Dissociated blastula cells of Xenopus laevis are agglutinated with wheat germ agglutinin (WGA), Ricinus communis agglutinin (RCA), concanavalin A (Con A) and, to a lesser extent with soya bean agglutinin (SBA). They are not agglutinated with fucose-binding protein. Neuraminidase treatment of cells enhances their agglutinability with RCA and SBA, but has no effect on Con A- and WGA-mediated aggl...

Mouse oocytes are induced by cytochalasin B to undergo 'pseudo-cleavage' in vitro into 2 equally sized and separable compartments. This response to the drug is dependent upon the meiotic state of the oocytes, as well as upon the presence of an intact zona pellucida. The resulting 2 cellular compartments can be completely separated from another and cultured in vitro. Each of the compartments pos...

The distribution of surface-bound concanavalin A on the membranes of 3T3, and simian virus 40-transformed 3T3 cultured mouse fibroblasts was examined using a shadow-cast replica technique with a hemocyanin marker. When cells were prefixed in paraformaldehyde, the binding site distribution was always random on both cell types. On the other hand, labeling of transformed cells with concanavalin A ...

Actin-based motor protein requirements and nitric oxide (NO) production are important features of macrophage activity during phagocytosis or microbicidal processes. Different classes of myosins contribute directly or indirectly to phagocytosis by providing mechanical force for phagosome closure or organelle movement. Recent data have shown the presence of myosins IC, II, V and IXb in phagosomes...

Polylysine was found to induce polymerization of muscle actin in a low ionic strength buffer containing 0.4 mM MgCl2. The rate of induced polymerization was dependent on the amount and on the molecular size of the polylysine added. A similar effect was obtained by adding actin nuclei (containing about 2-4 actin subunits) cross-linked by p-N,N'-phenylenebismaleimide to G-actin under the same con...

The characteristics of glucose transport were investigated in erythrocytes of a primitive vertebrate, the Pacific hagfish (Eptatretus stouti) Lockington. Transport of glucose by intact hagfish erythrocytes and by phospholipid vesicles reconstituted with noctylglucoside extract of hagfish erythrocyte membranes was rapid and mediated by a saturable stereospecific mechanism sensitive to inhibition...

Increased extracellular pressure stimulates colon cancer cell adhesion by activating focal adhesion kinase (FAK) and Src. We investigated the role of the cytoskeleton in pressure-induced inside-out FAK and Src phosphorylation and pressure-stimulated adhesion. We perturbed actin polymerization with phalloidin, cytochalasin D and latrunculin B, and microtubule organization with colchicine and pac...

Parthenogenetic embryos are an ethically acceptable alternative for the derivation of human embryonic stem cells. In this work, we propose a new strategy to produce bovine parthenogenetic embryos inhibiting the emission of the first polar body during in vitro maturation, and allowing the extrusion of the second polar body during oocyte activation. Cytochalasin B, an inhibitor of actin microfila...

Cytochalasin B (5 mug/ml) elicits a differential effect on myoblasts and fibroblasts in culture. After 1 day in culture in the presence of the drug, two types of cells were observed, round cells and cells with elongated arms, designated "arborized" cells. Both cell types were examined in the electron microscope. The round cells contained aggregates of thin and thick filaments as well as a few i...