• Animal cells and systems
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• v.2 no.1
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• pp.99-106
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• 1998

In this study, we have examined the role of cAMP in gap junctional communication (GJC) in preimplantation mouse embryos. GJC was monitored by Lucifer Yellow (LY) injected into one blastomere of compacted embryos. The speed of GJC was defined as the time taken for the last blastomere of the embryo to become visibly fluorescent. The median time for 8-cell embrvos (140 sec) was similar to that for 16-cell (135 sec). To determine whether cAMP and cAMP-dependent protein kinase (PKA) are involved in the regulation of GJC, the effects of PKA inhibitor (H8) and cAMP analogues (Rp-cAMP and 8-Br-cAMP) on dye transfer between blastomeres of compacted embryos were examined. Some of the embryos treated with either H8 or Rp-cAMP failed to transfer LY to all blastomeres within 10 min. In contrast, 8-Br-cAMP speeded up fluorescent dye transfer. The median time to fill all blastomeres with LY was 140 sec in untreated controls and 90 sec in siblings treated with 8-Br-cAMP. Inhibition of PKA by H8 or Rp-cAMP induced delay or arrest in embryo development after compaction, but the increase of intracellular cAMP showed no effect. These findings suggest that GJC in preimplantation mouse embryos is regulated by cAMP-PKA pathway and transient interference by PKA inhibitors induces the developmental delay beyond compaction.

• Clinical and Experimental Reproductive Medicine
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• v.21 no.1
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• pp.49-62
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• 1994

In mammalian development, the embryo which is in the process of compaction, involves a progressive flattening of blastomeres against each other with the consequence that the embryo assumes a spherical shape. This stage happens in the first differentiation. The present study was aimed to examine the involvement of other metal ions in compaction by treating with various divalent cations in the absence of $Ca^{++}$. When 8-cell embryos were cultured in $Ca^{++}$-free medium for 24hrs, they developed to 16-cell stage but did not compaction, and degenerated after 48hrs of culture. Embryos were cultured in $Ca^{++}$-free medium for 24hrs and then transferred to the control medium showed the normal compaction afterwards. When 8-cell embryos were cultured in the presence of $Ni^{++}$, known as a $Ca^{++}$ inhibitor, they cleaved to 16-cell stage but did not compact in the absence of $Ca^{++}$. On the other hand, embryos cultured in the media containing both $Ca^{++}$ and $Ni^{++}$ developed normally so that they underwent compaction during culture for 48hrs. However, they failed to hatch during further 24hrs in the same medium, indicationg that $Ni^{++}$ may exert some harmful effects. Embryos grow in the control medium that contained $Ca^{++}$ but not $Ni^{++}$, developed to the hatched blastocysts. The treatment with $Cd^{++}$ $10^{-1}$,$10^{-2}{\mu}M$, $Mn^{++}$ or $Ba^{++}$ 10,100, $1000{\mu}M$ in $Ca^{++}$-free medium, respectively, inhibited compaction and embryonic degeneration began as in $Ca^{++}$-free medium. When 3, 5, 10mM of $Sr^{++}$, known as a substitute for $Ca^{++}$ in cell, was added to $Ca^{++}$-free medium, respectively, compaction was induced unlike the above metal ions. Embryos were cultured in $Sr^{++}$ developed to blastocysts, but failed to hatch after 72hrs and degenrated. On the other hand, when embryos were cultured in 3, 5, 10mM of $Sr^{++}$ but in $Ca^{++}$-free medium for 24hrs respectively and then transferred to the control, they showed the similiar development as that in the control.

