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O WYSS

Publications and source records attributed to O WYSS.

At least 19 recordsLinked to original sources
PubMed1965

RADIATION RESISTANCE OF SOIL AZOTOBACTER.

Vela, Gerard R. (School of Aerospace Medicine, Brooks Air Force Base, Tex.), and Orville Wyss. Radiation resistance of soil Azotobacter. J. Bacteriol. 89:1280-1285. 1965.-Quantitative recovery of Azotobacter from soils subjected to gamma-radiation from a cobalt-60 source showed the soil populations to be much more highly resistant than isolates from such cultures grown on laboratory media. Even in the encysted state, the laboratory populations were reduced 10,000-fold by exposure to 200 kr, whereas the soil populations were not measurably reduced by that dose.

Azotobacter↗
PubMed1965

CHARACTERIZATION OF CONJUGATION FACTORS IN ESCHERICHIA COLI CELL WALLS. I. INHIBITION OF RECOMBINATION BY CELL WALLS AND CELL EXTRACTS.

Lancaster, John H. (University of Texas, Austin), E. P. Goldschmidt, and Orville Wyss. Characterization of conjugation factors in Escherichia coli cell walls. I. Inhibition of recombination by cell walls and cell extracts. J. Bacteriol. 89:1478-1481. 1965.-An assay procedure was devised to determine quantitatively the interference with conjugation of cell-wall fragments from both male and female strains of Escherichia coli. The fertility of the donor is reflected in the assay. Phenol extracts from the cell walls were active, and chemical analysis suggested that the activity resided in the lipopolysaccharide fraction.

Cell Extracts↗
PubMed1962

Resistance of the Azotobacter cyst.

Socolofsky, M. D. (University of Texas, Austin) and Orville Wyss. Resistance of the Azotobacter cyst. J. Bacteriol. 84:119-124. 1962-The Azotobacter cysts were found to be more resistant than the vegetative cells to various harmful agents. Studies involving ultraviolet irradiation indicated that cysts required twice as great a dosage, as correspondingly treated vegetative cells, to be 90% inactivated. The acquisition of ultraviolet resistance during the encystment process was gradual and appeared to be related to the formation of exine and intine. A slow loss of ultraviolet resistance during germination was also noted. The cysts exhibited no marked resistance to heat, although they were extremely resistant to gamma radiation, sonic treatment, and desiccation. Evidence was presented indicating that the cyst is not a bacterial endospore. The encystment process may confer a survival advantage upon the organism by coupling the low endogenous respiration rate with the ability to withstand desiccation.

Azotobacter↗
PubMed1961

Development and germination of the Azotobacter cyst.

The fine structure of Azotobacter vinelandii has been studied by means of electron microscopy of ultrathin sections made of the encysting and germinating cells. The organisms were fixed with KMnO(4) and embedded in epoxy resin. On an encystment medium the rod-shaped bacteria begin to assume an almost spherical form and then bark-like exine appears in 1(1/2) to 2 days. The exine thickens and an electron permeable intine forms between it and the shrinking cell body. In 5 days the intine makes up more than half of the cyst volume and begins to show a definite two-layered structure. Meanwhile the peripheral bodies, which may be extensions of the cell membrane of the vegetative cell, disappear as the encystment progresses. The cell wall and membrane of the vegetative cell remain demonstrable as the confining structure of the shrinking central body of the mature cyst. In this central body lipoidal globules appear together with aggregations of nuclear material. Cyst germination begins with an increase in the size of the central body at the expense of the intine. The nuclear aggregations become more diffuse and the lipoidal globules disappear. The exine may be pushed outward and the bark-like fragments separate as the emerging vegetative cell develops. Invagination of the cell wall and membrane may occur at this stage leading to cell division. Empty exines remain as horseshoe-shaped structures.

Azotobacter↗