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Meiosis, egg activation, and nuclear envelope breakdown are differentially reliant on Ca2+, whereas germinal vesicle breakdown is Ca2+ independent in the mouse oocyteDuring early development, intracellular Ca2+ mobilization is not only essential for fertilization, but has also been implicated during other meiotic and mitotic events, such as germinal vesicle breakdown (GVBD) and nuclear envelope breakdown (NEBD). In this study, the roles of intracellular and extracellular Ca2+ were examined during meiotic maturation and reinitiation at parthenogenetic activation and during first mitosis in a single species using the same methodologies. Cumulus-free metaphase II mouse oocytes immediately resumed anaphase upon the induction of a large, transient Ca2+ elevation. This resumption of meiosis and associated events, such as cortical granule discharge, were not sensitive to extracellular Ca2+ removal, but were blocked by intracellular Ca2+ chelators. In contrast, meiosis I was dependent on external Ca2+; in its absence, the formation and function of the first meiotic spindle was delayed, the first polar body did not form and an interphase-like state was induced. GVBD was not dependent on external Ca2+ and showed no associated Ca2+ changes. NEBD at first mitosis in fertilized eggs, on the other hand, was frequently, but not always associated with a brief Ca2+ transient and was dependent on Ca2+ mobilization. We conclude that GVBD is Ca2+ independent, but that the dependence of NEBD on Ca2+ suggests regulation by more than one pathway. As cells develop from Ca(2+)-independent germinal vesicle oocytes to internal Ca(2+)-dependent pronuclear eggs, internal Ca2+ pools increase by approximately fourfold.
Document ID
20050000716
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Tombes, R. M. (University of Wisconsin Madison 53706)
Simerly, C.
Borisy, G. G.
Schatten, G.
Date Acquired
August 22, 2013
Publication Date
May 1, 1992
Publication Information
Publication: The Journal of cell biology
Volume: 117
Issue: 4
ISSN: 0021-9525
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: HD22902
CONTRACT_GRANT: GM25062
CONTRACT_GRANT: T32 HD7342
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Cell Biology
NASA Discipline Developmental Biology