The importance of the terminal hemi-acetal group for the ionophoric properties of nigericin

Opening of the terminal hemi-acetal in dihydronigericin drastically reduces the ionophoric properties of nigericin and dehydroxymethylnigericin with 6 intact heterocycles. This is shown by 2 complementary methods, first with a liquid membrane electrode system, secondly by testing their ionophoric activities in rat liver mitochondria.     

The importance of the forecast

Careful forecasts, as accurate as possible, are central to the successful implementation of policy. There are fundamental reasons why policy makers cannot ‘play by ear’, adjusting policy quickly to each unexpected deviation in economic outcomes. Specific incidents are described where economic policy went awry because of faulty forecasts. The policy process is described in detail to show precisely where the forecast enters. Forecasting as a validation tool for establishing credibility in policy formation is analysed and discussed. Some estimated measure of forecast accuracy is presented, together with commentary on the necessary degrees of precision for successful implementation of policy.     

Studies by the newt test on the possible importance of conjugated double-bonds and trans-isomerization for carcinogenic properties of lipids

Zusammenfassung Mittels der Salamander-Schnell-methode für Karzinogen-Prüfung wurde eine Reihe von Fettprodukten und verwandten Verbindungen untersucht. Äthylelaidat erwies sich als unwirksam, während Vitamin A, Ergosterol, Holzöl und konjugiertes Äthyllinoleat wirksam waren. Die Ergebnisse weisen auf eine grössere Bedeutung der konjugierten Doppelbindungen hin, während der quantitative Vergleich zeigt, dass auch andere Aspekte der chemischen Struktur von Bedeutung sein können.

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This work was supported by a grant from the Danish Anti-Cancer League.     

The importance of extracellular calcium for acetylcholine-evoked salivary secretion

Zusammenfassung 5 min nach Beginn der Perfusion der Submandibularisdrüse der Katze mit einer kalziumfreien Flüssigkeit ist die Acetylcholin-induzierte Sekretionsrate nich reduziert, während dieselbe 5 min nach Einführen einer Na-freien Saccharoselösung blockiert ist. Dies zeigt, dass der Sekretionsprozess nicht durch Einströmen von Ca aus dem Extrazellulär- in den Intrazellulärraum ausgelöst wird.

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The technical assistance ofB. Lynderup andG. Pedersen is gratefully acknowledged.     

The importance of autoplastically transplanted pituitaries for survival and for regeneration of adultTriturus

Résumé Une hypophyse greffée autoplastiquement dans la chambre antérieure de l'il, dans lemanus ou dans letarsus s'est avérée capable de remplacer l'hypophysein situ dans son action sur la régénération et la survie chez le Triton, à condition que s'établisse une vascularisation satisfaisante du greffon et que la durée de l'expérience ne dépasse pas plusieurs mois.     

The importance of extracellular sodium and potassium for acetylcholine-evoked salivary secretion

Zusammenfassung Es wird gezeigt, dass die Speichelsekretionsrate der perfundierten SubmandibulardrÜse der Katze stark von der Natriumkonzentration im Perfusat abhängt. Die Sekretionsrate wird erhöht bei Perfusion mit kaliumfreier Lösung und reduziert während der Perfusion mit Lösungen erhöhter Kaliumkonzentrationen. Es ist möglich, dass ein durch Acetylcholin induzierter Natriumstrom in die Azinarzellen hinein den Sekretions mechanismus aktiviert.

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With the technical assistance of G.Pedersen.     

The importance of microbiology in waste management

Until a hundred years ago, the waste products from human activities were returned into the environment and underwent the biosphere's natural elimination processes without there being any long-term charge on the environment. During the last century, the increase in the amount of refuse has been accompanied by a decrease in its quality, mainly due to the production and dispersal of heavy metals and xenobiotic compounds. Both useful and noxious microbial processes have been underestimated in applied research in the field of waste management which, until now, has dealt mainly with artificial technologies. This paper presents some examples of microbiological processes occurring in waste treatment, particularly dumping, waste incineration, composting and biomethanization.     

The N-acyl group of oxonitine

Zusammenfassung Das Oxonitin, welches durch Oxydation von Aconitin mit KMnO₄ entsteht, ist ein Gemisch des N-Acetyl- und N-Formyl-Derivats.     

The functional importance of co-evolving residues in proteins

Computational approaches for detecting co-evolution in proteins allow for the identification of protein–protein interaction networks in different organisms and the assignment of function to under-explored proteins. The detection of co-variation of amino acids within or between proteins, moreover, allows for the discovery of residue–residue contacts and highlights functional residues that can affect the binding affinity, catalytic activity, or substrate specificity of a protein. To explore the functional impact of co-evolutionary changes in proteins, a combined experimental and computational approach must be recruited. Here, we review recent studies that apply computational and experimental tools to obtain novel insight into the structure, function, and evolution of proteins. Specifically, we describe the application of co-evolutionary analysis for predicting high-resolution three-dimensional structures of proteins. In addition, we describe computational approaches followed by experimental analysis for identifying specificity-determining residues in proteins. Finally, we discuss studies addressing the importance of such residues in terms of the functional divergence of proteins, allowing proteins to evolve new functions while avoiding crosstalk with existing cellular pathways or forming reproductive barriers and hence promoting speciation.     

