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  • 1
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The composition of African savanna vegetation10 and the foraging behaviour of large herbivores in African savannas9'11 are correlated with soil fertility. Eutrophic Acacia savanna is characterized by palatable woody species, whereas dystrophic savanna-woodland is dominated by unpalatable species ...
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  • 2
    Publication Date: 2018-12-01
    Description: Fidelity and sequencing requirements of simulation stimuli for lunar landing and long term space missions
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Format: text
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  • 3
    ISSN: 1432-1939
    Keywords: Populus tremuloides ; Carbon/nutrient balance ; Choristoneura conflictana ; Plant/herbivore interaction ; Secondary metabolite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We investigated the effects of nitrogen fertilization upon the concentrations of nitrogen, condensed tannin and phenolic glycosides of young quaking aspen (Populus tremuloides) leaves and the quality of these leaves as food for larvae of the large aspen tortrix (Choristoneura conflictana), a Lepidopteran that periodically defoliates quaking aspen growing in North America. Nitrogen fertilization resulted in decreased concentrations of condensed tannin and phenolic glycosides in aspen leaves and an increase in their nitrogen concentration and value as food for the large aspen tortrix. These results indicate that plant carbon/nutrient balance influences the quality of aspen leaves as food for the large aspen tortrix in two ways, by increasing the concentrations of positive factors (e.g. nitrogen) and decreasing the concentrations of negative factors (eg. carbon-based secondary metabolites) in leaves. Addition of purified aspen leaf condensed tannin and a methanol extract of young aspen leaves that contained condensed tannin and phenolic glycosides to artificial diets at high and low levels of dietary nitrogen supported this hypothesis. Increasing dietary nitrogen increased larval growth whereas increasing the concentrations of condensed tannin and phenolic glycosides decreased growth. Additionally, the methanol extract prevented pupation. These results indicate that future studies of woody plant/insect defoliator interactions must consider plant carbon/nutrient balance as a potentially important control over the nutritional value of foliage for insect herbivores.
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  • 4
    ISSN: 1573-1561
    Keywords: Balsam poplar ; Populus balsamifera ; snowshoe hare ; Lepus americanus ; plant chemical defense ; herbivore ; cineol ; benzyl alcohol ; bisabolol ; 6-hydroxycyclohexenone ; salicaldehyde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Palatabilities of parts and growth stages of balsam poplar (Populus balsamifera) to snowshoe hares (Lepus americanus) are related to concentrations of specific plant metabolites that act as antifeedants. Buds are defended from hares by cineol, benzyl alcohol, and (+)-α-bisabolol. Internodes are defended by 6-hydroxycylohexenone (6-HCH) and salicaldehyde. Although defense of interaodes depends upon both compounds, the defense of juvenile internodes is principally related to salicaldehyde concentration; the defense of internode current annual growth is principally related to 6-HCH concentration. The concentration of 6-HCH can be supplemented by the hydrolysis of phenol glycosides when plant tissue is disrupted, raising the possibility of a dynamic element of the chemical defense of poplar.
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  • 5
    ISSN: 1573-1561
    Keywords: Labrador tea ; Ledum groenlandicum ; snowshoe hare ; Lepus americanus ; herbivore ; plant chemical defense ; germacrone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Labrador tea (Ledum groenlandicum), a slow-growing late successional evergreen, is highly unpalatable to snowshoe hares (Lepus americanus). Germacrone, a sesquiterpene that is the major component of the essential oil ofL. groenlandicum, was shown by bioassay to be a potent antifeedant to hares. Its concentrations in leaves and intemodes of the plant are high enough to defendL. groenlandicum from hares. This chemical defense of Labrador tea from herbivory is consistent with the resource availability theory of antiherbivore defense.
