Two phases of calcium requirement during starfish meiotic maturation

Hiroaki Tosuji, Yukari Seki, Keiichiro Kyozuka

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


During meiosis in oocytes of the starfish, Asterina pectinifera, a Ca2+ transient has been observed. To clarify the role of Ca2+ during oocyte maturation in starfish, an intracellular Ca2+ blocker, TMB-8, was applied. The oocyte maturation induced by 1-methyladenine (1-MA) was blocked by 100 μM TMB-8. Reinitiation of meiosis with germinal vesicle breakdown (GVBD) and the following chromosome condensation did not take place. Maturation-promoting factor (MPF) activity did not increase and GVBD and chromosome condensation did not occur. Ca2+ transient observed immediately after 1-MA application in control oocytes was also blocked by TMB-8. When calyculin A, which activate the MPF directly, was applied to the oocytes instead of 1-MA in seawater containing 100 μM TMB-8, GVBD and chromosome condensation were blocked. Cytoplasmic transplantation studies confirmed that MPF was activated, although TMB-8 blocked GVBD. These results show that TMB-8 blocked the increase of MPF activity induced by 1-MA and the process of active MPF inducing GVBD and subsequent chromosome condensation. Together with the above phenomena, it is conceivable that there are two phases of Ca2+ requirement during starfish oocyte maturation. These are the activation of MPF, moreover, GVBD, and the subsequent chromosome condensation.

Original languageEnglish
Pages (from-to)432-437
Number of pages6
JournalComparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Issue number2 SPEC. ISS.
Publication statusPublished - 2007 Jun


  • Calcium wave
  • Cdc2
  • Chromosome condensation
  • GVBD
  • Histone kinase
  • MPF
  • Oocyte maturation
  • TMB-8

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Molecular Biology


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