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The processes of oocyte growth, acquisition of meiotic competence and meiotic maturation are regulated by a large number of molecules. One of them could be calcineurin consisting of catalytic subunit A (Aα, Aβ, Aγ isoforms) and regulatory subunit B (B1, B2 isoforms). Calcineurin is involved in the meiotic maturation of oocytes in invertebrates or in lower(More)
BACKGROUND Selenium (Se) is important for the postnatal development of the calf. In the first weeks of life, milk is the only source of Se for the calf and insufficient level of Se in the milk may lead to Se deficiency. Maternal Se supplementation is used to prevent this.We investigated the effect of dietary Se-enriched yeast (SY) or sodium selenite (SS)(More)
Germinal vesicle breakdown (GVBD) of bovine oocytes was completely blocked by cycloheximide added to culture medium at concentrations of 1-20 micrograms/ml. Nevertheless, under such conditions a certain degree of chromatin condensation inside the germinal vesicle was observed. The inhibitory effect was not influenced by the presence or absence of cumulus(More)
Porcine cumulus oocyte complexes (COCs) were cultured together in 10-microliters droplets of culture medium. When 10 COCs were cultured for 24 h, germinal vesicle breakdown (GVBD) occurred in 81% of them. When more COCs (20 or 40) were put into the same volume of medium the frequency of GVBD gradually decreased. This inhibition was not observed in denuded(More)
Pig oocytes matured in vitro are parthenogenetically activated after treatment with nitric oxide (NO)-donor SNAP. The chelation of intracellular calcium ions with BAPTA-AM suppressed the SNAP-induced activation in a dose-dependent manner. Activation by a NO-donor is dependent on the influx of calcium from extracellular spaces, because the blockage of(More)
Hydrogen sulfide (H2S) has been revealed to be a signal molecule with second messenger action in the somatic cells of many tissues, including the reproductive tract. The aim of this study was to address how exogenous H2S acts on the meiotic maturation of porcine oocytes, including key maturation factors such as MPF and MAPK, and cumulus expansion intensity(More)
After reaching metaphase II, in vitro matured oocytes undergo the complex processes referred to as oocyte aging. Under our culture conditions, some aged oocytes remained at the stage of metaphase II, some underwent spontaneous parthenogenetic activation and others underwent cellular death, either through apoptosis (fragmentation) or lysis. We investigated(More)
Total inhibition of germinal vesicle breakdown (GVBD) was observed in growing pig oocytes (internal diameter 80, 90 and 100 microns) when they were cultured in a medium conditioned by cumulus oocyte complexes (COCs) of fully grown oocytes. In denuded growing oocytes, only partial inhibition was observed. The inhibitory effect was fully reversible. The(More)
Cyclopiazonic acid (CPA), a potent inhibitor of endogenous calcium-dependent ATPases, is able to induce parthenogenetic activation in pig oocytes matured in vitro. Sixty-four percent of matured pig eggs cultured with 100 nM CPA for 4 hr were activated. A similar activation rate was observed in oocytes treated with thapsigargin, another inhibitor of(More)
Porcine oocytes that have matured in in vitro conditions undergo the process of aging during prolonged cultivation, which is manifested by spontaneous parthenogenetic activation, lysis or fragmentation of aged oocytes. This study focused on the role of hydrogen sulfide (H2S) in the process of porcine oocyte aging. H2S is a gaseous signaling molecule and is(More)