title: Spatiotemporal pattern of calmodulin and [Ca2+]i is related to resumption of meiosis in mouse oocytes.
abstract: During meiotic maturation, mammalian oocytes undergo a series of morphological and physiological changes that prepare them for fertilization. Calcium-initiated signaling is thought to trigger these processes. In this study, we examine the spatio-temporal pattern of calcium and calmodulin (CaM), its downstream receptor, in order to investigate their association with meiotic maturation. Intracellular free calcium and activated CaM levels were measured using the fluorescent probes Calcium Green-1 and TA-CaM, respectively. The distribution patterns were examined using confocal microscopy. Both calcium and activated CaM showed a dynamic spatiotemporal distribution during meiotic maturation. After release from IBMX buffer, calcium was found to periodically translocate from the perinuclear region to the germinal vesicle (GV) in 90 s intervals. After 90 min, calcium stopped oscillating and became concentrated within the GV. After a further 60 min, the GV broke down and calcium dispersed into the ooplasm, but calcium levels were slightly lower here than in the original nuclear region. Activated CaM also showed a dynamic patterning process similar to calcium. Taking the data from calcium chelation and CaM inhibition together, our results suggest that the dynamic distribution patterns of calcium and activated CaM are crucial for oocyte maturation.
authors.affiliation: State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Chun-Ming
authors.initials: CM
authors.lastname: Bi
authors.forename: Gu
authors.initials: G
authors.lastname: Dai
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.forename: Yao-Chun
authors.initials: YC
authors.lastname: Wu
authors.forename: Xi-Ran
authors.initials: XR
authors.lastname: Zhang
authors.forename: Chao-Jun
authors.initials: CJ
authors.lastname: Li
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology; D002147:Calmodulin / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry; D008540:Meiosis / Q000502:physiology*; D051379:Mice; D018613:Microscopy, Confocal; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D005456:Fluorescent Dyes; D002118:Calcium