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.

A novel type of energy metabolism involving fermentation of inorganic sulphur compounds

Abstract: Two processes are known whereby energy is conserved during substrate metabolism in heterotrophic organisms: respiration and fermentation. Both involve oxidation–reduction reactions; but whereas in respiration the electrons are transferred from substrate to an electron acceptor, in fermentation part of the substrate molecule itself accepts the electrons. Fermentation is therefore a type of disproportionation, and does not involve an overall change in oxidation state of the substrate. All fermentative substrates known to date are organic molecules. We have discovered a novel type of fermentation involving the disproportionation of inorganic sulphur compounds in certain sulphate-reducing bacteria1. Initially discovered in a newly isolated sulphate-reducing bacterium, Desulfovibrio sulfodismutans, the capacity for disproportionation of sulphur compounds is also found in some known sulphate-reducing bacteria and various bacteria isolated from freshwater, brackish or marine sediments.

Oxidation of methane in the oxic surface layer of a deep lake sediment (Lake Constance)

Abstract: Oxygen and methane metabolism were measured using intact sediment cores taken from the profundal (147 m depth) of Lake Constance. Vertical O2 profiles were determined with O2 microelectrodes. Oxygen penetrated into the sediment to a depth of about 1.5–2.5 mm. The potential O2 consumption rates did not differ significantly between various sampling dates and sampling sites on the deep lake floor. Dissolved CH4 increased linearly between 2 and 20 cm depth resulting linearly between 2 and 10 cm depth resulting in a diffusive flux of about 369 μmol CH4 m−2 d−1 into the oxic sediment surface layer as calculated form Fick's law. Activities of methanogenesis were measured in slurried sediment subcores. Integration of these activities over 2–10 cm depth indicated a total production of 1400 μmol CH4 m−2 d−1. Incubation of intact sediment cores overlaid with O2-containing hypolimnetic water resulted in a flux of about 35 μmol CH4 m−2 d−1 out of the sediment into the water. However, as soon as dissolved O2 had decreased to less than about 18 μM O2, the CH4 flux abruptly increased to about 480 μmol CH4 m−2 d−1. This anaerobic CH4 flux was similar to the CH4 production estimated from the vertical distribution of dissolved CH4, but was much higher than the CH4 flux measured under aerobic conditions. Therefore, about 93% of the produced CH4 must have been oxidized within the oxic sediment surface layer by aerobic methanotrophic bacteria which consumed about > 9% of the O2 flux into the sediment.

Voronoi treemaps for the visualization of software metrics

Abstract: In this paper we present a hierarchy-based visualization approach for software metrics using Treemaps. Contrary to existing rectangle-based Treemap layout algorithms, we introduce layouts based on arbitrary polygons that are advantageous with respect to the aspect ratio between width and height of the objects and the identification of boundaries between and within the hierarchy levels in the Treemap. The layouts are computed by the iterative relaxation of Voronoi tessellations. Additionally, we describe techniques that allow the user to investigate software metric data of complex systems by utilizing transparencies in combination with interactive zooming.

Osmotic regulation of rpoS-dependent genes in Escherichia coli.

Abstract: The rpoS gene, which encodes a putative alternative sigma factor (sigma S), is essential for the expression of a variety of stationary-phase-induced genes as well as for stationary-phase-specific multiple-stress resistance. As previously shown for the otsA and otsB genes (R. Hengge-Aronis, W. Klein, R. Lange, M. Rimmele, and W. Boos, J. Bacteriol. 173:7918-7924, 1991), we demonstrate here that additional rpoS-controlled genes (bolA, csi-5) as well as at least 18 proteins on two-dimensional O'Farrell gels could be induced in growing cells by osmotic upshift via an rpoS-dependent mechanism. Also, rpoS-dependent thermotolerance and resistance against hydrogen peroxide could be osmotically stimulated. In contrast, the expression of glgS, while exhibiting strong stationary-phase induction, was only weakly increased by elevated osmolarity, and several rpoS-dependent proteins previously identified on two-dimensional gels were not osmotically induced. During osmotic induction of rpoS-dependent genes, rpoS transcription and the level of sigma S remained unchanged. We conclude that osmotically regulated genes represent a subfamily within the rpoS regulon that requires differential regulation in addition to that provided by sigma S.