Separation of spleen colony-forming units and prothymocytes by use of a monoclonal antibody detecting an H-2K determinant

The density of H-2K antigens was determined on both the mouse hemopoietic stem cell, using an assay for spleen colony-forming units (CFU-S), and the prothymocyte, using a thymus repopulation assay. This was done by light-activated cell sorting of bone marrow cells labeled first with a biotinylated antibody against H-2Kk and then with avidin-fluorescein isothiocyanate. Almost all CFU-S were found to be present among the 4% bone marrow cells with high forward light scatter (FLS), low perpendicular light scatter (PLS), and bright immunofluorescence. Thymus regeneration by this brightly fluorescent fraction was delayed 3 days compared to thymus regeneration by unsorted cells, although the same number of CFU-S was present in each cell suspension. This delay indicates that differentiation from CFU-S to prothymocytes takes 3 days. The fraction of cells in the FLS/PLS window with dull anti-H-2Kk fluorescence contained few CFU-S and gave rise to a transient thymus regeneration. These findings indicate that the prothymocyte carries fewer H-2K antigens than does the CFU-S. The H-2K antigen is a marker with which CFU-S and prothymocytes can be separated. Therefore, during early T-cell differentiation, the number of H-2K molecules on the cell surface decreases (CFU-S----prothymocyte----cortical thymocyte). During maturation of T cells, a reexpression of H-2K molecules occurs, since lymph node cells and spleen cells were shown to be brightly positive for H-2K antigen.     

13C-NMR studies on the influence of pH and nitrogen source on polyol pool formation in Aspergillus nidulans

Abstract The composition of the polyol pools in Aspergillus nidulans mycelium during active growth on sucrose depends strongly on pH. At pH 2.5, only mannitol is present. A comparison between nitrate- and ammonium-grown cultures shows stimulation of the arabitol content with nitrate a former nitrogen source. When starved mycelium is incubated either with natural-abundance or ¹³C-enriched glucose, label appears rapidly in mannitol and arabitol, regardless of the nitrogen source or the pH used.     

Monoclonal antibodies against human beta-glucocerebrosidase

Monoclonal antibodies were obtained against the membrane-bound lysosomal enzyme beta-glucocerebrosidase (acid beta-glucosidase), which is deficient in Gaucher's disease. BALB/c mice were immunized with homogeneous enzyme protein extracted from a sodium dodecyl sulphate/polyacrylamide gel. The mice were subsequently hyperimmunized with partially purified enzyme prior to fusion of spleen cells with myeloma cells. After fusion, 32 primary hybrid cell populations were obtained which continued to produce antibodies against beta-glucocerebrosidase after prolonged time of culture. All antibodies reacted with both native and denatured enzyme. Four primary cell populations were subcloned and the antibodies produced were characterized. The antibodies were all four of the IgG1 subclass. Three of these antibodies bind to protein A whereas one does not. The results of binding assays indicated that three of the antibodies react with the same antigenic domain (epitope 1), but the fourth with a different one (epitope 2). Probably two antigenic determinants are present in epitope 1 since one of the antibodies with specificity for epitope 1 is inactivated after iodination by the chloramine-T procedure whereas a second one is not.     

Foraminifera from the Silberberg Formation («Lower Oligocene») at Silberberg,near Helmstedt (Germany)

From the Silberberg Quarry, type locality of the Silberberg Formation (Martini &Ritzkowski 1968), some planktonic foraminifera are described:Globigerina officinalis Subbotina, Globigerina ouachitaensisHowe &Wallace,G. praebulloides leroyi Blow &Banner, G.praebulloides occlusa Blow &Banner which taxa are here suggested to form intergrading morphotypes within the range of variation of a population dominated byG. officinalis. In addition,G. cf.danvillensis Howe &Wallace is found. The planktonic fauna, together with some elements in the benthonic fauna, suggests a possible correlation with the Danville Landing Member of the Jackson Formation, Louisiana, traditionally ascribed to the Upper Eocene. There is some similarity with European Uppermost Eocene — Lower Oligocene faunas described by various authors. The Silberberg Formation was suggested to be a Neostratotype for the Latdorfian Stage of the Lower Oligocene byMartini &Ritzkowski (1968). It is suggested that the Silberberg Formation may well be coeval with the Upper Priabonian as proposed byCita 1969.     

Biochemical Studies of Bacterial Sporulation and Germination XIV. Phospholipids in Bacillus megaterium

The principal phospholipids of Bacillus megaterium throughout the cycle of growth and sporulation were found to be phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, and a hitherto unidentified isomer of glycosaminyl-phosphatidylglycerol. Phosphatidylglycerol predominated during vegetative cell growth and then declined as spores developed, whereas diphosphatidylglycerol became more prominent during spore maturation. The latter phosphatide was relatively inaccessible in the vegetative cell and was more accessible in the spore, as judged by solvent extraction under various conditions.