• Journal of Embryo Transfer
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• v.12 no.2
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• pp.171-179
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• 1997

The objectives of the present study were improvements in the efficiency of developmental rates to morula and blastocyst stages to produce a large number of genetically identical nuclear transplant embryos. The oocytes collected from slaughterhouse ovaries were matured for 24 h and then enucleated and cultured to allow cytoplasmic maturation and gain activation competence. And then the donor embryos were treated for 12 h with 10 $\pi$g /ml nocodazole and 7.5 $\pi$g /ml cytochalasin B to synchronize the cell cycle stage at 26 h after the onset of culture. The blastomeres were transferred into the perivitelline space of the enucleated nocytes and blastomeres and oocytes were fused by electrofusion. The cloned embryos were then cultured in various conditions to allow further development. The age of the recipient(30 vs 40 h) had no significant effect on the fusion rates(82.4 vs 82.1%) and the developmental rates to morula /blastocyst(9.8 vs 11.0%). Effect of Nocodazole treatment on the donor cell cyle synchronization to improve the developmental rates of bovine nuclear transplant embryos was significantly higher than control group(21.4 vs 10.1%, p<0.05). Significant differences were in the percentage of fusion rates(72.9,77.1vs 61.9%) in three types of fusion medium(PBS(+), mannitol and sucrose, p<0.01). The developmental rates of bovine nuclear transplant embryos appeared to be highest in mSOF medium under 5% 0$_2$ condition, but no significant differences were found when compared with TCM199-BOEC and mSOF under two different oxygen ratio(5 and 20%).

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.8
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• pp.1057-1061
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• 2001

In this study we explored the possibility of performing nuclear transfer in the domestic cat and assessed the ability of different culture media to support in vitro development of reconstructed cat embryos. Donor somatic cells were derived from cultured cumulus cells or explants of oviduct tissue, and recipient cytoplasts from in vitro matured oocytes. A higher percentage of cleavage (84.6% and 86.5%) and development to the morula stage (35.9% and 44.2%) was found when reconstructed embryos receiving cumulus or oviduct cells were cultured in MK1 medium, compared with those cultured in CR1aa (58.7% and 72.5%, 13.8% and 13.6%, respectively). There was no significant difference between MK1 and CR1aa media with respect to the proportion developing to the blastocyst stage (15.4% and 17.3% vs 6.8% and 8.6%, respectively, p>0.05). There was no significant effect (p>0.05) of donor cell type (cumulus and oviduct cells) on the rates of fusion (65.0% and 52.5%), cleavage (84.6% and 86.5%), development to the morula (35.9% and 44.2%), and blastocyst (15.4% and 17.3%) stages when reconstructed embryos were cultured in MK1 medium. Similar results were found for the reconstructed embryos cultured in CR1aa medium. These results show that culture medium has a significant impact on the early development of reconstructed cat embryos, whereas donor cell type does not have a significant effect.

• Korean Journal of Animal Reproduction
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• v.10 no.1
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• pp.76-82
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• 1986

This experiment was conducted to determine the effects of trophoblastic vesicles (TV) and estradiol-17$\beta$ on the development in vitro of rabbit embryos. Thirty matured female rabbits were treated with PMSG followed by HCG injection and mating. Embryos were recovered with D-PBS (Dulbecco's Phosphate Buffered Saline) after superovulation, and normally developed to two-to four-cell embryos were used in the subsequent in vitro culture. Basal medium was Medium-199 su, pp.emented with 1.5% bovine serum albumin. Embryo on Day 5 after mating (Day 0) was cut into two or three pieces to remove the embryonic disc. Each piece of tissue was cultured for 24 hours at 37$^{\circ}C$ in 0.5 mlMedium-199 in 5% CO2. During culture, peices of trophoblastic tissue changed into spherical vesicles which were used for co-culture. These spheres were called trophoblstic vesicles. Two-to four-cell embryos were cultured for 4 days in Medium-199 in the absence or presence of trophoblastic vesicle, and two-to four-cell embryos cultured with varing concentration (0, 0.1, 1, 10ng/ml) of estradiol-17$\beta$ for 4 dyas. Culture vessels used were watch glass for coculture with trophoblastic vesicles and micortube for estradiol-17$\beta$ infusion. Compared with the Medium-199 alone as basal culture medium, more blastocysts (46.7% vs 15.1%; P<0.01) and morulae (84.4% vs 56.6%; P<0.05) were developed in the co-culture with trophoblastic vesicles. Estradiol-17$\beta$ infused in culture medium was not effective for embryo development to blastocysts (78.3% in control, 50.0% in 0.1ng/ml, 61.5% in 1ng/ml and 64.4% in 10ng/ml) and also to morulae (91.3% in control, 84.2% in 0.1ng/ml, 92.3% in 1ng/ml and 91.1% in 10ng/ml). Compared with the watch glass culture mehotd, more (P<0.01) blastocysts were developed in microtube culture (78.3% vs 56.6%) and more (P<0.01) morulae in microtube culture (91.3% vs 56.6%).

