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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    World journal of microbiology and biotechnology 8 (1992), S. 301-304 
    ISSN: 1573-0972
    Keywords: Bacillus thuringiensis ; cell yield ; δ-endotoxin ; oxygen ; oxygen-limited growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The production of crystals and spores ofBacillus thuringiensis var.israelensis was studied under different aeration conditions. The results with 4 l batch cultures showed that for O2 non-limited, cultures cell yield, toxin production and spore count were constant for all oxygen transfer rates (OTR). Under O2 limitation, °-endotoxin concentrations and spore counts were lower than those obtained in non-limited cultures. In addition, δ-endotoxin yields diminished under O2 limitation, suggesting that the toxin synthesis mechanism could have been affected.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-0972
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Résumé On a étudié l'influence de diverses sources d'azote organique et inorganique et des rapports C∶N en relation avec la croissance et la production de protéine parBacillus thuringiensis var.israelensis. On fait l'hypothèse que la production de protéines est proportionnelle à la production de delta-endotoxine. La concentration de delta-endotoxine croît quand on ajoute au milieu du (NH4)2SO4, mais le rapport delta-endotoxine: poids sec de biomasse n'est pas affecté par différents rapports C∶N. On peut remplacer partiellement la source organique d'azote, l'extrait de levure, par du (NH4)2SO4 avec une augmentation significative de production de delta-endotoxine.
    Notes: Abstract The influence of different organic and inorganic nitrogen source combinations and C∶N ratios was studied in connection with growth and protein production ofBacillus thuringiensis var.israelensis. Protein production was assumed to be proportional to delta-endotoxin production. Delta-endotoxin concentration increased when media were supplemented with (NH4)2SO4, but the delta-endotoxin: biomass dry weight ratio was unaffected by different C∶N ratios. Organic nitrogen source, yeast extract, could be partially replaced by (NH4)2SO4 with a significant increase in delta-endotoxin production.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Siberian mathematical journal 9 (1968), S. 166-168 
    ISSN: 1573-9260
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Meteorology and atmospheric physics 73 (2000), S. 139-156 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Summary The surface low of a mature extra-tropical cyclone is often surmounted by a troposphere-spanning column of anomalously high potential vorticity (PV). In this study the growth and decay of such a PV-tower is traced for one major North Atlantic frontal-wave cyclone using the ECMWF analysis fields and adopting both Eulerian and Lagrangian frameworks. A tower’s structure and composition relates intimately to the strength, scale and structure of the associated surface cyclone. It is shown that the tower comprised a vertical superposition of three elements: (?) a quasi-seclusion of stratospheric air extruded from an upper-level trough, (ℬ) a mid-tropospheric layer of intermingled air from diverse sources, but with a substantial component originating from the system’s cold front, and (?) a low-tropospheric layer of diabatically-induced PV that was linked to and originated from flow along a bent-back warm front. An examination of the tower’s growth and decay helps identify the factors influencing the onset and rapidity of the cyclogenesis. There was first an in-phase development of a surface baroclinic wave with the precursor of element (?), and also the emergence of element (ℬ) in the form of a low-level elongated band of PV aligned along the cold front. Thereafter a short period of rapid growth was marked by the appearance of a low-level band of PV along the warm front (element ?), and it co-spiraled with and beneath the upper-level stratospheric intrusion (element ?). Demise of the tower followed a loss of amplitude of its central portion and a loss of coherency aloft. Evidence of the modulating as opposed to the dominating influence of diabatic processes upon the cyclone’s structure and strength is derived from consideration of: the tower’s durable and ephemeral potential vorticity, the PV production along the warm front, and sets of model simulations of the event that selectively suppress diabatic PV production.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Summary  The precipitation forecasts of four operational numerical weather prediction models over the Alpine region are evaluated and intercompared for two periods of interest to the Mesoscale Alpine Programme (MAP). The new analysis of Alpine rainfall of Frei and Schaär (1998) is used to validate the models. It is found that the models have a tendency to overestimate the total precipitation and the frequency of intense rain events over high orography. The skill scores show good consistency between models, except for the ability to forecast light rain or heavy rain events. The partition between convective and stratiform rainfall is rather variable between the models.