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Journal of Cell Science, Vol 16, 377-383, Copyright © 1974 by Company of Biologists

Submitted on March 18, 1974

The Antagonistic Effects of Antimitotic Agents on Contraction and Re-Extension in the Ciliate Spirostomum Ambiguum

E. M. ETTIENNE 1 and M. SELITSKY 2

1 The Marine Biological Laboratory, Woods Hole, Massachusetts and Oakland University, Rochester, Michigan, U.S.A.; Department of Anatomy Harvard Medical School, Boston, Mass., U.S.A.
2 The Marine Biological Laboratory, Woods Hole, Massachusetts and Oakland University, Rochester, Michigan, U.S.A.

Contraction in Spirostomum is apparently directed by 2 antagonistic systems which respond to changes in free calcium concentration. The system responsible for imparting contractile tension consists of bundles of 4-5 nm microfilaments which can be calcium-activated. The second system consists of pellicular microtubules which may have the capacity to impart tensile force and react with each other through cross-bridging. Cells subjected to electrical stimulation to induce contraction in the presence of 0.1 mM 2,4-dinitrophenol and KCN failed to recover their original resting lengths. Similar treatment with colchicine produced the same effect, implying an interruption in the activity or structural integrity of the microtubular system. Treatment with 0.5 µg/ml cytochalasin B inhibited all contractile responses, presumably by blocking the activity of microfilaments.

Submitted on March 18, 1974






© The Company of Biologists Ltd 1974