Contraction behaviors of Vorticella sp. stalk investigated using high-speed video camera. II: Viscosity effect of several types of polymer additives

Abstract

The contraction process of living Vorticella sp. in polymer solutions with various viscosities has been investigated by image processing using a high-speed video camera. The viscosity of the external fluid ranges from 1 to 5mPa·s for different polymer additives such as hydroxypropyl cellulose, polyethylene oxide, and Ficoll. The temporal change in the contraction length of Vorticella sp. in various macromolecular solutions is fitted well by a stretched exponential function based on the nucleation and growth model. The maximum speed of the contractile process monotonically decreases with an increase in the external viscosity, in accordance with power law behavior. The index values approximate to 0.5 and this suggests that the viscous energy dissipated by the contraction of Vorticella sp. is constant in a macromolecular environment.

Vorticella: A Protozoan for Bio-Inspired Engineering

“…Upadhyaya et al first noticed that power dissipation of multiple V. convallaria cells, which is the product of force and velocity, was 1–3 nW even with significant increase in the medium viscosity [ 14 ]. Recently, Kamiguri et al used various polymer additives and made similar observations [ 121 ]. The idea of power-limited contraction was more rigorously examined by Ryu and Matsudaira [ 9 ], who calculated that the power dissipation of a single V. convallaria was maintained at 1.2–1.6 nW over one order of magnitude change in the viscosity ( Figure 10 B inset).…”

Contraction behaviors of Vorticella sp. stalk investigated using high-speed video camera. I: Nucleation and growth model

“…in the aqueous culture media as shown in this report, but it is unsuccessful for the contraction process of Vorticella sp. in the aqueous polymer solution 11 . In addition, a double exponential function is a little bit troublesome in the fitting operation to the data as compared with the following stretched exponential function.…”