ECB-ART-41736
J Biophotonics
2011 May 01;45:324-34. doi: 10.1002/jbio.201000076.
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High- and low-frequency mechanical properties of living starfish oocytes.
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We studied the mechanical properties of living starfish oocytes belonging to two species, Astropecten Auranciacus and Asterina pectinifera, over a wide range of timescales. We monitored the Brownian motion of microspheres injected in the cytoplasm using laser particle-tracking (LPT) and video multiple-particle-tracking (MPT) techniques, to explore high- and low-frequency response ranges, respectively. The analysis of the mean-square-displacements (MSD) allowed us to characterize the samples on different timescales. The MSD behavior is explained by three power-law exponents: for short times (τ < 1 ms) it reflects the semiflexible behavior of the actin network; for intermediate timescales (1 ms < τ < 1 s) it is similar to that of a soft-glass material; finally for long times (τ > 1 s) it behaves mainly like a viscous medium. We computed and compared the viscoelastic moduli using a recently proposed model describing the frequency response of the cell material. The large fluctuations found in the MSD over hundreds of trajectories indicate and confirm the significant cytoplasm heterogeneity.
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Genes referenced: LOC115919910 LOC115925415 LOC590297