Elongation and Contraction of Blepharisma, Evoked by Mechanical or Light Stimulation

Summary Cell body of Blepharisma was found to elongate by means of mechanical or light stimulation. Mean length of the normal vegetative cells was 320-330 μm when the cells were adapted to an experimental solution containing 1 mM CaCl2, 1 mM KCl and 5 mM Tris-HCl (pH 7.2) for 24 h. After the cells were stimulated by pipetting or light irradiation (5 × 103 lx), they elongated gradually to reach a maximum level; 459 μm by pipetting and 482 μm by light stimulation. Elongation of the cell body was found to occur strikingly in the posterior region, while the anterior region could hardly elongate. Recovery duration or process of the elongated cells caused by light application or mechanical stimulation was different from each other. The mechanically stimulated cells gradually shortened to their initial lengths, while the cells applied by the light stimulation rapidly recovered. Moreoever, the electron microscopical observations revealed that the three fibrous components (Km fiber, myoneme and vacuole-associated microtubules) might be involved with cell elongation and/or contraction of Blepharisma.