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  • 6
    ISSN: 1573-1561
    Keywords: condensed tannin ; procyanidin ; blackbrush ; bitterbrush ; plant defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Condensed tannins were isolated from bitterbnish (Purshia tridentata) and blackbrush (Coleogyne ramosissima). Structural analyses showed that both tannins were procyanidins of similar polymer length. The overall stereochemistries at C-3 and C-4, however, differed between the two tannins. These changes in stereochemistry resulted in blackbrush tannins being less preferred than bitterbrush tannins when offered to snowshoe hares (Lepus americanus). It is unlikely that differences in protein-precipitating abilities are the cause for the preference of the bitterbrush over the blackbrush tannins. Instead, we hypothesize that condensed tannins may be depolymerized and absorbed following ingestion. Differences in tannin structure can lead to different depolymerized products and rates of depolymerization, both of which may affect herbivore preferences.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 21 (1995), S. 661-662 
    ISSN: 1573-1561
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
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  • 8
    ISSN: 1432-1939
    Keywords: Tissue wounding ; Induced defense ; Secondary phenolics ; Willows ; Salicaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We studied the effects of natural wounding by insects and artificial wounding by clipping with scissors on the phenolic chemistry of two willows, Salix myrsinifolia and Salix pentandra. Half of the blade of a mature leaf was removed from each experimental plant either by allowing insects (chrysomellid beetles) to feed on the leaf or by clipping off half the blade of a leaf with scissors. We also examined the ability of wounded plants to warn neighboring plants of imminent wounding by an airborne signal by maintainign one set of control plants in the room containing the wounded plants and another set of control plants in a room hermetically sealed from the room containing the wounded plants. After 48 h, the experimental leaf and the fourth leaf and eighth leaf upwards in the leaf sequence from the experimental leaf were analyzed for phenols by high-pressure liquid chromatography. The same leaves in the leaf sequence from each control plant were similarly analyzed for phenols. Only one phenol, salicortin in leaves of S. myrsinifolia, increased in concentration in response to defoliation, and the observed response was small. The type of wounding affected this increase in salicortin, with natural wounding by insects causing a greater response than artificial wounding in one S. myrsinifolia clone, and artificial wounding causing a greater response than insect wounding in the other clone. This result indicates that S. myrsinifolia cannot control the effects of diffeeent types of wounding on its leaf secondary chemistry. We also found no indication of airborne warning signals between wounded and unwounded plants that trigger an elevation of leaf defenses in unwounded plants in anticipation of herbivore attack.
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  • 9
    ISSN: 1432-1939
    Keywords: Carbon/nutrient balance hypothesis ; Plant defense ; Snowshoe hare ; Balsam poplar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The carbon/nutrient balance hypothesis fails to correctly predict effects of fertilization and shading on concentrations of defensive metabolites in Alaskan balsam poplar (Populus balsamifera). Of six metabolites analyzed, only one responded in the predicted fashion to fertilization and one to shading. These results and those of other similar studies suggest that while the carbon/nutrient balance hypothesis may correctly predict the effects of fertilization and shading on the concentrations of metabolic “end products”, it fails for many metabolites because of the dynamics associated with their production and turnover. In metabolites that turn over, static concentration is a poor predictor of defensive investment.
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  • 10
    ISSN: 1432-1939
    Keywords: Snowshoe hare ; Birch ; Alder ; Chemical defense ; Plant carbon/nutrient balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plant carbon/nutrient balance has been implicated as an important factor in plant defensive chemistry and palatability to herbivores. We tested this hypothesis by fertilizing juvenile growth form Alaska paper birch and green alder with N, P and N-plus-P in a balanced 2x2 factorial experiment. Additionally, we shaded unfertilized plants of both species. Fertilization with N and N-plus-P increased growth of Alaska paper birch, reduced the concentration of papyriferic acid in internodes and increased the palatability of birch twigs to snowshoe hares. Shading decreased birch growth, decreased the concentration of papyriferic acid in internodes and increased twig palatability. These results indicate that the defensive chemistry and palatability of winter-dormant juvenile Alaska paper birch are sensitive to soil fertility and shade. Conversely the defensive chemistry and palatability of green alder twigs to snowshoe hares were not significantly affected by soil fertility or shade. The greater sensitivity of Alaska paper birch defensive chemistry and palatability to snowshoe hares in comparison to green alder is in agreement with the hypothesis that early successional woody plants that are adapted to high resource availability are more plastic in their chemical responses to the physical environment than are species from less favorable environments.
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