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 language | English |
---|---|
Pages (from-to) | 1995-2003 |
Number of pages | 9 |
Journal | Development |
Volume | 122 |
Issue number | 7 |
Publication status | Published - 1996 Jul 29 |
Keywords
- Ascidian
- Calcium oscillation
- Ciona intestinalis
- MPF
- Meiosis
- Oocyte
ASJC Scopus subject areas
- Molecular Biology
- Developmental Biology