• Clinical and Experimental Reproductive Medicine
• /
• v.22 no.3
• /
• pp.253-258
• /
• 1995

Microtubules and microfilaments are major cytoskeletal components in mammalian ova that provide the framework for chromosomal movement and cellular division. Extensive changes of cytoskeletal organization occur during maturation and fertilization. The changes in cytoskeletons are essential for the normal meiotic maturation and for the formation of the biparental diploid genome of the embryo, and thus are repeated at each cell cycle during embryonic development. Disturbance of the cytoskeletal organization could result in abnormal gamete development and early embryonic death.

• Clinical and Experimental Reproductive Medicine
• /
• v.39 no.2
• /
• pp.58-67
• /
• 2012

Objective: Previously, we identified that transketolase (Tkt), an important enzyme in the pentose phosphate pathway, is highly expressed at 2 hours of spontaneous maturation in oocytes. Therefore, this study was performed to determine the function of Tkt in meiotic cell cycle regulation, especially at the point of germinal vesicle breakdown (GVBD). Methods: We evaluated the loss-of-function of Tkt by microinjecting Tkt double-stranded RNAs (dsRNAs) into germinal vesicle-stage oocytes, and the oocytes were cultured in vitro to evaluate phenotypic changes during oocyte maturation. In addition to maturation rates, meiotic spindle and chromosome rearrangements, and changes in expression of other enzymes in the pentose phosphate pathway were determined after Tkt RNA interference (RNAi). Results: Despite the complete and specific knockdown of Tkt expression, GVBD occurred and meiosis was arrested at the metaphase I (MI) stage. The arrested oocytes exhibited spindle loss, chromosomal aggregation, and declined maturation promoting factor and mitogen-activated protein kinase activities. The modified expression of two enzymes in the pentose phosphate pathway, Prps1 and Rbks, after Tkt RNAi and decreased maturation rates were amended when ribose-5-phosphate was supplemented in the culture medium, suggesting that the Tkt and pentose phosphate pathway are important for the maturation process. Conclusion: We concluded that Tkt and its associated pentose phosphate pathway play an important role in the MI-MII transition of the oocytes' meiotic cell cycle, but not in the process of GVBD.

• Korean Journal of Animal Reproduction
• /
• v.22 no.3
• /
• pp.253-264
• /
• 1998

Porcine follicular oocyte, collected from antral follicles (2~5 mm in diameter) of gilt ovaries were matured in vitro porcine follicular fluid (pFF) with PMSG (pFF-PMSG) buffer with at 37$^{\circ}C$ under 5% CO2 in air their ability of maturation promoting factor (MPF), of GV and GVBD formation was examined followed during time after in vitro culture. Formation of second metaphase was observed in 57.6% and 71.2% of matured in with pFF-PMSG buffer to 45 and 50 hours after invitro. Porcine oocytes cultured in pFF-PMSG for various periods of up to 30 hours were stained with Hoechst-33342 and classified according to maturation before assaying. Histone H1 kinase (H1K) activity was assayed during meiotic maturation in porcine oocytes matured in pFF-PMSG buffer in vitro. In oocytes matured in pFF-PMSG, H1K activity was at the 30 hours after culture and increased about 15 fold than at the germinal vesicle stage with before at the cultured in vitro. This pattern is similar to those reported in non-mammalian species and su, pp.rts the concepts that H1K is ubiquitous in eukaryotes and controls the meiotic cell cycle in mammals. These results suggest that the maturation pFF-PMSG buffer used influences the fluctuation pattern of H1K activity and biological characteristics of porcine oocytes cultured in vitro.

• Clinical and Experimental Reproductive Medicine
• /
• v.21 no.2
• /
• pp.191-200
• /
• 1994

The influence of hypoxanthine and ovarian steroids on the meiotic maturation process of mouse oocytes was investigated for the qualified application of culture medium in in vitro fertilization(IVF). Mouse oocytes were cultured in hypoxanthine and various ovarian steroids(progesterone, estradiol-17${\beta}$ and testosterone) and their effects on the oocyte maturation had been observed. When mouse oocytes were cultured in the various concentration(1-4mM) of hypoxanthine, meiotic maturation of cumulus cell-enclosed oocytes was inhibited by presence itself, which was a dose-dependent effect in meiotic arrest of mouse oocytes. The presence of progesterone, estradiol-17${\beta}$ and testosterone have made the mouse oocyte mature properly. Meanwhile maturation of cumulus cell-enclosed oocyte was severely inhibited by 3 hoursculture in the media of progesterone supplemented with hypoxanthine. However the continuous presence lasting 24 hours of progesterone even supplemented with hypoxanthine had got rid of the inhibition of oocytes maturation. Not only estradiol-17${\beta}$ supplemented with hypoxanthine but also testosterone supplemented with hypoxanthine exert the severe inhibition of the maturation of cumulus cell-enclosed oocytes for 3-hours culture. However the continuous presence lasting 24 hours of estradiol-17${\beta}$ and testosterone even supplemented with· hypoxanthine had relieved the inhibition of oocytes maturation. These results make us suggest that hypoxanthine inhibits the mouse oocyte maturation, particularly markedly in conjunction with ovarian steroids for short period, which indicated some sort of the synergistic inhibitory retationship between the ovarian steroids and hypoxanthine.

