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A G Marr

Publications and source records attributed to A G Marr.

23 records · Page 2Linked to original sources
PubMed1966

Measurement of size distributions of bacterial cells.

Harvey, R. J. (University of California, Davis), and Allen G. Marr. Measurement of size distributions of bacterial cells. J. Bacteriol. 92:805-811. 1966.-Apparatus for the automatic determination of the volume distribution of particles by measurement of the amplitude of pulses generated in a Coulter transducer is described. Distributions of volume estimated by direct measurement of pulse amplitude are distorted by coincidence. Differentiation and integration of the pulses followed by automatic pulse-height analysis permit precise measurement of volume of latex spheres and of bacteria over a range of at least 0.25 to 20 mu(3). The apparatus is also capable of accurate determination of particle concentration over a wide range. Other advantages are the speed of both measurement and data processing.

Bacteria↗
PubMed1962

LOCALIZATION OF RESPIRATORY ENZYMES IN INTRACYTOPLASMIC MEMBRANES OF AZOTOBACTER AGILIS.

Pangborn, J. (University of California, Davis), Allen G. Marr, and S. A. Robrish. Localization of respiratory enzymes in intracytoplasmic membranes of Azotobacter agilis. J. Bacteriol. 84:669-678. 1962.-Thin sections of the cells of Azotobacter agilis which have been disrupted by sonic treatment, by osmotic shock, or by ballistic disintegration reveal a network of internal membranes in the form of vesicles and tubules. The internal membranes are attached to the envelope. Treatment in a Mickle disintegrator of envelopes emptied of cytoplasm by osmotic shock results in the loss of the internal membranes and a concomitant release of reduced diphosphopyridine nucleotide oxidase from the envelopes. Thus, the intracytoplasmic membranes are the probable locus of the respiratory enzymes of the cell. Thin sections of whole cells show tubular intracytoplasmic membranes which are obscured by ribosomes and other dense cytoplasmic constituents.

Journal Article↗
PubMed1962

EFFECT OF TEMPERATURE ON THE COMPOSITION OF FATTY ACIDS IN ESCHERICHIA COLI.

Marr, Allen G. (University of California, Davis) and John L. Ingraham. Effect of temperature on composition of fatty acids in Escherichia coli. J. Bacteriol. 84:1260-1267. 1962.-Variations in the temperature of growth and in the composition of the medium alter the proportions of individual fatty acids in the lipids of Escherichia coli. As the temperature of growth is lowered, the proportion of unsaturated fatty acids (hexadecenoic and octadecenoic acids) increases. The increase in content of unsaturated acids with a decrease in temperature of growth occurs in both minimal and complex media. Cells harvested in the stationary phase contained large amounts of cyclopropane fatty acids (methylenehexadecanoic and methylene octadecanoic acids) in comparison with cells harvested during exponential growth. Cells grown in a chemostat, limited by the concentration of ammonium salts, show a much higher content of saturated fatty acids (principally palmitic acid) than do cells harvested from an exponentially-growing batch culture in the same medium. Cells grown in a chemostat, limited by the concentration of glucose, show a slightly higher content of unsaturated fatty acids than cells from the corresponding batch culture. The results do not indicate a direct relation between fatty acid composition and minimal growth temperature.

Journal Article↗