title: Intracellular calcium signaling in the fertilized eggs of Annelida.
abstract: Fertilization is such a universal and indispensable step in sexual reproduction, but a high degree of variability exists in the way it takes place in the animal kingdom. As discussed in other reviews in this issue, recent works on this subject clarified many points. However, important results on the mechanisms of fertilization are obtained mainly from a few restricted model organisms. In this sense, it is utterly important to collect more information from various phyla. In this review, we have re-introduced Annelida as one of the most suitable models for the analysis of fertilization process. We have briefly reviewed the historical works on the fertilization of Annelida. Then, we have described recent findings on the two independent Ca(2+) increases in the fertilized eggs of Annelida, which arise from two different mechanisms and may have distinct physiological roles toward sperm entry and egg activation. We propose that the Ca(2+) increase in the fertilized eggs reflect the specific needs of the zygote in a given species.
authors: Research Center for Marine Biology, Asamushi, Graduate School of Life Science, Tohoku University Asamushi, Aomori 039-3501, Japan. Electronic address: tsuyoshigou25@yahoo.co.jp.
authors: Takeshi
authors: T
authors: Nakano
authors: Department of Biology, Miyagi University of Education, Sendai, Miyagi 980-0845, Japan. Electronic address: deguchi@staff.miyakyo-u.ac.jp.
authors: Ryusaku
authors: R
authors: Deguchi
authors: Research Center for Marine Biology, Asamushi, Graduate School of Life Science, Tohoku University Asamushi, Aomori 039-3501, Japan. Electronic address: kkyozuka@m.tohoku.ac.jp.
authors: Keiichiro
authors: K
authors: Kyozuka
mesh_terms: D000818:Animals; D000845:Annelida / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology*; D005260:Female; D005306:Fertilization / Q000502:physiology*; D008297:Male; D023421:Models, Animal; D008954:Models, Biological; D009865:Oocytes / Q000502:physiology; D011077:Polychaeta / Q000502:physiology; D013084:Sperm-Ovum Interactions / Q000502:physiology; D015053:Zygote / Q000502:physiology*
keywords: Annelida; Cortical protrusion; Egg activation; Egg microvilli; Fertilization; Sperm incorporation