• Animal Bioscience
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• v.36 no.8
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• pp.1180-1189
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• 2023

Objective: Discovering the mechanism of cell specification is important to manipulate cellular lineages. To obtain lineage-specific cell lines, the target lineage needs to be promoted, and counterpart lineages should be suppressed. Embryos in the early blastocyst stage possess two different cell populations, the inner cell mass (ICM) and trophectoderm. Then, cells in the ICM segregate into epiblasts (Epi) and primitive endoderm (PrE). PrE cells in embryos show specific expression of platelet-derived growth factor (PDGF) and its receptor, PDGF receptor A (PDGFRA). In this study, we suppressed PDGF signaling using two methods (CRISPR/Cas9 injection and inhibitor treatment) to provide insight into the segregation of embryonic lineages. Methods: CRISPR/Cas9 RNAs were injected into parthenogenetically activated and in vitro fertilized embryos. The PDGF receptor inhibitor AG1296 was treated at 0, 5, 10, and 20 µM concentration. The developmental competence of the embryos and the number of cells expressing marker proteins (SOX2 for ICM and SOX17 for PrE) were measured after the treatments. The expression levels of the marker genes with the inhibitor were examined during embryo development. Results: Microinjection targeting the PDGF receptor (PDGFR) A reduced the number of SOX17-positive cell populations in a subset of day 7 blastocysts (n = 9/12). However, microinjection accompanied diminution of Epi cells in the blastocyst. The PDGF receptor inhibitor AG1296 (5 µM) suppressed SOX17-positive cells without reducing SOX2-positive cells in both parthenogenetic activated and in vitro fertilized embryos. Within the transcriptional target of PDGF signaling, the inhibitor significantly upregulated the Txnip gene in embryos. Conclusion: We identified that PDGF signaling is important to sustain the PrE population in porcine blastocysts. Additionally, treatment with inhibitors was a better method to suppress PrE cells than CRISPR/Cas9 microinjection of anti-PDGF receptor α gene, because microinjection suppressed number of Epi cells. The PDGF receptor might control the number of PrE cells by repressing the proapoptotic gene Txnip. Our results can help to isolate Epi-specific cell lines from blastocysts.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.5
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• pp.711-717
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• 2007

In this study, two cell types from porcine females, namely fetal fibroblasts (pFFs) and adult ear fibroblasts (pAEFs) and two passages (3-4 and 7-8) were investigated by evaluating the development rate, blastocyst cell number and the incidence of apoptosis. No significant differences were observed in the cleavage rates of cloned and IVF embryos. The blastocyst rates between the embryos cloned with pFFs ($15.1{\pm}3.2$) and pAEFs ($10.4{\pm}2.6$) did not differ significantly but was significantly (p<0.05) lower in pAEFs than that in IVF ($22.5{\pm}4.5$) embryos. Total cell number in pFFs ($28.4{\pm}4.3$) and pAEFs cloned blastocysts ($24.2{\pm}5.1$) was significantly (p<0.05) lesser than IVF control ($35.4{\pm}3.2$). Apoptosis rates between cloned blastocysts differed significantly (p<0.05) and were significantly (p<0.05) higher than IVF embryos. The blastocyst rates between the cloned embryos cloned with different cell passages did not differ significantly but in embryos cloned with 7-8 cell passage was significantly (p<0.05) lower than the IVF control. Apoptosis signals were detected in IVF and cloned embryos as early as day 3 and the rates of apoptosis increased concurrently with the embryo development. In conclusion, high apoptosis during in vitro preimplantation development resulted in low development rate and total cell number of cloned embryos. Moreover, based on the apoptotic incidence in cloned blastocysts, fetal fibroblasts are more suitable for production of cloned embryos in porcine.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.11
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• pp.1665-1672
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• 2008

