Some ultrastructural features ofPlanctomyces bekefii,morphotype I of theBlastocaulis-Planctomyces group of budding and appendaged bacteria

The ultrastructure ofPlanctomyces bekefii, a budding and appendaged bacterium, has been examined using samples obtained directly from pond water, its natural habitat. The prokaryotic nature of this morphologically unusual microbe was verified by observations of thin sections. Its major appendage, the nonprosthecate stalk, is shown to have a tubular structure, with a substructure of hollow fibers. Some details of the budding process and other ultrastructural features are presented.     

Unsaturated fatty acid mutants of Saccharomyces cerevisiae

Resnick, Michael A. (University of California, Berkeley), and Robert K. Mortimer. Unsaturated fatty acid mutants of Saccharomyces cerevisiae. J. Bacteriol. 92:597-600. 1966.-The wild type of the yeast Saccharomyces cerevisiae does not require fatty acids or sterols for growth. Two types of lipid nutritional mutants have been induced in this organism. One of these classes of mutants requires an unsaturated fatty acid and is associated with a locus on chromosome VII. The other class of mutants needs either an unsaturated fatty acid or ergosterol for growth. Experiments involving identification and characterization of these mutants are presented.     

Immunoferritin labeling shows de novo synthesis of surface components in buds of a prokaryote belonging to morphotype IV of theBlastocaulis-Planctomyces group

Indirect immunoferritin labeling provided evidence for the de novo synthesis of antigenic cell-surface components of the daughter cell (bud) of a freshwater isolate belonging to morphotype IV of theBlastocaulis-Planctomyces group of budding and nonprosthecately appendaged prokaryotes. The cell surfaces of the buds produced by immunoferritin-labeled mother cells remained unlabeled through development to flagellated swarmers. Double-labeling experiments verified the de novo synthesis of cell-surface antigens over the entire bud, and also showed a labeling pattern indicative of intercalation of newly formed sites on the surface of the mother cell during the later stages of its maturation.     

Evaluation of porcine corpora lutea during organ culture: A histological,ultrastructural and hormonal assessment

Porcine corpora lutea (CL) were cultured for 5 days using an organ culture technique which had previously been used for human CL. Progesterone levels in the media declined continuously throughout culture and closer examination demonstrated no synthesis of progesterone during the culture period but merely leakage into the media. Although light microscopy showed the cells to be maintained to the same extent as the human tissue, an ultrastructural study indicated that extensive cell death had occurred.     

Ultrastructural features of budding cells in a prokaryote belonging to morphotype IV of theBlastocaulis-Planctomyces group

Budding cells of prokaryotes belonging to morphotype IV of theBlastocaulis-Planctomyces group showed several unusual ultrastructural features. Those presented in this preliminary survey pertain to the cell envelope, the nucleoplasm, the connecting channel between mother cell and bud, and an assortment of cellular inclusions.     

Effects of vasopressin on the water and ionic composition of toad bladder epithelial cells

Summary Isolated sheets of epithelial cells as well as epithelial cells scraped from paired hemibladders mounted in chambers both showed significant increases in water, sodium and chloride contents after exposure to vasopressin (100 mU/ml), without any change in potassium content. In the isolated cells these changes were prevented by amiloride (10^–5 m), suggesting that the gain of sodium after vasopressin occurs across the mucosal membrane. This hypothesis was confirmed in experiments in which it was found that, in hemibladders mounted in chambers and bathed on their mucosal surface by sodium Ringer's with²⁴Na, the gains of chemical sodium and²⁴Na after vasopressin were equivalent.