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  • 1980-1984  (3)
  • Acquisition  (1)
  • Asparagine linked oligosaccharides  (1)
  • Community matrix  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 79 (1983), S. 115-119 
    ISSN: 1432-2072
    Keywords: Dopamine ; Acquisition ; Brain lesions ; 6-Hydroxydopamine ; Neonatal rat ; Operant behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In an attempt to examine the ability of brain dopamine (DA) depletion to alter learning ability in the developing rat, the rate of acquisition of a positively reinforced lever pressing response was examined in rats during days 30–45 of life following treatment with desmethylimipramine (DMI, 20 mg/kg IP) and 6-hydroxydopamine (6-OHDA, 35 μg intraventricularly) at 3 and 6 days of age, respectively. The 6-OHDA treatment produced a 40%–70% reduction of brain DA without altering growth rate, water intake, or locomotor activity. On the average, water-deprived control rats achieved the criterion for acquisition (50 reinforced lever presses/h) on a fixed-ratio 1 schedule of water reinforcement after 3.1±0.5 sessions (mean ± SEM). In contrast, nearly one-fourth of the DMI + 6-OHDA-treated rats failed to acquire the response after 16 sessions and the remaining 6-OHDA-treated rats required more than twice as long as controls for acquisition (7.8±0.7 sessions). These results suggest that brain DA depletion in neonatal life can impair the acquisition of an operant response during development and that this deficit is independent of changes in growth rate or locomotor activity.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2048
    Keywords: Asparagine linked oligosaccharides ; Cotyledon ; Glycoprotein ; Lectin ; Phaseolus (lectin structure) ; Phytohemagglutinin (structure)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phytohemagglutinin, the major lectin in the seeds of the common bean Phaseolus vulgaris L., was isolated by affinity chromatography from cotyledons of nearly mature seeds and from developing cotyledons labeled with [3H]glucosamine, [3H]mannose or [3H]fucose. The protein was subjected to exhaustive proteolysis and the carbohydrate composition of the resulting glycopeptides examined. Two classes of oligosaccharide side-chains were found. The sidechains of the first class are of the high-mannose type, containing two residues of N-acetylglucosamine and 8 or 9 mannose residues. The sidechains of the second class are of the modified type containing N-acetylglucosamine, mannose, fucose, xylose in molar ratios of 2:3.8:0.6:0.5. Two-dimensional gel electrophoresis shows that phytohemagglutinin can be fractionated into seven different glycosylated polypeptides, and that each one contains at least one modified oligosaccharide chain. The results indicate that most glycosylated polypeptides probably contain one chain of each class. The carbohydrate composition of the two types of chains is similar to that found in other plant glycoproteins, but this is the first report of a plant glycoprotein with both highmannose and modified oligosaccharides on the same polypeptide chain.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of mathematical biology 16 (1982), S. 25-31 
    ISSN: 1432-1416
    Keywords: Stability ; Community matrix ; Lotka-Volterra models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The explicit function of the community matrix of a three dimensional Lotka-Volterra model is delineated by a set of necessary and sufficient conditions for a positive equilibrium to be asymptotically stable. In the special case that the community matrix is quasi weakly diagonally dominant, it is shown that a positive determinant for the community matrix is not only necessary but is also sufficient for stability. The results are specific to three dimensional models and do not extend to communities of dimension greater than three.
    Type of Medium: Electronic Resource
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