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  • 1
    Electronic Resource
    Electronic Resource
    Continental-scale patterns of nutrient and fish effects on shallow lakes: introduction to a pan-European mesocosm experiment (2004)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 49 (2004), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Shallow lake ecosystems are normally dominated by submerged and emergent plants. Biological stabilising mechanisms help preserve this dominance. The systems may switch to dominance by phytoplankton, however, with loss of submerged plants. This process usually takes place against a background of increasing nutrient loadings but also requires additional switch mechanisms, which damage the plants or interfere with their stabilising mechanisms.2. The extent to which the details or even major features of this general model may change with geographical location are not clear. Manipulation of the fish community (biomanipulation) has often been used to clear the water of algae and restore the aquatic plants in northerly locations, but it is again not clear whether this is equally appropriate at lower latitudes.3. Eleven parallel experiments (collectively the International Mesocosm Experiment, IME) were carried out in six lakes in Finland, Sweden, England, the Netherlands and Spain in 1998 and 1999 to investigate the between-year and large-scale spatial variation in relationships between nutrient loading and zooplanktivorous fish on submerged plant and plankton communities in shallow lakes.4. Comparability of experiments in different locations was achieved to a high degree. Cross-laboratory comparisons of chemical analyses revealed some systematic differences between laboratories. These are unlikely to lead to major misinterpretations.5. Nutrient addition, overall, had its greatest effect on water chemistry then substantial effects on phytoplankton and zooplankton. Fish addition had its major effect on zooplankton and did not systematically change the water chemistry. There was no trend in the relative importance of fish effects with latitude, but nutrient addition affected more variables with decreasing latitude.6. The relative importance of top-down and bottom-up influences on the plankton differed in different locations and between years at the same location. The outcome of the experiments in different years was more predictable with decreasing latitude and this was attributed to more variable weather at higher latitudes that created more variable starting conditions for the experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.2004.01302.x
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  • 2
    Electronic Resource
    Electronic Resource
    Continental-scale patterns of nutrient and fish effects on shallow lakes: synthesis of a pan-European mesocosm experiment (2004)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 49 (2004), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Results are analysed from 11 experiments in which effects of fish addition and nutrient loading on shallow lakes were studied in mesocosms. The experiments, five in 1998, six in 1999, were carried out in six lakes, distributed from Finland to southern Spain, according to a standard protocol.2. Effects of the treatments on 29 standard chemical, phytoplankton and zooplankton variables are examined to assess the relative importance of bottom-up (nutrient enrichment) and top-down (fish predation) effects. For each year, the experiments in different locations are treated as replicates in a meta-analysis. Results of individual experiments are then compared in terms of the patterns of significant influences of nutrient addition and fish predation with these overall results (the baseline), and between years in the same location.3. The overall meta-analysis gave consistent results across the 2 years, with nutrient loading influencing all of the chemical variables, and on average 31% of primary producer and 39% of zooplankton variables. In contrast, fish influenced none of the chemical variables, 11% of the primary producer and 44% of the zooplankton variables. Nutrient effects on the system were thus about three times greater than fish effects, although fish effects were not inconsiderable.4. The relative importance of nutrients and fish in individual experiments often differed between years at the same location and effects deviated to varying degrees from the baseline. These deviations were treated as measures of consistency (predictability) of conclusions in repeat experiments. Consistency increased southwards and this is interpreted as a consequence of more variable annual weather northwards.5. The influence of nutrient loading was greater southwards and this was probably manifested through naturally greater annual macrophyte abundance in warmer locations in consequence of the longer plant growing-season. There was no trend in the relative importance of fish effects with latitude but this may partly be an artefact of the simple fish community used. These findings suggest that nutrient control should be a greater priority than biomanipulation in the restoration of eutrophicated shallow lakes in warm temperate regions.6. Starting conditions affected the outcome of experiments. High initial concentrations of total phosphorus and planktonic chlorophyll a concentration (created by local conditions prior to the experiment) led to de-emphasis of the importance of nutrient loading in the experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.2004.01304.x
