Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PHOSPHOTUNGSTIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,297 records · Page 72Linked to original sources
PubMed1997

Cell surface structures of Actinomyces israelii.

Actinomyces israelii is the most common cause of human actinomycosis, a chronic granulomatous infection. Periapical actinomycosis involving A. israelii has been identified as an important cause of failure of conventional endodontic treatment. Structures on the bacterial cell surface have been implicated in the pathogenicity of Actinomyces. In this study the ultrastructure of A. israelii was investigated by electron microscopy. Negatively stained preparations revealed the presence of hairlike fimbriae protruding through a thick surface coat on some species, whilst thin sectioning disclosed a Gram-positive cell wall surrounded by a fuzzy outer coat. These structures may be important for the pathogenicity of A. israelii.

Actinomyces↗
PubMed1970

Spherical protein shell formation from an 11S subunit of bacteriophage f2.

An 11S protein component obtained from specific dissociation of bacteriophage f(2) underwent a change in the state of association when dialyzed to pH 4. At low temperatures a dissociation to 5.5S subunits was observed, while at 24 degrees to 34 degrees C a 37S particle was formed. The latter particles have properties which closely resemble those expected for the RNA-free viral capsid.

Coliphages↗
PubMed1971

Cholestasis: lamellar structure of the abnormal human serum lipoprotein.

An abnormal lipoprotein was visualized directly in serum by electron microscopy of preparations negatively stained with potassium phosphotungstate. It appears as a unique disk-shaped particle with major axis measuring 400 to 600 angstroms and minor axis measuring about 100 angstroms. Chemical analysis, viscosity measurements, and x-ray diffraction analysis of purified preparations indicate that the particle, consisting of a one-to-one molar mixture of cholesterol and choline phosphatides associated with a small amount of protein, is a flattened vesicle, the wall of which is a continuous lipid bilayer.

Blood Protein Disorders↗
PubMed1971

Virus-like particles in Cephalosporium acremonium.

Cephalosporium acremonium cultures were studied for the presence of virus-like particles. Relatively few particles were found in the preparations, indicating that the number of particles present in these cells may be much lower than in Penicillium species.

Acremonium↗
PubMed1974

Morphology of the bacteriophages of lactic streptococci.

Electron microscope studies have been made of a number of phages of lactic streptococci, seven of which were phages of Streptococcus lactis C10. Two of the phages are thought to be identical; five have been classified by the method of Tikhonenko as belonging to group IV (phages with noncontractile tails) with type III tail plates; one belongs to group V (phages with tails possessing a contractile sheath). Both prolate polyhedral heads and isometric polyhedral heads are represented among the group IV phages. The phage drc3 of S. diacetilactis DRC3 has been shown to have similar structure to the group IV phages of S. lactis C10 with prolate polyhedral heads. The phages ml1, hp, c11, and z8 of the S. cremoris strains ML1, HP, C11, and Z8, respectively, were shown to belong to the group IV phages with type III tail plates by the method of Tikhonenko. All had octahedral heads and tended to be larger than most of the other phages studied.

Bacteriophages↗
PubMed1974

Serotyping of adenoviruses using immune electron microscopy.

Immune electron microscopy may be used to determine the type specificity of several common human adenoviruses. The method described utilized equine antisera and was used to serotype adenoviruses within hours after typical cytopathic effect was observed in tissue culture. Adenovirus types 1, 2, 3, 5, 7a, 8, and 11 were isolated from clinical specimens and serotyped by serum neutralization and immune electron microscopy. Five of the seven types were identified consistently and identically by the two methods. Types 7a and 11 were indistinguishable by immune electron microscopy.

Adenoviridae↗
PubMed1974

Ultrastucture of the surface of Rickettsia prowazeki and Rickettsia akari.

Negative-contrast electron microscopy revealed that the outer layer of the envelope of rickettsiae is composed of a matrix of tetragonally arranged subunits. The layer projects approximately 7 nm from the cell wall. It is suggested that this outer layer is analogous to the structure considered capsule-like in morphology.

Antigens, Bacterial↗
PubMed1975

Presence of two virus-like particles in Penicillium citrinum.

Two icosahedral virus-like particles (28 and 19 nm in diameter, respectively) have been detected in sporogenic and asporogenic segregants of a strain of Penicillium citrinum. The distribution of the two particles differed among the two segregants.

