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  • 1990-1994  (4)
  • nuclear polyhedrosis virus  (2)
  • perennial ryegrass  (2)
  • 1
    Electronic Resource
    Electronic Resource
    A re-examination of phosphorus-lime interactions in perennial ryegrass (1991)
    Springer
    Plant and soil 135 (1991), S. 185-196 
    Details
    ISSN: 1573-5036
    Keywords: calcium ; critical phosphorus concentration ; gypsum ; lime ; perennial ryegrass ; root membranes ; soluble carbohydrate ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The results of a previous study had suggested that under conditions of limited P availability, Ca may be able to compensate for P in the shoot tissue of perennial ryegrass. To verify this preliminary finding, a factorial experiment was set up which simultaneously tested the effects of Ca and P fertilization on the yield and chemical composition of perennial ryegrass. Calcium was supplied as either lime or gypsum in order to differentiate between the effects of Ca and pH on the response of perennial ryegrass to P fertilization. In the final stage of the experiment a Zn treatment was included, to see whether altering the P/Zn ratios of plant shoots had any influence on the purported interaction between Ca and P. The results demonstrated that the P-sparing effect of lime occurs, at least partly, because Ca application improves the efficiency of absorbed P for DM production. However, it was reasonably clear that the site of the interaction between Ca and P was the soil-root interface, and not shoot tissue. It was suggested that under conditions of limited P supply, Ca stablizes root membranes and thereby minimizes both the efflux losses of nutrients from root tissue, and the compensatory flow of photosynthates from shoots to roots. No interaction was observed between P and Zn treatments in this study. Instead, a positive interaction was found between lime and Zn treatments, which suggests that the stabilizing action of Ca on root membranes requires Zn as a co-stabilizing factor. It is proposed that chemical analysis of shoot tissue alone may not be sufficient to accurately diagnose the P, Ca or Zn status of whole plants, since the critical levels of these elements in shoots appear to bear little relation to their requirements in the rhizosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010906
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of gypsum on the uptake, assimilation and cycling of 15N-labelled ammonium and nitrate-N by perennial ryegrass (1992)
    Springer
    Plant and soil 143 (1992), S. 19-31 
    Details
    ISSN: 1573-5036
    Keywords: ammonium ; calcium ; carboxylate/organic nitrogen ratio ; 15N isotope ; nitrate ; nitrogen cycling ; perennial ryegrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Solution culture studies have shown that plant uptake of NH4 + and NO3 - can be improved by increasing the concentration of Ca2+ in the root environment: the same may be true for grass grown in soil culture. An experiment was set up to see whether gypsum (CaSO4 2H2O) increased the rate at which perennial ryegrass absorbed 15NH4 + and 15NO3 - from soil. The results demonstrated that gypsum increases the rates of uptake of both NH4 + and NO3 - by perennial ryegrass. However because there was little potential for mineral-N loss from the experimental system, either by gaseous emission or by N immobilization, long term improvements in fertilizer efficiency were not observed. Nitrogen cycling from shoots to roots commenced once net uptake of N into plants had ceased. Labelled N transferred thus to roots underwent isotopic exchange with unlabelled soil N. It was suggested that this exchange of N might constitute an energy drain from the plant, if plant organic N was exchanged for soil inorganic N. The fact that the exchange occurred at all cast doubt on the suitability of the 15N-isotope dilution technique for assessing fertilizer efficiency in medium to long term experiments. There was evidence that the ‘extra’ NO3 --N taken up by plants on the all-nitrate treatments as a result of gypsum application, was reduced in root tissue rather than in shoots, but to the detriment of subsequent root growth and N uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00009125
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Modeling the population dynamics of baculovirus-infected insect cells: Optimizing infection strategies for enhanced recombinant protein yields (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 432-441 
    Details
    ISSN: 0006-3592
    Keywords: nuclear polyhedrosis virus ; polyhedrin promoter ; population dynamics ; multiplicity of infection ; Poisson distribution ; baculovirus ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The insect cell-baculovirus model presented here is capable of simulating cell population dynamics, extracellular virion densities, and heterologous product titers in reasonable agreement with experimental data for a wide rang of multiplicities of infection (MOI) and times of infection. The model accounts for the infection of a single cell by multiple virions and the consequences on the time course of infection. The probability of infection by more than one virion was approximated using the Poisson distribution, which proved to be a refinement over second-order kinetics. The model tracks initiation and duration of important events in the progression of infected cell development (virus replication, recombinant protein synthesis, and cell lysis) for subpopulations delineated by the time and extent of their initial infection. The model suggests infection strategies, weighing the importance of MOI and infection time. Maximum product titers result from infection in the early exponential growth phase with low MOI.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260390409
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Production of a discrete, heterogeneous population of β-galactosidase polypeptides using baculovirus expression vectors (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 932-944 
    Details
    ISSN: 0006-3592
    Keywords: Spodoptera frugiperda ; Autographa californica ; nuclear polyhedrosis virus ; polyhedrin promoter ; β-galactosidase ; heterogeneous polypeptides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gel electrophoresis analysis of immunoprecipitated β-galactosidase and polyhedrin-β-galactosidase expressed in Spodoptera frugiperda cells infected with recombinant Autograph californica nuclear polyhedrosis virus revealed the existence of a population of discrete β-galactosidase polypeptides. Several of the polypeptides observed in the fusion protein expression experiments exhibit a consistent pattern of slightly greater molecular weight when compared to the nonfusion β-galactosidase that is compatible with the hypothesis that these fusion protein fragments retain the N-terminal polyhedrin residues. Pulse-chase experiments showed that overall β-galactosidase degradation occurred at a negligible rate compared to the synthesis rate at 96 h postinfection, yet the fragments are observed for short pulse times. Degradation of several different β-galactosidase polypeptides was observed 24 h postinfection. Ribonucleic acid hybridization analysis of lacZ transcripts shows significant heterogeneity that may result from premature transcription termination. Although a proteolytic origin cannot be excluded, the data assembled suggest that premature termination of transcription or translation is the likely cause for the heterogeneous population of immunoreactive peptides observed. Many discrete forms of β-galactosidase polypeptides were also observed in studies with Escherichia coli, indicating that production of these heterogeneous forms is not a consequence of heterologous expression of the enzyme.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260390908
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    Paper (German National Licenses)
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