20 C yields glycerol and a polymer formed by galactose and arabinose (in a ratio of 1:1) which is resistant to a second oxidation. Therefore, the polysaccharide is probably formed by a main chain of glactose linked 1,3 and arabinose linked 1,2 or 1,3 or both, and nonreducing side chains of arabofuranose residues. The intact polysaccharide cross-reacts with sera from patients with active tuberculosis, and this, as well as the homologous reaction, is abolished by oxidation with periodate.     

Avian Oncornavirus Group-Specific Antigen: Detection and Quantification by Radioimmunoassay

A double-antibody competitive-inhibition radioimmunoassay for avian group-specific antigen is described. A viral protein preparation, consisting primarily of gs-1, was labeled with radioiodine. Hamster and rabbit antisera were reacted with the labeled antigen, and the resultant antibody-antigen complexes were precipitated with the appropriate antiglobulin. Standard curves based on the inhibition of binding of labeled antigen to antibody after preincubation with unlabeled antigen were prepared. These showed the lower limit of sensitivity to be 2 to 10 ng of unlabeled protein when labeled antigen of 2,000 to 5,000 counts per min per ng of specific activity was used in the assay. Extracts of avian oncornavirus-infected cells, likewise, were able to inhibit binding of labeled antigen. This technique will be very useful for the quantification of small amounts of oncornavirus group-specific protein.     

Immunoelectrophoretic Analysis of Avian Ribonucleic Acid Tumor Virus Group-Specific Antigens

Tumors induced in pigeons by inoculation with the Schmidt-Ruppin strain of Rous sarcoma virus regressed after about 6 weeks. Sera from these pigeons, taken 8 weeks after inoculation, had complement-fixing group-specific antibody titers of 1:2 to 1:256. In immunoelectrophoresis with the pigeon serum, disrupted BAI strain A (myeloblastosis) avian tumor virus showed at least five precipitin arcs. The pattern of precipitin lines was dependent in part on the means used for virus disruption, and ethyl ether and nonionic detergents appeared to be both effective and relatively mild reagents. Immunoelectrophoretic comparison of pigeon serum with serum from a tumor-bearing hamster and that from virus-inoculated rabbits yielded similar, though not identical, results.     

Group-Specific Antibodies against Zearalenone and Its Metabolites and Synthetic Analogs

Formation kinetics, specificity, and analytical potential of polyclonal antibodies raised in rabbits against BSA conjugates of zearalanone carboxymethyloxime (CMO-ZAN) and zearalenone carboxymethyloxime (CMO-ZEN) have been studied. Preparation of the conjugates involved conversion of CMO-ZAN and CMO-ZEN into activated esters or carbodiimide condensation. Two versions of a group-specific enzyme immunoassay (for zearalenone/-zearalenol and zearalanone/-zearalanol) based on the heterologous combination of solid-phase antigens are described (sensitivity, 0.01 ng/ml).     

Decomposing multilocus linkage disequilibrium

We present a mathematically precise formulation of total linkage disequilibrium between multiple loci as the deviation from probabilistic independence and provide explicit formulas for all higher-order terms of linkage disequilibrium, thereby combining J. Dausset et al.'s 1978 definition of linkage disequilibrium with H. Geiringer's 1944 approach. We recursively decompose higher-order linkage disequilibrium terms into lower-order ones. Our greatest simplification comes from defining linkage disequilibrium at a single locus as allele frequency at that locus. At each level, decomposition of linkage disequilibrium is mathematically equivalent to number theoretic compositions of positive integers; i.e., we have converted a genetic decomposition into a mathematical decomposition.     

微生物源抗菌肽研究概况

抗菌肽是广泛存在于生物体内的一种小分子多肽,具有分子量小、高效、稳定、作用机制独特和不易产生耐药性等特点,对细菌、真菌、寄生虫、病毒以及肿瘤细胞均有抑制作用。介绍了微生物来源,尤其是细菌源抗菌肽的结构特点、生物活性、作用机制及其在感染性疾病中的应用情况。     

Expression of Endogenous RNA C-Type Virus Group-Specific Antigens in Mammalian Cells

Highly sensitive and specific radioimmunoassays are described for quantitation of the intraspecies determinants of several mammalian C-type viral group-specific (gs) antigens. An interspecies (gs-3) immunoassay has been developed which has both the broad reactivity and great sensitivity necessary for detection of C-type viruses where intraspecies gs assays are not available. By using these immunoassays, the expression of endogenous virus-specified gs antigens in mammalian cells of different species has been studied. Whereas mouse gs antigen was clearly detectable in tissue culture cells of several mouse strains, the respective gs antigens of rat, cat, Chinese hamster, woolly monkey, and gibbon ape were not detectable in cells of those species, using assays of comparable sensitivity. Thus, differences exist in the level of endogenous virus expression in cells of different mammalian species.     

