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  • 1990-1994  (7)
  • 1960-1964  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of legiolysin (lly), responsible for haemolytic activity, colour production and fluorescence of Legionella pneumophila (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 5 (1991), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A genomic library of Legionella pneumophila, the causative agent of Legionnaires’disease in humans was constructed in Escherichia coli K12 and the recombinant clones were tested for haemolysis and other phenotypic properties. Seven clones were identified which were able to confer haemolysis of human, sheep, and canine erythrocytes but which were unable to mediate proteolytic activities or cyto-toxic effects on CHO- or Vero cells. Clones that exhibited this haemolytic property were also able to produce a brown colour and a yellow-green fluorescence activity detected on M9 plates containing tyrosine. The genetic determinant encoding these properties, termed legiolysin (lly) was mapped by Tn 1000 mutagenesis and by subcloning experiments. Southern hybridization with an lly-specific gene probe showed that this determinant is part of the genome of L. pneumophila but is not identical to a protease gene of L. pneumophila which also mediates haemolysis. Minicell analysis of lly-specific plasmids exhibited a protein of 39kDa. Polyclonal antibodies generated against a LacZ-Lly hybrid protein also recognized a 39kDa protein produced either by the recombinant legiolysin-positive E. coli K12 clones or by L. pneumophila wild-type strains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1991.tb01886.x
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  • 2
    Electronic Resource
    Electronic Resource
    Aneuploids in Oat Varietal Populations (1963)
    [s.l.] : Nature Publishing Group
    Nature 197 (1963), S. 924-925 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] As Avena sativa is a hexaploid, there is considerable duplication of genetic material and, in consequence, relatively high levels of aneuploidy are tolerated. Mono-somics and nullisomics have been reported to be viable and, to some extent, fertile1. Thus once an aneuploid has arisen in a ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/197924a0
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Intracellular survival and expression of virulence determinants of Legionella pneumophila (1991)
    Springer
    Infection 19 (1991), S. S198 
    Details
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung L. pneumophila, der Erreger der Legionärskrankheit, hat die Fähigkeit, sowohl in Makrophagen als auch in Protozoen zu leben und sich dort zu vermehren. Legionellen inhibieren die Fusion von Phagosom und Lysosom und hemmen die Ansäuerung des Phagosoms. Mit Hilfe von zwei unterschiedlichen Zellkultur-Systemen konnte gezeigt werden, daßLegionella-Stämme ihre Virulenz nach Laborpassage verlieren. Um die Mechanismen zu studieren, die für das intrazelluläre Überleben von Legionellen verantwortlich sind, haben wir eine Genbank desLegionella pneumophila-Stammes Philadelphia I inEscherichia coli K-12 angelegt. Mit Hilfe der Cosmid-Klonierungstechnik war es möglich, fünf putative Virulenzfaktoren zu klonieren. Zwei von diesen Faktoren haben hämolytische Eigenschaften und drei sind Membran-as-soziierte Proteine mit Molekulargewichten von 19, 26 und 60 kilodalton. Eines der hämolytischen Proteine, das Legiolysin, lysiert spezifisch humane Erythrozyten. Das zweite Hämolysin zeigt zusätzlich proteolytische Eigenschaften und schädigt sowohl Vero- als auch CHO-Zellen. Weitere Studien sind notwendig, um die Rolle der klonierten Proteine in der Pathogenese vonLegionella exakt zu bestimmen.
    Notes: Summary Legionella pneumophila, the causative agent of Legionnaires' disease is able to live and multiply within macrophages as well as within protozoan organisms.Legionella strains inhibit phagosome-lysosome fusion and phagosome acidification. By using two different cell culture systems, one derived from human macrophages and the other from human embryo lung fibroblastic cells, it is demonstrated thatLegionella strains lose their virulence following cultivation in the laboratory. In order to study the mechanisms involved in intracellular survival ofLegionella a genomic library of strainLegionella pneumophila Philadelphia I was established inEscherichia coli K-12. By cosmid cloning technique we were able to clone five putative virulence factors, two of which exhibit hemolytic activities and three of which represent membrane-associated proteins of 19, 26 and 60 kilodalton. One of the hemolytic proteins, termed legiolysin, represents a new toxin which specifically lyses human erythrocytes. The other hemolysin exhibits proteolytic properties in addition and is cytolytic for Vero and CHO cells. Further studies will be necessary to determine the exact role of the cloned proteins in the pathogenesis ofLegionella.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01644033
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  • 4
    Electronic Resource
    Electronic Resource
    S-fimbriae mediated adhesion ofEscherichia coli to human buccal epithelial cells is age independent (1992)
    Springer
    Infection 20 (1992), S. 273-275 
    Details
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung S-Fimbrien tragendeEscherichia coli, die Sepsis und Meningitis im Neugeborenenalter verursachen, binden an sialinsäurehaltige Glycoproteine auf der Oberfläche menschlicher Mundschleimhautzellen. Wir untersuchten die Abhängigkeit der Bindung vom Alter des Schleimhautzellenspenders. S-Fimbrien tragendeE. coli banden in vergleichbarer Zahl an Zellen von Neugeborenen, Säuglingen, älteren Kindern und Erwachsenen (23,0 ± 8,6; 23,1 ± 11,5; 24,7 ± 7,9; 28,9 ± 8,8). Die vermehrte Empfänglichkeit von Neugeborenen für Infektionen, die durch S- Fimbrien tragendeE. coli verursacht werden, kann nicht mit einer verstärkten Adhäsion an Mundschleimhautzellen erklärt werden.
