04 Fakultät Energie-, Verfahrens- und Biotechnik
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Item Open Access Air pollution control strategies : a comparative analysis for Poland and the Federal Republic of Germany(1990) Balandynowicz, Henryk W.; Cofala, Janus; Parczewski, Zygmunt; Schmid, Günter; Voß, AlfredThe study has four main objectives, namely: - to describe and compare the energy and environmental situation in Poland and in the FRG, - to develop and compare energy-environment models for Poland and for the FRG, - to elaborate emission control strategies for the next twenty years for Poland and for the FRG, - to perform a comparative analysis. The study refers to two countries being very different in many aspects. Different levels of development and a different economic system are basic causes of differences concerning the way in which energy is used.Item Open Access Extraordinary biological membrane structures resulting from different local membrane curvatures(1992) Meyer, Helmut W.; Hülser, Dieter F.The bilayer arrangement of amphiphilic molecules is not only the basic structure of rather flat biological membranes, but also of regularly curved bilayers in most cubic phase structures. The basis of these cubic phase structures are infinite periodical minimal surfaces (IPMS). Extraordinary biological membrane structures resembling such IPMS were found as periodically curved bilayers in areas of the plasma membrane in a Streptomyces strain and in liposomes prepared from its extracted lipids. This structure consists of a transition of convex to concave curvatures and vice versa. A structure with curvatures in one direction only was observed in vacuolar membranes of yeast cells with a genetic defect. Our electron microscopical analysis of freeze fractured membranes of these cells revealed not only fully invaginated but also flat particle-free areas which were mainly circularly shaped, some elongated areas, however, were also present. In addition, sometimes periodical arrangements were detected which obviously are not related to IPMS structures. Both structures, however, indicate a high proportion of wedge-shaped lipid molecules in the bilayer.Item Open Access A systems biology approach to analyse leaf carbohydrate metabolism in Arabidopsis thaliana(2011) Henkel, Sebastian; Nägele, Thomas; Hörmiller, Imke; Sauter, Thomas; Sawodny, Oliver; Ederer, Michael; Heyer, Arnd G.Plant carbohydrate metabolism comprises numerous metabolite interconversions, some of which form cycles of metabolite degradation and re-synthesis and are thus referred to as futile cycles. In this study, we present a systems biology approach to analyse any possible regulatory principle that operates such futile cycles based on experimental data for sucrose (Scr) cycling in photosynthetically active leaves of the model plant Arabidopsis thaliana. Kinetic parameters of enzymatic steps in Scr cycling were identified by fitting model simulations to experimental data. A statistical analysis of the kinetic parameters and calculated flux rates allowed for estimation of the variability and supported the predictability of the model. A principal component analysis of the parameter results revealed the identifiability of the model parameters. We investigated the stability properties of Scr cycling and found that feedback inhibition of enzymes catalysing metabolite interconversions at different steps of the cycle have differential influence on stability. Applying this observation to futile cycling of Scr in leaf cells points to the enzyme hexokinase as an important regulator, while the step of Scr degradation by invertases appears subordinate.Item Open Access Incorporation of 14C-photosynthate into major chemical fractions of leaves and bark of Ceratonia siliqua L. at different seasons(1993) Diehl, Susanne; Kull, Ulrich; Diamantoglou, StergosParts of branches of Ceratonia siliqua (L.) were exposed to 14CO2 for 3h during the growth period in April, after termination of growth (end of May), in the summer drought period (August) and in the cool winter (February). Twigs were harvested immediately after the end of the feeding period as well as after 48 and 144h. Simultaneously with the last harvest of exposed plant parts, controls from outside the exposure-chamber were also gathered. The total 14C-incorporation into leaves and bark as well as the labelling and contents of soluble sugars, starch, total lipids and other