ANALYSIS OF CELL-MOVEMENT DURING THE CULMINATION PHASE OF DICTYOSTELIUM DEVELOPMENT

Go-ordinated cell movement of tens of thousands of cells and periodic signals characterise the multicellular development of the cellular sli me mould Dictyostelium discoideum. We investigated cell movement by an alysing time-lapse video recordings made during the slug stage and the culmination phase of Dictyostelium development, Slugs viewed from the side showed an even, straight forward movement with the tip slightly raised in the air, Slugs, that had migrated for a prolonged period of time either culminated or showed a behaviour best described as abortiv e culmination, Culmination is initiated by a local aggregation of ante rior-like cells at the base of the slug at the prestalk-prespore bound ary, where they form a stationary mass of cells, Prespore cells contin ue to move forward over this stationary pile and, as a result, are lif ted into the air, The stationary group of anterior-like cells thereby end up to the back of the slug, At this point the slug either falls ba ck on the agar surface or continues culmination, If the slug continues to migrate these cells regain motility, move forward to the prespore- prestalk boundary and form a new pile again. In the case of culminatio n the neutral red stained cells in the pile move to the back of the sl ug and form a second signalling centre beside the tip, Both centres ar e characterised by vigorous rotational cell movement, The cells belong ing to the basal centre will form the basal disc and the lower cup in the fruiting body, The upper cup will be formed by the prestalk cells rotating most vigorously at the prestalk-prespore boundary, The remain ing neutral red stained anterior-like cells in the prespore zone sort either to the upper or lower organising centre in the fruiting body.