• 대한생식의학회:학술대회논문집
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• 2002.05a
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• pp.11-17
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• 2002

Animal clones derived from somatic cells have been successfully produced in a variety of mammalian species such as sheep, cattle, mice, goats, pigs, cat and rabbits. However, there are still many unsolved problems in the present cloning technology. Somatic cell nuclear transfer has shown several developmental aberrancies including high rate of abortion in early gestation and increased perinatal death. These developmental failures of cloned embryos may arise from abnormal reprogramming of donor genome and/or incomplete cloning procedure. We have found that overall genomic methylation status of cloned bovine embryos is quite different from that of normal embryos in various genomic regions, suggesting that the developmental failures of cloned embryos may be due to incomplete reprogramming of donor genomic DNA. Many of the advances in understanding the molecular events for reprogramming of donor genome will more clarify the developmental defects of cloned embryos.

• Korean Journal of Veterinary Research
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• v.55 no.4
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• pp.253-257
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• 2015

Oregano (Origanum vulgare) is an aromatic herb belonging to the Lamiaceae family. This study evaluated the therapeutic effect of oregano essential oil (OEO) on clinical bovine mastitis caused by Staphylococcus (S.) aureus and/or Escherichia (E.) coli. Thirty-two quarters from 18 lactating cows with subclinical mastitis were selected from a dairy farm and were divided into 4 groups (8 quarters/group): negative control (CON), positive control (GEN) and two OEO-treated groups (OEO-1 and OEO-2). Each group was intramammarily treated with saline, 10 g/tube of gentamicin ointment, and single and double doses of 0.9 mL OEO ointment twice a day for three days, respectively. After the treatments, physical udder conditions were greatly improved in GEN and OEO groups. In CON group, somatic cell counts (SCCs), number of white blood cells (WBC) and bacteria were increased. However, in OEO groups, SCCs and number of WBC were significantly decreased and S. aureus and E. coli were not detected in milk as compared with those before the treatments as well as GEN group. These results suggest that OEO may be a useful alternative to antibiotics for the control of subclinical bovine mastitis caused by S. aureus and/or E. coli.

• Reproductive and Developmental Biology
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• v.34 no.4
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• pp.283-288
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• 2010

During normal early embryonic development in mammals, the global pattern of genomic DNA methylation undergoes marked. changes. The level of methylation is high in male and female gametes. Thus, we cloned the cDNA of the porcine DNA methyltransferase 1 (Dnmt1) gene to promote the efficiency of the generation of porcine clones. In this study, porcine Dnmt1 cDNA was sequenced, and Dnmt1 mRNA expression was detected by reverse transcription-polymerase reaction (RT-PCR) in porcine tissues during embryonic development. The porcine Dnmt1 cDNA sequence showed more homology with that of bovine than human, mouse, and rat. The complete sequence of porcine Dnmt1 cDNA was 4,774-bp long and consisted of an open reading frame encoding a protein of 1611 amino acids. The amino acid sequence of porcine DNMT1 showed significant homology with those of bovine (91%), human (88%), rat (76%), and mouse (75%) Dnmt1. The expression of porcine Dnmt1 mRNA was detected during porcine embryogenesis. The mRNA was detected at stages of porcine preimplantation development (1-cell, 2-cell, 4-cell, 8-cell, morula, and blastocyst stages). It was also abundantly expressed in tissues (lung, ovary, kidney and somatic cells). Further investigations are necessary to understand the complex links between methyltransferase 1 and the transcriptional activity in cloned porcine tissues.

• Journal of Embryo Transfer
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• v.10 no.2
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• pp.121-129
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• 1995