precipitable soluble compounds were determined. Total 14C-incorporation immediately after termination of 14CO2 application is a measure of the assimilation rate; it was high and nearly identical in April and May, but low (only about 5% of the April value) in summer ;and winter. The incorporation of 14C into soluble structural components was highest in April. Uptake of total 14C and labelling of soluble compounds during the 6-day period of the experiments show that metabolic rates were very low in summer but high during spring. The turnover of soluble compounds in February was remarkably high regarding the low CO2-fixation rate. The labelling of soluble sugars in leaves decreased in all experiments; the specific activity of starch remained rather stable. The incorporation of 14C into the lipid fraction was weak in all seasons and significant alterations took place only during the growing period. Variation in assimilation rates of Ceratonia at different seasons was comparable to that found for other mediterranean species using IRGA methods. There was no indication that lipids in Ceratonia are true storage compounds and participate in cyclic metabolic processes preventing stress effects. The weak turnover of lipids leads to the conclusion that maintenance costs for these compounds, as calculated by Merino et al. (1984). perhaps are too high, at least for Ceratonia. Our results do not suggest a specific adaptation of the metabolism of storage compounds to summer drought in Ceratonia.Item Open Access Transduction of chemical signals in dictyostelium cells(1984) Gerisch, Günther; Tsiomenko, Arnold; Stadler, Joachim; Claviez, Michael; Hülser, Dieter F.; Rossier, ClaudeThree different functions of cyclic AMP in D discoideum are known: (1) cAMP acts as a chemoattractant during cell aggregation, (2) it controls cell development, particularly the acquisition of aggregation competence, and (3) it is involved in terminal cell differentiation. In this report we will concentrate on the functions 1 and 2 of cAMP. Chemotaxis requires the recognition of concentration gradients in the environment by attractant binding to cell surface receptors, the processing of signals from the receptors to the contractile system of the cells, extension of pseudopods at one part, and contraction at other parts of the cells in accord with the external gradient. One pathway of signal processing from the receptors to the contractile system involves the regulation of a myosin kinase. The control of development up to aggregation competence is largely dependent on the temporal pattern of cAMP application: Only repetitive pulses enhance development. This effect has been studied using the expression of a membrane glycoprotein called contact site A as a differentiation marker.Item Open Access Energieversorgungsstrategien für die Bundesrepublik Deutschland(1983) Terhorst, Wilhelm; Voß, AlfredMit der Darstellung der wesentlichen Ergebnisse einer Untersuchung der Perspektiven der Energieversorgung des Verkehrs im energiewirtschaftlichen Kontext, sollte das Ziel verfolgt werden, aufzuzeigen, daß trotz der bestehenden Unsicherheiten brauchbare Hilfen für die im Bereich der Energiewirtschaft und Energiepolitik anstehenden strategischen Entscheidungen gegeben werden können. Dabei ist die Erstellung von "Prognosen" im eigentlichen Sinne des Wortes wenig hilfreich, sondern es müssen unter expliziter Berücksichtigung von Unsicherheit und Ungewißheit alternative Entwicklungen von Energienachfrage und -versorgung analysiert werden, um diejenigen Entscheidungen und Maßnahmen zu identifizieren, die heute zur Sicherung einer kostengünstigen und umweltverträglichen Energieversorgung einzuleiten sind.Item Open Access A systems biology approach to dynamic modeling and inter-subject variability of statin pharmacokinetics in human hepatocytes(2011) Bucher, Joachim; Riedmaier, Stephan; Schnabel, Anke; Marcus, Katrin; Vacun, Gabriele; Weiss, Thomas S.; Thasler, Wolfgang E.; Nüssler, Andreas K.; Zanger, Ulrich M.; Reuss, MatthiasBackground The individual character of pharmacokinetics is of great importance in the risk assessment of new drug leads in pharmacological research. Amongst others, it is severely influenced by the properties and inter-individual variability of the enzymes and transporters of the drug detoxification system of the liver. Predicting individual drug biotransformation capacity requires quantitative and detailed models. Results