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  • Articles  (39)
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  • Articles: DFG German National Licenses  (39)
  • Springer  (36)
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  • 2000-2004  (13)
  • 1980-1984  (26)
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  • Articles  (39)
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  • 1
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effects of mycorrhizal infection, soil P availability and fruit production on the male function of reproduction were examined in two cultivars of tomato (Lycopersicon esculentum Mill.). Tomato plants were grown in a greenhouse under three treatment combinations: non-mycorrhizal, low P (NMPO); non-mycorrhizal, high P (NMP3); and mycorrhizal, low P (MPO). In addition, all treatment combinations were grown both with and without fruit. Fruit production decreased final leaf biomass, flower production and in vitro pollen tube growth rates, often reducing the beneficial effects of increased P uptake. Thus, fruit production diverted resources from subsequent vegetative growth, flower production and pollen development. As the growing season progressed, mean pollen production per flower and in vitro germination and tube growth decreased. Mycorrhizal infection and high soil P conditions increased final leaf biomass, flower production, mean pollen production per flower (in one cultivar) and in vitro pollen tube growth rates. Thus, mycorrhizal infection and high soil P conditions increased pollen quantity and quality, thereby enhancing fitness through the male function. Similar trends in these treatments suggested that mycorrhizal effects on the male function were largely the result of improved P acquisition.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Weed research 44 (2004), S. 0 
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Classical Mendelian experiments were conducted to determine the genetics and inheritance of quinclorac and acetolactate synthase (ALS)-inhibitor resistance in a biotype of Galium spurium. Plants were screened with the formulated product of either quinclorac or the ALS-inhibitor, thifensulfuron, at the field dose of 125 or 6 g active ingredient (a.i.) ha−1 respectively. Segregation in the F2 generation indicated that quinclorac resistance was a single, recessive nuclear trait, based on a 1 : 3 segregation ratio [resistant : susceptible (R : S)]. Resistance to ALS inhibitors was due to a single, dominant nuclear trait, segregating in the F2 generation in a 3 : 1 ratio (R : S). The genetic models were confirmed by herbicide screens of F1 and backcrosses between the F1 and the S parent. F2 plants that survived quinclorac treatment set seed and the resulting F3 progeny were screened with either herbicide. Quinclorac-treated F3 plants segregated in a 1 : 0 ratio (R : S), hence F2 progenitors were homozygous for quinclorac resistance. In contrast, F3 progeny segregated into three ratios: 1 : 0, 3 : 1 and 0 : 1 (R : S) in response to ALS-inhibitor treatment. This segregation pattern indicates that their F2 parents were either homozygous or heterozygous for ALS-inhibitor resistance. Therefore, there were clearly two distinct resistance mechanisms encoded by two genes that were not tightly linked as demonstrated by segregation patterns of the F3.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 44 (2002), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Spo0A~P is the essential response regulator and transcription factor for sporulation initiation in Bacillus subtilis. The phosphorylation level of Spo0A in the cell is determined by the sensor kinase activity of the phosphorelay, donating phosphoryl groups, and the antagonistic effects of dephosphorylation mediated by the Rap and Spo0E families of phosphatases. In this study, spo0A mutations were generated that encoded proteins less sensitive to the activity of Spo0E than the wild-type protein. The Spo0A substitutions N12K, P60S, L62P and F88L are surface exposed and localize to the same face of the molecule as the active site and in its close proximity on the β1–α1, β3–α3 and β4–α4 loops. The corresponding surface in the Spo0F response regulator was shown previously to be involved in the interaction with the RapB phosphatase, as well as the KinA histidine kinase and the Spo0B phosphotransferase. Thus, residues occupying the same position (N12:Q12, F88:Y84) and the same loops in Spo0A or Spo0F are involved in the interaction with the structurally unrelated Spo0E and RapB phosphatases, respectively, in addition to kinases and phosphotransferase. The specificity in phosphatase target recognition must be the result of side-chain variability within the response regulators and the interactions they promote. The residues involved in Spo0E interaction are identical in all Spo0A orthologues from spore-forming Bacilli encoding Spo0E phosphatases.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 24 (2000), S. 267-274 
    ISSN: 1476-5535
    Keywords: Keywords: vitamins; activated sludge; industrial wastewater; porous pots; Amtox™
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The process performance and metabolic rates of samples of activated sludge dosed with vitamin supplements have been compared. After initial screening, four vitamins and two metals as single supplements and in pairs, were dosed continuously into the mixed liquor of an activated sludge simulation. Toxicity, oxygen demand removal, respiration rates and suspended solids were measured to monitor the effect on process efficiency. It was confirmed experimentally that an industrial wastewater stream did not contain a sufficient supply of micronutrients for efficient biological treatment. This was concluded from the observation that control sludge batches (receiving no supplements) averaged chemical oxygen demand removal efficiency of 58%. Dosing micronutrients into the mixed liquor produced removal efficiencies of up to 69%. Some of the supplements increased the respiration rate of the sludge while some decreased it, indicating a range of stimulatory and inhibitory effects. Complex interactions between micronutrients that were dosed simultaneously were evident. Several positive effects led to the conclusion that micronutrients have the potential to optimise process performance of activated sludge plants treating industrial wastewater. The addition of phosphorus/niacin and molybdenum/lactoflavin removed wastewater components that were toxic to nitrifiers as indicated through toxicity testing, thus protecting downstream nitrification/denitrification treatment processes. Journal of Industrial Microbiology & Biotechnology (2000) 24, 267–274.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 12 (1980), S. 143-158 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract In this paper, the radiation losses caused by film thickness and refractive index discontinuities in asymmetric slab waveguides are examined theoretically. A technique developed by Mahmoud and Beal for dealing with the continuous part of the radiation spectrum is used. Several numerical examples which show the radiation loss for various waveguide configurations are presented and discussed and, where appropriate, comparisons with other related work made. In the case of asymmetric thickness steps, the radiation losses are found to be appreciably higher than those computed for symmetric guides. The radiation losses for guides having the same thickness were found to decrease as the guide thickness increased. Once the TE1 mode become guided, the losses decreased rapidly. However, if the two guides had different thickness then it was found that the losses exhibited a minimum.