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 46 (1996), S. 78-84 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The glucose carbon fluxes in continuous cultures of Bacillus thuringiensis grown in a complex medium have been studied as a function of the growth rate. The results are discussed in the light of a growth model. From reduced nicotinamide adenine dinucleotide (NADH) and carbon balances it was determined that the fraction of glucose consumed for biomass synthesis decreased with the growth rate, while the glucose flux through the tricarboxylic acid (TCA) cycle diminished after a threshold value of D=0.34 h-1, where D=dilution rate. At the highest growth rate tested, glucose was used almost exclusively as the energy source, via fermentative pathways, which indicates that the yeast extract was used as the carbon source. The specific rate of oxygen consumption increased with growth even after the beginning of the accumulation of acids, indicating that the respiratory chain was not saturated. The results suggest that there is a mismatch between glycolysis and TCA cycle capacity, depending on the growth rate. Furthermore, values of (P/O) ratio and m ATP are presented, where (P/O) is mole of ATP formed per gram atom oxygen consumed by the respiratory chains and m ATP is the maintenance requirement for ATP.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-9699
    Keywords: two-component systems ; sensors ; regulators ; quorum sensing ; autoinducers ; homoserine lactones ; prokaryotes ; phosphoryl transfer ; cascades ; networks ; signal transduction ; photoreceptors ; photoactive yellow protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Among the signal transfer systems in bacteria two types predominate: two-component regulatory systems and quorum sensing systems. Both types of system can mediate signal transfer across the bacterial cell envelope; however, the signalling molecule typically is not taken up into the cells in the former type of system, whereas it usually is in the latter. The Two-component systems include the recently described (eukaryotic) phosphorelay systems; quorum sensing systems can be based upon autoinducers of the N-acylated homoserine lactones, and on autoinducers of a peptidic nature. A single bacterial cell contains many signalling modules that primarily operate in parallel. This may give rise to neural-network behaviour. Recently, however, for both types of basic signal transfer modules, it has been demonstrated that they also can be organised in series (i.e. in a hierarchical order). Besides their hierarchical position in the signal transduction network of the cell, the spatial distribution of individual signalling modules may also be an important factor in their efficiency in signal transfer. Many challenges lie hidden in future work to understand these signal transfer processes in more detail. These are discussed here, with emphasis on the mutual interactions between different signal transfer processes. Successful contributions to this work will require rigorous mathematical modelling of the performance of signal transduction components, and -networks, as well as studies on light-sensing signal transduction systems, because of the unsurpassed time resolution obtainable in those latter systems, the opportunity to apply repeated reproducible stimuli, etc. The increased understanding of bacterial behaviour that already has resulted – and may further result – from these studies, can be used to fine-tune the beneficial activities of bacteria and/or more efficiently inhibit their deleterious ones.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta mathematica hungarica 38 (1981), S. 69-72 
    ISSN: 1588-2632
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Plant ecology 142 (1999), S. 121-132 
    ISSN: 1573-5052
    Keywords: Aseasonal rainfall ; Chlorophyll a fluorescence ; Gas exchange ; Leaf orientation ; Photorespiration ; Temperature optimum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Namaqualand, a semi-arid winter rainfall region of South Africa, supports an exceptional diversity of geophytic species. The survey focused on gas exchange reactions and chlorophyll a fluorescence in geophytes with different leaf orientation in relation to environmental variability. Although the above ground life cycle of geophytes can be extremely short, unlike desert annuals, they are not characterized by a high photosynthetic CO2 uptake. Maximum CO2 uptake ranged from 4 to 20 μmol CO2 m-2 s-1. Temperature optima of photosynthetic CO2 uptake were comparably low and ranged from 12 to 22 °C for eleven species tested, with only one species above 19 °C. The decrease of CO2 uptake with rising temperatures was associated with a substantial increase of photorespiration. Net photosynthesis was saturated between 500 and 900 μmol photons m-2 s-1 while electron transport through PSII was saturated at higher photon flux densities. At light intensities beyond saturation, a high variability of PSII efficiency occurred. It was highest for horizontal leaves and lowest for upright leaves. However, the maximum quantum yield of PSII (Fv/Fm)remained constant during the course of a day, regardless of leaf orientation. This indicates the absence of photoinhibitory effects and a well protected photosynthetic apparatus. Leaf orientation determined interception of solar radiation and thus leaf temperature which was highest for horizontal leaves. In conclusion, Namaqualand geophytes show photosynthetic characteristics that are well adapted to the mild and generally moist conditions during the growing season.
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  • 10
    Publication Date: 2011-08-24
    Print ISSN: 0277-5212
    Electronic ISSN: 1943-6246
    Topics: Biology
    Published by Springer
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