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Journal of Cell Science, Vol 87, 555-564, Copyright © 1987 by Company of Biologists

Submitted on December 15, 1986
Accepted on February 9, 1987

Signal-induced reorganization of the microtubular cytoskeleton in the ciliated protozoon Euplotes octocarinatus

MARIA JERKA-DZIADOSZ 1, CHRISTINE DOSCHE 2, HANS-WERNER KUHLMANN 2, and KLAUS HECKMANN 2

1 Department of Cell Biology, M. Nencki Institute of Experimental Biology 3 Pasteur St, 02-093 Warsavc, Poland
2 Zoological Institute of the University of Münster, Schlo{beta}platz 5, D-4400 Münster, FRG

Author for correspondence

A predator-released substance induces the freshwater ciliate Euplotes octocarinatus to undergo, within a few hours, a drastic change in cell form that makes engulfment by the predator more difficult or even impossible. During this transformation, the outline of the cell changes from ovoid to circular and the size increases considerably. The cells cease dividing while they transform, but later continue divisional morphogenesis and maintain the circular form for many cell generations if the concentration of the predator factor is maintained.

The microtubular cytoskeleton of Euplotes was studied by transmission electron microscopy of cells from which the cytoplasm had been extracted by mild treatment with Triton X-100. This procedure increased the visibility of microtubules, especially single microtubules located in the endoplasm. In transformed cells, a considerable increase in number of microtubular triads on the dorsal and ventral surfaces and the appearance of extra single microtubules between the dorsal triads was observed. However, certain interconnected groupings of microtubules located on the dorsal surface were greatly diminished after transformation. Intracytoplasmic microtubules were also more abundant in the enlarged cells than in the untreated ovoid ones. The spacing and general pattern of microtubules, however, appears to be the same in untreated and treated cells.

We conclude from these observations that the transformation of Euplotes cells from their typical ovoid form into the enlarged circular form is accompanied by the mobilization and utilization of microtubules already present in subcortical regions and an assembly of new microtubules needed for support of the expanding cell cortex.

Key words: microtubules, cytoskeleton reorganization, Euplotes

Submitted on December 15, 1986
Accepted on February 9, 1987






© The Company of Biologists Ltd 1987