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  • 6
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Reductions of oxygen in inspired gas from 20% to 15%, in anesthetized dogs, reduced arterial PO2 and increased the renal efflux of PGE2 but not PGF2a . Renal blood flow, blood pressure, plasma renin activity as well as arterial pH and PCO2 were unaffected. PGs may mediate the renal hemodynamic or excretory consequences of alterations in PO2. In addition, minor variations in PO2 might account, in part, for the variable renal venous PGE2 concentrations reported under basal conditions.
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  • 7
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The geographic distribution of mercury concentrations in the California mussel Mytilus californianus, collected from 1977–1978 at 43 sites along the western coastline of the continental United States is marked by consistently elevated levels at two locations. These two sites, which are relatively isolated from anthropogenic inputs and mercuryrich minerals, both contain large pinniped and marine bird populations. The relatively elevated mercury levels measured in the excrement of a pinniped from one of those locales indicate that the concentrated discharge of mercuryrich waste products from the marine ecosystem's top carnivores is contaminating lower trophic levels.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 81 (1984), S. 223-230 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stable carbon isotope ratios (δ13C) of eelgrass Zostera marina and of kelp Laminaria longicruris showed considerable variation in time and space. The isotopic composition of Z. marina varied seasonally from a mean of-6‰ for leaves formed in June to a mean of-10‰ for leaves formed in February. The maximum range for individual leaves was from-5 to-11.4‰. Once a leaf was fully formed, its isotopic composition appeared not to change. In L. longicruris there was no clear seasonal pattern of variation, but in any given blade there was a spatial pattern of variation, with the thickened central band tending to be least negative and the margins most negative. In one blade the range was from-12 to-20‰. Since this range overlaps values that are found in various other macrophytes and in seston, the value of the stable carbon isotope ratio as a tracer in food webs involving macroalgae is questioned. For Z. marina, in which the values are seasonally predictable, the technique may be useful if interpreted with care. The most probable explanation of variation in the ratios is differential storage of biochemical components of different isotopic compostion.
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  • 9
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. A study was designed to investigate the effects of intra and inter-specific competition on the productivity of single and multi-species stands of plants normally dominant in first year old-field communities of mid-Michigan. The four species used were Amaranthus retroflexus, Chenopodium album, Panicum capillare and Setaria viridis. 2. Specifically, we tested (1) the relationship between diversity and productivity, (2) the effect of arrangement (pattern) of individuals within an array of old-field dominants on yield and (3) the expression of dominance and resultant allocation of yields within mixture arrays of different plant species. In direct contrast to many earlier studies, our experiments were completed in the field under natural conditions. 3. Mean yield of the highest yielding monoculture, Amaranthus, was greater than any of the yields of the mixture plots. 4. Changing the pattern within mixtures had no significant effect on the yields of the mixture plots. Distribution of biomass among the component species followed a geometric pattern similar to that predicted by the niche pre-emption hypothesis (Whittaker, 1965, 1969). Using yield as a criterion, dominance was clearly expressed in the mixture plots. Amaranthus contributed more than 50% of the yield in all of the mixture plots. 5. A relative competitive ability index (RCA) was developed to demonstrate more clearly the intra and interspecific relationships among the species in mixture plots and to “equalize” the inherent weight differential among species. Relative Competitive Ability, from highest to lowest, was Amaranthus, Chenopodium, Setaria and Panicum. 6. The paired species experiment demonstrated that the performance of species in multi-species arrays cannot be predicted from paired competition experiments. 7. In the diversity-yield experiment and the paired-species competitive ability experiment, dicotyledons were clearly superior to monocotyledons.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 55 (1982), S. 110-113 
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Stable carbon isotope analysis was used to define the food sources of bivalve Chione (Austrovenus) stutchburyi in the Avon-Heathcote Estuary, Christchurch, New Zealand. δ13C values of C. stutchburyi tissue were significantly different (from -16.7‰ to -23.5‰ relative to the PDB standard) at five locations separated by less than 4 km but subject to different hydrological regimes. This is related to differences in the isotopic composition of the suspended particulate matter of the inflowing water. C. stutchburyi is shown to utilise carbon of terrestrial and marine origin depending upon its position within the estuary and local hydrology.
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