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Planta

, Volume 210, Issue 2, pp 286–294 | Cite as

Chlamydomonas contains calcium stores that are mobilized when phospholipase C is activated

  • Hilda Kuin
  • Henk Koerten
  • Wim E.J.M. Ghijsen
  • Teun Munnik
  • Herman van den Ende
  • Alan Musgrave
Article

Abstract.

Mastoparan induces Ca2+-dependent deflagellation of the unicellular green alga Chlamydomonas moewusii Gerloff, as well as the activation of phospholipase C and the production of inositol 1,4,5-trisphosphate (InsP3; T. Munnik et al., 1998, Planta 207: 133–145). Even in the absence of extracellular Ca2+, mastoparan still induces deflagellation (L.M. Quarmby and H.C. Hartzell, 1994, J Cell Biol 124: 807–815; J.A.J. van Himbergen et al., 1999, J Exp Bot, in press) suggesting that InsP3 mediates Ca2+ release from intracellular stores. To test this hypothesis, cells were pre-loaded with 45Ca2+ and their plasma membranes permeabilized by digitonin. Subsequent treatment of the cells with mastoparan (3.5 μM) induced release of intracellular 45Ca2+. Mastoparan also activated phospholipase C in permeabilized cells, as demonstrated by the breakdown of 32P-phosphatidylinositol 4,5-bisphosphate and the production of diacylglycerol. The mastoparan analogues mas7 and mas17 were also effective and their efficacy was correlated with their biological activity. X-ray microanalysis showed that electron-dense bodies (EDBs) are a major Ca2+ store in  C. moewusii. Analysis of digitonin-permeabilized cells showed that EDBs lost calcium at digitonin concentrations that released radioactivity from 45Ca2+-labelled cells, suggesting that 45Ca2+ monitored the content of EDBs. X-ray microanaysis of living cells treated with mastoparan also revealed that calcium was released from EDBs.

Key words: Calcium –Chlamydomonas– Mastoparan – Phospholipase C – Signalling 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • Hilda Kuin
    • 1
  • Henk Koerten
    • 2
  • Wim E.J.M. Ghijsen
    • 3
  • Teun Munnik
    • 1
  • Herman van den Ende
    • 1
  • Alan Musgrave
    • 1
  1. 1.Institute for Molecular Cell Biology, BioCentrum Amsterdam, University of Amsterdam, Kruislaan 318, 1098 SM Amsterdam, The NetherlandsNL
  2. 2.Laboratory for Electron Microscopy, University of Leiden, Rijnsburgerweg 10, 2333 AA Leiden, The NetherlandsNL
  3. 3.Institute for Neurobiology, University of Amsterdam, Kruislaan 320, 1098 SM Amsterdam, The NetherlandsNL

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