Identification by combined gas chromatography-mass spectrometry of phaseic acid and dihydrophaseic acid and characterization of further abscisic acid metabolites in pea seedlings.

Seven day old seedlings of Pisum sativum L., cv. Kleine Rheinländerin, were wilted for 3 days. After partially removing the roots, they were rewatered and at the same time radioactive abscisic acid([1-(14)C]ABA, spec. activity 1.7·10(8)d s(-1)mmol(-1)) was applied for 1 h via the xylem of the roots. After 24 h, 4 days, and 12 days the seedlings were extracted and the metabolites of ABA were analyzed by means of thin-layer and gas chromatography in combination with mass spectrometry, autoradiography, and scintillation counting. Phaseic acid (PA) and dihydrophaseic acid (DPA) were identified as metabolites of ABA. The presence of another ABA-metabolite was also demonstrated. From its mass spectrum it has been postulated that this metabolite is 4'-desoxy-ABA. In addition to these substances, several other metabolites, which are more polar than ABA and its known degradation products, were present in the seedlings. The quantity and number of these unknown metabolites increased with time.

[Primary oxidation mechanisms in degradation of aliphatic hydrocarbons by bacterial enzyme systems (author's transl)]. / Primäre Oxydationsmechanismen beim Abbau aliphatischer Kohlenwasserstoffe durch bakterielle Enzymsysteme

The bacterial dissimilation of aliphatic hydrocarbons is catalysed by a monooxygenase mechanism with incorporation of molecular oxygen. Numerous publications have shown the cytochrome P 450-dependent hydroxylation of hydrocarbons, but there is considerably less information of hemo-protein-independent hydroxylations by alkanhydroxylases. In a marine Pseudomonad we found a system sensitive to cyanide: The oxygenase could be divided into three protein fractions. A cytochrome P 450 type spectrum was not detected. The NADH-dependent hydroxylation of n-decane can be activated by Mg2+ and Fe2+ ions. A noncompetitive product inhibition occurs which deserves special attention. An alcohol-dehydrogenase is closely associated with the oxygenase system by a kind of multienzyme-complex. Studies on kinetics and substrate specificity of this enzyme show an inhibition by excess substrate increasing with the chain length of the alcohols. The whole complex (alkanhydroxylase, alcoholdehydrogenase and aldehyddehydrogenase) is induceable by bacterial growth on alkanes, primary alcohols and fatty acids as sole carbon source.

[Accumulation of salt in the embryo of Rhizophora mangle L. developing on the mother plant]. / Die Salzspeicherung im Keimling von Rhizophora mangle L. während der Entwicklung auf der Mutterpflanze.

1. Accumulation of Cl, Na, K, Ca, and N in various stages of the growing embryo of Rhizophora mangle has been analysed during the development on the mother plant. 2. The determination has been carried out for 7 stages of development and for the following tissues: bottom of flower, pericarp, testa, cotyledonary body, and hypocotyl. Hypocotyl was divided into further stages. 3. Contents of Cl increase in the course of development in all tissues except testa. Contents of Cl also agree with decreasing osmotic value between pericarp and testa found by WALTER and PANNIER. 4. Contents of Na, K, and Ca partly increase and partly decrease in the various tissues and stages of age. While contents of Na in the hypocotyl are decreasing from base to top, contents of K are increasing in the same direction. 5. Contents of N increase in the bottom of the flower and cotyledonary body and decrease in the other tissues during development. 6. Changes in the contents of the analysed elements indicate that there is a barrier between cotyledonary body and the periphery tissues.