Device for linear gradient dehydration of specimens for electron microscopy.
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Histological Techniques↗
Biomedical subjects
R M Pfister
Publications and source records attributed to R M Pfister.
Fine structure and composition of the zoogloeal matrix surrounding Zoogloea ramigera.
The fingerlike projections, which have been considered to be characteristic of the genus Zoogloea, appear to consist of generally globular packets of cells, each surrounded by capsular matrix. The individual packets which surround Z. ramigera 115 cells appear to adhere one to another by intermeshed fibrils that measure 2 to 5 nm in diameter. The fibril polymer appears to be polyglucose that is susceptible to cellulase. The polymer resembles cellulose in several respects, with the exception that it is soluble in 1 n NaOH. Although Z. ramigera I-16-M does not possess an observable zoogloeal matrix when viewed under a light microscope, chemical data indicate that it does produce cellulase-susceptible polymer. Fibrils can be observed under the electron microscope, which are resistant to 1 n NaOH and may be cellulose. Less polymer fibrils are observed around isolate I-16-M cells than around isolate 115 cells; the inability to observe the I-16-M material as a zoogloeal matrix under light microscopy may be due to lack of sufficient amount of polymer.
Bacteria↗
Production of a pyrrole antibiotic by a marine bacterium.
Evidence is presented for the isolation and identification of bacteria able to synthesize an unusual antibiotic containing five bromine atoms per molecule. The identification and taxonomic position of these bacteria was made by use of a computer in conjunction with traditional methods. These microorganisms and closely related strains have been isolated on various occasions from tropical water in the vicinity of Puerto Rico. One bacterium, a pseudomonad, has been given the name Pseudomonas bromoutilis because of its distinctive capability. The antibiotic has been extracted, purified, and obtained in crystal form, and its structure has been determined. Although clinical tests of its properties were not encouraging, it may be of significant value and interest from an ecological standpoint.
Anti-Bacterial Agents↗
Numerical taxonomy of some bacteria isolated from antarctic and tropical seawaters.
Pfister, Robert M. (Lamont Geological Observatory, Palisades, N.Y.), and Paul R. Burkholder. Numerical taxonomy of some bacteria isolated from Antarctic and tropical seawaters. J. Bacteriol. 90:863-872. 1965.-Microorganisms from Antarctic seas and from tropical waters near Puerto Rico were examined with a series of morphological, physiological, and biochemical tests. The results of these analyses were coded on punch cards, and similarity matrices were computed with a program for an IBM 1620 computer. When the matrix was reordered by use of the single-linkage technique, and the results were plotted with four symbols for different per cent similarity ranges, nine groups of microorganisms were revealed. The data suggest that organisms occurring in different areas of the open ocean may be profitably studied with standardized computer techniques.
Antarctic Regions↗