22 research outputs found
Hydroxylated jasmonates are commonly occurring metabolites of jasmonic acid and contribute to a partial switch‐off in jasmonate signaling
No full textIn potato 12-hydroxyjasmonic acid (12-OH-JA) is a tuber-inducing compound. Here, it is demonstrated that 12-OH-JA, as well as its sulfated and glucosylated derivatives, are constituents of various organs of many plant species. All accumulate differentially and usually to much higher concentrations than jasmonic acid (JA). In wounded tomato leaves, 12-OH-JA and its sulfated, as well as glucosylated, derivative accumulate after JA, and their diminished accumulation in wounded leaves of the JA-deficient mutants spr2 and acx1 and also a JA-deficient 35S::AOCantisense line suggest their JA-dependent formation. To elucidate how signaling properties of JA/JAME (jasmonic acid methyl ester) are affected by hydroxylation and sulfation, germination and root growth were recorded in the presence of the different jasmonates, indicating that 12-OH-JA and 12-hydroxyjasmonic acid sulfate (12-HSO4-JA) were not bioactive. Expression analyses for 29 genes showed that expression of wound-inducible genes such as those coding for PROTEINASE INHIBITOR2, POLYPHENOL OXIDASE, THREONINE DEAMINASE or ARGINASE was induced by JAME and less induced or even down-regulated by 12-OH-JA and 12-HSO4-JA. Almost all genes coding for enzymes in JA biosynthesis were up-regulated by JAME but down-regulated by 12-OH-JA and 12-HSO4-JA. The data suggest that wound-induced metabolic conversion of JA/JAME into 12-OH-JA alters expression pattern of genes including a switch off in JA signaling for a subset of genes
Transformation von Phospholipiden durch Phospholipasen A1 und Phospholipasen D - [kumulative Dissertation]
No full textAufgrund ihrer Reaktions- und Regioselektivität haben Phospholipasen eine bedeutende Rolle in der synthetischen Lipidchemie erlangt. Die vorliegende Arbeit widmet sich der Charakterisierung enzymatischer Phospholipid-Transformationen und stellt neue Ansätze zur Auffindung von Phospholipasen mit erweitertem biokatalytischem Potential vor. Der Austausch des Kopfgruppenalkohols gegen Ethanolamin und Analoga durch Phospholipasen D (PLDs) wurde zur Synthese artifizieller Phospholipide genutzt. Die Reaktion diente zudem - in Kombination mit einem neuartigen Bestimmungsverfahren für Phosphatidsäure - zur Entwicklung eines high-throughput-Assays, welcher das Screening nach effizienten PLD-Enzymen ermöglicht. Ein Nachweis von Acylhydrolasen des Phospholipase A1 (PLA1)-Typs in Fruchtkörpern des Basidiomyceten Armillaria ostoyae stellte den Ausgangspunkt zur Gewinnung von vier neuen PLA1s dar, welche hinsichtlich ihrer katalytischen Eigenschaften und biologischen Funktion charakterisiert wurden.Reactions catalyzed by phospholipases are valuable tools in synthetic lipid chemistry because they proceed with high specificity. In this thesis, enzymatic phospholipid transformations and new approaches for the discovery of phospholipases with improved biocatalytic properties are described. The substitution of the phospholipid head group by ethanolamine and derivatives catalyzed by phospholipases D (PLDs) was used for the synthesis of a series of artificial phospholipids. Based on this reaction and a novel method for the determination of phosphatidic acid, a high-throughput assay for the screening for efficient PLD enzymes was developed. Purification of the high acylhydrolase activity found in fruiting bodies of the basidiomycete Armillaria ostoyae yielded four individual enzymes. The proteins which were assigned to the phospholipases A1 subfamily were characterized with respect to catalytic properties as well as their biological function.von Martin Dipp
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Schlussbericht zum Verwendungsnachweis zur Sondierungsphase des Projekts: "IBÖ06 - Protein-Tags zur Reinigung und Immobilisierung an neuartigen Trägermaterialien" (Acronym: ProMin)
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A Spectrophotometric Microtiterplate Assay to Determine the Transphosphatidylation Potential of Phospholipase D
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Can Climate Models Simulate the Observed Strong Summer Surface Cooling in the Equatorial Atlantic?
No full textVariability in the tropical Atlantic Ocean is dominated by the seasonal cycle. A defining feature is the migration of the inter-tropical convergence zone into the northern hemisphere and the formation of a so-called cold tongue in sea surface temperatures (SSTs) in late boreal spring. Between April and August, cooling leads to a drop in SSTs of approximately 5°. The pronounced seasonal cycle in the equatorial Atlantic affects surrounding continents, and even minor deviations from it can have striking consequences for local agricultures.
Here, we report how state-of-the-art coupled global climate models (CGCMs) still struggle to simulate the observed seasonal cycle in the equatorial Atlantic, focusing on the formation of the cold tongue. We review the basic processes that establish the observed seasonal cycle in the tropical Atlantic, highlight common biases and their potential origins, and discuss how they relate to the dynamics of the real world. We also briefly discuss the implications of the equatorial Atlantic warm bias for CGCM-based reliable, socio-economically relevant seasonal predictions in the region
