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Very rapidly frozen cells of Escherichia coli and Bacillus subtilis were substituted at low temperature into acetone with 1% OsO4 and embedded in Epon. They showed ribosome-free spaces filled with globular and fibrillar material of up to 15 nm. The sizes of structures seen do not exclude DNA superstructures such as supercoils, aggregates, and nucleosomes.(More)
Whole cells of Mycobacterium avium, characterized by their negative response in the nine biochemical tests used for mycobacterial identification in our laboratory, turned positive for nitrate reductase, Tween-80 hydrolysis, beta-glucosidase, acid phosphatase, alkaline phosphatase, penicillinase, and trehalase after their wall portion was removed to yield(More)
The study of plasma membrane and phagosome membrane of Dictyostelium discoideum was performed using 2 lectins: concanavalin A (Con A) and Wheat Germ Agglutinin (WGA), and 2 markers of anionic sites: colloidal iron hydroxide (CIH) and cationized ferritin (CF). These labellings were applied to fixed partially broken cells, which had ingested a large quantity(More)
The intracellular redistribution of membrane internalized during endocytosis was studied quantitatively by a biochemical approach and by a morphometric analysis of autoradiographs in electron microscopy. Plasma membrane glycoconjugates, enzymatically labelled with radioactive galactose, were used as a membrane marker. In cells labelled at their surface(More)
Virulent strains of Shigella flexneri invade HeLa cells with high efficiency. This crucial step in the pathogenic process is encoded by a 140-megadalton plasmid which induces phagocytosis of the bacteria by host cells. In this report we used pWR100, the virulence plasmid of S. flexneri serotype 5, and pHS4108, a 32-megadalton subclone of pWR100, to(More)
Listeria monocytogenes penetrates and multiplies within professional phagocytes and other cells such as the Caco-2 human enterocytelike cell line. Listeriolysin O, a membrane-damaging cytotoxin accounts for intracellular multiplication through lysis of the membrane-bound phagocytic vacuole. This work demonstrates that once released within the cytosol, L.(More)
The LamB protein is a trimeric integral outer membrane protein from Escherichia coli K12 which functions as a pore for maltodextrins and a receptor for bacteriophages. When inserted into two selected sites of LamB, a foreign antigen, the C3 epitope from poliovirus, was exposed at the cell surface with its normal antigenic properties. Since these genetic(More)
The nucleoids of Eseherichia coil, independently of the physiological state of the bacteria, are shown to be preserved as a fine-stranded fibrillar nucleoplasm by an OsO4 fixation under defined conditions: acetate-veronal buffer pH 6, presence of Ca ++ and amino acids, stabilization with uranyl-acetate before dehydration. The same fixation procedure applied(More)