Investigation of interactions between the organelle motion and filamentous structures within cells by cytomatomagnetometry.

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We studied the feasibility and efficacy of a mangetometric method for investigations of intracellular motions, particularly the possible interactions between phagosome membrane and filamentous strucures within the cell. The present investigation has focued on showing that this method can be a good probe in investiating the elementary processes in phagosome motions. Cytomagnetometry, as we call it, has the following advantages. 1)Intracellular motions within living cells can be measured ; 2)Measurement itself is relatively easy ; 3)Magnetic particles can be manipulated by an external force non-invasively and thus can be subject to a large variety of experiments ; 4)The measurement is done on a large number of cells at a time, resulting in enough averaging.It has now become clear that cytomagnetometry yields data which reflect intracellular motions of phagosomes and by manipulating the magnetic particles within cells one can obtain data which also reflect the rheological properties.Our experiments focused upon the hypothesis of phagosome motion through interaction of actinfilaments and myosin on the phagosome membrane. The results show that actin filaments do play some role in phagosme motion, although the results were not as clear cut and decisive as we had hoped. Experiments performed to see viscocity generation by actin filaments yielded intriguing but interesting results which further suggest actin's involvement in phagosome motions.We also built a mathematical model in which phagosome motions are caused by association of myosin on the phagosome membrane with an actin filament surrounding the phagosome and its decomposition caused by ATP hydrolysis. Association and decomposition were assumed to be Poisson processes and it was shown that it caused a rotationary random walk and also that the association acts as friction to external forces.