Spheroplast production by lysozyme and ethylenediaminetetraacetate (EDTA) was examined as a means of obtaining osmotically sensitive cells for studies of enzyme localization. Physiologically young cells plasmolyzed with 0.5 M sucrose in 0.01 M tris(hydroxymethyl)aminomethane (Tris) buffer (pH 7, 8, or 9) were quantitatively converted to plasmolyzed osmotically sensitive rods after lysozyme treatment. Although such cells were osmotically sensitive, a 1:1 dilution in Tris buffer was necessary for conversion of rods into spheroplasts. Addition of EDTA resulted in a rapid conversion of the plasmolyzed spheroplasts into spherical structures devoid of a plasmolysis vacuole. These structures, which we call EDTA-lysozyme spheroplasts, contained a number of attached membranes. We believe that this conversion results from a weakening of the outer trilaminar component of the cell wall by EDTA, resulting in the collapse of the plasmolysis vacuole. Dilution of sucrose below 0.15 M also resulted in the collapse of the plasmolysis vacuole. Both the lysozyme spheroplasts and the EDTA-lysozyme spheroplasts were osmotically sensitive. Thin sections of the EDTA-lysozyme spheroplasts demonstrated that the outer trilaminar component of the cell wall was broken, exposing large areas of the cytoplasmic membrane to the environment.

Adsorption of Actinomyces viscosus strains T14V and T14AV to hydroxyapatite (HA) surfaces was studied, using an adsorption model based on the Langmuir adsorption isotherm. Data generally followed the adsorption model as judged by high correlation coefficients obtained for both strains to most of the treated surfaces studied. The number of binding sites for strains T14V and T14AV cells to human saliva-treated HA was similar to that for untreated HA. The affinity of strain T14V for saliva-treated HA was tenfold greater than the affinity of strain T14AV for that surface. To approximate the pellicle of the gingival crevice and margin and to determine whether adherence by strain T14V was to specific saliva or serum receptors, experimental pellicles were formed on HA by saliva/serum mixtures. The number of binding sites on the saliva/serum-treated HA remained the same as for the saliva-treated surface. Although the affinity of strain T14V cells for the saliva/serum HA surface remained generally the same as the affinity for the HA treated with saliva alone, the affinity of strain T14AV cells decreased further as the serum content increased. Strain T14V cell numbers adsorbed to serum-treated HA, and albumin-treated HA were less than those adsorbed to saliva-treated HA, indicating that the adherence by strain T14V was to specific saliva receptors. In vivo results from streptomycin-resistant mutants of both strains T14V and T14AV confirmed in vitro results using saliva-serum pellicles. Pretreatment of strain T14V with proteolytic enzymes and heat inhibited adherence to saliva-treated HA, suggesting that the adherence receptor(s) on the cell surface of strain T14V is protein in nature.

Women who undergo breast augmentation with silicone implants have a lower risk of breast cancer than the general population. This finding suggests that these women are drawn from a population already at low risk and that the implants do not substantially increase the risk.

Interactions between concanavalin A and cell wall digests of Bacillus subtilis 168 resulted in insoluble complexes as observed by double gel diffusion, turbidity, and analysis of the precipitate. The macromolecular constituent of the cell walls complexing with concanavalin A was the polyglucosylglycerol phosphate teichoic acid. The complex exhibited two pH optima: 3.1 and 7.4. The complex could be dissociated by saccharides which bind to concanavalin A. In contrast to concanavalin A-neutral polysaccharide complexes, formation of the concanavalin A-wall complex was inhibited by salts. It was subsequently shown that salts induce conformational changes in cell wall digests. The data suggested that for complex formation to occur a rigid rod conformation in the glucosylated teichoic acid is probably necessary. Concanavalin A can be used as a probe to study structural features of bacterial cell walls.

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Several physicochemical properties of the teichoic acid of Bacillus subtilis 168 have been determined. The teichoic acid partial specific volume was found to be 0.57 ml/g. The apparent weight-average molecular weight of the polymer was 24,800. Sedimentation was strongly dependent on solvent. The sedimentation coefficient of the teichoic acid was found to have a value of s25w' = 1.90S. In

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