630 resultados para Kähler


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Plant defences vary in space and time, which may translate into specific herbivore-foraging patterns and feeding niche differentiation. To date, little is known about the effect of secondary metabolite patterning on within-plant herbivore foraging. We investigated how variation in the major maize secondary metabolites, 1,4-benzoxazin-3-one derivatives (BXDs), affects the foraging behaviour of two leaf-chewing herbivores. BXD levels varied substantially within plants. Older leaves had higher levels of constitutive BXDs while younger leaves were consistently more inducible. These differences were observed independently of plant age, even though the concentrations of most BXDs declined markedly in older plants. Larvae of the well-adapted maize pest Spodoptera frugiperda preferred and grew better on young inducible leaves irrespective of plant age, while larvae of the generalist Spodoptera littoralis preferred and tended to grow better on old leaves. In BXD-free mutants, the differences in herbivore weight gain between old and young leaves were absent for both species, and leaf preferences of S. frugiperda were attenuated. In contrast, S. littoralis foraging patterns were not affected. In summary, our study shows that plant secondary metabolites differentially affect performance and foraging of adapted and non-adapted herbivores and thereby likely contribute to feeding niche differentiation

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In order to defend themselves against arthropod herbivores, maize plants produce 1,4-benzoxazin-3-ones (BXs), which are stored as weakly active glucosides in the vacuole. Upon tissue disruption, BXs come into contact with β-glucosidases, resulting in the release of active aglycones and their breakdown products. While some aglycones can be reglucosylated by specialist herbivores, little is known about how they detoxify BX breakdown products. Here we report on the structure of an N-glucoside, 3-β-d-glucopyranosyl-6-methoxy-2-benzoxazolinone (MBOA-N-Glc), purified from Spodoptera frugiperda faeces. In vitro assays showed that MBOA-N-Glc is formed enzymatically in the insect gut using the BX breakdown product 6-methoxy-2-benzoxazolinone (MBOA) as precursor. While Spodoptera littoralis and S. frugiperda caterpillars readily glucosylated MBOA, larvae of the European corn borer Ostrinia nubilalis were hardly able to process the molecule. Accordingly, Spodoptera caterpillar growth was unaffected by the presence of MBOA, while O. nubilalis growth was reduced. We conclude that glucosylation of MBOA is an important detoxification mechanism that helps insects tolerate maize BXs.

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Boberach: Den Hauptteil bilden die Sitzungsprotokolle mit 42 Reden von 22 Abgeordneten, die dahin kommentiert werden, daß vier Fünftel des Vorparlaments für die kontitutionelle Monarchie eintraten und die Linke mit dem Versuch scheiterte, eine provisorische Regierung zu schaffen

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Welsch (Projektbearbeiter): Sammlung von insgesamt 103 Gedichten (in zweiter Auflage; die erste erschien bereits 1846/47). Der Verfasser, ein Schriftsteller und Mitarbeiter an belletristischen Zeitschriften, mußte (vor 1848) aufgrund burschenschaftlicher Zugehörigkeit seinen Wohnsitz Leipzig verlassen und wurde eines mißliebigen Artikels wegen mit einer vierwöchentlichen Gefängnisstrafe belegt

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[F. H. K.]

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Welsch (Projektbearbeiter): Annahme des Gesetzentwurfes in folgender Form: Die Verwaltung der Domänen und Staatsforsten wird von der Regierung getrennt und an Beamte übertragen, die vom König ernannt werden. Die Befugnisse jener Beamten umfassen nicht die Ausübung der polizeilichen sowie der kommunalen Verwaltung

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Ludwig Köhler

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Ludwig Köhler

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von Leon da Modena Redivivus [d. i. Leopold Löw]