• Journal of Embryo Transfer
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• v.12 no.2
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• pp.133-139
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• 1997

Large scale production of cloned embryos requires the technology of multiple generational nuclear transfer(NT) by using NT embryos itself as the subsequent donor nuclei. In this work we investigated comparatively the effects of enucleated oocytes treated with ionomycin and 6-DMAP on the electrofusion rate and in vitro developmental potential in the first and second NT embryos. The embryos of 16-cell stage were collected from the mated does by flushing oviducts with Dulbecco's phosphate buffered saline(D-PBS) containing 10% fetal calf serum(FCS) at 47 hours after hCG injection. The recipient cytoplasms were obtained by removing the nucleus and the first polar body from the oocytes collected at 15 hours after hCG injection. The enucleated oocytes were pre-activated by 5 min incubation in 5$\mu$M ionomycin and 2 hours incubation in 2 mM 6-DMAP at 19~20 hours post-hCG before microinjection. In the first and second generation NT, the unsynchronized 16-cell stage embryos were used as nuclear donor. The separated donor blastomeres were injected into the enucleated activated recipient oocytes by micromanipulation and were electrofused by electrical stimulation of single pulse for 60 $\mu$sec at 1.25kV/cm in $Ca^2$+, $Mg^2$+ - free 0.28 M mannitol solution. In the non-preactivation group, the electrofusion and electrical stimulation was given 3 pulses for 60 $\mu$sec at 1.25 kV/cm in 100$\mu$M $Ca^2$+, $Mg^2$+ 0.28 M mannitol solution. The fused oocytes were co-cultured with a monolayer of rabbit oviductal epithelial cells in TCM-199 solution containing 10% FCS for 120 hours at 39$^{\circ}C$ in a 5% $CO_2$ incubator. The results obtained were summarized as follows: 1. In the first generational NT embryos, the electrofusion rate of preactivated and non-activated oocytes(80.4 and 87.8%) was not significantly different, but in the second generational NT embryos, the electrofusion rate was significantly(P<0.05) higher in the non-activated oocytes(85.7%) than in the preactivated oocytes(70.1%). 2) In the first and second generational NT embryos, the developmental potential to biastocyst stage was significantly(P<0.05) higher in the preactivated oocytes(39.3 and35.7%) than in the non-preactivated oocytes(16.0 and 13.3%). No significant difference in the developmental potential was shown between the first and second generational NT embryos derived from the preactivated oocytes. In conclusion, it may be efficient to use the oocytes preactivated with ionomycin and 6-DMAP for the multiple production of cloned embryos by recycling nuclear transfer.

• Korean Journal of Medicinal Crop Science
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• v.14 no.4
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• pp.255-260
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• 2006

Culture conditions for high frequency plant regeneration via somatic embryogenesis from embryogenic cell suspension cultures of Hovenia dulcis are described. Germinated somatic embryos were selected for induction of secondary embryogenesis. Friable embryogenic cells were induced directly from somatic embryos when transfer to 1/3 MS solid or liquid medium lacking plant growth regulators. The temperature strongly effected on induction of secondary embryognesis than other conditions in culture. All somatic embryos produced friable embryogenic cell clumps within 10 days when germinated somatic embryos cultured in 1/3 MS medium at $30^{\circ}C$ in suspension culture. No somatic embryos formed from embryogenic cell suspension cultures at $18^{\circ}C$. Numerous somatic embryos were induced and subsequently developed uniformly into germination stage from suspended cell clumps after 4 weeks of culture on $18^{\circ}C$. Plantlets conversion were observed on $18^{\circ}C$ when germinated somatic embryos were transferred to 1/3 MS solid medium without plant growth regulators or supplemented with 0.1-0.5 mg/l benzyladenine.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.9
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• pp.1152-1158
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• 2010

