• Journal of Embryo Transfer
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• v.28 no.1
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• pp.1-6
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• 2013

A lot of works have been dedicated to clarify the reasons why the establishment of embryonic stem cells (ESCs) from pig is more difficult than that from mouse and human. Several concomitant factors such as culture condition including feeder layer, sensitivity of cell to cell contact, definitive markers of pluripotency for evaluation of the validity and optimal timing of derivation have been suggested as the disturbing factors in the establishment of porcine ESCs Traditionally, attempts to derive stem cells from porcine embryos have depend on protocols established for mouse ESCs using inner cell mass (ICM) for the isolation and culture. And more recently, protocols used for primate ESCs were also applied. However, there is no report for the establishment of porcine ESCs. Indeed, ungulate species including pigs have crucial developmental differences unlike rodents and primates. Here we will review recent studies about issues for establishment of porcine ESCs and discuss the promise and strategies focusing on the timing for derivation and pluripotent state of porcine ESCs.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.3
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• pp.205-211
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• 2019

In this study, we investigated the possibility of using mouse embryonic stem cell conditioned medium (ESCM) and embryonic stem cell medium (ESM) for in vitro maturation in the efficient in vitro production of blastocysts from porcine follicular oocyte. Depending on the concentration of supplement of ESCM added to the NCSU-23 solution did not affect 2-cell development rates and blastocysts development. However, in particular, the survival rate (10 days of culture) of blastocyst was significantly higher than that of the control group as the additive concentration (30%) increased (p < 0.05). The survival rate of blastocysts showed a similar tendency even with addition of ESM (30%) alone. On the other hand, the duration of the addition of these additives during IVM (0-44 h) was that the IVM I period (0-22 h) were more effective than the IVM II period (22-44 h). Thus, the effect of these additives is probably due to the combination of the various physiologically active substances of ESCM or the appropriate amino acids and vitamins of ESM. In particular, these additives were more effective during the first half (IVM I) of in vitro maturation. In summary, optimization of ESCM or ESM supplementation may improve in vitro maturation of porcine oocyte and affect developmental competency. Therefore, if more efficient methods of adding ESCM or ESM to basal culture medium can be developed during in vitro maturation of porcine follicle oocytes, high quality blastocysts will be developed from low porcine follicular oocyte compared to other domestic animals.

• Reproductive and Developmental Biology
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• v.36 no.1
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• pp.71-77
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• 2012

The objective of this study was to examine the effect of thymidine treatment during $in$ $vitro$ maturation (IVM) of porcine follicular oocytes on blastocyst development. Porcine oocytes were treated with thymidine (10 mM, 20 mM and 30 mM) for 2 or 6 hr in the preiods of IVM I and/or II. The survival rates of the blastocysts in the 6 hr treatment groups of 10 mM and 20 mM during IVM I period were significantly higher than those of control group ($p$<0.05). However, the survival rate of the blastocysts in the 2 hr treatment group of 20 mM during IVM II period was significantly higher than control group ($p$<0.05). Furthermore, the survival rate of the blastocysts in the 6 hr treatment group of 30 mM during IVM II period was significantly lower than control group ($p$<0.05). Consistent with the previous result, blastocyst development of both IVM I and II treatment group was also showed as similar pattern. Total and apoptotic cell numbers of blastocysts derived from thymidine treated porcine oocytes were examined by using Tunel assay. The results showed that there was no significant differences in total cell number of blastocysts between thymidine treated and untreated groups. However, apoptosis-positive cells in the thymidine treated group (6 hr IVM I) were significantly lower than those of other groups ($p$<0.05). Taken together, these results indicate that high quality oocytes were selected by DNA synthesis mechanism according to high concentration thymidine treatment during porcine oocyte maturation. Therefore, we concluded that presumptive selected oocytes by thymidine treatment during maturation periods improved the further embryo development and embryonic quality of IVF embryos by decreasing the incidence of apoptosis in preimplantation porcine embryos.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.6
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• pp.789-793
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• 2012

Fertilization of the oocyte commences embryogenesis during which maternally inherited mRNAs are degraded and the embryonic genome is activated. Transcription of embryonic mRNA is initiated by embryonic genome activation (EGA). RNA polymerase II (RNA Pol II) is responsible for the synthesis of mRNAs and most small nuclear RNAs, and consists of 12 subunits, the largest of which characteristically harbors a unique C-terminal domain (CTD). Transcriptional activity of RNA Pol II is highly regulated, in particular, by phosphorylation of serine residues in the CTD. Here, we have shown the presence of RNA Pol II CTD phosphoisoforms in porcine oocytes and preimplantation embryos. The distribution pattern as well as phosphorylation dynamics in germinal vesicles and during embryogenesis differed in developmental stages with these isoforms, indicating a role of RNA Pol II CTD phosphorylation at the serine residue in transcriptional activation during both oocyte growth and embryonic genome activation. We additionally examined the effects of the RNA Pol II inhibitor, ${\alpha}$-amanitin, on embryo development. Our results show that inhibition of polymerase, even at very early stages and for a short period of time, dramatically impaired blastocyst formation. These findings collectively suggest that the functionality of maternal RNA Pol II, and consequently, expression of early genes regulated by this enzyme are essential for proper embryo development.

