Local translation of oskar (osk) mRNA at the posterior pole of the Drosophila oocyte is essential for axial patterning of the embryo, and is achieved by a program of translational repression, mRNA localization, and translational activation. Multiple forms of repression are used to prevent Oskar protein from accumulating at sites other than the oocyte posterior. Activation is mediated by several...

Quiescent full-grown Xenopus oocytes remain arrested at the G(2)/M border of meiosis I until exposed to progesterone, their natural mitogen. Progesterone triggers rapid, nontranscriptional responses that lead to the translational activation of stored mRNAs, resumption of the meiotic cell cycles, and maturation of the oocyte into a fertilizable egg. It has long been presumed that progesterone ac...

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...

Fertilization is triggered by changes in intracellular calcium concentration. In mammals, these transients in ooplasmic calcium concentration take the form of repetitive spikes, so called calcium oscillations (Ca-oscillations). These oscillations are important for relieve of meiotic arrest and to induce all the other events of oocyte activation. Although a surface mediated way of oocyte activat...

Mammalian oocyte activation is mediated by cytosolic calcium (Ca(2+)) oscillations initiated upon delivery of a putative 'sperm factor' by the fertilizing sperm. Previous studies suggest the identity of this sperm factor as the testis-specific phospholipase C-zeta (PLCζ). Recently, a post-acrosomal sheath WW domain-binding protein (PAWP) has been proposed as an alternative sperm factor candidat...

Human sperm have been documented to display apoptosis-like features such as externalization of phosphatidylserine (EPS), disruption of the transmembrane mitochondrial potential (MMP) and activation of caspases. Our aim was to evaluate possible association between activation of the apoptosis cascade in human sperm and its oocyte penetration capacity using the zona free hamster oocyte penetration...

Oocyte maturation is associated with suppression of transcriptional activity. Consequently, gene expression during oocyte maturation, fertilization and early embryo development, until zygotic genome activation (ZGA) is primarily regulated by translational activation of maternally derived mRNAs. Embryonic poly(A)-binding protein (EPAB) is the predominant poly(A)-binding protein in Xenopus, mouse...

Protein synthesis of cyclin B by translational activation of the dormant mRNA stored in oocytes is required for normal progression of maturation. In this study, we investigated the involvement of Xenopus Pumilio (XPum), a cyclin B1 mRNA-binding protein, in the mRNA-specific translational activation. XPum exhibits high homology to mammalian counterparts, with amino acid identity close to 90%, ev...