University of Konstanz

About: University of Konstanz is a education organization based out in Konstanz, Baden-Württemberg, Germany. It is known for research contribution in the topics: Population & Visualization. The organization has 12115 authors who have published 27401 publications receiving 951162 citations. The organization is also known as: University of Constance & Universität Konstanz.

Copper-mediated Lipid Peroxidation Processes in Photosynthetic Membranes

Abstract: The phytotoxic effect of Cu via the photosynthetic electron transport system was studied with isolated spinach chloroplasts. Cu(II) ions induce a light-driven peroxidation of membrane lipids leading to ethylene formation, the latter dominating over a concurrent ethane production. Seemingly, the hydroxyl radical originating from superoxide anion is the starting reactive O2 species. Cu ions inhibit photosynthetic electron transport and apparently catalyze the formation of hydroxyl radical and Fenton-type reactions that result in destruction of unsaturated membrane fatty acids. The concept on the mode of action of Cu(II) and Cu(I) ions in lipid peroxidation as presented here suggests the influence of Cu on different reactions. Two sites are in the photosynthetic redox system; Cu participates in two Fenton-type reactions and in the conversion of ethyl radical to ethylene and ethane.

Cohomological methods in transformation groups

Abstract: Preface 1. Equivalent cohomology of G-CW-complexes and the Borel construction 2. Summary of some aspects of rational homotopy theory 3. Localisation 4. General results on torus and p-torus actions 5. Actions on Poincare duality spaces Appendices References Indexes.

Global trade will accelerate plant invasions in emerging economies under climate change

Abstract: Trade plays a key role in the spread of alien species and has arguably contributed to the recent enormous acceleration of biological invasions, thus homogenizing biotas worldwide. Combining data on 60-year trends of bilateral trade, as well as on biodiversity and climate, we modeled the global spread of plant species among 147 countries. The model results were compared with a recently compiled unique global data set on numbers of naturalized alien vascular plant species representing the most comprehensive collection of naturalized plant distributions currently available. The model identifies major source regions, introduction routes, and hot spots of plant invasions that agree well with observed naturalized plant numbers. In contrast to common knowledge, we show that the ‘imperialist dogma,’ stating that Europe has been a net exporter of naturalized plants since colonial times, does not hold for the past 60 years, when more naturalized plants were being imported to than exported from Europe. Our results highlight that the current distribution of naturalized plants is best predicted by socioeconomic activities 20 years ago. We took advantage of the observed time lag and used trade developments until recent times to predict naturalized plant trajectories for the next two decades. This shows that particularly strong increases in naturalized plant numbers are expected in the next 20 years for emerging economies in megadiverse regions. The interaction with predicted future climate change will increase invasions in northern temperate countries and reduce them in tropical and (sub)tropical regions, yet not by enough to cancel out the trade-related increase.

Acyl-CoA dehydrogenases - a mechanistic overview

Abstract: Acyl-CoA dehydrogenases constitute a family of flavoproteins that catalyze the α,β-dehydrogenation of fatty acid acyl-CoA conjugates While they differ widely in their specificity, they share the same basic chemical mechanism of α,β-dehydrogenation Medium chain acyl-CoA dehydrogenase is probably the best-studied member of the class and serves as a model for the study of catalytic mechanisms Based on medium chain acyl-CoA dehydrogenase we discuss the main factors that bring about catalysis, promote specificity and determine the selective transfer of electrons to electron transferring flavoprotein The mechanism of α,β-dehydrogenation is viewed as a process in which the substrate αC-H and βC-H bonds are ruptured concertedly, the first hydrogen being removed by the active center base Glu376-COO– as an H+, the second being transferred as a hydride to the flavin N(5) position Hereby the pKa of the substrate αC-H is lowered from > 20 to ≈ 8 by the effect of specific hydrogen bonds Concomitantly, the pKa of Glu376-COO– is also raised to 8–9 due to the decrease in polarity brought about by substrate binding The kinetic sequence of medium chain acyl-CoA dehydrogenase is rather complex and involves several intermediates A prominent one is the molecular complex of reduced enzyme with the enoyl-CoA product that is characterized by an intense charge transfer absorption and serves as the point of transfer of electrons to the electron transferring flavoprotein These views are also discussed in the context of the accompanying paper on the three-dimensional properties of acyl-CoA dehydrogenases