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  • Chemical Engineering
  • Electron microscopy
  • LUNAR AND PLANETARY EXPLORATION
  • Polymer and Materials Science
  • Springer  (92)
  • 1985-1989  (92)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 263 (1985), S. 116-119 
    ISSN: 1435-1536
    Keywords: Electron microscopy ; staining ; morphology ; nylon-12 ; orientation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The morphology of drawn and annealed sheets of nylon-12 was investigated by transmission electron microscopy of stained sections, and the results compared with equivalent small-angle X-ray scattering (SAXS) patterns. A three-component structure was observed, consisting of crystalline (C) and amorphous (A) regions in the microfibrils and an interfibrillar component whose density was deduced to be intermediate between that of the C and A regions. The crystallite width was given satisfactorily by a Guinier analysis of the SAXS profile.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Current genetics 14 (1988), S. 163-170 
    ISSN: 1432-0983
    Keywords: Plant mtDNA ; Electron microscopy ; Restriction enzymes ; Hairpin structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Broad bean (Vicia faba) mitochondrial DNA (mtDNA) includes three circular plasmids: mt-plasmid 1 (1,704 ntp), mt-plasmid 2 (1,695 ntp) and mt-plasmid 3 (1,476 ntp). Partially replicated circular forms of these mt-plasmids have been observed in electron microscope preparations. Restriction enzymes that cleave either mt-plasmid 2 (but not mt-plasmids 1 and 3) or mt-plasmid 3 (but not mt-plasmids 1 and 2) were used to generate linear forms of partially replicated mt-plasmid 2 and mt-plasmid 3 molecules. Analyses of these linearized replicative intermediates, observed by electron microscopy, indicated that in both mt-plasmid 2 and mt-plasmid 3 replication originates at a specific location and proceeds in the same, single direction around the molecules. The replication origins of mt-plasmid 2 and mt-plasmid 3 map close to sequences that can fold into hairpin structures.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0983
    Keywords: Sugar beet ; Cytoplasmic male sterility ; Mitochondrial DNA ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitochondrial (mt) DNAs from normal (N) and male sterile (S) cytoplasms of sugar been have been isolated and investigated by electron microscopy. The results showed that mtDNA was composed of a heterogeneous population of circular molecules. Their contour lengths varied from 0.28 to 51 μm, but unlike in the case of maize, a large difference was not observed in the distribution of molecular classes greater than 1.0 μm between N and S cytoplasms of sugar beet. On the other hand, N and S cytoplasms were shown to contain their own characteristic combinations of small circular mtDNA species with lengths between 0.28 μm and 0.6 μm. Mitochondrial DNAs from various sources of male-sterile cytoplasms were analyzed by agarose gel electrophoresis to determine the extent of cytoplasmic variation. Additional low molecular weight DNA bands appeared in all male-sterile lines examined, and as a result, three distinctive banding patterns were recognized. These data are in general agreement with those based upon restriction endonuclease digestion of mt and chloroplast DNAs and the genetic analysis of fertility restoration in test crosses.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 26 (1987), S. 347-357 
    ISSN: 1432-1432
    Keywords: Ribosome structure ; Electron microscopy ; Image analysis ; Evolutionary lineages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Multivariate statistical analysis and classification techniques are powerful tools in sorting noisy electron micrographs of single particles according to their principal features, enabling one to form average images with an enhanced signal-to-noise ratio and a better reproducible resolution. We apply this methodology here to determining the characteristic views of the large (50S) ribosomal subunits from the eubacteriumEscherichia coli and the archaebacteriaMethanococcus vannielii, Sulfolobus solfataricus, andHalobacterium marismortui. Average images were obtained of the subunit in the common crown and kidney projections, but views of the particle in orientations intermediate between these two extremes were also elucidated for all species. These averages show reproducible detail of up to 2.0 nm resolution, thus enabling the visualization and interspecies comparison of many structural features as a first step toward comparing the actual three-dimensional structures. Our results disprove evolutionary lineages recently postulated on the basis of electron microscopical images of ribosomal subunits.