Interspecies somatic cell nuclear transfer (iSCNT) is a useful method to preserve endangered species and to study the reprogramming event of a nuclear donor cell by the oocyte. Although several studies of iSCNT using murine cells and bovine oocytes have been reported, the development of murine-bovine iSCNT embryos beyond the 8-cell stage has not been successful. In this paper, we examined the developmental potential of embryos reconstructed with a murine embryonic fibroblast as the nuclear donor and a bovine oocyte as the cytoplasm recipient. The reconstructed embryos were cultured in CZB (murine medium) or CR1aa (bovine medium). In addition, for the development of a murine-bovine iSCNT blastocyst, the antioxidant ${\beta}$-mercaptoethanol (${\beta}ME$) was supplemented to CR1aa medium. Furthermore, to verify the mouse genome activation in murine-bovine iSCNT embryos, RT-PCR analysis of murine Xist was performed. The development of the murine-bovine iSCNT embryos cultured in CR1aa was significantly higher than that in CZB (p<0.05). With respect to the effect of BME on the development of the murine-bovine iSCNT blastocyst, addition of BME produced a significant increase in blastocyst development (p<0.05). Karyotype analysis confirmed that the reconstructed embryos were derived from murine cells (40XX). The Xist gene was gradually increased from the 8-cell stage to the blastocyst stage. This is the first report of blastocyst development of iSCNT embryos derived from murine somatic cells and bovine oocytes. These results demonstrate that bovine cytoplasm can support the development of later stages of a preimplantation embryo from murine-bovine iSCNT.

• Clinical and Experimental Reproductive Medicine
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• v.23 no.1
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• pp.25-32
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• 1996

This work has been carried out to examine the number of Total, ICM and TE cells of F1 mouse blastcysts at day 4 after IVF by differential labelling of the nuclei with polynucleotide-specific fluorochromes and to obtain a fundamental information of preimplantation mouse embryo development. Blastocysts produced by superovulated B6CBA F1(C57BL/${\times}$CBA) eggs were inseminated with $1{\times}10^6$spermatozoa/ml and cultured in M16 medium at $37^{\circ}C$, 5% $CO_2$ incubator for 95hrs. Blastocysts were classified as early, middle, expanded and hatching stage according to the developmental morphology; blastocoel expansion and zona thickness. The results obtained in these experiments were summarized as follows; 1) The development rate of blastocysts at 95hrs after IVF was 86.7% and classified blastocysts to early, middle, expanded and hatching were 16.3%, 18.9%, 10.5% and 40.9%, respectively. 2) The numbers of total blastomere using bisbenzimide in the classified blastocysts to early, middle, expanded and hatching were 35.6${\pm}$1O.4, 49.4${\pm}$8.6, 60.8${\pm}$1O.7 and 62.7${\pm}$13.9, respectively. 3) In ICM and TE cell number by using differential labelling with polynucleotide-specific fluorochrome in the classified blastocysts to early, middle, expanded and hatching; ICM numbers were 9.6${\pm}$3.0, 13.6${\pm}$3.9, 16.0${\pm}$3.3 and 19.5${\pm}$4.6, respectively and TE cell numbers were 30.6${\pm}$5.1, 39.9${\pm}$5.8, 42.2${\pm}$8.1 and 43.7${\pm}$11.1, respectively. These results showed the same increase pattern according to development advance level. Also, when compared with the results of total count were obtained between bisbenzimide only and differential labelling, both of them showed the same increase pattern according to development level and at the same time their cell numbers were almost the same. So, rapid and simple cell count method using differential labelling can be used for the examination of later preimplantation development or as an indicator of embryo quality according to the variables of culture conditions.

• Clinical and Experimental Reproductive Medicine
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• v.11 no.2
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• pp.51-57
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• 1984

The success of human in vitro fertilization (IVF) & embryo transfer (ET) has focused attention on the culture conditions that can provide optimal development of the preimplantation embryo. Studies of in vitro fertilization using mouse have direct implications to human IVF, since similar conditions are used for both species. Mouse IVF as a quality control system for human IVF & ET was studied since Feb., 1984. The results were as follows: 1. Egg retrieval following superovulation in IeR mice was l5.1${\pm}$5.3 eggs ovulated/mouse (Mean${\pm}$ S.D.) 2. In vitro cleavage rate was 61.7% (1146 eggs cleaved/l858 eggs inseminated) and % blastocyst was 42.6%. 3. In comparison with two media of Ham's F-10 and m-KRB, in vitro cleavage rate were 40.9%/63.l% and %blastocyst were 44.3%/61.2% (P<0.05). 4. It was concluded that mouse IVF system has a valuable place in human IVF & ET as a quality-control system and in human reproductive physiology as a research model.

