a:4:{s:10:"Background";s:1707:"Early embryonic development in mammals begins in transcriptional silence with an oocyte-mediated transcriptional reprogramming of parental gametes occurs during a so called across-the-board process of “erase-and-rebuild”. In this process, the parental transcription programs are erased long before (maternal) or soon thereafter (paternal) fertilization to generate a...

Background: Fully grown mammalian oocyte utilizes transcripts synthetized and stored during earlier development. In the mouse oocyte there are three forms of cap-dependent translational repressors: 4E-BP1, 4E-BP2, and 4E-BP3. The dominant form, 4E-BP1, inhibits cap-dependent translation by binding to the eIF4E translation initiation factor. Hyperphosphorylation of 4E-BP1 disrupts this inhibitor...

BACKGROUND Mammalian sperm-oocyte interaction at fertilization involves several combined interactions between integrins on the oocyte and integrin ligands (disintegrins) on the sperm. Recent research has indicated the ability of peptides containing the RGD sequence that characterized several sperm disintegrins, to induce intracellular Ca2+ transients and to initiate parthenogenetic development ...

The oocyte-to-embryo transition refers to the process whereby a fully grown, relatively quiescent oocyte undergoes maturation, fertilization, and is converted into a developmentally active, mitotically dividing embryo, arguably one of the most dramatic transitions in biology. This transition occurs very rapidly in Caenorhabditis elegans, with fertilization of a new oocyte occurring every 23 min...

Previous studies have shown that ripe Xenopus 00cytes, 1.4 mm in diameter and suitable for microinjection, undergo meiotic cell division in response to progesterone by a mechanism involving a decrease in the level of CAMP. In order to investigate the mechanism by which the level of CAMP is reduced by progesterone treatment, adenylate cyclase activity was measured in manually dissected plasma me...

Understanding the mechanisms regulating oocyte developmental competence is essential to enhance the clinical efficiency of assisted reproduction. FSH orchestrates the acquisition of oocyte competence, both in vivo and in vitro. Multiple pathways are implicated in FSH signalling; however, their precise coordination remains unresolved. A robust system to investigate FSH signalling is oocyte in vi...

One of the first events that occurs at fertilization is a transient modification of the electrical properties of the oocyte plasma membrane. The whole-cell voltage clamp technique was used to demonstrate an outward ion current and a hyperpolarization of the plasma membrane after fertilization in bovine oocytes. These electrical events, together with measurement of internal calcium concentration...

BACKGROUND Recently we reported that an oocyte activation ability in human and mouse sperm is associated with head flatness or the presence of perinuclear theca (PT) substance, MN13, which is an oocyte activation-related protein localized on the post-acrosomal sheath (PAS). As such, we hypothesize that the appearance of oocyte activation ability is stage-specifically regulated and depends on th...

Background: The objective of the current study was to determine the effect of activation of injected oocytes with dithiothreitol on development of ovine embryos derived from in vitro-matured oocytes and intracytoplasmic sperm.The injected oocytes with non-treated sperm were activated with 1) ionomycin (Io) + 6-dimethylaminopurine (6-DMAP) 2) DTT, 3) DTT+ ionomycin (I)+6-DMAP. Materials and Meth...

Nitric oxide (NO) is reported to play significant a role in oocyte activation and maturation, implantation, and early embryonic development. Previously we have shown that NO forms an important component of the oocyte microenvironment, and functions effectively to delay oocyte aging. Thus, precise information about intra-oocyte NO concentrations [NO] will result in designing more accurate treatm...