Cryopreservation of bovine buffy coat leukocytes for use in immunologic studies

A simple cryogenic technique for preserving bovine buffy coat leukocytes was developed. This was coupled with a variation of the standard discontinuous gradient technique to purify mononuclear cells that retained immunologic function. The total number of mononuclear cells recovered from cyropreserved samples were only 87 to 42% of those recovered from freshly obtained blood samples. However, the functional capabilities of mononuclear cells from cyopreserved buffy coat preparations were retained. Polyclonal proliferative responses to 3 mitogens were measured, using a titration of mitogen concentrations, and were found to be normal, compared with those of cells isolated from fresh blood. Blood samples collected after vaccination with Brucella abortus contained leukocytes that responded to irradiated B abortus. These antigen-specific responses were also retained through cyopreservation. Cell surface expression of T-lymphocyte antigens, CD2, CD4, and CD8, and cell-surface IgM on B lymphocytes was also evaluated. Flow cytometric analysis of fresh and cryopreserved mononuclear cell preparations indicated that the relative proportions of different subpopulations were not altered. The technical simplicity of our cryopreservation system will allow processing of large numbers of samples with the ability to assay various immune functions at a later time.     

Elektronenmikroskopische Beiträge zum Feinbau des buchenholzes (Fagus sylvatica L.)—Erste Mitteilung: Untersuchungen an Markstrahl-Parenchymzellen

Ohne Zusammenfassung

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Electron-microscopic contributions to the fine structure of beechwood (Fagus sylvatica L.)—Part I: investigations on ray parenchyma cells

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Mitteilung aus dem Institut für Holzforschung und Holztechnik der Universit?t München

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Herrn Dr. Eberhard Schmidt bin ich für die Anregung zu dieser Arbeit und fruchtbare Diskussionen sehr verbunden. Fr?ulein E. Baldermann danke ich für die sorgf?ltige Ausführung der elektronenmikroskopischen Pr?parationen.     

Verfahren zur Kristallisation aus Lösungen

Crystallization from solution . In general the processes occurring in crystallizers have previously been treated in only summary and phenomenological manner because only little was known about the joint action of the individual steps. An attempt has therefore been made, in the present survey, to examine the relationship between the physico-chemical properties of the relevant system, the process chosen, and engineering economics.     

Die einzelnen Lebensmittel (Chemie, Technologie, Analytik)

Ohne Zusammenfassung     

Backyard range-a real backyard (actually front yard, garage anddriveway) antenna range on a shoestring

The evolution of a range for developing and measuring antennas in the author's home, which is the location of his consulting company, is discussed. The range hardware is described. Examples of the pattern produced by the system are presented     

A single gene of chloroplast origin codes for mitochondrial and chloroplastic methionyl-tRNA synthetase in Arabidopsis thaliana

One-fifth of the tRNAs used in plant mitochondrial translation is coded for by chloroplast-derived tRNA genes. To understand how aminoacyl-tRNA synthetases have adapted to the presence of these tRNAs in mitochondria, we have cloned an Arabidopsis thaliana cDNA coding for a methionyl-tRNA synthetase. This enzyme was chosen because chloroplast-like elongator tRNAMet genes have been described in several plant species, including A. thaliana. We demonstrate here that the isolated cDNA codes for both the chloroplastic and the mitochondrial methionyl-tRNA synthetase (MetRS). The protein is transported into isolated chloroplasts and mitochondria and is processed to its mature form in both organelles. Transient expression assays using the green fluorescent protein demonstrated that the N-terminal region of the MetRS is sufficient to address the protein to both chloroplasts and mitochondria. Moreover, characterization of MetRS activities from mitochondria and chloroplasts of pea showed that only one MetRS activity exists in each organelle and that both are indistinguishable by their behavior on ion exchange and hydrophobic chromatographies. The high degree of sequence similarity between A. thaliana and Synechocystis MetRS strongly suggests that the A. thaliana MetRS gene described here is of chloroplast origin.     

Motivation for and possibilities of using nuclear process heat

A reduction in the use of fossil energy carriers on the energy supply sector will be made possible by a more efficient utilization of energy and the commercial application of nuclear energy. The resources of fossil energy carriers will be saved and the long-term supply of raw materials for the chemical industry will be ensured. High temperature reactors (HTRs) with spherical fuel elements are not only characterized by high conversion rates reducing uranium requirements to a minimum, but they also supply heat at a high temperature level. Besides electricity supply, this will also open up the much larger heat market to nuclear energy. Nuclear process heat can be used for heating purposes by way of energy transported over long distances or by district heating; it may also be used to cover the heat requirements in refining plants. This is shown by means of a supply strategy for the Federal Republic of Germany using secondary energy carriers. Profitability studies have shown that nuclear process heat has a number of economic advantages over conventional heat generation, which are still supplemented by ecological benefits (e.g. reduction in waste heat, SO₂ and CO₂ emissions). The ecological aspect will, no doubt, be of particular significance in the future, since even today some of the man-induced rates are reaching the levels of natural rates of mobilization of materials.