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KMID : 0380219930260040346
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Journal of Biochemistry and Molecular Biology
1993 Volume.26 No. 4 p.346 ~ p.351
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Determination of the Cytoplasic Free-Calcium-Ion Concentration Changes by Phytochrome Action in Oat Cell Using Fluo-3/AM
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Bong-Deok Han and Quae Chae
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Abstract
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Calcium specific fluorescence probes such as Quin-2 and Fura-2 have been proved to have a few defects in determining cytosolic free Ca^(2+) in cells (Hallett et al., 1990; Callaham et al., 1991; Steinberg et al., 1987; Kao et al., 1989; Minta et al., 1989; Zee et al., 1989). In this report, a new probe Fluo-3/AM was employed to determine cytosolic free Ca^(2+) concentration in oat cells and it was identified not to be penetrated into the intracellular calcium store (vacuole). Phytochrome action in changing the cytosolic free Ca^2+ concentration in oat cell was investigated by irradiating red and far-red lights to isolated oat protoplasts. Red light irradiation (fluence rate : 320 μ㏖·m^(-2)·s^(-1)) for 30 sec increased the cytosolic free Ca^(2+) from 101 nM to 115 nM, but far-red light (fluence rate : 427 μ㏖·m^(-2)·s^(-1)) did not. Photoreversibility of phytochrome in changing cytosolic Ca^(2+) concentration was clearly observed. Mobilization of Ca^(2+) from the intracellular calcium store to the cytoplasm by 5 min irradiation of red light was observed to be 6 nM under conditions that external Ca^(2+) were removed by excess EGTA, and that calcium channels of the plasma membrane were blocked by their blockers (verapamil and lanthanum ion). These results imply that Pfr form of phytochrome functions in the process of influx of Ca^(2+), but also in the mobilization process of Ca^(2+) from its pool in the cell.
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