• Journal of Embryo Transfer
• /
• v.25 no.4
• /
• pp.251-258
• /
• 2010

In the present study, effects of concentration and time of culture in presence of roscovitine on nuclear maturation and meiotic spindle configuration, chromosomal alignment were examined in porcine oocytes. In experiment 1, porcine cumulus oocyte complexes (COCs) were cultured at $39^{\circ}C$ in a 5% $CO_2$ atmosphere in North Carolina State University 23 (NCSU-23) supplemented with 25, 50, 75 or $100\;{\mu}M$ roscovitine for 22 h and then were cultured for additional 22 h after removal of roscovitine. Nuclear maturation and morphology of the meiotic spindle and chromosomal alignment were examined to determine the optimal concentration of roscovitine in oocyte maturation. In experiment 2, COCs were cultured in NCSU-23 supplemented with $50\;{\mu}M$ roscovitine for 17, 20, 27 or 42 h and then an additional 22 h without roscovitine was followed to determine the optimal time of culture. The optimal concentration of roscovitine to arrest and resume meiosis of porcine oocyte was $50\;{\mu}M$ by examining nuclear status (p<0.05) and normal spindle and chromosome configuration. The optimal time of culture in presence of roscovitine to arrest meiosis of porcine oocyte was 17 h (p<0.05), although MII rates and normal morphology of the meiotic spindle and chromosomal alignment were not significantly different among various times of culture. In conclusion, the optimal concentration and time of culture in presence of roscovitine to arrest porcine oocytes are $50\;{\mu}M$ and 17 h, respectively.

• Journal of Animal Reproduction and Biotechnology
• /
• v.34 no.3
• /
• pp.212-221
• /
• 2019

Sestrin-2 (SESN2) as a stress-metabolic protein is known for its anti-oxidative effects as a downstream factor of PERK pathways in mammalian cells. However, the expression patterns of SESN2 in conjunction with the UPR signaling against to ER stress on porcine oocyte maturation in vitro, have not been reported. Therefore, we confirmed the expression pattern of SESN2 protein, for which to examine the relationship between PERK signaling and SESN2 in porcine oocyte during IVM. We investigated the SESN2 expression patterns using Western blot analysis in denuded oocytes (DOs), cumulus cells (CCs), and cumulus-oocyte complexes (COCs) at 22 and 44 h of IVM. As expected, the SESN2 protein level significantly increased (p < 0.01) in porcine COCs during 44 h of IVM. We investigated the meiotic maturation after applying ER stress inhibitor in various concentration (50, 100 and 200 μM) of tauroursodeoxycholic acid (TUDCA). We confirmed significant increase (p < 0.05) of meiotic maturation rate in TUDCA 200 μM treated COCs for 44 h of IVM. Finally, we confirmed the protein level of SESN2 and meiotic maturation via regulating ER-stress by only tunicamycin (Tm), only TUDCA, and Tm + TUDCA treatment in porcine COCs. As a result, treatment of the TUDCA following Tm pre-treatment reduced SESN2 protein level in porcine COCs. In addition, SESN2 protein level significantly reduced in only TUDCA treated porcine COCs. Our results suggest that the SESN2 expression is related to the stress mediator response to ER stress through the PERK signaling pathways in porcine oocyte maturation.

• Journal of Embryo Transfer
• /
• v.18 no.3
• /
• pp.263-267
• /
• 2003

This study was carried out to test the efficacy of pharmacological inhibitors of the cell cycle transition in keeping bovine oocytes at the germinal vesicle(GV) stage and the reversibility of this inhibition. Bovine oocytes were incubated for 22∼24 hrs in the presence of various inhibitors : cycloheximide (2$\mu\textrm{g}$/$m\ell$), 6-DMAP (2 mM), and roscovitine (50$\mu$M). Bovine oocytes cultured with any of the inhibitors were significantly blocked at the GV stage. Reversibility of pharmacological inhibitors was assessed by culturing oocytes an additional 22∼24 hours in inhibitor-free medium. Examination of oocytes revealed that the inhibitory effect was fully reversible and effect of resuming meiotic progression on nuclear maturation varied according to the various inhibitors. This study suggests that cycloheximide, 6-DMAP and roscovitine can be applied to control meiotic arrest and resumption in maturation culture of bovine oocytes in vitro. More investigations are needed to better understand how the cell cycle of oocyte is blocked without problems to future developmental competence.