Group-Specific Multiplex PCR Detection Systems for the Identification of Flying Insect Prey

The applicability of species-specific primers to study feeding interactions is restricted to those ecosystems where the targeted prey species occur. Therefore, group-specific primer pairs, targeting higher taxonomic levels, are often desired to investigate interactions in a range of habitats that do not share the same species but the same groups of prey. Such primers are also valuable to study the diet of generalist predators when next generation sequencing approaches cannot be applied beneficially. Moreover, due to the large range of prey consumed by generalists, it is impossible to investigate the breadth of their diet with species-specific primers, even if multiplexing them. However, only few group-specific primers are available to date and important groups of prey such as flying insects have rarely been targeted. Our aim was to fill this gap and develop group-specific primers suitable to detect and identify the DNA of common taxa of flying insects. The primers were combined in two multiplex PCR systems, which allow a time- and cost-effective screening of samples for DNA of the dipteran subsection Calyptratae (including Anthomyiidae, Calliphoridae, Muscidae), other common dipteran families (Phoridae, Syrphidae, Bibionidae, Chironomidae, Sciaridae, Tipulidae), three orders of flying insects (Hymenoptera, Lepidoptera, Plecoptera) and coniferous aphids within the genus Cinara. The two PCR assays were highly specific and sensitive and their suitability to detect prey was confirmed by testing field-collected dietary samples from arthropods and vertebrates. The PCR assays presented here allow targeting prey at higher taxonomic levels such as family or order and therefore improve our ability to assess (trophic) interactions with flying insects in terrestrial and aquatic habitats.     

Origin and Structure of the Group-Specific, Complement-Fixing Antigen of Rickettsia rickettsii

Rickettsia rickettsii was treated with ether and examined by negative-contrast electron microscopy. Group-specific complement-fixing antigen was seen to be originating from the cell wall. The antigen was composed predominately of round particles 10 to 60 nm in diameter. Intact R. rickettsii and antigen from ether-treated organisms were purified by density gradient centrifugation and analyzed by polyacrylamide gel electrophoresis. The whole rickettsial cell was composed of a minimum of 30 proteins which ranged in molecular weight from about 23,000 to 155,000. The "soluble" antigen contained nine proteins ranging in molecular weight from about 28,000 to 150,000.     

草酸分解细菌U-1的鉴定及其分解草酸的生物学测定

从油菜菌核病常年发病较轻的油菜根围土中分离得到1株草酸分解菌U-1。通过对这株菌株的菌落形态观察、革兰染色镜检及生理生化反应的检测,初步确定菌株为节杆菌属(Arthrobacter)的细菌。以水稻出苗实验作为体系检测U-1对草酸解毒的生物学反应,研究结果表明,U-1可以显著解除草酸对水稻出苗的抑制作用。     

Creatinine Decomposing Enzymes in Pseudomonas putida

Creatinine was found to be rapidly decomposed by several strains belonging to Pseudomonas, one of which was assigned to P. putida. Analyses of the metabolites indicated that creatinine was converted to sarcosine via creatine and further to glycine. The enzymes involving in a metabolic pathway of creatinine, i.e. creatinine amidohydrolase (EC 3.5.2), creatine amidinohydrolase (EC 3.5.3.3) and sarcosine dehydrogenase (EC 1.5.99.1), were found to be inducibly formed and accumulated in the bacterial cells. A novel assay method for sarcosine dehydrogenase activity was also described.     

Decomposing protein networks into domain-domain interactions

The application of novel experimental techniques has generated large networks of protein-protein interactions. Frequently, important information on the structure and cellular function of protein-protein interactions can be gained from the domains of interacting proteins. We have designed a Cytoscape plugin that decomposes interacting proteins into their respective domains and computes a putative network of corresponding domain-domain interactions. To this end, the network graph of proteins has been extended by additional node and edge types for domain interactions, including different node and edge shapes and coloring schemes used for visualization. An additional plugin provides supplementary web links to Internet resources on domain function and structure. AVAILABILITY: Both Cytoscape plugins can be downloaded from http://www.cytoscape.org