Unilateral Cleavage Furrows in Multinucleate Cells

Multinucleate cells can be produced in Dictyostelium by electric-pulse induced fusion. In these cells unilateral cleavage furrows are formed at spaces between areas that are controlled by aster microtubules. A peculiarity of unilateral cleavage furrows is their propensity to join laterally with other furrows into rings to form constrictions. This means, cytokinesis is biphasic in multinucleate cells, the final abscission of daughter cells being independent of the initial direction of furrow progression. Myosin-II and the actin-filament cross-linking protein cortexillin accumulate in the unilateral furrows, as they do in the normal cleavage furrows of mononucleate cells. Myosin-II is not essential for cytokinesis, but stabilizes and confines the position of the cleavage furrows.