In vitro studies of meiotic maturation of mouse oocytes have been carried out in the presence of several drugs. The individual steps of nuclear progression, including dissolution of the nuclear (germinal vesicle) membrane, condensation of dictyate chromatin into compact bivalents, formation of the first metaphase spindle, and extrusion of the first polar body, are each susceptible to one or mor...

The physiological role of cumulus cells (CC) surrounding oocytes is particularly important for normal cytoplasmic maturation of oocytes. However, removal of CC from oocytes is inevitable for some embryo manipulation techniques, such as germinal vesicle (GV) transfer, somatic cell haploidization, and oocyte cryopreservation. The present study was designed to determine an optimal method to cultur...

Mammalian oocyte maturation and early embryo development processes are Ca(2+)-dependent. In this study, we used confocal microscopy to investigate the distribution pattern of Ca(2+) and its dynamic changes in the processes of bovine oocytes maturation, in vitro fertilization (IVF), parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT) embryo development. During the germinal v...

Cyclin J is a cyclin family member that appears to have evolved before the metazoan radiation. Its evolutionary conservation argues for an important role but functional characterizations of Cyclin J have remained very limited. In Drosophila, Cyclin J is expressed only in females. Using transgenic Drosophila lines expressing Cyclin J versions with N- or C-terminal GFP extensions, we demonstrate ...

Meiotic maturation of oocytes requires a variety of ATP-dependent reactions, such as germinal vesicle breakdown, spindle formation, and rearrangement of plasma membrane structure, which is required for fertilization. Mitochondria are accordingly expected be localized to subcellular sites of energy utilization. Although microtubule-dependent cellular traffic for mitochondria has been studied ext...

Development of a porcine germinal vesicle oocyte (GVO) to a 4-cell stage embryo occurs during a transcriptionally silent period when the oocyte/embryo relies on maternally derived mRNA to encode proteins required for development. Regulation of translation and degradation of maternal mRNA is thought to be partially dependent upon cytoplasmic polyadenylation elements (CPEs) within the 3! untransl...

We cloned the Xenopus laevis form of Gq alpha subunit to study its effects on oocyte maturation. Injection of Xenopus Gq alpha mRNA into stage 6 oocytes activated the phospholipase C/phosphatidylinositol pathway. The oocyte membrane became permeable to calcium ions and was able to generate transient inward currents (T(in)), due to the opening of Ca(2+)-dependent Cl- channels. The T(in) amplitud...