The extracellular matrix (ECM) protein thrombospondin (TSP) binds specifically to polymorphonuclear leucocyte (PMN) surface receptors and promotes cell adhesion and motility. TSP receptor expression increases 30-fold after activation with the synthetic chemotactic peptide, N-formylmethionyl-leucylphenylalanine (FMLP) or the Ca2+ ionophore A23187, in combination with cytochalasin B. The expressi...

To examine the relationship between binding of surface-active stimuli to human neutrophils and activation of the superoxide (02. ) and peroxide (H202) forming oxidase(s) of these cells. oxygen (02) consumption and 02. and H202 release were measured following stimulation by plant lectins. Both concanavalin A (Con-A) and phytohemagglutinin (PHA) were more active than other lectins in stimulating ...

To examine the relationship between binding of surface-active stimuli to human neutrophils and activation of the superoxide (02. ) and peroxide (H202) forming oxidase(s) of these cells. oxygen (02) consumption and 02. and H202 release were measured following stimulation by plant lectins. Both concanavalin A (Con-A) and phytohemagglutinin (PHA) were more active than other lectins in stimulating ...

In order to determine whether or not a crucial number of DNA replications are prerequisite for cellular differentiation, we have studied development of a tissue-specific enzyme, muscle acetylcholinesterase (AChE) in the presumptive muscle cells of cleavage-arrested ascidian embryos. Embryos were cleavage-arrested with cytochalasin B (an inhibitor of cytokinesis) and aphidicolin (an inhibitor of...

Villin, a 95,000-dalton protein, is a major component of microvillus cores isolated from intestinal brush borders. In this study, we compared the Ca2+-dependent action of this protein on actin filaments with that of cytochalasin B, a fungal metabolite that binds to the "barbed" end of actin filaments and nuclei. We found that substoichiometric levels of villin inhibit actin filament elongation ...

Friend erythroleukemia cells grown in culture and induced to differentiate along the erythroid developmental pathway by dimethyl sulfoxide (DMSO) were used as a model system to investigate the requirement for cellular replication to express a differentiated erythroid phenotype. That cytokinesis is not essential for DMSO-induced erythroid differentiation as measured by the synthesis and accumula...

In this work we have applied in situ hybridization with alphoid centromeric probes specific to chromosomes 7 and 11 to ana-telophase cells from human primary fibroblasts. The aim was to visualize the events leading to aneuploidy directly during anaphase, analyse the induction of aneuploidy during this mitotic stage and compare the frequencies of chromosome malsegregation observed in ana-telopha...