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.

Peroxynitrite and vascular endothelial dysfunction in diabetes mellitus.

Abstract: Macro and microvascular diseases are the principal causes of morbidity and mortality in patients with type I and II diabetes mellitus. Growing evidence implicates reactive nitrogen species (RNS), s...

Binding of glycolytic enzymes to structure proteins of the muscle.

Abstract: 1 Only 60–70% of the total activity of aldolase can be extracted from rat or rabbit muscle homogenates with aqueous solutions of relatively low ionic strength. The extraction of aldolase from muscle tissue is only complete in aqueous solutions with an ionic strength greater than 0.2. The fraction of aldolase which is set free at high ionic strength is not located within a special cellular compartment but is present in a bound form and is desorbed in dependence of the ionic strength of the extraction medium. 2 F-actin, myosin, acto-myosin and stroma-protein were prepared from rabbit muscle and the binding of aldolase to each of these structure proteins was studied in vitro. A completely reversible binding of aldolase to F-actin, actomyosin, myosin and stroma protein was found. F-actin possesses by far the highest binding capacity. 100% of the enzyme is bound when 1 mg of aldolase is added to 1 mg of highly purified F-actin. Under identical experimental conditions acto-myosin binds 40%, myosin 25%, and stroma protein only 15% of the aldolase activity. 3 A modified Langmuir isotherm is derived, and the analytical evaluation supports the assumption that the binding of aldolase to F-actin occurs at two different binding sites. 4 The binding of aldolase to F-actin and other structure proteins depends on the ionic strength. At 150 mM KCl, a complete desorption occurs, and 50% of the actin-bound aldolase is set free at a concentration of 80 mM KCl. The sigmoid shape of the desorption curve indicates a cooperative mechanism of the binding phenomenon. 5 Within the physiological range, the pH does not influence the binding of aldolase to F-actin. 6 Similar to aldolase, glyceraldehydephosphate dehydrogenase is bound to F-actin, and under the experimental conditions, 1 mg of F-actin binds up to 1.2 mg of glyceraldehydephosphate dehydrogenase. 7 Studies with a purified preparation of myogen reveal that also fructose-6-phosphate kinase, and in a lower degree phosphoglycerate kinase, pyruvate kinase and lactate dehydrogenase can be adsorbed to F-actin. No binding occurs in the case of creatine kinase. 8 The possible significance of the binding phenomenon is discussed with respect to the location of the Embden-Meyerhof system at the site of the actin filaments within the isotropic zones of the cross-striated muscle fiber.

Diversity within cyanobacterial mat communities in variable salinity meltwater ponds of McMurdo Ice Shelf, Antarctica

Abstract: Summary This study investigated the diversity of cyanobacterial mat communities of three meltwater ponds – Fresh, Orange and Salt Ponds, south of Bratina Island, McMurdo Ice Shelf, Antarctica. A combined morphological and genetic approach using clone libraries was used to investigate the influence of salinity on cyanobacterial diversity within these ecosystems without prior cultivation or isolation of cyanobacteria. We were able to identify 22 phylotypes belonging to Phormidium sp., Oscillatoria sp. and Lyngbya sp. In addition, we identified Antarctic Nostoc sp., Nodularia sp. and Anabaena sp. from the clone libraries. Fresh (17 phylotypes) and Orange (nine phylotypes) Ponds showed a similar diversity in contrast to that of the hypersaline Salt Pond (five phylotypes), where the diversity within cyanobacterial mats was reduced. Using the comparison of identified phylotypes with existing Antarctic sequence data, it was possible to gain further insight into the different levels of distribution of phylotypes identified in the investigated cyanobacterial mat communities of McMurdo Ice Shelf.