Investigation of the functions of microfilaments and microtubules by cytomagnetometry, immunoflurescent microscopy and differential interference microscopy.

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We investigated intracellular motility of living cells by cytomagnetometry and optical observations including immunoflurescent microscopy and differential interference microscopy. Cytomagnetometric method is our own invention and one of few methods able to investigate intracellular movement and the functions of the cytoskeletons within living cells. In the present study we concentrated on the measurement of the energy (E_r) of the intracellular movements responsible for the random movements of the phagosomes which causes the magnetic relaxation measured after magnetizing the magnetic particles engulfed by the cells. We used cytoskeletal drugs which affect the cytoskeletons such as microfilaments and microtubules, and measured E_r and observed the effects of those drugs on the filaments by immunoflurescent microscopy. One peculiar result was that MIA which inhibits ATP synthesis increased E_r which seems contradictory. MIA also inhibited microfilament synthesis, which may have to do with the increase in E_r although cytochalasin B which disrupts microfilaments decreased E_r. Colchicine, which has been known to break microtubules increased E_r also. This is probably due to its side effect of activation of cellular movements (which has been observed by other researchers) and of increasing microfilaments which has been clearly seen by immunoflurescent microscopy. Our measurement of E_r thus captured the phenomenon quantitatively. A different application of cytomagnetometry is measurement of the stiffness of the cell membrane. This was done by making magnetic particles coated with fibronectin adhere to the cell membrane and twisting them by an external magnetic field. This method was tentatively applied to investigate the relationship between the cytoskeletons and the cell membrane and seems promising to measure the mechanical properties of the cell membrane and their dependence on the cytoskeletons.