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  • 3
    Electronic Resource
    Electronic Resource
    Responses of phytoplankton to fish predation and nutrient loading in shallow lakes: a pan-European mesocosm experiment (2004)
    Oxford, UK : Blackwell Publishing
    Freshwater biology 49 (2004), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. The impacts of nutrients (phosphorus and nitrogen) and planktivorous fish on phytoplankton composition and biomass were studied in six shallow, macrophyte-dominated lakes across Europe using mesocosm experiments.2. Phytoplankton biomass was more influenced by nutrients than by densities of planktivorous fish. Nutrient addition resulted in increased algal biomass at all locations. In some experiments, a decrease was noted at the highest nutrient loadings, corresponding to added concentrations of 1 mg L−1 P and 10 mg L−1 N.3. Chlorophyll a was a more precise parameter to quantify phytoplankton biomass than algal biovolume, with lower within-treatment variability.4. Higher densities of planktivorous fish shifted phytoplankton composition toward smaller algae (GALD 〈 50 μm). High nutrient loadings selected in favour of chlorophytes and cyanobacteria, while biovolumes of diatoms and dinophytes decreased. High temperatures also may increase the contribution of cyanobacteria to total phytoplankton biovolume in shallow lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.2004.01307.x
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  • 4
    Electronic Resource
    Electronic Resource
    The differential expression of a heat shock promoter in floral and reproductive tissues (2001)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 24 (2001), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A detailed histochemical analysis of the expression of the soybean small heat shock protein gene promoter, GmHSP 17·5E, fused to the GUS reporter gene, has been made in all organs and tissues of the flower as a function of stage of development and heat stress. This promoter is not uniformly expressed after a heat shock in all floral tissues and organs. Expression is seen at all stages of development in the sepals but not in the petals. The expression pattern in the pistil and in anthers is complex. Heat stress-induced GUS staining is seen in the style and upper portion of the ovary, but not in the stigmatic papillae or in the lower part of the ovary or in ovules. In stamens the heat shock response is seen in the filament and in the extension of the vascular tissue from the filament into the anther. No induction is seen in other tissues of the anther or in microspores or pollen at any stage of development. Vegetative organs in contrast are more uniform in the heat shock inducibility of GUS activity. Based on evidence from transient assays after microprojectile particle bombardment of the GmHSP 17·5E/GUS construct into pollen, it is likely that the gene is transcriptionally in an inactive configuration in pollen nuclei in stably transformed transgenic plants. These results are discussed with reference to other information in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2001.00727.x
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  • 5
    Electronic Resource
    Electronic Resource
    Critical Slowing Down on the Dynamics of a Bistable Reaction-Diffusion System in the Neighborhood of Its Critical Point (1999)
    Springer
    Journal of statistical physics 97 (1999), S. 803-809 
    Details
    ISSN: 1572-9613
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We investigate the nature of some critical decay processes in a bounded bistable reaction-diffusion system, through a perturbative expansion of its nonequilibrium potential. We elucidate the scaling behavior of the damped relaxation time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004627611784
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  • 6
    Electronic Resource
    Electronic Resource
    Boundary Effects on the Structural Stability of Stationary Patterns in a Bistable Reaction-Diffusion System (1998)
    Springer
    Journal of statistical physics 90 (1998), S. 103-117 
    Details
    ISSN: 1572-9613
    Keywords: Hot-spot model ; reaction-diffusion ; structural stability ; non-equilibrium potential ; albedo BCs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study a piecewise linear version of a one-component, two-dimensional bistable reaction-diffusion system subjected to partially reflecting boundary conditions, with the aim of analyzing the structural stability of its stationary patterns. Dirichlet and Neumann boundary conditions are included as limiting cases. We find a critical line in the space of the parameters which divides different dynamical behaviors. That critical line merges as the locus of the coalescence of metastable and unstable nonuniform structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023295416567
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  • 7
    Electronic Resource
    Electronic Resource
    Spanish national strong motion network. Recording of the Huelva earthquake of 20 December, 1989 (1991)
    Springer
