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H J MOROWITZ

Publications and source records attributed to H J MOROWITZ.

At least 19 recordsLinked to original sources
PubMed1965

STUDIES OF THE ULTRASTRUCTURE AND RIBOSOMAL ARRANGEMENTS OF THE PLEUROPNEUMONIA-LIKE ORGANISM A5969.

Thin-section electron microscopy, together with isolation of cellular organelles by differential centrifugation and chemical analysis, has been used to investigate the ultrastructure of the avian pleuropneumonia-like organism A5969. Each cell (approximate diameter 5500 A) was surrounded by a 150 A plasma membrane. In the center of the cell was an unbounded area, granular in appearance and containing the cell's DNA. The periphery of the cell contained granules of several different sizes and densities. The most dense particles (150 A) corresponded to the 78S ribosomes. These particles exhibited two predominant arrangements: (a) sometimes they showed cubic packing; (b) most arrays, however, were consistent with cylindrical arrangements of approximately 50 particles. Bundles of up to 18 arrays were observed. Structured blebs have been found protruding from the surface of log phase cells.

Cell Biology↗
PubMed1964

DEFINED MEDIUM FOR MYCOPLASMA LAIDLAWII.

Tourtellotte, Mark E. (University of Connecticut, Storrs), Harold J. Morowitz, and Phil Kasimer. Defined medium for Mycoplasma laidlawii. J. Bacteriol. 88:11-15. 1964.-A defined medium for the pleuropneumonia-like organism Mycoplasma laidlawii B is described in which absolute requirements for coenzyme A and longchain fatty acids were demonstrated. This organism did not require cholesterol or macromolecules of high molecular weight, but did show a growth requirement for peptides. Optimal growth in the basal medium was obtained in the presence of two purified peptides from crystalline ribonuclease, one of which has the amino acid sequence threonine - threonine - glutamine - alanine - asparagine-lysine, and the other lysine-glutamic acid-threonine-alanine-alanine-alanine-lysine. Continuous, but suboptimal, growth was obtained with the single ribonuclease peptide: lysine-glutamic acid-threonine-alanine-alanine-alanine-lysine.

Acholeplasma laidlawii↗
PubMed1963

LIPID COMPOSITION AND SYNTHESIS IN THE PLEUROPNEUMONIA-LIKE ORGANISM MYCOPLASMA GALLISEPTICUM.

Tourtellotte, Mark E. (University of Connecticut, Storrs), Robert G. Jensen, George W. Gander, and Harold J. Morowitz. Lipid composition and synthesis in the pleuropneumonia-like organism Mycoplasma gallisepticum. J. Bacteriol. 86:370-379. 1963.-A simple method of extracting lipids from cells of Mycoplasma gallisepticum by use of silicic acid columns is described. Proteolipids (peptides) extracted with chloroform-methanol (2:1) by other methods were not extracted with the lipid by this method, nor were proteins and nucleic acids. Fractionation of lipids of M. gallisepticum demonstrated the presence of saturated hydrocarbons, free fatty acids, cholesterol, cholesterol esters, di- and triglycerides, phosphatidic acids, cephalins, inositides, phosphatidyl choline, and sphingomyelin. The fatty acid composition of the various fractions was also determined. The positive identification of cholesterol and cholesterol esters in this organism by chromatography, melting point, and infrared spectroscopy confirms reports by others that cholesterol is present in the pleuropneumonia group of microorganisms. The incorporation of P(32) orthophosphate into four phospholipid fractions, of oleic acid-1-C(14) into neutral and phospholipids, and cholesterol-4-C(14) into cholesterol esters clearly demonstrated the ability of M. gallisepticum to synthesize these lipids from simpler compounds. Between 70 and 80% of the lipid of this organism was found in the membrane.

Biological Products↗
PubMed1962

Electrical properties of the membranes of the pleuropneumonia-like organism A 5969.

The electrical properties of the pleuropneumonia-like organism A 5969 have been determined over the frequency range from 0.5 to 250 Mcps. The frequency dependence of the dielectric constant and conductivity of PPLO suspensions is completely consistent with the existence of a membrane. The PPLO has an internal conductance which in part reflects its ionic equilibrium with normal nutrient and macromolecular constituents. But it is fairly independent from variation in external ionic strength.

Membranes↗