The importance of radioactivity in geoscience and mining

Almost simultaneously with Roentgen rays, natural radioactivity was discovered. Its investigation led to important fundamentals of the geosciences: petrophysics, terrestrial heat flow, isotope geology, and absolute geological chronology. In applied geophysics and geology, exploration of radioactive ores and of tectonic faults, and radiometric well loggings, are used. Production of radioactive water and mining for uranium ores are discussed, including their development (especially in the Saxon ore mountains) and the consequences on health (radon in underground air and houses). Disposal of radioactive waste is touched on briefly.     

The physiological and nutritional importance of dietary fibre

Summary Fibrous material is an integral part of the daily diet, and it exerts direct physiological effects throughout the gastrointestinal tract, in addition to affecting metabolic activities more indirectly. The interplay of these effects is responsible for the presumed desirable influence of fibre on weight regulation, carbohydrate and lipid metabolism, and on colon function. Numerous mechanisms of action have been identified which are related to the type and the physicochemical nature of the fibre. This review concentrates mainly on the serum cholesterol-lowering effect of dietary fibre, its colonic fermentation, and finally on some possible adverse effects that one should be aware of when consuming high amounts of dietary fibre.     

A tale of tails: deciphering the contribution of terminal tails to the biochemical properties of two Dps proteins from Streptomyces coelicolor

Dps proteins are members of an extensive family of proteins that oxidise and deposit iron in the form of ferric oxide, and are also able to bind DNA. Ferroxidation centres are formed at the interface of anti-parallel dimers, which further assemble into dodecameric nanocages with a hollow core where ferric oxide is deposited. Streptomyces coelicolor encodes three Dps-like proteins (DpsA, B and C). Despite sharing the conserved four-helix bundle organisation observed in members of the Dps family, they display significant differences in the length of terminal extensions, or tails. DpsA possess both N- and C-terminal tails of different lengths, and their removal affects quaternary structure assembly to varying degrees. DpsC quaternary structure, on the other hand, is heavily dependent on its N-terminal tail as its removal abolishes correct protein folding. Analysis of the crystal structure of dodecamers from both proteins revealed remarkable differences in the position of tails and interface surface area; and provides insight to explain the differences in biochemical behaviour observed while comparing DpsA and DpsC.     

The prosthetic group of the green chromoprotein ofPatella ova

Résumé Les ovaires des PatellesPatella vulgata etPatella caerulea contiennent un chromoprotéide vert qui a été précédemment étudié. Dans le présent travail, le groupe prosthétique de ce pigment est identifié. Il s'agit d'un tètrapyrrole dont la structure est proche de celle de la chlorophyllea. L'identification repose sur l'isolement des esters méthyliques du phéophorbidea d'une part (à partir des gonades entières) et de la chlorinea ₆ d'autre part (à partir du chromoprotéide).     

The physiological importance of the interaction of oxygenation between the heme groups of hemoglobin

Zusammenfassung Eine theoretische Betrachtung der Gleichungen vonKlotz bestätigt folgendes: a) die O₂-Aufnahme von Hämoglobin ist nicht nur durch statistische Faktoren bedingt; b) die Bindung der ersten O₂-Moleküle erleichtert die Bindung weiterer Moleküle. Das steht in Übereinstimmung mit der Annahme vonPauling. Die physiologische Bedeutung dieses Phänomens wird graphisch dargestellt. Es wird eine Hypothese vorgeschlagen, die das Auftreten von hyperbolischen Dissoziationskurven unter bestimmten Bedingungen zu erklären vermag.     

The importance of the lateral line system for the perception of surface waves in the claw toad,Xenopus laevis daudin

Zusammenfassung Blinde Krallenfrösche reagieren auch dann auf konzentrische Oberflächenwellen, wenn das gesamte Seitenliniensystem zerstört wird. Weitere Ausschaltversuche zeigen, dass der Reiz (Eintauchen eines Stabes) sehr wahrscheinlich über das Labyrinth perzipiert wird. Ob die Oberflächenwelle selbst oder (und) das Geräusch beim Eintauchen des Stabes wahrgenommen wird, ist noch nicht sicher entschieden.

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My thanks are due to Dr.M. L. Mittelstaedt for critical help and to MissA. Middelmann for valuable technical assistance. This work was partly supported by a grant from the DFG.     

The physiological and nutritional importance of dietary fibre.

Fibrous material is an integral part of the daily diet, and it exerts direct physiological effects throughout the gastrointestinal tract, in addition to affecting metabolic activities more indirectly. The interplay of these effects is responsible for the presumed desirable influence of fibre on weight regulation, carbohydrate and lipid metabolism, and on colon function. Numerous mechanisms of action have been identified which are related to the type and the physicochemical nature of the fibre. This review concentrates mainly on the serum cholesterol-lowering effect of dietary fibre, its colonic fermentation, and finally on some possible adverse effects that one should be aware of when consuming high amounts of dietary fibre.