Studies on Ca2+-channel distribution in maturation arrested mouse oocyte.
The present study was carried out to identify the existence of voltage-dependent Ca2+-channels (P/Q-, N-, and L-type) and their distributional differences in germinal vesicle (GV) and GV breakdown (GVBD)-arrested mouse oocytes which includes GVBD to telophase I of meiosis I and matured oocytes (MII, metaphase of meiosis II) by using the immunocytochemical method and a confocal laser scanning microscope. (1) Comparison between follicular oocytes (GV) and GV-arrested oocytes after 17 hr of in vitro culture. In follicular oocytes, P/Q-, N-, L (anti-alpha1C anti-alpha1D)-type Ca2+-channels showed both localized and uniform staining. In contrast, GV-arrested oocytes, after in vitro culture for 17 hr, showed no presence of Ca2+-channels in most oocytes. (2) Comparison between GVBD oocytes after culture in vitro for 3 hr and GVBD-arrested oocytes after culture in vitro for 17 hr. In GVBD oocytes, P/Q-, N-, L (anti-1C, anti-alpha1D)-type Ca2+-channels showed both localized and uniform staining. In contrast, in GVBD-arrested oocytes, none of the three types of Ca2+-channels were identified in 72-86% of oocytes. The present study demonstrates that in most GVBD-arrested oocytes that do not mature to MII, there is no Ca2+-channel identified. Therefore, most of the GVBD-arrested oocytes seem to have defects in Ca2+-channel expression/translation. Also, distributional changes of Ca2+-channels take place depending on the maturation progress in GV oocytes and MII stage oocytes (ovulated and 17 hr cultured MII stage oocytes). In addition, we found evidence that a functional voltage-dependent Ca2+-channel (L-type) exists in mouse oocytes (ovulated and cultured MII staged oocytes by a confocal laser scanning microscope).
Department of Biology, College of Natural Sciences, Sungshin Women's University, Sungbuk-Ku, Seoul, Korea.
Jae-Hyun
JH
Lee
Sook-Young
SY
Yoon
In-Ha
IH
Bae
D000818:Animals; D015220:Calcium Channels / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020865:Calcium Channels, P-Type / Q000378:metabolism; D020907:Calcium Channels, Q-Type / Q000378:metabolism; D002478:Cells, Cultured; D005260:Female; D007150:Immunohistochemistry; D051379:Mice; D008813:Mice, Inbred ICR; D018613:Microscopy, Confocal; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D010060:Ovulation / Q000378:metabolism; D013997:Time Factors
D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D020865:Calcium Channels, P-Type; D020907:Calcium Channels, Q-Type