    Notes: Summary S-fimbriatedEscherichia coli, which cause sepsis and meningitis in the newborn, bind to sialic acid-containing glycoprotein structures on the surface of human buccal epithelial cells. The dependence of this binding on host age was examined. S-fimbriatedE. coli adhered in comparable numbers to cells in newborns, infants, children and adults (23.0 ± 8.6; 23.1 ± 11.5; 24.7 ± 7.9; 28.9 ± 8.8). Thus, the increased susceptibility of neonates to infections caused by S-fimbriatedE. coli cannot be explained by enhanced adhesion to epithelial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01710793
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  • 5
    Electronic Resource
    Electronic Resource
    The composite shape and structure of coherent eddies in the convective boundary layer (1992)
    Springer
    Boundary layer meteorology 61 (1992), S. 213-245 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Conditional sampling is used to locate coherent structures in a large data set obtained from flights by an instrumented light aircraft in convective boundary layers over Eyre Peninsula, South Australia. The high resolution and excellent spatial coverage of the data enable a detailed study of the internal structure of surface-layer plumes and mixed-layer thermals. A compositing technique is used to construct averaged traverses through coherent structures located within aircraft data runs of different altitudes and directions. Groups of composites are combined to form horizontal and vertical cross-sections which describe the internal flow patterns and the distribution of physical variables associated with “typical” coherent structures and their environment. In addition to the well-known along-wind features of surface-layer plumes, a strong, consistent inflow/entrainment pattern is evident in the lateral direction. Air from the horizontal plane channels around the sides and then in behind the microfront present at the upstream edge. Forces set up by the driving instability in the along-wind and vertical directions are counter-balanced by organised flow in the across-wind direction. It is found that mixed-layer thermal towers have a relatively simple form, consisting primarily of large columns of warm, upward-moving turbulent air, which may occasionally be in a state of slow rotation. An analysis of possible geometrical distortions within the results is performed, leading to a comparison ofδw/δz estimated from the horizontal velocity convergence field inside plumes/thermals, with that computed from the slope of partitionedw profiles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02042933
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    An observational aircraft-based study of sea-breeze frontogenesis (1990)
    Springer
    Boundary layer meteorology 53 (1990), S. 223-265 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In the summer of 1988/89 flights were carried out in the Coorong coastal area of South Australia to investigate sea-breeze fronts. The flights yielded data sets of the structure of the fronts in the cross-frontal direction with a spatial resolution of approximately 3 m. The study is focused on the budgets of sensible and latent heat in the vicinity of the front and on frontogenesis/frontolysis processes which are closely related to budget considerations. The frontogenesis relationships and the budgets were established on a 2 km length scale by low-pass filtering of the space series. As the wind components were measured with high accuracy, all processes which determine frontogenesis could be evaluated and are displayed in x,z-cross-sections: these are the confluence, shear and diabatic effects, all of which play a role in ∂q/∂x-, ∂q/∂z-, ∂θ/∂x- as well as ∂θ/∂z-frontogenesis. A detailed analysis is given for two different states of frontal development. The presented results shed much light on the governing physical processes in the frontal region with strong emphasis on the effects of confluence-generated updrafts, on shear instabilities causing bulges and clefts in the frontal surface as well as producing the elevated frontal head, and on processes related to differential heating and moistening.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00154443
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Interactions between coherent eddies in the lower convective boundary layer (1993)
    Springer
    Boundary layer meteorology 64 (1993), S. 55-74 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The processes of interaction between the atmospheric surface and mixed layers in daytime convective conditions over land are studied using a data set obtained during flights by an instrumented aircraft. Profiles of partitioned run-averaged statistics and examples of time series plots are discussed in the light of results from a recently published study by the authors, in which the average structure and flow within coherent eddies was reconstruced using a compositing technique. This evidence is used to support a conceptual model of the mechanisms of interaction between surface-layer plumes and mixed-layer thermal columns. The divergent flow created near the surface by the downdraft arms of the large-scale mixed-layer circulation patterns, forces the development of lines of convergence in the surface layer (the so-called “thermal walls”), which channel air into the bases of the mixed-layer thermals. Plumes progressively group and merge together with height in the surface and free convection layers, and move along these convergence lines toward large “collector” plumes at the intersection points, or “hubs”. Above the “hubs” are the thermals, and air parcels originating from plumes and their environment are strongly mixed as they rise, leading to an increased difficulty of the conditional sampling method to distinguish between them. The observed influence of mixed-layer convective processes far down into the surface layer, and the form of the averaged profiles, supports recent refinements of the theory of surface-layer structure suggested in Kader and Yaglom (1990).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705662
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  • 8
    Electronic Resource
    Electronic Resource
    Breeding and evaluation of Digitaria eriantha for improved spring yield and seed production (1993)
    Springer
    Euphytica 68 (1993), S. 193-204 
    Details
    ISSN: 1573-5060
    Keywords: Digitaria eriantha ; tropical grasses ; seed production ; spring growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Digitaria eriantha is a subtropical grass which is widely sown as a pasture species in South Africa and cultivars have recently been released in Australia. The species is variable in seed production and in other agronomic attributes. This paper describes a breeding program designed to combine the seed production of cv. Premier with the high productivity in winter-spring of an almost sterile genotype. Hybrids between the two accessions were either triploid and sterile, or diploid with low fertility. The F2 to F5 generations were selected intensively for fertility and, at two contrasting sites, for spring productivity, with both maternal and paternal selection. The F6 generation was grown as replicated swards and yield in spring, and fertility, were used for selection of elite F5 plants to comprise the parents of a new cultivar (cv. Advance). In evaluation trials, spring dry matter production of Advance averaged 40% higher than that of Premier. On average, seed production of Advance was 11% lower than that of Premier and botanical fertility was consistently about half that of Premier. Experimental yields of cleaned seed of Advance were up to 138 kg/ha. In commerce, seed yields of Advance are likely to be lower than those of Premier unless higher inflorescence densities than Premier can be achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029873
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