To examine the critical effect of oxygen concentration on embryonic development, in vitro fertilized embryos were cultured in media(TCM199 vs. SOF) supplemented sera(1O% FCS vs. 10% HS) with and without bovine oviduct epithelial cells under two gas atmosphere (5% $CO_2$ in air vs. 5% $CO_2$, 5% $O_2$, 90% $N_2$). Oocytes, obtained from abattoir ovaries, were matured in EGF containing TCM199 medium co-cultured with BOEC for 24 hours, followed by exposure to frozen-thawed, heparin4reated spermatozoa in TALP for 30 hours. And then early embryos(1~2 cell) were cultured in both TCM199 and SOF supplemented with 10% FCS or 10% RS under 5% $CO_2$ in air or 5% COi, 5% $O_2$, 90% $N_2$. Development to morulae and blastocysts was recorded on days 7, after the start of in vitro fertilization. The developmental rates of in vitro fertilized embryos to morulae and blastocysts cultured in SOF with BOEC under 5% $CO_2$, 5% $O_2$, 90% $N_2$(24.4%) were significantly(p<0.05) higher than cultured in SOF with BOEC under 5% $CO_2$ in air(14.1%) at seven days after in vitro fertilization. When early bovine embryos were cultured in TCM 199 and SOF under two different gas atmosphere, there were no significant differences in the developmental rates to morulae and blastocysts between supplements of 10% FCS and 10% HS. The rates of development to morulae and blastocysts were significantly(p<0.01) higher in TCM 199 with BOEC(24.7%) than TCM199 without BOEC(10.9%) under 5% $CO_2$ in air, otherwise SOF without BOEC(36.4%) were significantly (p<0.05) higher than in SOF with BOEC (24.4%) under 5% $CO_2$, 5% $O_2$, 90% $N_2$. In summary, these experiments have proved that the culture system in SOF supplemented 10% ES is effective on in vitro development of early bovine embryos under 5% $CO_2$, 5% $O_2$, 90% $N_2$. In addition, it is effective to development of bovine embryos that TCM 199 should be co-cultured with BOEC and SOF should be cultured without somatic cells under two different gas atmosphere.

• Reproductive and Developmental Biology
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• v.41 no.1
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• pp.7-16
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• 2017

The knock-in efficiency in the fibroblast is very important to produce transgenic domestic animal using nuclear transfer. In this research, we constructed three kinds of different knock-in vectors to study the efficiency of knock-in depending on structure of knock-in vector with different size of homologous arm on the ${\beta}-casein$ gene locus in the somatic cells; DT-A_cEndo Knock-in vector, DT-A_tEndo Knock-in vector I, and DT-A_tEndo Knock-in vector II. The knock-in vector consists of 4.8 kb or 1.06 kb of 5' arm region and 1.8 kb or 0.64 kb of 3' arm region, and neomycin resistance gene(neor) as a positive selection marker gene. The cEndo Knock-in vector had 4.8 kb and 1.8 kb homologous arm. The tEndo Knock-in vector I had 1.06 kb and 0.64 kb homologous arm and tEndo Knock-in vector II had 1.06 kb and 1.8 kb homologous arm. To express endostatin gene as transgene, the F2A sequence was fused to the 5' terminal of endostatin gene and inserted into exon 7 of the ${\beta}-casein$ gene. The knock-in vector and TALEN were introduced into the bovine fibroblast by electroporation. The knock-in efficiencies of cEndo, tEndo I, and tEndo II vector were 4.6%, 2.2% and 4.8%, respectively. These results indicated that size of 3' arm in the knock-in vector is important for TALEN-mediated homologous recombination in the fibroblast. In conclusion, our knock-in system may help to create transgenic dairy cattle expressing human endostatin protein via the endogenous expression system of the bovine ${\beta}-casein$ gene in the mammary gland.

• Korean Journal of Animal Reproduction
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• v.26 no.3
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• pp.245-252
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• 2002

This study was to evaluate the in vitro survival of bovine enucleated MII (eMII) oocytes according to minimum volume cooling (MVC) freezing method and activation timing, and their in vitro development after somatic cell nuclear transfer (SONT). in vitro matured bovine oocytes for 20 h were stained with 5 $\mu\textrm{g}$/$m\ell$ Hoechst, and their 1st polar body and MII plate were removed by enucleation micropipette under UV filter. Also, eMII oocytes were subjected to activation after (group II) and before (group III) vitrification in 5 ${\mu}{\textrm}{m}$ ionomycin added CRlaa medium for 5 min. For vitrification, eMll oocytes were pretreated with EG10 for 5 min, exposed to EG30 for 30 sec and then directly plunged into L$N_2$. Thawing was taken by 4-step procedures at 37$^{\circ}C$. Survived eMII oocytes were subjected to SONT with cultured adult bovine ear cells. Reconstructed oocytes were cultured in 10 $\mu\textrm{g}$/$m\ell$ of cycloheximide and 2.5 $\mu\textrm{g}$/$m\ell$ of cytochalasin D added CRlaa medium for 1 h, and then in 10 $\mu\textrm{g}$/$m\ell$ of cycloheximide added CRlaa medium for 4 h. Subsequently, the reconstructed oocytes were incubated for 2 days and cleaved embryos were further cultured on cumulus-cell monolayer drop in CRlaa medium for 6 days. Survival rates of bovine vitrified-thawed eMII oocytes in group II (activation after vitrification and thawing) and III (activation before vitrification) were 81.0% and 84.9%, respectively. Fusion rates of cytoplasts and oocytes in group II and III were 69.0% and 70.0%, respectively, and their results were not different with non-frozen NT group (control, 75.2%). Although their cleaved rates (53.4% and 58.4%) were not different, cytoplasmic fragment rate in group II (32.8%) was significantly higher than that in group III (15.6%)(P<0.05). Also, subsequent development rate into >morula in group II (8.6%) was low than that in group III(15.6%). However, in vitro development rate in group III was not different with that in control (24.8%). This result suggested that MVC method was appropriate freezing method for the bovine eMII oocytes and vitrified eMII oocytes after pre-activation could support in vitro embryonic development after SONT as equally well as fresh oocytes.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.86-86
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• 2003