• Korean Journal of Animal Reproduction
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• v.20 no.2
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• pp.89-99
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• 1996

The purpose of this study was to develop the diagnosis techniques for sex determination of rabbit embryos at preimplantation stage. To detect male specific sequences using polymerase chain reaction, two genes functional on sex determination including SRY and ZFX/Y genes were targeted using multiple oligonucleotide primer sets. Three of them for conserved SRY gene were used for appropriate amplification pattern, and then only one primer set #3 proved to be most efficient, showing male-specific strong signal ofamplified sequences. Using this male specific bandsfrom human, cattle, pig and mouse, the gender of rabbit was determined. As an another system for sex determination system, amplified 910bp fragment from ZFX/Y was digested with several restriction endonuclease and showed gender specific restriction fragments only by Hinf I. Using two different system for sex identification of rabbit in this study, blind tests for 17 samples was conducted and showed identical results from two different methods. And then, amplification limit of PCR reaction for template DNA was estimated using various amounts of DNA for both SRY and ZFX/Y systems, resulted as 20pg and 800pg, respectively. With this results, test for gender identification of rabbit embryos were performed using SRY derived amplification system. From total 22 embryos selected for its developmental state 18 were identified as male embryos, showing significant difference from expected sex ratio 1:1. This biased sex ratio was interpreted as to have been caused by the fact, reported by the fact, reported by several researchers, that male embryos develop more rapidly and are more resistant against the in vitro manipulation than female embryos.

• Reproductive and Developmental Biology
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• v.33 no.2
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• pp.93-98
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• 2009

In this study, bovine Dnmt1 cDNA was sequenced and detected Dnmt1 mRNA level in bovine tissues by northern blot, methylation pattern of genome by southern blot, specific localization of Dnmt1 in mouse and bovine preimplantation embryos by immunocytostaining and Dnmt1 protein level in ovary and testis by western blot. Bovine Dnmt1 cDNA sequence showed more homology with that of human than mouse and rat. The RNA level of Dnmt1 was 10 times higher expression in placenta than other tissues. This indicates that placenta was hypermethylated compared to others organs. The genomic DNA could not be cut by a specific restriction enzyme (HpaII) in placenta, lung and liver of bovine. It suggests that Dnmt1 in some somatic cells was already methylated. Dnmt1, which has the antibody epitope 1316~1616, was distributed in nucleus and cytoplasm including the stage of pronuclear stage and maturation of oocyte and gradually weaken to blastocyst stage compare to negative. In addition, Dnmt1 was strongly expressed in tetraploid embryo and cloned 8-cell than IVF 8-cell. An aberrant pattern of DNA methylation in cloned embryo may be abnormal development of fetus, embryonic lethality and placenta dysfunction. The somatic specific band (190kDa) was appeared in ovary and testis, but oocyte specific band (175kDa) was not. Further investigations are necessary to understand the complex links between the methyltransferases and the transcriptional activity of genes in the cloned bovine tissues.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.22-22
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• 2003

This study was conducted to determine effects of polyvinyl alcohol (PVA), fetal bovine serum (FBS) and bovine serum albumin (BSA) on blastocoel formation, cell number, apoptosis and apoptosis-related gene expression of porcine diploid parthenotes developing in vitro. Embryos were collected from 2-cell or late 4-cell diploid parthenotes that activated with electro pulse, and in vitro cultured in the NCSU 23 medium supplemented without or with 0.1% PVA, 10% FBS or 0.4% BSA for day 7. The morphological analysis of apoptosis in embryos was carried out using propidium iodide staining and terminal deoxynucleotidyl transferase mediated dUTP nick end labeling. The expressions of Bcl-xL, Bak and P53 in blastocyst stage parthenotes and in vivo-derived blastocysts were determined using semiquantitative RT-PCR. The addition of 0.4% BSA to the culture medium enhanced the development of 2- or late 4-cell stage parthenotes to the blastocysts stage (P < 0.01) while FBS decreased the incidence of blastocoel formation. FBS also reduced cell numbers of blastocysts developed from both 2- (P < 0.001) and late 4-cell (P < 0.05) embryos and increased percentage of apoptosis in the blastocysts (P < 0.001). The relative abundance of Bcl-xL mRNA in diploid parthenotes cultured from 2-cell stage in the presence of BSA is similar with that in in vivo derived embryos, but is significantly higher than in parthenotes cultured with FBS, PVA or none protein supplement control. Bak mRNA showed a significant increase at the blastocyst stage in FBS supplement medium. This result suggests that apoptosis related gene expression is significantly affected by protein supplements, which may result in alteration of apoptosis and embryo viability of porcine embryos developing in vitro.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.12
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• pp.1680-1688
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• 2013

