Ein neuer Scinti-Scanner

Summary An apparatus for automatic scanning of radioactive parts of the body is described (scinti scanner). A lead protected scintillation counter is moved over the organ to be examined. The registered impulses are recorded on a special paper with a writing mechanism rigidly fixed with the counter.Three scanning sizes, scanning speeds and ray collimators are provided. The measuring time varies between 4 min and 4 h.Measurements are mainly done with iodine 131 (inorganic or linked to serum albumine or di-iodofluorescein) and gold 198.     

Ein Zellhomogenisator nach dem Prinzip vonMerkenschlager undSchlossmann

Summary The construction of a very effective cell homogenisator based on the principle ofMerkenschlager et al. is described. This apparatus permits one to obtain, in a short time, highly active preparations of soluble enzymes and fully active and intact cell components.     

Isolation and structural elucidation of 3,6-dioxo-hexahydro-pyrrolo [1,2-a]-pyrazine from the echinodermLuidia clathrata

Zusammenfassung Es wird über die Isolierung und Charakterisierung der Titelverbindung (Gly-l-Pro Lactam, I) aus dem SeesternLuidia clathrata berichtet. Die Kristallstruktur dieses Dioxopiperazinderivats wurde ermittelt. Der Piperazinring liegt in der Wannen-Konformation vor.

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This investigation was supported by contract No. NIH-71-2308 from Chemotherapy, National Cancer Institute, National Institutes of Health and by Public Health Service Research Grant No. CA-11451-03 from the National Cancer Institute. The authors also gratefully acknowledge support from the National Science Foundation which provided the X-ray diffractometer and mass spectrometer. For the previous contribution of this series seeG. R. Pettit, R. H. Ode andT. B. Harvey, III, Lloydia,36 (1973).     

Microbial potential in deep-sea sediments

Summary In spite of high pressures and low temperatures in abyssal sediments of the North Atlantic Ocean, bacterial activity is evident and highest in the top 10 cm. At these locations the input of degradable organic material to the deep-sea bottom is low. Oxygen, therefore, remains the dominant oxidant in surface sediments. Although alternative electron acceptors like nitrate, oxidized manganese and sulfate are present in large amounts, they are not utilized in this natural habitat. In sediment cores which were collected from the site for laboratory perturbation studies, it was possible to stimulate microbially mediated processes which are dormant in situ. When the oxygen supply was cut off, nitrate and manganese reduction occurred. Denitrification was the major process observed in the upper anoxic layers, while nitrate-ammonification and manganese reduction occurred in deeper sediment strata (4–8 cm). This is evidence for the presence of a variety of different bacteria and of an anaerobic heterotrophic potential. Most of the activity is located in the top 10 cm of these sediments. The shift to anaerobiosis initiates microbial activities through which metals are converted into their mobile species at the lowered redox potential. Evaluation of the suitability of the deep sea as a repository for waste materials will have to account for the large dormant potential of microbial activities and the consequences of their release by changing the environmental conditions at the sea floor.