In this contribution we present the de novo deterministic modeling of atorvastatin biotransformation based on comprehensive published knowledge on involved metabolic and transport pathways as well as physicochemical properties. The model was evaluated on primary human hepatocytes and parameter identifiability analysis was performed under multiple experimental constraints. Dynamic simulations of atorvastatin biotransformation considering the inter-individual variability of the two major involved enzymes CYP3A4 and UGT1A3 based on quantitative protein expression data in a large human liver bank (n = 150) highlighted the variability in the individual biotransformation profiles and therefore also points to the individuality of pharmacokinetics. Conclusions A dynamic model for the biotransformation of atorvastatin has been developed using quantitative metabolite measurements in primary human hepatocytes. The model comprises kinetics for transport processes and metabolic enzymes as well as population liver expression data allowing us to assess the impact of inter-individual variability of concentrations of key proteins. Application of computational tools for parameter sensitivity analysis enabled us to considerably improve the validity of the model and to create a consistent framework for precise computer-aided simulations in toxicology.Item Open Access Die Fettsäurenzusammensetzung der verseifbaren Lipide aus Nadeln von Taxus baccata L. an Standorten unterschiedlicher Immissionsbelastung(1979) Höllwarth, Michael; Kull, UlrichThe fatty acid composition of saponifiable lipids in needles of Taxus baccata grown in three areas with different immission-stresses (forest, park within the town, place of high traffic-density in the city), was measured by gas-liquid-chromatography of methyl esters during the course of a year. No distinct periodicity of fatty acids during the year was found, but there were characteristic differences of the fatty acid patterns from the different places, with regard mostly to palmitic, linoleic, and linolenic acids. At places with higher immission-stresses the percentage of saturated fatty acids is reduced and that of linoleic and linolenic acids increased. Similar effects were induced when twigs of Taxus were fumigated with 0.5 ppm SO 2. Distinct effects were also measured after fumigation with car-exhaust-gas.Item Open Access Kohlenhydratgehalte und osmotische Verhältnisse bei Blättern und Rinden von Arbutus unedo L. und Arbutus andrachne L. im Jahresgang(1984) Diamantoglou, Stergos; Kull, UlrichIn den letzten Jahren wurden an den beiden Arbutus-Arten des Mittelmeergebiets mehrfach ökophysiologische Untersuchungen durchgeführt, insbesondere nachdem sich gezeigt hatte, daß sie sich beim mittäglichen Spaltenschluß unterschiedlich verhalten. Befunde zur Speicherungsphysiologie liegen von verschiedenen Ericaceen Mitteleuropas vor; daher schien es von Interesse, die mediterrane Gattung Arbutus damit zu vergleichen. Über den Lipidhaushalt der beiden Arbutus-Arten wurde bereits berichtet; dabei zeigte sich, daß im Gegensatz zu verschiedenen mitteleuropäischen Ericaccen und zu anderen mediterranen Sklerophyllen in Arbutus keine sehr starke Lipidakkumulation stattfindet. Wie bei anderen Sklerophyllen liegt das Minimum des Lipidgehaltes in der Zeit der sommerlichen Dürre. Wir berichten hier über die Jahresperiodik der Kohlenhydrate und des Energiehaushaltes der Reservestoffe in Blättern und Rinden der beiden Arbutus-Arten.Item Open Access Enrichment of dibenzofuran utilizing bacteria with high co-metabolic potential towards dibenzodioxin and other anellated aromatics(1989) Strubel, Volker; Rast, Hans G.; Fietz, Walter H.; Knackmuss, Hans-Joachim; Engesser, Karl-HeinrichDibenzofuran degrading bacteria were enriched from various environmental sources. A mutualistic mixed culture of strain DPO 220 and strain DPO 230 was characterized. Strain DPO 220 alone showed limited growth with dibenzofuran as sole source of carbon and energy (td ≥ 4.5 h). A labile degradation product, C12H10O5, and salicylate were isolated from the culture fluid. Salicylate was found to be a central intermediate of DBF-degradation.Strain DPO 220 co-metabolized a wide range of anellated aromatics as well as heteroaromatics. High rates of co-oxidation of dibenzodioxin demonstrate analogue-enrichment to be a powerful technique for selecting enzymatic activities for otherwise non-degradable substrates.