996 resultados para 1-(O-hexose)-3,25,27-octacosanetriol per unit mass organic carbon


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Vorlage d. Digitalisats ohne Schriftenreihe-Angaben

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par Verax [d. i. Radu Rosetti]

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hrsg. vom Zentralbuero d. Union d. Zionisten Revisionisten

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composed by A. Kaiser

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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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In monocotyledonous plants, 1,4-benzoxazin-3-ones, also referred to as benzoxazinoids or hydroxamic acids, are one of the most important chemical barriers against herbivores. However, knowledge about their behavior after attack, mode of action and potential detoxification by specialized insects remains limited. We chose an innovative analytical approach to understand the role of maize 1,4-benzoxazin-3-ones in plant–insect interactions. By combining unbiased metabolomics screening and simultaneous measurements of living and digested plant tissue, we created a quantitative dynamic map of 1,4-benzoxazin-3-ones at the plant–insect interface. Hypotheses derived from this map were tested by specifically developed in vitro assays using purified 1,4-benzoxazin-3-ones and active extracts from mutant plants lacking 1,4-benzoxazin-3-ones. Our data show that maize plants possess a two-step defensive system that effectively fends off both the generalist Spodoptera littoralis and the specialist Spodoptera frugiperda. In the first step, upon insect attack, large quantities of 2-β-d-glucopyranosyloxy-4,7-dimethoxy-1,4-benzoxazin-3-one (HDMBOA-Glc) are formed. In the second step, after tissue disruption by the herbivores, highly unstable 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one (HDMBOA) is released by plant-derived β-glucosidases. HDMBOA acts as a strong deterrent to both S. littoralis and S. frugiperda. Although constitutively produced 1,4-benzoxazin-3-ones such as 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) are detoxified via glycosylation by the insects, no conjugation of HDMBOA in the insect gut was found, which may explain why even the specialist S. frugiperda has not evolved immunity against this plant defense. Taken together, our results show the benefit of using a plant–insect interface approach to elucidate plant defensive processes and unravel a potent resistance mechanism in maize.

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Welsch (Projektbearbeiter): Festsetzung der Wahl des Abgeordneten der Freien Stadt Frankfurt zur Deutschen Nationalversammlung auf den 28. April 1848. Organisatorisches

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Hans Hildebrandt, "Der Kunstunterricht an Hochschulen", Typoskript, 2 Blatt; "Das Wirtschaftsprinzip", Typoskript, 3 Blatt (GS 11, S. 13-16); "Betr. Scheler - Sombart", Manuskript, 2 Blatt; "Zur Psychologie des Denkens nach Benno Erdmann", Manuskript, 2 Blatt, davon 1 leer; "Zur Phänomenologie der Erkenntnis", Typoskript, 3 Blatt; "Zu Kants Kritik der Urteilskraft", Typoskript mir eigenhändigen Korrekturen, 5 Blatt (GS 11, S. 70-75); "Naturwissenschaftliche Methode und Erkenntnistheorie. Über Kant", Typoskript mit zahlreichen eigenhändigen Notizen, 2 Blatt; "Beantwortung der Frage: Was heißt vom Standpunkt des Transcendentalen Idealismus aus die Behauptung, daß die materielle Entwicklung der Entwicklung des Bewußtseins vorhergegangen ist?", Typoskript, 3 Blatt (GS 11, S. 17-21); "Sprache und Denken", Typoskript, 8 Seiten (GS 11, S. 119-132); "Psychologie und Erkenntnistheorie", Typoskript, 2 Blatt; "Zu David Hume", Typoskript, 3 Blatt; "Wie ist das Bewußtsein einer Mehrheit von Gegenständen möglich?", Typoskript, 6 Blatt; "Gegenstand der Psychologie nach Cornelius", Typoskript, 2 Blatt; "Psychologie und Philosophie bei Hume und Cornelius", Typoskript, 12 Blatt; "Das Wiedererkennen", Typoskript von 19.12.1919, 8 Blatt; Exzerpte über: Gustav Landauer, Arthur Wolfgang Cohn, Karl Vorländer, Friedrich Engels, Karl Kautsky, L. B. Boudin, Karl Marx, Arthur Schopenhauer, 1 Heft, Manuskript, 42 Blatt; Manuskript, 1 Heft, 13 Blatt, davon 1 leer;

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