Ciliary movements in protozoa exhibit metachronal wave-like coordination, in which a constant phase difference is maintained between adjacent cilia. It is at present generally thought that metachronal waves require hydrodynamic coupling between adjacent cilia and the extracellular fluid. To test this hypothesis, we aspirated a Paramecium cell using a micropipette which completely sealed the surface of the cell such that no fluid could pass through the micropipette. Thus, the anterior and the posterior regions of the cell were hydrodynamically decoupled. Nevertheless, we still observed that metachronal waves continued to propagate from the anterior to the posterior ends of the cell, suggesting that in addition to hydrodynamic coupling, there are other mechanisms that can also transmit the metachronal waves. Such transmission was also observed in computational modeling where the fluid was fully decoupled between two partitions of a beating ciliary array. We also imposed cyclic stretching on the surface of live Paramecium cells and found that metachronal waves persisted in the presence of cyclic stretching. This demonstrated that, in addition to hydrodynamic coupling, a compliant substrate can also play a critical role in mediating the propagation of metachronal waves.
It is believed that the loop L5 of kinesin is important region for motor function. Interestingly mitotic kinesin Eg5 has a several times longer L5 in comparing with other kinesins. It has been demonstrated that the L5 of Eg5 performed as a stabilizer for the Eg5-specific inhibitors (STLC, monastrol) complexes. In this study, we prepared 8 mutants of Eg5 which have a single cysteine in L5 in order to incorporate photochromic molecules. We also synthesized thiol reactive spiropyran derivative monoiodoacetylspiropyran (IASP). IASP was incorporated into the mutants stoichiometrically. The Eg5 mutant E118C modified with IASP showed reversible alteration of microtubule dependent ATPase activity upon UV and visible light irradiations. The other mutants were also examined. In the AFM, a liquid-immersion objective lens was employed to focus and collect the laser light for optical lever. The AFM allowed us to map the height and the Young's modulus of cells in a range of about 300 mm × 300 mm. The spatial correlation of confluent cells' mechanics will be discussed. 2P176 原子間力顕微鏡によるコンフルエント細胞の力学測定 2P177 ゾウリムシのメタクロナールウェーブは外液の粘性だけでな く細胞表層の弾性も使って伝播できるMetachronal wave travels not only in outer viscous fluid but also on elastic cell surface of Paramecium cellsCiliary movements in protozoa show metachronal coordination so as to maintain a constant phase difference between adjacent cilia. This coordination is called as "metachronal wave". It is now generally thought that metachronal waves arise from hydrodynamic coupling between adjacent cilia at extracellular fluid. To confirm this, we planed to breakdown the hydrodynamic coupling of ciliary movements at a restricted portion of a Paramecium cell and observe whether metachronal coordination collapses or not. Metachronal waves passed over the portion where the hydrodynamic coupling was broken. To clarify the other mediator of the wave, we applied cyclic stretching of cell body. The frequency of metachronal wave became equal to that of the cyclic stretching. Cell mechanics is crucial not only for understanding the mechanism of cell functions but also for diagnosing cell disease. Previous studies revealed that the averaged cell mechanical properties largely changed in intracellular positions. However, little is known how the cell-cell variability of cell mechanics depends on the cell positions. Using atomic force microscopy, we investigated the complex shear modulus, which exhibits single power-law behavior [1], of single cells cultured on micropatterned substrates. We found that the variation of the cell modulus decreased toward the cell center. We will show the detail relationship between the variability and the cell cytoskeleton. We developed a method to measure cell adhesion force by mechanical detachment from substrate. An AFM probe was fabricated to a needle shape with a hook-shaped tip to penetrate cellular membrane and pull up cells vertically. The adhesion forces defined as peak forces in detaching process were successfully measured for seven cell lines. We supposed that th...
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