High-speed video cinematographic demonstration of stalk and zooid contraction of Vorticella convallaria.
Stalk contraction and zooid contraction of living Vorticella convallaria were studied by high-speed video cinematography. Contraction was monitored at a speed of 9000 frames per second to study the contractile process in detail. Complete stalk contraction required approximately 9 ms. The maximal contraction velocity, 8.8 cm/s, was observed 2 ms after the start of contraction. We found that a twist appeared in the zooid during contraction. As this twist unwound, the zooid began to rotate like a right-handed screw. The subsequent stalk contraction steps, the behavior of which was similar to that of a damped harmonic oscillator, were analyzed by means of the equation of motion. From the beginning of stalk contraction, the Hookean force constant increased, and reached an upper limit of 2.23 x 10(-4) N/m 2-3 ms after the start of contraction. Thus, within 2 ms, the contraction signal spread to the entire stalk, allowing the stalk to generate the full force of contraction. The tension of an extended stalk was estimated to be 5.58 x 10(-8) N from the Hookean force constant of a stalk. This value coincides with that of the isometric tension of a glycerol-treated V. convallaria, confirming that the contractile system of V. convallaria is well preserved despite glycerol treatment.
Moriyama
Y
Y
Department of Physics, School of Science and Engineering, Waseda University, Tokyo, Japan. moriyama@po.cnet-sc.ne.jp
Hiyama
S
S
Asai
H
H
D000818:Animals; D002465:Cell Movement / Q000502:physiology; D016798:Ciliophora / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure*; D005990:Glycerol / Q000494:pharmacology; D007700:Kinetics; D018715:Microscopy, Video / Q000379:methods; D013997:Time Factors
D005990:Glycerol