|Cancer||Cell death||Cell cycle||Cytoskeleton||Exo/endocytosis||Differentiation||Division||Organelles||Signalling||Stem cells||Trafficking|
Calcium wave for cytoplasmic streaming of Physarum polycephalum
Shinji Yoshiyama*†, Mitsuo Ishigami*, Akio Nakamura† and Kazuhiro Kohama*1
*Department of Biology, Faculty of Education, Shiga University, Otsu, Shiga 520-0862, Japan, and †Department of Molecular and Cellular Pharmacology, Gunma University Graduate School of Medicine, Gunma 371-8511, Japan
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.
Key words: actin, calcium, contraction, myosin, Physarum plasmodia, relaxation
Abbreviations: [Ca2+]i, intracellular Ca2+ concentration, CCD, charge-coupled device
1To whom correspondence should be addressed (email firstname.lastname@example.org).
Received 4 November 2008/17 June 2009; accepted 10 September 2009
Published as Cell Biology International Immediate Publication 10 September 2009, doi:10.1042/CBI20090158
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