Masashi Kurachi

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We used direct buckling force measurements with optical traps to determine the flexural rigidity of individual microtubules bound to polystyrene beads. To optimize the accuracy of the measurement, we used two optical traps and antibody-coated beads to manipulate each microtubule. We then applied a new analytical model assuming nonaxial buckling.(More)
As major determinants of cell shape and polarity, microtubules are required to have suitable rigidity. However, our knowledge of the mechanical properties of microtubules is far from satisfactory. We report here a new method of measuring the flexural rigidity of a single microtubule by direct buckling using the optical trapping technique. Microtubule(More)
Polyethylene glycol (PEG) dehydrogenase in crude extracts of a PEG 20,000-utilizing mixed culture was purified 24 times by precipitation with ammonium sulfate, solubilization with laurylbetaine, and chromatography with diethylamino-ethyl-cellulose, hydroxylapatite, and Sephadex G-200. The purified enzyme was confirmed to be homogeneous by sodium dodecyl(More)
We previously reported that CD44-positive cells were candidates for astrocyte precursor cells in the developing cerebellum, because cells expressing high levels of CD44 selected by fluorescence-activated cell sorting (FACS) gave rise only to astrocytes in vitro. However, whether CD44 is a specific cell marker for cerebellar astrocyte precursor cells in vivo(More)
Evidence is presented to demonstrate that colour polymorphism in a beetle arises from structural colours produced by a five-layered reflector in the elytron. The colour of leaf beetles, Plateumaris sericea, ranges across the visible spectrum from blackish-blue to red. The elytra have two distinct layers: epicuticle and exocuticle. Morphological observations(More)
Ischemic insults affecting the internal capsule result in sensory-motor disabilities which adversely affect the patient's life. Cerebral endothelial cells have been reported to exert a protective effect against brain damage, so the transplantation of healthy endothelial cells might have a beneficial effect on the outcome of ischemic brain damage. In this(More)
To investigate the mechanisms underlying pseudopod protrusion in locomoting neutrophils, we measured the intracellular stiffness and viscosity in the leading region, main body, and trailing region from displacements of oscillating intracellular granules driven with an optical trap. Experiments were done in control conditions and after treatment with(More)
By dissolving the membrane with detergent perfusion, we have shown that the established neurites of dorsal root ganglion cells cultured for more than 5 days contained microtubules which persisted outside the cell for a few minutes to more than 1h [Tashiro et al., 1997: J. Neurosci. Res. 50:81-93]. To investigate their stabilization mechanism, we transected(More)
Neural stem cells are generally considered to be committed to becoming precursor cells before terminally differentiating into either neurons or glial cells during neural development. Neuronal and oligodendrocyte precursor cells have been identified in several areas in the murine central nervous system. The presence of astrocyte precursor cells (APCs) is not(More)
We tested the stability of microtubules (MTs) in the neurites of cultured dorsal root ganglion cells by dissolving the cytoplasmic membrane with detergent and exposing them to defined extracellular medium under observation with a video-enhanced differential interference contrast (DIC) microscope. Smooth cytoplasmic filaments visualized after membrane(More)