QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sugi, H. Articles by Chaen, S. Search for Related Content PubMed PubMed Citation Articles by Sugi, H. Articles by Chaen, S.

Force–velocity relationships in actin–myosin interactions causing cytoplasmic streaming in algal cells

Haruo Sugi^1,* and Shigeru Chaen²

¹ Department of Physiology, School of Medicine, Teikyo University, Itabashi-ku, Tokyo 173-8605, Japan
² Department of Applied Physics, College of Humanities and Science, Nihon University, Setagaya-ku,Tokyo 156-8550, Japan

View larger version (24K): [in a new window]   Fig. 1. Diagram of cytoplasmic streaming in the internodal cell of green algae. ac, actin cable; ch, chloroplast; cm, cytoplasmic myosin; co, cytoplasmic organelle; cs, cell sap; cw, cell wall; cy, streaming cytoplasm; ic, internodal cell. Arrows indicate direction of cytoplasmic streaming.

View larger version (33K): [in a new window]   Fig. 2. Centrifuge microscope for studying kinetic properties of ATP-dependent actin–myosin sliding. (A) Diagram showing the centrifuge microscope and video recording system. (B) Application of centrifugal forces serving as positive or negative loads on the beads sliding along actin cables. Reproduced from Oiwa et al. (1990).

View larger version (16K): [in a new window]   Fig. 3. Force–velocity (P–V) characteristics of ATP-dependent actin–myosin sliding in muscle contraction. (A) Constant velocity sliding of a skeletal muscle myosin-coated bead along actin cables under four different positive loads, expressed relative to maximum isometric force (P0). (B) Typical example of a steady-state P–V curve of actin–myosin sliding. Reproduced from Oiwa et al. (1990).

View larger version (24K): [in a new window]   Fig. 4. Force–velocity (P–V) characteristics of ATP-dependent actin–myosin sliding causing cytoplasmic streaming. (A) Constant velocity sliding of a cytoplasmic myosin-coated bead along actin cables under different positive beads. (B) P–V curve constructed from six different beads with large (8.6–13 pN) maximum isometric force (P0). (C) P–V curve constructed from six different beads with small (1.0–2.4 pN) maximum isometric force (P0). Data points in the P–V curves represent mean values, with vertical and horizontal bars indicating S.D. (N=6). (D) P–V curve for the movement of a bead under negative loads, expressed in pN.