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.4
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• pp.347-356
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• 2020

Gangliosides are glycolipids in which oligosaccharide is combined with sialic acids. Our previous studies have suggested an interplay between ganglioside GD1a/GT1b and meiotic maturation capacity in porcine oocyte maturation. Furthermore, ganglioside GD1a and GT1b are known for its antioxidant activity, but it is still unclear whether possible antioxidant role of GD1a and GT1b is involved in porcine embryos development competence during in vitro culture (IVC). Here, the effects of ganglioside GD1a and GT1b on the embryonic developmental competence during in vitro culture of porcine were investigated. The effects of ganglioside GD1a and GT1b on the expression of ST3GAL2 were confirmed during embryos development (2-cell, 4-cell, 8-cell and blastocyst) using immunofluorescent staining (IF). As a result, the fluorescent expression of ST3GAl2 was higher in embryos at 4-8 cells stage than blastocysts. Blastocyst development rate significantly increased in only 0.1 μM GD1a and GT1b treated groups compared with control group. To investigate the cellular apoptosis, we analyzed TUNEL assay. In case of only 0.1 μM GD1a and GT1b treated groups, the total number of cells in blastocyst compared with control group, but there was no significant difference in the rate of apoptotic cells. We identified the intracellular ROS levels using DCF-DA staining. According to the result, ROS production significantly decreased in blastocysts derived from the 0.1 μM GD1a and GT1b treated groups. These results suggest that ganglioside GD1a and GT1b improve the developmental competence of porcine embryos via reduction of intracellular ROS during preimplantation stage.

• Journal of Embryo Transfer
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• v.32 no.3
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• pp.95-104
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• 2017

This study was conducted to establish the optimal chemical post-activation conditions in porcine embryonic development after parthenogenesis (PA) and somatic cell nuclear transfer (SCNT) using 4 different chemical compositions (cytochalasin B (CB), cyclohexamide (CHX), demecolcine (DC), 6-dimethylaminopurine (DMAP). Porcine embryos were produced by PA and SCNT and then, cultured for post-activation with CB ($7.5{\mu}g/mL$), CB ($7.5{\mu}g/mL$) + CHX ($10{\mu}g/mL$), CB ($7.5{\mu}g/mL$) +DC ($0.4{\mu}g/mL$), and CB ($7.5{\mu}g/mL$) + DMAP (2 mM). In PA embryonic development, cleavage rates have been significantly higher in CB group (94.7%) and CB+DMAP group (94.1%) than that of CB+CHX and CB+DC group (88.1 and 84.3%, respectively). There have been no significant differences in blastocyst formation rates among the four groups. In cell number of blastocyst was shown in CB group (42.3%) significantly higher than CB+CHX and CB+DC group (40.6 and 40.6%, respectively). In SCNT embryonic development, CB+DMAP group (89.7%) significant differences were found on embryo cleavage rates when compared with other three groups. Blastocyst formation rates in CB+DMAP group (26.9%) were significantly higher when compared with CB, CB+CHX, and CB+DC groups (25.5, 20.2, and 22.1%, respectively). In blastocyst cell number, CB+DMAP group (41.4%) was found higher significant difference compared with other three groups. Additionally, we have investigated survivin expression in early development stages of porcine SCNT embryos for more confirmation. Our results establish that CB group and CB+DMAP group for 4 h during post-activation improves pre-implantation improvement of PA and SCNT embryos.

• Journal of Embryo Transfer
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• v.27 no.2
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• pp.113-119
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• 2012

Epigenetic modification including genome-wide DNA demethylation is essential for normal embryonic development. Insufficient demethylation of somatic cell genome may cause various anomalies and prenatal loss in the development of nuclear transfer embryos. Hence, the source of nuclear donor often affects later development of nuclear transfer (NT) embryos. In this study, appropriateness of porcine embryonic germ (EG) cells as karyoplasts for NT with respect to epigenetic modification was investigated. These cells follow methylation status of primordial germ cells from which they originated, so that they may contain less methylated genome than somatic cells. This may be advantageous to the development of NT embryos commonly known to be highly methylated. The rates of blastocyst development were similar among embryos from EG cell nuclear transfer (EGCNT), somatic cell nuclear transfer (SCNT), and intracytoplasmic sperm injection (ICSI) (16/62, 25.8% vs. 56/274, 20.4% vs. 16/74, 21.6%). Genomic DNA samples from EG cells (n=3), fetal fibroblasts (n=4) and blastocysts from EGCNT (n=8), SCNT (n=14) and ICSI (n=6) were isolated and treated with sodium bisulfite. The satellite region (GenBank Z75640) that involves nine selected CpG sites was amplified by PCR, and the rates of DNA methylation in each site were measured by pyrosequencing technique. The average methylation degrees of CpG sites in EG cells, fetal fibroblasts and blastocysts from EGCNT, SCNT and ICSI were 17.9, 37.7, 4.1, 9.8 and 8.9%, respectively. The genome of porcine EG cells were less methylated than that of somatic cells (p<0.05), and DNA demethylation occurred in embryos from both EGCNT (p<0.05) and SCNT (p<0.01). Interestingly, the degree of DNA methylation in EGCNT embryos was approximately one half of SCNT (p<0.01) and ICSI (p<0.05) embryos, while SCNT and ICSI embryos contained demethylated genome with similar degrees. The present study demonstrates that porcine EG cell nuclear transfer resulted in hypomethylation of DNA in cloned embryos yet leading normal preimplantation development. Further studies are needed to investigate whether such modification affects long-term survival of cloned embryos.

