Intracellular microrheology of motile Amoeba proteus.

Abstract:

:The motility of 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 timescales, corresponding to thermal motion in a viscoelastic medium, and superdiffusive motion at long timescales due to the convection of the cytoplasm. Subdiffusive motion was characterized by a rheological scaling exponent of 3/4 in the cortex, indicative of the semiflexible dynamics of the actin fibers. 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.

journal_name

Biophys J

journal_title

Biophysical journal

authors

Rogers SS,Waigh TA,Lu JR

doi

10.1529/biophysj.107.123851

subject

Has Abstract

pub_date

2008-04-15 00:00:00

pages

3313-22

issue

8

eissn

0006-3495

issn

1542-0086

pii

S0006-3495(08)70487-9

journal_volume

94

pub_type

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