    Pure and applied geophysics 136 (1991), S. 395-404 
    Details
    ISSN: 1420-9136
    Keywords: Strong-motion ; focal mechanism ; attenuation ; acceleration-intensity ; spectral response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In recent years a network of 30 accelerographs has been installed through the zones of highest seismic activity of Spain. For the first time, digital strong motion records have been obtained in Spain, with a maximum horizontal acceleration value of 0.06 g. A comprehensive study is made of the strong motion recordings of an earthquake which occurred in southwest Spain, on December 20, 1989. The isoseismal map is drawn and the data confirm the main attenuation directions in the area observed in other shocks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00878577
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  • 8
    Electronic Resource
    Electronic Resource
    A comparative study of somatic embryogenesis in Secale vavilovii (1991)
    Springer
    Plant cell reports 10 (1991), S. 265-268 
    Details
    ISSN: 1432-203X
    Keywords: Gramineae-Secale ; vavilovii-Somatic ; embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ability of immature embryos, inflorescences and leaves of Secale vavilovii to form embryogenic callus was tested on Murashige and Skoog (1962) medium supplemented with different concentrations of 2,4-D. All cultured immature embryos formed calluses. The highest percentage of embryogenic callus production was from 1–2 mm embryos. Young leaves also formed calluses, mainly from the 10–15 mm basal segment, the percentages of embryogenic calluses being higher when cultures were maintained in darkness. Embryogenic calluses were obtained also from all the cultured immature inflorescences, in the three cases, rooted green plants were obtained and grown in soil. Comparison of the responses of the three explants used indicates that immature inflorescence is the most useful explant for obtaining regenerated plants in Secale vavilovii.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232572
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  • 9
    Electronic Resource
    Electronic Resource
    Comparison of transient and stable expression by a pollen-specific promoter: the transformation results do not always agree (2000)
    Springer
    Sexual plant reproduction 12 (2000), S. 292-295 
    Details
    ISSN: 1432-2145
    Keywords: Key words Zm13 pollen-specific promoter ; Transient transformation ; Transgenic plants ; Transcription factor competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In the analysis of 5’ sequence elements necessary for promoter activity in pollen various promoter- reporter gene constructs usually show similar patterns of expression in pollen when assayed by either transient transformations or after stable transformations in transgenic plants. Out of several fragment lengths of the Zm13 pollen-specific promoter linked to GUS, we found that the largest fragment (–1001 to +61) showed approximately eightfold higher expression in pollen of transgenic plants than transient transformations by microprojectile bombardment. No other promoter fragment tested showed this difference. Titration of a limited number of transcription factors by the large number of potential binding sites in this promoter fragment along with the large number of promoter copies introduced during transient transformation are possible explanations for this observation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050197
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  • 10
    Electronic Resource
    Electronic Resource
    Reproducibility testing of RAPD, AFLP and SSR markers in plants by a network of European laboratories (1997)
    Springer
    Molecular breeding 3 (1997), S. 381-390 
    Details
    ISSN: 1572-9788
    Keywords: DNA markers ; RAPD ; AFLP ; SSR ; microsatellite ; network ; reproducibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A number of PCR-based techniques can be used to detect polymorphisms in plants. For their wide-scale usage in germplasm characterisation and breeding it is important that these marker technologies can be exchanged between laboratories, which in turn requires that they can be standardised to yield reproducible results, so that direct collation and comparison of the data are possible. This article describes a network experiment involving several European laboratories, in which the reproducibility of three popular molecular marker techniques was examined: random-amplified fragment length polymorphism (RAPD), amplified fragment length polymorphism (AFLP) and sequence-tagged microsatellites (SSR). For each technique, an optimal system was chosen, which had been standardised and routinely used by one laboratory. This system (genetic screening package) was distributed to different participating laboratories in the network and the results obtained compared with those of the original sender. Different experiences were gained in this exchange experiment with the different techniques. RAPDs proved difficult to reproduce. For AFLPs, a single-band difference was observed in one track, whilst SSR alleles were amplified by all laboratories, but small differences in their sizing were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009612517139
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