Intracellular magnetophoresis of statoliths in Chara rhizoids and analysis of cytoplasm viscoelasticity.

The statoliths in Chara rhizoids are denser and more diamagnetic than the cytoplasm, therefore they can be displaced inside a living cell by a sufficiently strong high gradient magnetic field (HGMF). An experimental setup for intracellular magnetophoresis of statoliths was developed. The movement of statoliths and rhizoid growth was measured by video microscopy either under the influence of gravity or a HGMF equivalent to about 2 g. The contribution of the cytoskeleton to statolith motility was assayed before and after depolymerizing microtubules with oryzalin and F-actin with latrunculin B. Application of latrunculin caused immediate cessation of growth, clumping of statoliths, and application of HGMF resulted in higher displacement of statoliths. Oryzalin had no effect on the behavior of statoliths. The data indicate that magnetophoresis is a useful tool to study the gravisensing system and rheology of the Chara rhizoid.