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Biomedical subjects

R Y Stanier

Publications and source records attributed to R Y Stanier.

At least 55 records · Page 3Linked to original sources
PubMed1967

Biochemical basis of obligate autotrophy in blue-green algae and thiobacilli.

Differential rates of incorporation of sugars, organic acids, and amino acids during autotrophic growth of several blue-green algae and thiobacilli have been determined. In obligate autotrophs (both blue-green algae and thiobacilli), exogenously furnished organic compounds make a very small contribution to cellular carbon; acetate, the most readily incorporated compound of those studied, contributes about 10% of newly synthesized cellular carbon. In Thiobacillus intermedius, a facultative chemoautotroph, acetate contributes over 40% of newly synthesized cellular carbon, and succinate and glutamate almost 90%. In the obligate autotrophs, carbon from pyruvate, acetate, and glutamate is incorporated into restricted groups of cellular amino acids, and the patterns of incorporation in all five organisms are essentially identical. These patterns suggest that the tricarboxylic acid cycle is blocked at the level of alpha-ketoglutarate oxidation. Enzymatic analyses confirmed the absence of alpha-ketoglutarate dehydrogenase in the obligate autotrophs, and also revealed that they lacked reduced nicotinamide adenine dinucleotide oxidase, and had extremely low levels of malic and succinic dehydrogenase. These enzymatic deficiencies were not manifested by the two facultative chemoautotrophs examined. On the basis of the data obtained, an interpretation of obligate autotrophy in both physiological and evolutionary terms has been developed.

Acetates↗
PubMed1966

The development of cellular stalks in bacteria.

Extensive stalk elongation in Caulobacter and Asticcacaulis can be obtained in a defined medium by limiting the concentration of phosphate. Caulobacter cells which were initiating stalk formation were labeled with tritiated glucose. After removal of exogenous tritiated material, the cells were subjected to phosphate limitation while stalk elongation occurred. The location of tritiated material in the elongated stalks as detected by radioautographic techniques allowed identification of the site of stalk development. The labeling pattern obtained was consistent with the hypothesis that the materials of the stalk are synthesized at the juncture of the stalk with the cell. Complementary labeling experiments with Caulobacter and Asticcacaulis confirmed this result. In spheroplasts of C. crescentus prepared by treatment with lysozyme, the stalks lost their normal rigid outline after several minutes of exposure to the enzyme, indicating that the rigid layer of the cell wall attacked by lysozyme is present in the stalk. In spheroplasts of growing cells induced with penicillin, the stalks did not appear to be affected, indicating that the stalk wall is a relatively inert, nongrowing structure. The morphogenetic implications of these findings are discussed.

Autoradiography↗