Ca2+-induced tension development in the stalks of glycerinated Vorticella convallaria

Yasushige Moriyama, Kenji Yasuda, Shin'ichi Ishiwata, Hiroshi Asai

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

We have developed a method of measuring the isometric tension in glycerinated stalks of Vorticella convallaria. Using this method, we measured tension vs. pCa relations in glycerinated V. convallaria stalks. The maximum isometric tension was 4 x 10-8 N on average. The Hill's parameter, n, which is the number of calcium ions bound simultaneously and cooperatively to a contractile element (a force generating element), is approximately 3.2 when the Ca2+ concentration is increased and 2.5 when it is decreased. In order to estimate the efficiency of the energy conversion of Ca2+ binding to mechanical work, we measured the Ca2+-induced Carnot cycle in the Vorticella stalk. The energy efficiency was tentatively estimated to be about 7%. With this method, we have also succeeded in measuring the isometric tension of isolated spasmoneme, the rubber-like contractile fibrous organelle in the stalk. The maximum tension of spasmoneme was approximately one tenth that of the glycerinated stalk. We speculate that the isolated spasmoneme was only partially functional due to damage sustained when it was pulled out of the stalk.

Original languageEnglish
Pages (from-to)271-278
Number of pages8
JournalCell Motility and the Cytoskeleton
Volume34
Issue number4
DOIs
Publication statusPublished - 1996 Aug 27

Keywords

  • Hill's parameter
  • calcium ion
  • energy efficiency
  • spasmoneme

ASJC Scopus subject areas

  • Structural Biology
  • Cell Biology

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