Meiotic maturation in mollusc oocytes.
Molluscs, annelids and other lower invertebrates belonging to the protostome group exhibit special features in their ionic regulation of meiotic maturation and in their molecular control of metaphase arrest. These oocytes proceed from prophase I upon fertilization or hormonal stimulation and then either complete meiotic maturation or secondarily arrest in metaphase I until fertilization. We review here the recent progress on identifying the initial trigger in prophase I-arrested oocytes, emphasizing the crucial role of an early Ca2+ influx through specific Ca2+ channels. Metaphase I arrest, a unique feature of protostome animals, appears to rely on a subtle equilibrium between protein synthesis rate and destruction of regulating proteins. Some well-known components of MPF (M-phase-promoting factor) play their regular roles in protostome animals, albeit in a different environment which has not been fully characterized yet.
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Laboratoire de Biologie Moléculaire et Cellulaire, CNRS-UMR 49, Ecole Normale Supérieure de Lyon 46, Alleacute;e d'Italie, Lyon, Cedex 07, 69364, France.
Dubé
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D000818:Animals; D020013:Calcium Signaling; D004527:Egg Proteins / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D016200:Maturation-Promoting Factor / Q000502:physiology; D008540:Meiosis / Q000187:drug effects / Q000502:physiology*; D008677:Metaphase / Q000187:drug effects; D008954:Models, Biological; D008974:Mollusca / Q000166:cytology*; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects; D009866:Oogenesis / Q000187:drug effects / Q000502:physiology*; D011418:Prophase; D011493:Protein Kinase C / Q000502:physiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology
D004527:Egg Proteins; D011500:Protein Synthesis Inhibitors; D011493:Protein Kinase C; D016200:Maturation-Promoting Factor