Many different approaches have been developed to improve the efficiency of animal cloning by somatic cell nuclear transfer (SCNT), one of which is to modify histone acetylation levels using histone deacetylase inhibitors (HDACi) such as trichostatin A (TSA). In the present study, we examined the effect of TSA on in vitro development of porcine embryos derived from SCNT. We found that TSA treatment (50 nM) for 24 h following oocyte activation improved blastocyst formation rates (to 22.0%) compared with 8.9% in the non-treatment group and total cell number of the blastocysts for determining embryo quality also increased significantly ($88.9{\rightarrow}114.4$). Changes in histone acetylation levels as a result of TSA treatment were examined using indirect immunofluorescence and confocal microscopy scanning. Results showed that the histone acetylation level in TSA-treated embryos was higher than that in controls at both acetylated histone H3 lysine 9 (AcH3K9) and acetylated histone H4 lysine 12 (AcH4K12). Next, we compared the expression patterns of seven genes (OCT4, ID1; the pluripotent genes, H19, NNAT, PEG1; the imprinting genes, cytokeratin 8 and 18; the trophoblast marker genes). The SCNT blastocysts both with and without TSA treatment showed lower levels of OCT4, ID1, cytokeratin 8 and 18 than those of the in vivo blastocysts. In the case of the imprinting genes H19 and NNAT, except PEG1, the SCNT blastocysts both with and without TSA treatment showed higher levels than those of the in vivo blastocysts. Although the gene expression patterns between cloned blastocysts and their in vivo counterparts were different regardless of TSA treatment, it appears that several genes in NT blastocysts after TSA treatment showed a slight tendency toward expression patterns of in vivo blastocysts. Our results suggest that TSA treatment may improve preimplantation porcine embryo development following SCNT.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.109-109
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• 2003

Even though success in birth of live offspring from nuclear transfer(NT) using somatic cells in many species, detailed information on processes or mechanisms of development are not well known. Cytoplasm of bovine oocyte has been known to support the development of nuclear transferred embryos using nuclear donor cells from different species. Therefore, interspecies NT might be used to find answers of some questions in basic aspect of nuclear transfer In this study, we examined the developmental potential of reconstructed embryos when bovine oocyte as a cytoplasm recipient and mouse embryonic fibroblast as a nuclear donor were used. The nuclear transfer units were aliocated in Group 1 (murine block media and normal media) and Group 2. (bovine block media and normal media). NT units were not blocked at 2-cell stage regardless of types of medium. On mouse media, poor development of interspecies NT units was observed compared to bovine media. However, as NT units cultured in bovine normal medium, embryos developed over 8-cell stage. Further studies performed to increase the developmental rate in condition of antioxidant treatment. Despite low development, bovine-murine interspecies nuclear transferred embryos could develop to blastocysts and they showed that blastocyts rate of antioxidant group was superior to those of non-antioxidant group. Next, we investigated gene expression pattern which is carried out for zygotic activation. The Xist gene is expressed in female mouse embryo after zygotic activation of 4-cell stage. But interspecies nuclear transferred embryos do not express Xist gene at 4-cell stage. As a result, it is suggested that the bovine cytoplasm controls the early preimplantation development in interspecies NT However, the development of later stages might require genomic control from transferred donor nucleus. Therefore, even though the involvement of several other factors such as mitochondrial incompatibility, effective development of embryos produced by interspecies NT requires proper genomic activation of donor nucleus after overcoming the cytoplasmic control of recipient oocytes.