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Biomedical subjects

D Branton

Publications and source records attributed to D Branton.

At least 109 records · Page 6Linked to original sources
PubMed1974

Intramembrane particle aggregation in erythrocyte ghosts. I. The effects of protein removal.

We have used freeze-etching and SDS-polyacrylamide gel electrophoresis to study the conditions under which the intramembrane particles of the human erythrocyte ghost may be aggregated. The fibrous membrane protein, spectrin, can be almost entirely removed from erythrocyte ghosts with little or no change in the distribution of the particles. However, after spectrin depletion, particle aggregation in the plane of the membrane may be induced by conditions which cause little aggregation in freshly prepared ghosts. This suggests that the spectrin molecules form a molecular meshwork which limits the translational mobility of the erythrocyte membrane particles.

Blood Proteins↗
PubMed1972

Control of daughter-cell number variation in multiple fission: genetic versus environmental determinants in Prototheca.

Prototheca zopfii has been developed as an experimental system for studying the control of cytokinesis and daughter-cell number variation in multiple fission. Although mean daughter-cell number increases linearly with growth rate, and this dependency is genetically controlled, pedigree analysis shows that daughter-cell number variation is not under direct genetic control. In a population growing in steady-state balanced growth, each cell has a given probability of dividing into 2, 4, 8 16, or 32 daughter-cells. These probabilities are independent of the division number of the cell in the preceding generation, and can be altered by changes in the culture medium.

Cell Count↗
PubMed1970

Membrane structure: spin labeling and freeze etching of Mycoplasma laidawii.

A spin-labeled fatty acid was incorporated in vivo into the polar lipids of Mycoplasma laidlawii membranes. The electron paramagnetic resonance signal from either intact cells or their extracted lipids reflected the fatty acid composition of the Mycoplasma membranes. Comparison of signals from intact cells, gramicidin-treated cells, heat-treated cells, and extracted lipids indicates that a major portion of the membrane lipids is in a semiviscous hydrocarbon environment. The results also show that the spin label in the intact membrane is slightly but significantly less mobile than it is in protein-free lipid extracts made from these membranes. Correlated electron microscope examinations using the freeze-etch technique reveal particulate components in the hydrophobic region of the membrane. The mobility of the lipids in the intact cell membrane may be influenced by their association with these particles.

Cell Membrane↗
PubMed1970

The septate junction: a structural basis for intercellular coupling.

Electron microscopy, freeze-etching, and optical diffraction show how the structure of the septate junction may provide the basis for the low-resistance pathway between the electrically coupled cells in mussel gill epithelia. Conventional electron microscopy suggests that the septa are pleated sheets that differentiate from and are structurally continuous with the junctional cell membranes. Freeze-etching exposes geometrically arranged rows of 85-A particles within the junctional cell membranes. Diffraction evidence shows that these membrane particles and the alternate vertices of the intercellular septal sheets are congruent and therefore superposable. Together, the membrane particles and septal sheets provide a channel that extends from the cytoplasm of one cell through the septate junction to the cytoplasm of the adjacent cell.

Animals↗