Untersuchungen über den osmotischen Wert polyploider Pflanzen

Zusammenfassung In der Mehrzahl der untersuchten Fälle (insgesamt über 1000 Einzelmessungen) wurden die osmotischen Werte der Tetraploiden niedriger gefunden als die der Diploiden, doch sind die Unterschiede im allgemeinen gering. Junge Pflanzen hatten immer niedrigere 4n-Werte; bei alten Pflanzen und bei Pflanzen unter extremen Kulturbedingungen waren aber vielfach die Werte der 4n höher. Es wird die Hypothese aufgestellt, daß niedrigere osmotische Werte der Tetraploiden den Normalzustand darstellen, daß aber die Polyploiden wie in anderen Eigenschaften, so auch in ihrer Osmotik variabler sind und unter dem Einfluß von Außen-bedingungen ihre osmotischen Werte stärker modifizieren.Unter physiologischen Zwangsbedingungen (Trockenkultur, Pfropfungen) wurde an den Tetraploiden eine unter den gegebenen Verhältnissen zweckmäßige Erhöhung ihrer osmotischen Werte über das Niveau der 2n beobachtet. Gegen Trockenklima erwiesen sich die untersuchten Tetraploiden im Vergleich mit den Diploiden resistenter.Irgendwelche artspezifischen Eigentümlichkeiten konnten im Rahmen der untersuchten Pflanzen nicht festgestellt werden.Mit 6 Textabbildungen.     

Anwendung der automatisierten Festphasenextraktion bei der Bestimmung von Ochratoxin A

For some foodstuffs, determination of the mycotoxin ochratoxin A (OTA) requires time consuming clean up by means of solid phase extraction (SPE). Therefore a system for automated SPE was tested for cleaning up roasted coffee as a possible way of shortening preparation time. Validation of the method in accordance to the so called “Concept '98” led to a LOD of 0.2 μg/kg and a recovery rate of 92%. By using the described procedure with samples of roasted coffee the OTA contents varied between the LOD and 3.4 μg/kg. This method was also used to determine ochratoxin A in liquorice roots, ginger and valerian.

Presented at the 26^th Mykotoxin Workshop in Herrsching, Germany, May 17–19, 2004     

Phosphorylation of Chromosomal Proteins in Resting and Wounded Potato Tuber Tissues

Wounding of quiescent white potato tuber tissue enhances chromatin-boundprotein phosphokinase activity, which exhibits two distinctphases during wound-healing. A moderate activation of the enzymesup to 20 hr after injury is followed by a dramatic increasein activity with a peak at 50 hr. This time-course resemblesthat of chromatinbound DNA-dependent RNA polymerase with a peakin activity at about 48 hr after wounding. The kinases phosphorylateendogenous proteins as well as added histones, phosvitin andcasein. The incorporated phosphate is stable under standardassay conditions, indicating the absence of protein phosphatases.Sensitivity of the incorporated phosphate toward trypsin andalkali, but not DNase, RNase, hydroxylamine or succinic acidpoints to seryl- and threonyl-bonds and proteins as acceptormolecules. Kinases from resting tissues are only weakly stimulatedeven by 100 mM MgCl₂, those from wounded tissues exhibit pronouncedMg^$$-optima at 5–10 mM with endogenous proteins, phosvitinand casein and 50 mM MgCl₂ with histones. Wounding also increasesthe sensitivity of the kinases toward p-hydroxymercuribenzoate. Chromatin preparations from both resting and wounded tissuescontain about 40 protein bands after polyacrylamide disc gelelectrophoresis. In vitro phosphorylation of these proteinsin chromatin from quiescent tissues is comparably low and uniform.Wounding induces changes in the protein and phosphorylationpattern with a general enhancement of phosphorylative capacityand preferential phosphorylation of low molecular weight proteins. (Received August 10, 1981; Accepted November 18, 1981)     

Continuous coenzyme dependent stereoselective synthesis of sulcatol by alcohol dehydrogenase

Summary 6-methyl-5-hepten-2-one was reduced to sulcatol ((+)-6-methyl-5-hepten-2-ol) by using alcohol dehydrogenase fromThermoanaerobium brockii in a continuous process. The cofactor NADP(H) was retained by a charged UF-membrane and regenerated by oxidation of isopropanol to acetone. Use of native NADP in a charged UF-membrane reactor proved to be superior to use of PEG coupled NADP in a uncharged UF-membrane reactor.     

Immunohistological detection of Saruplase (recombinant single-chain urokinase-type plasminogen activator) in normal rat tissue

Summary Saruplase — a recombinant single-chain urokinase-type plasminogen activator was identified immunohistochemically in normal rat tissue after intravenous administration by means of a polyclonal antibody. For this purpose, rat tissues were fixed in various ways (liquid nitrogen, ethanol, formaldehyd solution). Saruplase could be detected by the PAP method, streptavidinbiotin system and indirect immunofluorescence in the kidney (proximal tubule), liver (hepatocytes, Kupffer cells) and spleen (reticular cells). Saruplase was not localized in the rat endothelium. It is discussed that the ratspecific receptors for urokinase-type plasminogen activator on endothelial cells cannot bind Saruplase due to the extreme species specificity.