Contribution of Calcium Influx on Trichocyst Discharge in Paramecium caudatum(Cell Biology)(Origin and evolution of chordates)

元データ 2001-05-20 社団法人日本動物学会

概要

Trichocyst discharge in Paramecium spp. is known to be mediated by rapid exocytosis. Applied stimuli induce fusion of the trichocyst membrane and plasma membrane within 30 ms. Both Ca^<2+> release from intracellular store (s) and Ca^<2+> influx from extracellular region have been suggested to be related to the trichocyst discharge. We constructed a new system in which to record intracellular levels of Ca^<2+> ([Ca^<2+>]_i) and microscopic images simultaneously without changing the optical path. With this system, we recorded [Ca^<2+>]_i at 2 ms intervals and microscopic images of trichocyst discharge at video rate (33 ms intervals) simultaneously in Paramecium caudatum. Simultaneous application of Ca^<2+> chelator at 100 mM with secretagogue onto Paramecium cells resulted in only a slight increase in [Ca^<2+>]_i (Δ[Ca^<2+>]_i). Furthermore, no extrusion of trichocysts occurred. In contrast, application of secretagogue concomitant with Ca^<2+> chelator at 20 mM induced a Δ[Ca^<2+>]_i composed of two phases. In this case, extrusion of trichocysts occurred. These observations directly indicated that Ca^<2+> influx from the extracellular medium in addition to Ca^<2+> release from intracellular store (s) contributes to Δ[Ca^<2+>]_i during trichocyst discharge.

著者

Kikuyama Munehiro Biological Laboratory, The University of the Air
Kikuyama M Niigata Univ. Niigata Jpn
Iwadate Yoshiaki Department of Life Science, Faculty of Integrated Arts and Sciences, The University of Tokushima
Kikuyama Munehiro Biological Laboratory The University Of The Air.
Iwadate Y Univ. Tokushima Tokushima Jpn
Iwadate Yoshiaki Department Of Functional Molecular Biology Graduate School Of Medicine Yamaguchi University
Kikuyama Munehiro Biological Laboratory The University Of The Air

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