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Biomedical subjects

S W Watson

Publications and source records attributed to S W Watson.

29 records · Page 2Linked to original sources
PubMed1970

Fossil membranes and cell wall fragments from a 7000-year-old Black Sea sediment.

Lamellar and tubular membranes and orgacnic fragments resemnbling bacterial cell walls were abundant in Black Sea sediments deposited between 3000 and 7000 years ago. This time period was marked by a gradual transition from a freshwater to a seawater environment. The resulting salinity gradient in the interstitial solutions probably promoted natural chromatography and dissolution, redeposition, and preservation of organic molecules. The preservation of organic structures may have resulted from the lack of dissolved oxygen, high concentrations of metal ions, and structural reorganization during compaction.

Bacteria↗
PubMed1969

Macromolecular subunits in the walls of marine nitrifying bacteria.

The outteromost laver of the cell wall of all marine ammonia-oxidizing bacteria So far isolated is made up of protein subunits arranged in a regular manner and linked together through metal-oxygen bonds. This sculptured, outer wall layver appears to be uniique to the terrestrial ammonia-oxidizing bacteria.

Bacteria↗
PubMed1969

Fatty acids in the lipids of marine and terrestrial nitrifying bacteria.

Fatty acids in the lipids of 19 marine and terrestrial nitrifying bacteria have been analyzed. Ammonia-oxidizing bacteria have a very simple acid composition; palmitic and palmitoleic acid account for 96 to 100% of the total acids. The fatty acids of nitrite-oxidizing bacteria cover a wider range, from C(14) to C(19), but from two to four acids still account for more than 80% of the total acids. Branched iso- and anteiso-acids are present in traces only in 2 of the 19 bacteria. The chemical and morphological similarity between blue-green algae and these bacteria is discussed.

Ammonia↗
PubMed1968

Fine structure of Ectothiorhodospira mobilis Pelsh.

The cell wall structure, arrangement of photosynthetic membranes, and the attachment of flagella of Ectothiorhodospira mobilis strain 8112 were examined by using freeze-etching and conventional electron microscopic techniques. The outer coat of the multilayered cell wall is comprised of 50 A repeating subunits, arranged in a regular array. The photosynthetic membranes, which originate from and are attached to the plasma membrane, are arranged in a more complex pattern than previously seen in other bacteria. The tuft of flagella in E. mobilis is inserted into a polar organelle. The relationship of this organelle to the polar membrane and the mechanism of attachment of the flagella to the polar organelle is discussed.

Bacteria↗
PubMed1968

Autotrophy in Nitrosocystis oceanus.

Enzymatic assays of cell-free extracts of the ammonia-oxidizing bacterium Nitrosocystis oceanus failed to establish that the biochemical basis of its obligate autotrophy stemmed solely from a metabolic defect. All of the Embden-Meyerhof enzymes except phosphofructokinase, and all of the tricarboxylic acid-cycle enzymes, as well as reduced nicotinamide adenine dinucleotide oxidase, were found in these extracts. A phosphoenolpyruvate-CO(2)-fixing system was also demonstrated. Resting cells incubated with (14)C-d-glucose and (14)C-l-glutamate and cells grown in the presence of (14)C-labeled glucose, glutamate, pyruvate, and methionine incorporated these compounds into cellular material, but at a level too low to provide the cells' major carbon and energy needs.

Bacteria↗
PubMed1967

Fine structure of the cytomembranes of Nitrosocystis oceanus.

Thin-sectioned, negatively stained, and freeze-etched preparations of Nitrosocystis oceanus cytomembranes were compared. The cytomembranes in freeze-etched cells were covered with 80- to 120-A particles. When cells were disrupted and differentially centrifuged, various membrane and particle fractions were obtained. Negatively stained membrane fragments from the pellet centrifuged at 3,000 x g showed 70- to 80-A stalked particles, whereas those from the pellet centrifuged at 39,000 x g exhibited a crystalline array of subunits with a 30- to 40-A periodicity. High-speed supernatant and pellet fractions centrifuged at greater than 39,000 x g contained 40- to 120-A free particles but no membranes. In chemically fixed cells, 40-A particles were found embedded in the matrix of membranes. Results suggest that the larger 80- to 120-A particles are enzyme complexes, whereas the smaller 30- to 40-A particles represent a structural protein or a lipoprotein of the membrane.

Bacteria↗
PubMed1966

Reductive pentose phosphate cycle in Nitrosocystis oceanus.

Campbell, Ann E. (Woods Hole Oceanographic Institution, Woods Hole, Mass.), Johan A. Hellebust, and Stanley W. Watson. Reductive pentose phosphate cycle in Nitrosocystis oceanus. J. Bacteriol. 91:1178-1185. 1966.-Assays in cell-free extracts of Nitrosocystis oceanus, a marine chemoautotrophic bacterium, have demonstrated the presence of all of the enzymes of the reductive pentose phosphate cycle, with activities high enough to account for the normal growth rate of the cells. Studies on ribulosediphosphate carboxylase activity in these extracts showed that it is inhibited by MgCl(2) (30% at 0.01 m), MnCl(2) (70% at 0.01 m), NaCl and KCl (100% at 0.5 m, 63% at 0.2 m), and by sulfate (35% at 0.01 m); phosphate, glutathione, and ethylenediaminetetraacetic acid had no effect. The bacterial enzyme differs from the spinach enzyme with respect to its affinity for bicarbonate and its pH optimum. Whole cells were incubated with C(14)O(2), and the acid-soluble fraction was analyzed by paper chromatography and autoradiography. Phosphoglyceric acid and the sugar phosphates were the earliest labeled compounds; several amino acids and organic acids were also labeled. It is concluded that N. oceanus incorporates CO(2) primarily via the reductive pentose phosphate cycle.

Bacteria↗