Stalk-length-dependence of the contractility of Vorticella convallaria

Eun Gul Chung, Sangjin Ryu

Research output: Contribution to journalArticle

Abstract

Vorticella convallaria is a sessile protozoan of which the spasmoneme contracts on a millisecond timescale. Because this contraction is induced and powered by the binding of calcium ions (Ca2+), the spasmoneme showcases Ca2+-powered cellular motility. Because the isometric tension of V. convallaria increases linearly with its stalk length, it is hypothesized that the contractility of V. convallaria during unhindered contraction depends on the stalk length. In this study, the contractile force and energetics of V. convallaria cells of different stalk lengths were evaluated using a fluid dynamic drag model which accounts for the unsteadiness and finite Reynolds number of the water flow caused by contracting V. convallaria and the wall effect of the no-slip substrate. It was found that the contraction displacement, peak contraction speed, peak contractile force, total mechanical work, and peak power depended on the stalk length. The observed stalk-length-dependencies were simulated using a damped spring model, and the model estimated that the average spring constant of the contracting stalk was 1.34 nN μm-1. These observed length-dependencies of Vorticella's key contractility parameters reflect the biophysical mechanism of the spasmonemal contraction, and thus they should be considered in developing a theoretical model of the Vorticella spasmoneme.

Original languageEnglish (US)
Article number066002
JournalPhysical Biology
Volume14
Issue number6
DOIs
StatePublished - Nov 16 2017

Keywords

  • Vorticella spasmoneme
  • calcium-powered cell motility
  • damped spring model
  • finite Reynolds number
  • fluid dynamic model
  • unsteady drag
  • wall effect

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Molecular Biology
  • Cell Biology

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