Directional Locomotion Research Articles

Distinct chemokinetic and chemotactic responses in neutrophil granulocytes.

Evidence has been presented to show that chemokinesis and chemotaxis of human neutrophil granulocytes can be controlled by distinct cellular mechanisms and by different chemicals. Materials such as human serum albumin or fibrinogen had chemokinetic but no chemotactic properties. Highly purified preparations of serum-derived peptides containing classical anaphylatoxin had detectable chemotactic activity only. Chemokinetic as well as chemotactic substances were required for the expression of chemotaxis in the form of efficient directional locomotion. The roles of chemokinesis and chemotaxis in the regulation of directional locomotion have been analyzed. Further experiments showed that the chemotactic response conforms to the law of Weber-Fechner. The number of cells which had accumulated in response to a chemotactic simulus was proportional to the logarithm of the concentration of the chemical substance. Readaptation from high to low chemotactic stimulus occurred only to a limited extent.

A visual analysis of chemotactic and chemokinetic locomotion of human neutrophil leucocytes: Use of a new chemotaxis assay with Candida albicans as gradient source

The locomotion of human blood neutrophil leucocytes was observed and analysed by time-lapse cinematography (1) under conditions where chemokinetic locomotion was stimulated, i.e. in a uniform concentration of casein; (2) in response to chemotactic gradients generated at a point-like source, namely blastospores of the pathogenic yeast Candida albicans in normal human plasma, and (3) in response to soluble chemotactic factors diffusing from Sephadex beads. Neutrophils moving in purely chemokinetic conditions tended to persist in straight paths and showed a preference for narrow angles of turn suggesting a “persistent random walk” type of locomotion rather than a pure random walk. Cells responding to Candida spores showed near straight-line locomotion to the gradient source over short distances (ca 50 μm) and brief time periods. They phagocytosed the spores on arrival and were usually immediately able to respond to a new gradient. Colchicine treatment caused the cells to turn through wider angles, but they were still able to home onto and phagocytose the spores. Colchicine-treated cells showed bizarre and fluctuating shapes but were nonetheless usually polarized towards the gradient source. Gradients from large sources, such as Sephadex beads containing soluble chemotactic factors, were more easily disturbed than those from Candida spores and directional locomotion of cells towards the beads was only seen in certain sectors. The angles of turn made by moving cells under these conditions were an important determinant of chemotaxis since paths of those cells reaching beads showed longer straight segments and narrower angles of turn than those which failed to show a directional response.

Significance of Hageman factor (coagulation factor XII) for neutrophil locomotion and chemotaxis.

Neutrophils separated from Hageman factor-deficient blood exhibit normal random and directional locomotion. No defect in cytotaxin formation could be demonstrated in Hageman factor-deficient plasma, nor did kallikrein inhibitor interfere with the chemotactic activity of normal immune complex-activated human plasma. The results suggest that the chemotactic activity which is detectable in unfractionated human plasma is not derived from Hageman factor-dependent pathways.

Effect of colcemid on the locomotory behaviour of fibroblasts

ABSTRACT Effects of metaphase inhibitors (colcemid, colchicine, vinblastine) on mouse and human embryonic, fibroblast-like cells growing on glass and on an oriented substrate (fish scale) were studied. All three inhibitors caused similar changes in the form of interphase cells and inhibited their directional locomotion. The effects of two inhibitors (colcemid and vinblastine) were found to be completely reversible. Microcinematographic studies have shown that the most conspicuous change of locomotory behaviour induced by colcemid was the disappearance of non-active stable parts of the cell edge; in normal cells only the leading part of the edge was actively moving, while in colcemid-treated cells all parts of the edge eventually became active. Activation of the whole edge made these cells unable to perform directional translocation. It is suggested that colcemid and other metaphase inhibitors prevent stabilization of the non-active state of the cell surface. The possible role of this suggested colcemid-sensitive stabilization mechanism in the normal locomotory behaviour of fibroblasts is discussed. Electron-microscopic examination has shown that microtubules disappeared from the cytoplasm of colcemid-treated, mouse, fibroblast-like cells. The formation of microtubules as the possible structural basis of the stabilization of the non-active state of the cell surface is discussed.