Tensegrity model of pattern formation during cytokinesis of a ciliate, Paramecium: Effects of an inhibitor of phosphorylation, 6-dimethylaminopurine, and of adenine

During cytokinesis of the ciliate Paramecium, the two oral apparatuses (OAs), localized close to the fission line, are displaced to a mid-region of daughter cells by a tearing off of the OAs and adjacent-cortices from the fission line and their subsequent movement toward the poles of the dividing cell. Two possible mechanisms for this displacement were examined: 1) a mechanism whereby the contraction of the fission line in the vicinity of OAs brings about the change of configuration of the adjacent cortices and subsequent displacement of OAs and 2) a mechanism whereby programmed transient depolymerization of the inner cytoskeletal contractile infraciliary lattice in the vicinity of OAs acts as a motive force for displacement of the OAs, together with the most superficial outer lattice of the cytoskeleton which does not disassemble. Our working hypotheses were based on observations on the behavior of the outer lattice, where the infraciliary lattice disintegrates and the fission line assembles. To study the mechanics of pattern formation during cytokinesis of Paramecium, morphogenesis was followed in the presence of an inhibitor of phosphorylation, 6-dimethylaminopurine (6-DMAP), and of adenine, which prevented disassembly of the inner lattice and arrested cytokinesis and dislocation of OAs. Nearly all defects in morphogenesis were correlated with failure of the infraciliary lattice to disassemble and failure of the fission line to assemble. It appears that the superficial cortical structures and the contractile infraciliary lattice represent a tensegrity model of morphogenesis during cytokinesis in Paramecium. (C) 1995 Wiley-Liss, Inc.