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Calcium wave for cytoplasmic streaming of Physarum polycephalum

Authors

  • Shinji Yoshiyama,

    1. Department of Biology, Faculty of Education, Shiga University, Otsu, Shiga 520-0862, Japan
    2. Department of Molecular and Cellular Pharmacology, Gunma University Graduate School of Medicine, Gunma 371-8511, Japan
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  • Mitsuo Ishigami,

    1. Department of Biology, Faculty of Education, Shiga University, Otsu, Shiga 520-0862, Japan
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  • Akio Nakamura,

    1. Department of Molecular and Cellular Pharmacology, Gunma University Graduate School of Medicine, Gunma 371-8511, Japan
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  • Kazuhiro Kohama

    Corresponding author
    1. Department of Biology, Faculty of Education, Shiga University, Otsu, Shiga 520-0862, Japan
      email kohamak@med.gunma-u.ac.jp
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email kohamak@med.gunma-u.ac.jp

Abstract

The plasmodium Physarum polycepharum exhibits periodic cycles of cytoplasmic streaming in association with those of contraction and relaxation movement. In the present study, we injected Calcium Green dextran as a fluorescent Ca2+ indicator into the thin-spread living plasmodium. We found changes in the [Ca2+]i (intracellular concentration of Ca2+), which propagated in a wave-like form in its cytoplasm. The Ca2+ waves were also detected when we used Fura dextran which detected [Ca2+]i by the ratio of two wavelengths. We prepared the plasmodial fragment from the thin-spread and found that the cycles of the contraction–relaxation movement was so synchronized that the measurement of its area provided an indication of the movement. We observed that [Ca2+]i also synchronized in the entire fragment and that the relaxation ensued upon the reduction in [Ca2+]i. We suggest that the Ca2+ wave generated periodically is one of the major factors playing a crucial role in the relaxation of P. polycepharum.

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