In differentiating human embryonic stem (d-hES) cells there are a number of types of cells which may secrete various nutrients and helpful materials for pre-implantation embryonic development. This study examined whether the d-hES could function as a feeder cell in vitro to support mouse embryonic development. By RT-PCR analysis, the d-hES cells revealed high expression of three germ-layered differentiation markers while having markedly reduced expression of stem cell markers. Also, in d-hES cells, LIF expression in embryo implantation-related material was confirmed at a similar level to undifferentiated ES cells. When mouse 2PN embryos were cultured in control M16 medium, co-culture control CR1aa medium or co-cultured with d-hES cells, their blastocyst development rate at embryonic day 4 (83.9%) were significantly better in the d-hES cell group than in the CR1aa group (66.0%), while not better than in the M16 group (90.7%)(p<0.05). However, at embryonic days 5 and 6, embryo hatching and hatched-out rates of the dhES cell group (53.6 and 48.2%, respectively) were superior to those of the M16 group (40.7 and 40.7%, respectively). At embryonic day 4, blastocysts of the d-hES cell group were transferred into pseudo-pregnant recipients, and pregnancy rate (75.0%) was very high compared to the other groups (M16, 57.1%; CR1aa, 37.5%). In addition, embryo implantation (55.9%) and live fetus rate (38.2%) of the d-hES cell group were also better than those of the other groups (M16, 36.7 and 18.3%, respectively; CR1aa, 23.2 and 8.7%, respectively). These results demonstrated that d-hES cells can be used as a feeder cell for enhancing in vitro and in vivo developmental potential of mouse pre-implantation embryos.

• Reproductive and Developmental Biology
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• v.35 no.2
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• pp.191-195
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• 2011

The present study was conducted to examine the reactive oxygen species (ROS) generation levels in porcine parthenogenetic embryos. Porcine in vitro matured oocytes were activated by the combination of electric stimulus and 6-DMAP before in vitro culture. Porcine oocytes and parthenogenetic embryos were stained in 10 ${\mu}M$ dichlorohydrofluorescein diacetate (DCF) or 10 ${\mu}M$ hydroxyphenyl fluorescein (HPF) dye each for 30 min at $39^{\circ}C$. The fluorescent emissions from the samples were recoded as JPEG file and the intensity of fluorescence in oocytes and embryos were analyzed. $H_2O_2$ and $^{\cdot}OH$ radical levels of porcine oocytes were reduced immediately after electric stimulation. However, $H_2O_2$ and $^{\cdot}OH$ radical levels of parthenogenetic embryos were increased with time elapsed after electric stimulation from 0 h to 3 h and after DMAP culture. During in vitro culture, $H_2O_2$ and $^{\cdot}OH$ radical levels were gradually increased from the one-cell stage to the two- and four-cell stages. The result of the present study suggests that the ROS was not increased by electric pulse in porcine embryos. Rather than it seems to be associated with the stage of development and the culture condition.

• Journal of Embryo Transfer
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• v.12 no.3
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• pp.335-341
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• 1997

The aims of this study are to establish a stable isolation method of blastomeres from bovine early embryos and examine their developmental potential in vitro Early embryos were produced by maturation and fertilizaion in vitro of bovine follicular oocytes. Blastomeres were isolated from 2~8-cell embryos in $Ca^2$+-, $Mg^2$+-free PBS+EDTA after removing the zonae pellucidae Isolated blastomeres were cultured in CZB containing BOEC for upto 240 hpi. Cleavage rates of them were 18.5%(10 /54) in 1 /2 blastomeres, 33.3%(16/48) in 1/4 blastomeres and 34.2%(14 /41) in 1/8 blastomeres, respectively. The rates of blastocystic vesicle formed were 8.7%(4 /46) in 1/2 blastomeres, 26.6% (17/64) in 1/4 blastomeres and 10.3%(8 /78) in 1/8 blastomeres, respectively. Blastomeres developed into various types of blastocystic vesicles and trophoblastic vesicles as evidenced by the Hoechst 33258 staining and morphology. This results suggest that the isolation method used and subsequent culture of isolated blastomeres from bovine early embryos should be useful to obtain extra embryonic cells for various analyses such as PCR and putative ES cell culture.