Measurement of Chemotaxis in Dictyostelium

Abstract

The molecular mechanism of chemotaxis contributes to the explanation of signal transduction. To investigate the transfer of chemotactic signals one has to measure the response to chemoattractants. A shift from observing cell behavior to exploring the mechanism of signal transduction required sophisticated chemotactic assays. Measurement of simple qualitative positive or negative responses is supplemented with semiquantitative observation of chemotaxis. Several assays are developed; some have already been applied to other cells, and others are specifically designed to measure a chemotactic response in the slime molds. The first chemotaxis assays for cellular slime molds are meant to prove that amoebae move chemotactically to the center of an aggregate. These qualitative assays are gradually succeeded by semiquantitative assays when chemoattractants are isolated, purified, characterized, and sometimes identified. The further development of assays is directed to the elucidation of cell behavior in gradients of chemoattractants. A considerable extension of automation of data acquisition is presented. This automation allows new assays to be performed which focus both on the cell population and on individual cells in chemotactic gradients with defined temporal and spatial components. © 1987, Academic Press Inc.