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.1
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• pp.94-101
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• 2020

In the early development of parthenogenetic embryo, cytoplasm and nucleic acid fragmentation may be a cause of lower embryo development. The purpose of this study was to evaluate whether embryonic development and apoptosis factors can be reduced by controlling the in-vitro culture environment by the addition of hormones, pregnancy serum and uterine milk. Our study showed that the activity of Casp-3 increased within the cytoplasm when artificially used hormones to induce the incubation environment, and PCNA's manifestation was low. However, the addition of pregnant serum appeared to lower the Casp-3 activity compared to the other groups. In addition, MMP-9 activity was increased and early embryo development and cytoplasmic fidelity were also increased. Therefore, the results of the present study showed that the use of gestational serum in the development of parthenogenetic embryo inhibit apoptosis and increases cytoplasmic reorganization by natural environmental control in in vitro culture.

• Reproductive and Developmental Biology
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• v.36 no.4
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• pp.237-241
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• 2012

Embryonic genome activation (EGA) is the first major transition that occurs after fertilization, and entails a dramatic reprogramming of gene expression that is essential for continued development. Although it has been suggested that EGA in porcine embryos starts at the four-cell stage, recent evidence indicates that EGA may commence even earlier; however, the molecular details of EGA remain incompletely understood. The RNA polymerase II of eukaryotes transcribes mRNAs and most small nuclear RNAs. The largest subunit of RNA polymerase II can become phosphorylated in the C-terminal domain. The unphosphorylated form of the RNA polymerase II largest subunit C-terminal domain (IIa) plays a role in initiation of transcription, and the phosphorylated form (IIo) is required for transcriptional elongation and mRNA splicing. In the present study, we explored the nuclear translocation, nuclear localization, and phosphorylation dynamics of the RNA polymerase II C-terminal domain in immature pig oocytes, mature oocytes, two-, four-, and eight-cell embryos, and the morula and blastocyst. To this end, we used antibodies specific for the IIa and IIo forms of RNA polymerase II to stain the proteins. Unphosphorylated RNA polymerase II stained strongly in the nuclei of germinal vesicle oocytes, whereas the phosphorylated form of the enzyme was confined to the chromatin of prophase I oocytes. After fertilization, both unphosphorylated and phosphorylated RNA polymerase II began to accumulate in the nuclei of early stage one-cell embryos, and this pattern was maintained through to the blastocyst stage. The results suggest that both porcine oocytes and early embryos are transcriptionally competent, and that transcription of embryonic genes during the first three cell cycles parallels expression of phosphorylated RNA polymerase II.

• Journal of Animal Reproduction and Biotechnology
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• v.39 no.2
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• pp.131-137
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• 2024

Background: Porcine embryonic development is widely utilized in the medical industry. However, the blastocyst development rate in vitro is lower compared to in vivo. To address this issue, various supplements are employed. Extracellular vesicles (EVs) play the role of communicators that carry many bioactive cargoes. Additionally, the contents of EVs can vary on the estrous cycle. Methods: We compared the effects of adding EVs derived from porcine uterine fluid (UF), categorized as non-EV (G1), EVs in estrus (G2) and EVs in diestrus (G3). After in vitro culture (IVC) was performed in three different groups, cleavage rate and blastocyst development rate were examined. In addition, glutathione (GSH) and reactive oxygen species (ROS) levels were measured 2 days after activation to assess oxidative stress. Results: Using NTA and cryo-TEM, we confirmed the presence of EVs with sizes ranging from 30 nm to 200 nm, that the particles were suitable for analysis for analysis. In IVC data, the highest cleavage rate was observed in G2, which was significantly different from G1 but not significantly different from the next highest, G3. Similarly, the highest blastocyst development rate was observed in G2, which was significantly different from G1 but not significantly different from the next highest, G3. Conclusions: These results indicate that estrus derived EVs contain biofactors beneficial for early blastocyst development, including GSH which protects the blastocyst from oxidative stress. Additionally, although diestrus-derived EVs are expected to have some effect on blastocyst development, it appeared to be less effective than estrus-derived EVs.