Microscopy, Electron↗
PubMed1974

Fungal viruses.

Explore the source record for details and available documents.

Basidiomycota↗
PubMed1970

Structural properties and features of parasitic Bdellovibrio bacteriovorus.

The structure of five parasitic strains of Bdellovibrio bacteriovorus was studied by electron microscope after negative staining and in shadow-case and etched freeze-fractured preparations. Special attention was paid to the cell wall and the flagellar sheath which is continuous with the wall or part of it. These structural components reveal distinct features which are induced by certain staining substances; they are exceedingly susceptible to disruption by physical treatments, and in old cells often appear impaired. In freeze-fractured cells the wall shows characteristic fracturing tendencies not known in other microorganisms. These structural properties and features are distinct to Bdellovibrio wall and flagellar sheath, the structural integrity of which is a fundamental requirement for the infectivity and survival of this organism. The anterior end of Bdellovibrio is differentiated: 6 to 12 ring-like structures (9 to 12 nm, outer diameter) are built into its wall and several fibers (7 to 10 nm wide, up to 1.5 mum long) emerge from it. Intracellular structures, which are revealed as compact oval bodies bulging from the cell border and have internal laminated organization, are characteristic of Bdellovibrio after negative staining with certain compounds. These findings on the structure of parasitic Bdellovibrio substantiate previous observations indicating the uniqueness of this organism and add criteria for the identification of this genus.

Bacteria↗
PubMed1971

Comparison of the biochemistry and rates of synthesis of mesosomal and peripheral membranes in Bacillus subtilis.

The membrane vesicle (beaded chain) portion of the mesosomes and peripheral (ghost) membrane of Bacillus subtilis were obtained by protoplast lysis and separated by differential and sucrose gradient centrifugation. Electron microscopy revealed that both fractions were satisfactorily homogeneous. Comparison of the two membrane preparations showed that they were similar with respect to total protein, total phosphorus, and lipid-soluble phosphorus content. Their protein patterns on acrylamide gel electrophreograms did not differ significantly. A possible point of distinction was revealed by a difference spectrum analysis of their cytochromes. The two preparations showed clear quantitative differences in all five of the enzyme activities assayed. Acrylamide gel electrophreograms of peripheral membrane stained for malate dehydrogenase showed four weak isozyme bands, whereas electrophreograms of mesosome membranes exhibited a single strong peak. (A survey of published data on enzymes in mesosome fractions shows a marked lack of correspondence between different species of bacteria.) Comparison of (3)H-acetate incorporation into the two membrane fractions showed that both were labeled at the same rate. Similarly, (35)SO(4) was taken up by both fractions at a comparable rate and was chased from both comparably. Lipid and protein labeling thus indicates that mesosome vesicle membrane is not a precursor or special growing point of peripheral membrane.

Acetates↗
PubMed1971

Some effects of temperature on the growth of F pili.

The effect of temperature on the production of F pili by an F(+) strain of Escherichia coli B/r was studied by electron microscopy and by a technique involving serum-blocking power. The latter method is based on the ability of F pili to adsorb F pili antibody which inhibits male-specific phage infection. The total amount of pili in a sample was estimated by serum-blocking power; the length of F pili and number per cell was determined by electron microscopy. Cell extracts prepared by sonic oscillation lacked serum-blocking power, suggesting that F pili are not present in the cytoplasm. The number of F pili per cell varied with the growth temperature, but the average length of F pili remained constant. Maximum number of pili per cell occurs between 37 and 42 C; below 37 C the number decreases, reaching zero at about 25 C. When cells are grown at 37 C, blended, and resuspended in fresh media at 25 C, they make F pili. These pili are probably assembled from a pool of subunits that were synthesized during growth at 37 C. The rates of assembly at 25 and 37 C, as judged by the rate of increase in length of F pili, are similar. When cells were grown at 25 C and shifted up to 37 C, there was a 30-min lag in pili production followed by a period of rapid outgrowth. When cells were shifted down from 37 to 20 C, outgrowth (assembly) of pili ceased, and approximately 50% of the attached pili were released in 2 min. No release was observed when cells were shifted to 0 C. This suggests that pili may be released from the cell by a mechanism that requires metabolic activity, but not the outgrowth of F pili.

Adsorption↗