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  • 5
    ISSN: 1432-0983
    Keywords: Electron microscopy ; Replicative intermediates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Some physicochemical properties of the mitochondrial DNAs (mtDNA) from plants of flax, broad bean and mung bean, and from tissue culture cells of jimson weed, soybean, petunia and tobacco were determined. Circular molecules were observed in electron microscope preparations of each mtDNA. In soybean, petunia, broad bean and mung bean mtDNAs, the circular molecules had a continuous distribution of lengths (ranges between 1 to 36 kb, and 1 to 126 kb), heavily skewed toward smaller molecules. Eighty-six percent of the flax circular molecules were from 27 to 54 kb in size, and 78% of the jimson weed circular molecules were from 4 to 15 kb. Replicative forms of 1.2–1.6 kb circular molecules were observed in electron microscope preparations of broad bean mtDNA.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 142 (1985), S. 333-339 
    ISSN: 1432-072X
    Keywords: Photosynthesis ; Membrane structure ; Electron microscopy ; Photosynthetic bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The organization of photosynthetic membranes in the cytoplasm of the photosynthetic bacterium Rh. viridis has been examined by several techniques for electron microscopy. Thin sections of membrane stacks show that the regular lattice of membrane subunits reported in other studies can be observed in thin section. Tilting of sections in the electron microscope shows that the regular lattices of several membranes overlap in a way that suggests they are in register with each other. This observation can be confirmed by freeze-fracture images in which a regular arrangement of membrane lattices can be observed, each perfectly aligned. Analysis of the spacings of membrane pairs shows that the photosynthetic membranes of Rh. viridis are very closely apposed. The mean diameter of two membranes is 160A, and the average space between two such membranes is only 42A. When a recently developed atomic level model of Rh. viridis reaction center is superimposed against these spacings, each reaction center extends from the surface of its respective membrane far enough to make contact with an apposing membrane. The limited free space between membranes and regular alignment of lattices has a number of implications for how this membrane is organized to carry out the process of energy transfer.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 146 (1986), S. 267-274 
    ISSN: 1432-072X
    Keywords: Photosynthesis ; Membrane structure ; Electron microscopy ; Ectothiorhodospira ; Serial thin sectioning ; Three dimensional reconstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The three dimensional organization of the complete photosynthetic apparatus of the extremely halophilic, bacteriochlorophyll b containing Ectothiorhodospira halochloris has been elaborated by several techniques of electron microscopy. Essentially all thylakoidal sacs are disc shaped and connected to the cytoplasmic membrane by small membraneous “bridges”. In sum, the lumina of all thylakoids (intrathylakoidal space) form one common periplasmic space. Thin sections confirm a paracrystalline arrangement of the photosynthetic complexes in situ. The ontogenic development of the photosynthetic apparatus is discussed based on a structural model derived from serial thin sections.
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  • 8
    ISSN: 1432-072X
    Keywords: Acidaminococcus fermentans ; Glutamate fermentation ; Electron microscopy ; Immunocytochemistry ; Post-embedding labelling ; Antibody-gold complexes ; Protein A-gold complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have investigated the in situ location of glutaconyl-CoA decarboxylase and 2-htdroxyglutaryl-CoA dehydratase in Acidaminococcus fermentans using the antibody-gold and protein A-gold techniques carried out as a post-embedding immunoelectron microscopic procedure. Polyclonal antisera were raised in rabbits against homogeneous fractions of the enzymes. Anaerobically grown cells of A. fermentans of the late exponential growth phase were fixed with 0.2% glutaraldehyde and 0.3% formaldehyde (final concentrations) in the growth medium. Dehydration of the cells was achieved with methanol. The cells were embedded in the low temperature embedding resin Lowicryl K4M. The markers indicative for antigenic sites of the two enzymes unequivocally demonstrate that the sodium pump glutaconyl-CoA decarboxylase is located at the cell periphery being a membrane-bound enzyme as expected whereas 2-hydroxyglutaryl-CoA dehydratase is a soluble cytoplasmic enzyme.
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  • 9
    ISSN: 1432-072X
    Keywords: Bacteriolysis ; Penicillin ; Autolysis ; Cell wall ; Electron microscopy ; Staphylococcus aureus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The actual reason for the penicillin-induced bacteriolysis of staphylococci was shown to be the “punching” of one or a few minute holes into the peripheral cell wall at predictable sites. These perforations were the result of the lytic activity of novel, extraplasmatic vesicular structures, located exclusively within the bacterial wall material, which we have named “murosomes”. In untreated staphylococci the punching of holes into the peripheral wall is a normal process which follows cross wall completion and represents the first visible step of cell separation. Under penicillin, however, analogous holes are punched by the murosomes at sites of presumptive cell separation even if no sufficient cross wall material had been assembled before at this site (but had rather been deposited at other sites). Consequently, because of the internal pressure of the protoplast, lytic death is the inevitable result of this perforation of the protective peripheral wall. Hence, the real mechanism of penicillin-induced bacteriolysis in staphylococci is considered to be mainly the result of a special morphogenetic wall defect: bacteriolysis is taking place regularly when a cell separation process is no longer preceeded by sufficient cross wall assembly at the correct place. However, hypotheses which are based purely on some variations of overall biochemical processes like total wall enzyme activities or total wall synthesis are not regarded to be sufficient to explain this type of lytic death.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 142 (1985), S. 259-261 
    ISSN: 1432-072X
    Keywords: Methanogenic bacteria ; Plasmid isolation ; Alkaline lysis ; CsCl gradient ; Restriction endonuclease mapping ; Electron microscopy ; DNA homology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Of 21 recently isolated strains of methanococci, one was found to harbor a small, cryptic, low copy number plasmid. Reproducible recovery was achieved by alkaline lysis of cells pretreated with proteinase K in an osmotically stabilizing buffer. The plasmid was found to contain a singleAval site. No homology was detected between the plasmid and DNA from any of the other new strains or from five known species of methanococci.
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