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Single centrosome manipulation reveals its electric charge and associated dynamic structure.


K. Habermann,  K.
Max Planck Society;

B.M.H. Lange,  B. M. H.
Max Planck Society;

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Hormeño, S., Ibarra, B., Chichón, F. J., K. Habermann, K., B.M.H. Lange, B. M. H., Valpuesta, J. M., et al. (2009). Single centrosome manipulation reveals its electric charge and associated dynamic structure. Biophysical Journal, 97(4), 1022-1030. Retrieved from

The centrosome is the major microtubule-organizing center in animal cells and consists of a pair of centrioles surrounded by a pericentriolar material. We demonstrate laser manipulation of individual early Drosophila embryo centrosomes in between two microelectrodes to reveal that it is a net negatively charged organelle with a very low isoelectric region (3.1 ± 0.1). From this single-organelle electrophoresis, we infer an effective charge smaller than or on the order of 103 electrons, which corresponds to a surface-charge density significantly smaller than that of microtubules. We show, however, that the charge of the centrosome has a remarkable influence over its own structure. Specifically, we investigate the hydrodynamic behavior of the centrosome by measuring its size by both Stokes law and thermal-fluctuation spectral analysis of force. We find, on the one hand, that the hydrodynamic size of the centrosome is 60% larger than its electron microscopy diameter, and on the other hand, that this physiological expansion is produced by the electric field that drains to the centrosome, a self-effect that modulates its structural behavior via environmental pH. This methodology further proves useful for studying the action of different environmental conditions, such as the presence of Ca2+, over the thermally induced dynamic structure of the centrosome.