Mechanosensitive Channels in the Cell Body of Chlamydomonas |
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Authors: | K Yoshimura |
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Institution: | (1) Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Tokyo 113-0033, Japan, JP |
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Abstract: | Mechanosensitive channels appear ubiquitous but they have not been well characterized in cells directly responding to mechanical
stimuli. Here, we identified tension-sensitive channel currents on the cell body of Chlamydomonas, a protist that shows a marked behavioral response to mechanical stimulation. When a negative pressure was applied to the
cell body with a patch clamp electrode, single-ion-channel currents of 2.4 pA in amplitude were observed. The currents were
inhibited by 10 μm gadolinium, a general blocker of mechanosensitive channels. The currents were most likely due to Ca2+ influxes because the current was absent in Ca2+-free solutions and the reversal potential was 98 mV positive to the resting potential. The distribution of channel-open times
conformed to a single exponential component and that of closed times to two exponential components. This mechanosensitive
channel was similar to the one found in the flagella in the following respects: both channels were inhibited by Gd3+ at 10 μm but not at 1 μm; both passed Ca2+ and Ba2+; their kinetic parameters for channel opening were similar. These observations raise the possibility that identical mechanosensitive
channels may function both in the behavioral control through the mechanoreception by the flagella and in the regulation of
cellular physiology in response to mechanical perturbation on the cell body.
Received: 13 May 1998/Revised: 2 September 1998 |
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Keywords: | : Mechanosensitive channel — Chlamydomonas— Calcium — Flagella — Patch clamp |
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