Rheological properties of living cytoplasm: A preliminary investigation of squid axoplasm (Loligo pealei)

Abstract

A magnetic sphere viscoelastometer has been developed to perform rheological experiments in living axoplasm of Loligo pealei. The technique includes the use of a calibrated magnetic sphere viscoelastometer on surgically implanted ferro-magnetic spheres in intact squid giant axons. The axoplasm was discerned to be "living" by the biological criterion of tubulovesicular organelle motility, which was observed before and after experimentation. From these in vivo experiments, new structural characteristics of the axoplasm have been identified. First, analysis of magnetic sphere trajectories has shown the axoplasm to be a complex viscoelastic fluid. Directional experimentation showed that this material is structurally anisotropic, with a greater elastic modulus in the direction parallel to the axon long axis. Second, both magnetic sphere and in vivo capillary experiments suggested that the axoplasm is tenaciously anchored to the axolemma. Third, it was found that axoplasm could be modelled as a linear viscoelastic material in the low shear rate range of 0.0001 to 0.004 s-1. The simplest mechanical model incorporating the discovered properties of the material in this range is Burger's model.

Cavitation in Non-Newtonian Fluids

“…1.3.3. Similar results have been later reported by Bausch et al (1998) for 3T3 murine fibroblasts (η = 2×10 3 Pa·s), Bausch et al (1999) for J774 macrophages (η = 2×10 2 Pa·s), and Sato et al (1984) for the cytoplasmic viscosity of the axoplasm of squid axon (η = 10 4 -10 5 Pa·s). Valberg and Feldman (1987) reported a comprehensive study of the cytoplasmic viscosity of pulmonary macrophages.…”

The Mechanical Structure of the Cytoplasm of the Echinoderm Egg Determined by “Gold Particle Method” using a Centrifuge Microscope

“…2,7,8,16,18). Such a recoil of the particle after terminating the centrifugal field was not definitely observed in the present study.…”

Arp2/3 Complex fromAcanthamoebaBinds Profilin and Cross-links Actin Filaments

“…Rheological measurements were made with a cone and plate Rheometrics rheometer (Rheometrics Inc., Piscataway, NJ) in the small amplitude(strain Յ 2%), forced oscillation mode (Sato et al, 1984). Arp2/3 complex in KME buffer (50 mM KCl, 10 mM imidazole, pH 7.0, 1 mM EGTA, and 1 mM MgCl 2 ) was mixed with actin in Buffer G [2 mM Tris-HCl (pH 8.0), 0.2 mM CaCl 2 , 0.2 mM ATP, 0.5 mM DTT, and 1 mM NaN 3 ], polymerized by adding one-tenth volume of 10 ϫ KME and immediately placed between the metal plates of the rheometer to polymerize at 25°C.…”