Physical Sciences and Mathematics Commons^™

Host And Prophage Modifications Of Ultraviolet Induction In Salmonella Potsdam, Bela B. Toth

Loma Linda University Electronic Theses, Dissertations & Projects

In induction experiments with naturally occurring and artificially lysogenic strains of S. potsdam, cells were irradiated in buffer, transferred to complete medium, and then assayed for free phage. Irradiation was followed by half hourly samples for free phage from the growing populations of irradiated cells. For an estimation of burst sizes, the irradiated cells were diluted out to a final concentration of 1 cell per ml and distributed to tubes in 0.5 ml quantities. All assays were done by the top-layer method with streptomycin incorporated in the top-layer and SP2-str^r as the bacterial indicator. The non-lysogenic strain S. …

Isolation Of A Toxic Substance From Centaurea Repens, Merton E. Sprengel

Loma Linda University Electronic Theses, Dissertations & Projects

A poisonous steroid-type compound was isolated from Centaurea repens. After extraction with absolute ethanol, removal of the solvent, addition of 2% HCl to precipitate the pigments, and filtering, the pH was adjusted to 9 with aqueous anunonia. This solution was exhaustively extracted with chloroform, evaporated to dryness, and extracted with ethyl ether.

This fraction was chromatographed on silica-gel plates, using 10:1 1,2-dichloroethane-methanol as the developer. The band at Rf 4.2 was removed and found toxic to mice. Labored, slow, gasping respiration and frequent involuntary muscular contractions became apparent within a few minutes following the intraperitoneal injection into each animal. Death …