Reversible Mechanochemical Cycle in the Contraction of Vorticella

Abstract

THE ciliate Vorticella has a stalk which is capable of coiling into a helix. The coiling is produced by the contraction of an intracytoplasmic thread, the spasmoneme, within a cylindrical sheath. Hoffmann-Berling¹ observed that the stalks of gly-cerinated preparations coiled in the presence of calcium ions and uncoiled when calcium was subsequently removed by the addition of ethylene diamine tetraacetate (EDTA), and that many cycles of contraction and relaxation could be produced by repeating this procedure, without adding adenosine triphos-phate (ATP). He also found that contraction was not abolished by ATPase inhibitors. Townes and Brown², however, were later unable to obtain reversible contractions. The behaviour of glycerinated preparations was therefore investigated under precisely defined conditions.