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 & Membrane. The organization has 12115 authors who have published 27401 publications receiving 951162 citations. The organization is also known as: University of Constance & Universität Konstanz.

Benzenedithiol: A Broad-Range Single-Channel Molecular Conductor

Abstract: More than a decade after the first report of single-molecule conductance, it remains a challenging goal to prove the exact nature of the transport through single molecules, including the number of transport channels and the origin of these channels from a molecular orbital point of view. We demonstrate for the archetypical organic molecule, benzenedithiol (BDT), incorporated into a mechanically controllable break junction at low temperature, how this information can be deduced from studies of the elastic and inelastic current contributions. We are able to tune the molecular conformation and thus the transport properties by displacing the nanogap electrodes. We observe stable contacts with low conductance in the order of 10–3 conductance quanta as well as with high conductance values above ∼0.5 quanta. Our observations show unambiguously that the conductance of BDT is carried by a single transport channel provided by the same molecular level, which is coupled to the metallic electrodes, through the whole c...

Nuclear protein-coding genes support lungfish and not the coelacanth as the closest living relatives of land vertebrates

Abstract: The colonization of land by tetrapod ancestors is one of the major questions in the evolution of vertebrates. Despite intense molecular phylogenetic research on this problem during the last 15 years, there is, until now, no statistically supported answer to the question of whether coelacanths or lungfish are the closest living relatives of tetrapods. We determined DNA sequences of the nuclear-encoded recombination activating genes (Rag1 and Rag2) from all three major lungfish groups, the Australian Neoceratodis forsteri, the South American Lepidosiren paradoxa and the African lungfish Protopterus dolloi, and the Indonesian coelacanth Latimeria menadoensis. Phylogenetic analyses of both the single gene and the concatenated data sets of RAG1 and RAG2 found that the lungfishes are the closest living relatives of the land vertebrates. These results are supported by high bootstrap values, Bayesian posterior probabilities, and likelihood ratio tests.

Life by a new decarboxylation-dependent energy conservation mechanism with Na as coupling ion.

Abstract: We report here a new mode of ATP synthesis in living cells The anaerobic bacterium Propionigenium modestum gains its total energy for growth from the conversion of succinate to propionate according to: succinate + H(2)O --> propionate + HCO(3) ( big up tri, openG' = -206 kJ/mol) The small free energy change of this reaction does not allow a substrate-linked phosphorylation mechanism, and no electron transport phosphorylation takes place Succinate was degraded by cell-free extracts to propionate and CO(2) via succinyl-CoA, methyl-malonyl-CoA and propionyl-CoA This pathway involves a membrane-bound methylmalonyl-CoA decarboxylase which couples the exergonic decarboxylation with a Na ion transport across the membrane The organism also contained a membrane-bound ATPase which was specifically activated by Na ions and catalyzed and transport of Na ions into inverted bacterial vesicles upon ATP hydrolysis The transport was abolished by monensin but not by the uncoupler carbonylcyanide-p-trifluoromethoxy phenylhydrazone Isolated membrane vesicles catalyzed the synthesis of ATP from ADP and inorganic phosphate when malonyl-CoA was decarboxylated and malonyl-CoA synthesis from acetyl-CoA when ATP was hydrolyzed These syntheses were sensitive to monensin which indicates that Na functions as the coupling ion We conclude from these results that ATP synthesis in P modestum is driven by a Na ion gradient which is generated upon decarboxylation of methylmalonyl-CoA

Uncovering Culture in Organizations

Abstract: There is a large interest in organization culture, yet only a few empirical studies address the topic. This fact may be due to the lack of appropriate research methods able to uncover such an elusi...

Functional expression of the Erwinia uredovora carotenoid biosynthesis gene crtl in transgenic plants showing an increase of beta-carotene biosynthesis activity and resistance to the bleaching herbicide norflurazon.

Abstract: Among the enzymes involved in carotenoid biosynthesis, phytoene desaturase is considered to be a rate-limiting enzyme in this pathway and is also the target of many bleaching herbicides. This enzyme shows diversity concerning its function and amino acid homology among various organisms. The phytoene desaturase gene crtl of Erwinia uredovora was expressed, the 5'-region of which was fused to the sequence for the transit peptide of a pea Rubisco small subunit, in tobacco plants under the control of the CaMV 35S promoter. This chimeric gene product was targeted into chloroplasts and processed in the transgenic plants. The production and processing of the corresponding protein could be demonstrated by Western blotting. Immunogold localization showed that the location of the gene product Crtl was preferentially in the thylakoids. A radioactive labeling study using the leaves demonstrated enhanced activity for the synthesis of beta-carotene. In addition, the transgenic tobacco acquired elevated resistance to the bleaching herbicide norflurazon.