Maturation Promoting Factor in ascidian oocytes is regulated by different intracellular signals at meiosis I and II

Gian Luigi Russo, Keiichiro Kyozuka, Livio Antonazzo, Elisabetta Tosti, Brian Dale

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)

Abstract

Using the fluorescent dye Calcium Green-dextran, we measured intracellular Ca2+ in oocytes of the ascidian Ciona intestinalis at fertilization and during progression through meiosis. The relative fluorescence intensity increased shortly after insemination in a single transient, the activation peak, and this was followed by several smaller oscillations that lasted for approximately 5 minutes (phase 1). The first polar body was extruded after the completion of the phase 1 transients, about 9 minutes after insemination, and then the intracellular calcium level remained at baseline for a period of 5 minutes (phase 2). At 14 minutes postinsemination a second series of oscillations was initiated that lasted 11 minutes (phase 3) and terminated at the time of second polar body extrusion. Phases 1 and 3 were inhibited by preloading oocytes with 5 mM heparin. Simultaneous measurements of membrane currents, in the whole-cell clamp configuration, showed that the 1-2 nA inward fertilization current correlated temporally with the activation peak, while a series of smaller oscillations of 0.1-0.3 nA amplitude were generated at the time of the phase 3 oscillations.

Original languageEnglish
Pages (from-to)1995-2003
Number of pages9
JournalDevelopment
Volume122
Issue number7
Publication statusPublished - 1996 Jul 29

Keywords

  • Ascidian
  • Calcium oscillation
  • Ciona intestinalis
  • MPF
  • Meiosis
  • Oocyte

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology

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