• Animal cells and systems
• /
• v.2 no.1
• /
• pp.87-91
• /
• 1998

The present study investigated the involvement of the phospholipase C (PLC) and protein kinase C (PKC) signaling pathways during progesteroneinduced meiotic maturation in amphibian (Rana dybowskii) oocytes. Prosesterone-induced germinal vesicle breakdown (GVBD) of oocytes was significantly inhibited by a PKC inhibitor, staurosporine and a PLC inhibitor, U73122, in a dose-dependent manner. In contrast, U73343, an inactive analogue of U73122, was ineffective in suppressing GVBD. PKC activity in oocytes reached a maximum level at 30 min after progesterone stimulation and this elevated PKC activity was effectively suppressed by U73122 or staurosporine, suggesting that the activation of PKC enzyme is closely linked to PLC signaling during oocyte maturation. In addition, these inhib itors blocked the maturation promoting factor (MPF) activity which appeared in oocytes in response to progesterone, suggesting that PKC activation is an important signal for MPF activity. Therefore, this study demonstrates that the activation of PKC via PLC signaling is directly linked to an intracellular protein kinase cascade related to the appearance of MPF activity during meiotic maturation in amphibian (Rana dybowskii) oocytes.

• Clinical and Experimental Reproductive Medicine
• /
• v.26 no.2
• /
• pp.137-148
• /
• 1999

Purpose of the present study was to find the optimal ovulation induction medicine for the maturation and development of immature oocytes and culture media for 2-cell embryos in the mouse model. ICR female mouse aged 6 to 8 weeks, were stimulated with 5 IU PMSG injection. At 47 to 50 hour post-PMSG injection, ovaries were dissected out and oocytes-cumulus complexes were punctured. The oocyte-cumulus complexes were cultured in media containing various ovulation induction medicine, CC, HMG and Metrodin for 18 hours. Female ICR mice were stimulated with 5 IU PMSG and 48 hours later were injected 5 IU of hCG, then female and male mice were mated. At 48 hour post-hCG injection, oviducts were dissected out and 2-cell embryos were flushed. The 2-cell embryos were cultured in various media, Ham's F-10 media of milli-Q water $(3^{\circ})$, Ham's F-10 media of HPLC (high performance liquid chromatography, Baxter) water, Medicult media, HTF (human tubal fluid) media for 96 hours. The results were as follows. 1. When the oocytes-cumulus complexes were cultured in $10^{-9}{\mu}g/ml{\sim}10^{-8}{\mu}g/ml$ of CC, those were suppressed in meiotic maturation $(28.2{\sim}33.7%)$. Whereas the oocytes-cumulus complexes were cultured in $10^{-7}{\mu}g/ml{\sim}10^{-4}{\mu}g/ml$, these were not effected in meiotic maturation $(54.5{\sim}72.7%)$. 2. When the oocytes-cumulus complexes were cultured in $10^{-4}{\mu}g/ml{\sim}10^{-1}{\mu}g/ml$ of Metrodin, those were suppressed in meiotic maturation $(35.7{\sim}41.5%)$. Meanwhile the oocytes-cumulus complexes were cultured in $10^{-7}{\mu}g/ml{\sim}10^{-5}{\mu}g/ml$, those were not effected in meiotic maturation $(54.2{\sim}70.3%)$. 3. When the oocytes-cumulus complexes were cultured in $10^{-5}{\mu}g/ml{\sim}10^{-4}{\mu}g/ml$ of HMG, those were suppressed in meiotic maturation $(48.2{\sim}50.4%)$. As being cultured in $10^{-7}{\mu}g/ml{\sim}10^{-6}{\mu}g/ml$, increased in meiotic maturation $(75.8{\sim}80.7%)$. 4. When the 2-cell embryos were cultured in Ham's F-10 media of milli-Q water $(3^{\circ})$, Ham's F-10 media of HPLC (high performance liquid chromatograpy, Baxter) water, Medicult media, HTF (human tubal fluid) media, developmental rates to blastocyst and hatching for 96 hour were 50.0%, 45.2%, 71.5% and 95.6%, respectively.

• 대한생식의학회:학술대회논문집
• /
• 1995.12a
• /
• pp.26-32
• /
• 1995