A simple technique for testing the in vitro response of rabbit lymphocytes to PHA and allogeneic cells

Summary Lymphocytes of rabbits can be separated from small quantities of heparinized whole blood using a simple density gradient of Ficoll-Ronpacon 1.09. This separation technique yields a pure suspension of viable cells allowing reproducible results from cultures stimulated either with PHA or allogeneic lymphocytes isolated by the same technique.Supported by the Swiss Science Foundation No. 3.890-0.77.     

Über die Konstitution der Visnagane und Khellactone ausAmmi visnaga L.

Summary The visnagans fromAmmi visnaga L. and the stereoisomeric khellactones and methyl-khellactones derived from them were transformed into seselin and umbelli-ferone-8-aldehyde. These transformations and other degradations lead to revised formulas for these natural compounds.     

Methanotrophic symbionts provide carbon for photosynthesis in peat bogs

Wetlands are the largest natural source of atmospheric methane, the second most important greenhouse gas. Methane flux to the atmosphere depends strongly on the climate; however, by far the largest part of the methane formed in wetland ecosystems is recycled and does not reach the atmosphere. The biogeochemical controls on the efficient oxidation of methane are still poorly understood. Here we show that submerged Sphagnum mosses, the dominant plants in some of these habitats, consume methane through symbiosis with partly endophytic methanotrophic bacteria, leading to highly effective in situ methane recycling. Molecular probes revealed the presence of the bacteria in the hyaline cells of the plant and on stem leaves. Incubation with (13)C-methane showed rapid in situ oxidation by these bacteria to carbon dioxide, which was subsequently fixed by Sphagnum, as shown by incorporation of (13)C-methane into plant sterols. In this way, methane acts as a significant (10-15%) carbon source for Sphagnum. The symbiosis explains both the efficient recycling of methane and the high organic carbon burial in these wetland ecosystems.     

Oral and parenteral toxicity ofBacillus thuringiensis ‘exotoxin’, and its inactivation in larvae ofGalleria mellonella

Zusammenfassung Es wird gezeigt, dass Larven der grossen Wachsmotte durch oral appliziertes «Exotoxin» vonBacillus thuringiensis vergiftet werden, die LD₅₀ aber ca. 250mal grösser ist als bei parenteraler Applikation. Oral verabreichtes «Exotoxin» wird zu einem grossen Teil im Raupendarm inaktiviert. Es konnte eine mathematische Beziehung zwischen der Inkubationszeit und der Inaktivierung des «Exotoxins» gefunden werden, die für einen enzymatischen Abbau des «Exotoxins» spricht.     

Further studies on bovine red cells having a different glycoprotein coat

Zusammenfassung Untersuchungen über den pronaselabilen Anteil der äusseren neuraminsäurehaltigen Glykoproteinschicht verschiedener Rindererythrozyten ergeben bei den einzelnen Tieren zwar signifikante Unterschiede, die jedoch in keiner direkten Beziehung zu den ebenfalls neuraminsäurehaltigen F-Antigenen dieser Zellen stehen.     

Die Synthese von14C-markiertem Phosphamidon,einem neuen systemischen Insektizid

Summary The synthesis of C¹⁴-labeled phosphamidon, a new systemic insecticide, is described.