A new continuous optical assay for isocitrate lyase

Summary A new continuous optical assay method for isocitrate lyase is reported. This is a coupled assay which requires lactate dehydrogenase as an ancillary enzyme. The method yields linear data up to 0.12 units/ml. The assay is also suitable for crude extracts.Acknowledgment. This research was supported by grants of the Italian Ministero della Pubblica Istruzione.     

Purification of porcine granulosa cells by continuous Percoll gradient

Granulosa cells purified on a continuous Percoll gradient have considerably increased responsiveness to FSH in formation of cAMP, secretion of progesterone, and 125I[hCG] binding to cells incubated for 4 days in culture.     

A rotating bottle culture method with continuous replacement of the gas phase

Summary A rotator culture method is described which provides a continuous flow of oxygenating gas to cultures in rotating bottles. The system maintains constant O₂ and CO₂ levels in the culture medium throughout the incubation period. It also provides a more stable pH than systems with sealed culture bottles.Acknowledgments. We would like to thank Mr B. Secker, Mr C. Hellon and Mr S. J. Ellis, of the Physiological Laboratory workshop, for constructing the rotator apparatus. We also thank the Medical Research Council, London, for financial support for the project.     

Manipulating the activity of immobilized enzymes with different organo-smectite complexes

Summary Enzymes may be immobilized on hydrophobic surfaces of organo-smectite complexes. The immobilized enzyme may be active, partially active, or inactive depending on the nature of the organic surface. These materials may be useful as models for enzymes in natural systems, and in medicine and industry.This work was partially supported by the National Science Foundation under Grant No. CHE-8306583. Journal Article No. 11603 of the Michigan Agricultural Experiment Station.     

Formation of ethanol by bacteria. A pledge for the use of extreme thermophilic anaerobic bacteria in industrial ethanol fermentation processes

Summary Many anaerobic, facultatively anaerobic and even some strictly aerobic microorganisms form various amounts of ethanol from glucose. Only few mesophilic and extreme thermophilic bacteria ferment glucose stoichiometrically to 2 ethanol and 2 carbondioxid. Biotechnological processes at elevated temperatures seem advantageous in many respects. Hence, thermophiles and extreme thermophiles can potentially substitute for yeast in ethanol production on an industrial scale. Advantages and disadvantages of thermophilic mixed cultures and of potentially useful organisms are discussed.Acknowledgment. This work was partly supported by Energy and Research Development Administration contract number EY-76-509-0888-M003 and by the Deutsche Forschungsgemeinschaft.     

A rotating bottle culture method with continuous replacement of the gas phase.

A 'rotator' culture method is described which provides a continuous flow of oxygenating gas to cultures in rotating bottles. The system maintains constant O2 and CO2 levels in the culture medium throughout the incubation period. It also provides a more stable pH than systems with sealed culture bottles.     

Evidence for the possible function of the fluorescent granular perithelial cells in brain as scavengers of high-molecular-weight waste products

Summary The fluorescent granular perithelium (FGP) of rats and humans under experimental and pathological conditions was examined with the electron microscope. The FGP incorporated high molecular-weight protein (ferritin) and carbon particles administered intraventricularly. In a case of spontaneous cerebral hemorrhage, the FGP was found to contain lipoidal products and minute fragmented cell debris. The FGP in a patient with lipidosis contained pale inclusion bodies. In aged individuals, the inclusion bodies formed irregular larger aggregates.     

A new device for simultaneous measurements of oxygen concentration,absorption and fluorescence changes in photosynthetic systems

Zusammenfassung Klein dimensionierter Küvettensatz für Suspensionen und Gewebe, welcher erlaubt, gleichzeitig verschiedene spektroskopische und elektrochemische Messgrössen zu ermitteln indem Lichtleiter zur Bestimmung optischer Daten eingesetzt werden können.

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The autor thanks ProfessorH. Metzner and ProfessorC. Sironval for their support.

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Support by EMBO (European Molecular Biology Organization) is gratefully acknowledged. All optical parts of the set-up were produced by the JENA er GlaswerkSchott & Gen. (Mainz/Germany).     

A simple and versatile apparatus for the continuous superfusion of nervous tissue preparations

Summary A bimodal apparatus for the continuous superfusion of both subcellular particles and whole tissue slices is described.The authors wish to thank Mr W. Maddison and the Physiology Department workshop for manufacture of this apparatus. Research was supported by the South African Medical Research Council and the Atomic Energy Board of South Africa.     

A structural view of translation initiation in bacteria

The assembly of the protein synthesis machinery occurs during translation initiation. In bacteria, this process involves the binding of messenger RNA(mRNA) start site and fMet-tRNA^fMet to the ribosome, which results in the formation of the first codon-anticodon interaction and sets the reading frame for the decoding of the mRNA. This interaction takes place in the peptidyl site of the 30S ribosomal subunit and is controlled by the initiation factors IF1, IF2 and IF3 to form the 30S initiation complex. The binding of the 50S subunit and the ejection of the IFs mark the irreversible transition to the elongation phase. Visualization of these ligands on the ribosome has been achieved by cryo-electron microscopy and X-ray crystallography studies, which has helped to understand the mechanism of translation initiation at the molecular level. Conformational changes associated with different functional states provide a dynamic view of the initiation process and of its regulation. Received 16 July 2008; received after revision 31 August 2008; accepted 10 September 2008 A. Simonetti, S. Marzid: These authors contributed equally to this work.     

The morphology of the Schwann cells and the unmyelinated fibers of a nerve supplying an immobilized muscle

Summary Hind limbs of cats were immobilized in the resting position for varying periods and the nerve supplying the medial head of the gastrocnemius muscle was studied while it was undergoing immobilization atrophy. Degenerative changes in the unmyelinated fibers and the Schwann, cells, followed by an abundant increase in collagen, were noticed after prolonged immobilization. Electron microscopic evidence that Schwann cells produce the collagen is discussed.     

A simple method for obtaining high plating efficiencies with cultured insect cells

Summary A technique has been developed for obtaining absolute plating efficiencies as high as 79% for culturedTrichoplusia ni (TN-368) cells. The method involves the use of conditioned medium and MES, BES, or ACES buffers. Cell growth and morphology are not altered under these conditions.     

Biodegradation of bitumen used for nuclear waste disposal

Summary Studies have been carried out to test microbial degradation of bitumen used for encapsulating radioactive waste in Sweden. Microorganisms have been isolated that degrade bitumen. In ong-term tests under conditions simulating those in the silo part of the final repository for low-and intermediate-level radioactive waste, both aerobic and anaerobic degradation of bitumen has been found, equivalent to 0.6–1.5 moles CO₂/month·mg bitumen and 1.1–1.5 moles CO₂/month·mg bitumen, respectively.     

Identification of cytotoxic cells responsible for lysis of target cells pretreated with concanavalin A in spleen populations of pregnant mice with suppressive activity]

During an alloimmunization, killer cells which lyse target cells only in the presence of a lectin are generated. That these cells, as well as suppressive cells, share immunocytological properties with specific killer cells, leads to the hypothesis that these cells may be concerned with the mechanism of immunosuppression. Two experimental results presented in this paper are consistent with this hypothesis: 1) Spleens from H-2k mice pregnant by H-2d males which bear a high suppressive activity also contain a relatively large number of killer cells having the ability to lyse Concanavalin A treated target cells and 2) supernatants of suppressive systems generated through an MLC block the cytolysis of specific target cells by the bound killer cells.