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T L Steck

Publications and source records attributed to T L Steck.

101 records · Page 6Linked to original sources
PubMed1970

Inside-out red cell membrane vesicles: preparation and purification.

Plasma membranes purified from human red cells were Converted into small vesicleS by disruption in alkaline buffer of low ionic strength. Most of these vesicles were inside-out. The presence of divalent cations prevented this inversion. The inside-out vesicles were separatcd from right-side-out vesicles by centrifugration to equilibrium in dextran density gradients.

Cell Membrane↗
PubMed1969

Analysis of the ribonucleic acid of murine leukemia virus.

Cells producing the Rauscher strain of murine leukemia virus (MLV) were exposed to (3)H-uridine, and labeled virus was collected at hourly intervals. Ribonucleic acid (RNA) extracted from virions (vRNA) had a characteristic single peak when analyzed by electrophoresis in polyacrylamide-agarose composite gels. Exposure of vRNA to dimethyl sulfoxide, urea, formaldehyde, or heat altered the mobility to a faster moving form (vRNA'). This vRNA' sedimented more slowly than native vRNA in sucrose gradients. Incubation of labeled virions at 37 C resulted in fragmentation of viral RNA which was detectable only after denaturation. Also, large differences in the temperature required for the change from vRNA to vRNA' were seen with alterations in NaCl concentration. These experiments demonstrate that the vRNA of MLV is held in a specific conformation by hydrogen bonds distributed over a large part of the molecule. The possibility that an undefined factor is associated with viral RNA is discussed.

Centrifugation, Density Gradient↗
PubMedDate not supplied

Osmotic homeostasis in Dictyostelium discoideum: excretion of amino acids and ingested solutes.

The response to osmotic stress in axenically cultured Dictyostelium discoideum was examined. Hypoosmotic buffers elicited two changes in the large (approximately 50 mM) cytosolic pool of amino acids: a) the total size of the pool diminished, while b) about half of the initial pool was excreted. Hyperosmotic stress had the opposite effect. Among the predominant amino acids in the pool were glycine, alanine and proline. Putrescine, the major diamine, was neither excreted nor modulated. Recently ingested radioactive amino acids were excreted in preference to those in the cytoplasm, suggesting that the endocytic pathway might be involved in water excretion. Furthermore, hypoosmotic stress stimulated the selective excretion of small, membrane-impermeable fluorescent dyes which had been ingested into endocytic vacuoles. Caffeine inhibited the excretion of the fluorophores but not the amino acids. We conclude that the response of Dictyostelium to osmotic stress is complex and includes both modulation of the cytoplasmic amino acid pool and the excretion of amino acids and other small solutes from the endocytic pathway.

Alanine↗