Fertilisation calcium signals in the ascidian egg

The egg of ascidians (urochordate), as virtually all animal and plant species, displays Ca 2+ signals upon fertilisation. These Ca 2+ signals are repetitive Ca 2+ waves that initiate in the cortex of the egg and spread through the whole egg interior. Two series of Ca 2+ waves triggered from two dist...

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Bibliographic Details
Published in:Biology of the Cell 2004-02, Vol.96 (1), p.29-36
Main Authors: Dumollard, Rémi, McDougall, Alex, Rouvière, Christian, Sardet, Christian
Format: Article
Language:English
Subjects:
Animals
Ascidia
Ascidiacea
Ca 2+ oscillations
Ca2+ oscillations
Calcium - metabolism
Calcium Signaling - physiology
Cellular Biology
Cortex
Cytoplasmic domains
Endoplasmic reticulum
Female
Fertilization - physiology
IP3
Life Sciences
Marine
Ovum - metabolism
Urochordata
Urochordata - metabolism
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Summary:The egg of ascidians (urochordate), as virtually all animal and plant species, displays Ca 2+ signals upon fertilisation. These Ca 2+ signals are repetitive Ca 2+ waves that initiate in the cortex of the egg and spread through the whole egg interior. Two series of Ca 2+ waves triggered from two distinct Ca 2+ wave pacemakers entrain the two meiotic divisions preceding entry into the first interphase. The second messenger inositol (1,4,5) trisphosphate (IP3) is the main mediator of these global Ca 2+ waves. Other Ca 2+ signalling pathways (RyR and NAADPR) are functional in the egg but they mediate localised cortical Ca 2+ signals whose physiological significance remains unclear. The meiosis I Ca 2+ wave pacemaker is mobile and relies on intracellular Ca 2+ release from the endoplasmic reticulum (ER) induced by a large production of IP3 at the sperm aster site. The meiosis II Ca 2+ wave pacemaker is stably localised in a vegetal protrusion called the contraction pole. It is probable that a local production of IP3 in the contraction pole determines the site of this second pacemaker while functional interactions between ER and mitochondria regulate its activity. Finally, a third ectopic pacemaker can be induced by a global increase in IP3, making the ascidian egg a unique system where three different Ca 2+ wave pacemakers coexist in the same cell.
ISSN:0248-4900
1768-322X
DOI:10.1016/j.biolcel.2003.11.002