| Abstrakt: |
Cell locomotion involves several structural-functional activities: membrane extensibility, microfilament regulation and adhesive interactions. There is evidence for Ca21- requirement in all of these. Our data may clarify the role of Ca2+ in locomotion and adhesion. Morphologic and spreading responses of isolated blastula-late gastrula Rana pipiens germ layer cells to varying molar concentrations of Ca2+: 0-Ca2+, Standard Ca2+ (Barth’s Xsolution), 1·5 × and 2·0 × Std Ca2+ were viewed by S.E.M. after 1 h in culture. Ionic strength and pH were constant. All cells showed quantitative relationships between Ca2+ concentration and surface extensibility, projection formation and presumably adhesion, but with tissue- and stagespecific variations. Cells in Ca2+-free medium fail to adhere (50%), flatten or form surface projections. Cells in media with increasing Ca2+ generally formed more numerous and extensive surface projections, spread and adhered to a greater extent. In some cases there were no quantitative differences in response between 1·5 × and 2·0×standard Ca2+. Cells in suspension for 1 h in standard solution remained spherical, forming no projections. We infer from these results that both Ca2+ and contact with a physical substratum, cell-cell or cellglass are required for mobilization of the various systems involved in locomotion and adhesion. In addition, components of these systems are quantitatively activated by increased availability of Ca2+. |
