Dynamics of the cytoskeleton during morphogenesis in the ciliate Euplotes I. Basal bodies related microtubular system.

In Euplotes, the infraciliary cytoskeletal complex consists mainly of basal bodies grouped into cirri from which bundles of microtubules emanate in specific orientations. The dynamics of this microtubular cytoskeleton has been followed by proteinate silver impregnation and immunocytochemical methods during the morphogenetic process of division. The patterning of this infraciliature involves the assembly of a series of complex microtubular arrays and the main results are the following: The interphasic microtubular pattern is thus restored at the end of cirral movements after successive steps including the elongation of the bidirectional system, the assembly of interphasic rootlets and the disappearance of the posterior longitudinal bundles of the bidirectional system. All of these basal body dependent systems are stable, i.e. they are not affected by a depolymerizing treatment (cold and vinblastin). The timing of these events outlines the shift between the localized events occurring at the beginning of the morphogenesis and the later ones, leading to a large scale pattern. These observations are discussed in relation to the dynamic properties of microtubular system.