2007/10/12 by Salman S. Rogers, Thomas Andrew Waigh, Thomas A. Waigh +1
Biochemistry, Genetics and Molecular Biology · Engineering · Medicine · Physics and Astronomy · #Amoeba (genus) #Amoeba proteus #Biology #Biophysics #Blood properties and coagulation #Cellular Mechanics and Interactions #Composite material #Flow (mathematics) #Hagen–Poiseuille equation #Isotropy #Materials science #Mechanics #Microrheology #Newtonian fluid #Optics #Particle Dynamics in Fluid Flows #Physics #Rheology #Viscoelasticity #cond-mat.soft #q-bio.CB
paper · pdf · doi:10.1529/biophysj.107.123851
arxiv created 2007/10/12 · openalex publication_date 2008/01/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The motility of motile Amoeba proteus was examined using the technique of passive particle tracking microrheology, with the aid of newly-developed particle tracking software, a fast digital camera and an optical microscope. We tracked large numbers of endogeneous particles in the amoebae, which displayed subdiffusive motion at short time scales, corresponding to thermal motion in a viscoelastic medium, and superdiffusive motion at long time scales due to the convection of the cytoplasm. Subdiffusive motion was characterised by a rheological scaling exponent of 3/4 in the cortex, indicative of the semiflexible dynamics of the actin fibres. We observed shear-thinning in the flowing endoplasm, where exponents increased with increasing flow rate; i.e. the endoplasm became more fluid-like. The rheology of the cortex is found to be isotropic, reflecting an isotropic actin gel. A clear difference was seen between cortical and endoplasmic layers in terms of both viscoelasticity and flow velocity, where the profile of the latter is close to a Poiseuille flow for a Newtonian fluid.