Research has been in progress for more than a decade to production of useful proteins by genetic modification in cattle. However, the levels of protein production in transgenic cattle have been reported very low. To enhance protein production in transgenic animal, we tried homologous recombination to donor cells for production of transgenic clone cattle through nuclear transfer procedure. Thus, we constructed the two targeting vectors of human thrombopoietin (TPO) at bovine $\beta$-casein locus using homologous recombination with 13.6 kb and 9.6 kb homology. In two targeting vectors, positive selection was through the neomycin resistance gene and negative selection was by the diphtheria toxin (DT). Gene targeting was attempted in bovine embryonic fibroblasts (bEF) and bovine ear skin fibroblasts (bESF). To determine the most appropriate concentration of neomycin for bEF and bESF, G4l8 resistance was confirmed by culturing the cells in various concentrations of the drug and both of the cells were optimally selected at $900 \mu g/ml$ of neomycin. The transfected bEF and bESF by the targeting vectors were colonized efficiently at the ratio of DNA to transfection reagent such as $4 \mu g$:2 ${mu}ell$ and $1 \mu g$:$2 \mu l$. Comparing number of healthy clones from passage 4 to passage 8, bESF (17%) persist in culture for much longer than bEF (6%). The two gene-targeted bESF clones of 30 random-integrated clones with 9.6 kb homology length were confirmed, however, nothing was out of 72 random integration clones with 13.6 kb homology length, The DT also worked more efficiently in clones transfected with the vector of 9.6 kb homology length. Our data suggests that the choice of donor cell for long culture period should be considered to obtain targeted cell clone, and the gene-targeting frequency and the DT working efficiency are dependent on the length of target homology.

• Proceedings of the KSAR Conference
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• 2002.06a
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• pp.40-40
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• 2002

Nuclear transfer (NT) has the potential to produce large number of identical progeny and would greatly benefit ongoing research efforts, Cloned animals produced by NT, however, may not be genetically identical to the donor cell. In NT procedures, nucleus genes originate from donor cell, and mitochondrial genes originate from recipient oocytes. (omitted)

• Journal of Embryo Transfer
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• v.29 no.4
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• pp.351-359
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• 2014

Phasianus colchicus is not only a beautiful bird but also a great value in science and under the threat of endanger. Hence, the aim of this study was to isolate the pheasant male germ cells (mGCs) and then induce them into elongated sperm-like cells in vitro. The mGCs were purified and enriched by a two-step plating method based on the different adherence velocities of mGCs and somatic cells. The percentage of the c-kit positive cells and c-kit negative cells examined by flow cytometry analysis (FCA) was 92.87% and 2.57%, respectively. Subsequently, the mGCs were induced for 48h in DMEM/F12 medium supplemented factors such as retinol acid, testosterone and bovine FSH, followed by 5 weeks in culture. We found that some elongated sperm-like cells appeared initially in vitro under inducement of stimulated factors. The elongated sperm-like cells showed in the expression of changed morphology and post-transcriptional marker such as spermatid associated (SPERT), spermatid perinuclear RNA binding protein (STRBP), round spermatid basic protein 1 (RSBN1) and SPER1L. Moreover, in DNA content identified assay, induced cells showed that the 1C DNA population markedly increased in differentiated group but it was not change in undifferentiated group. Successful in vitro differentiation of pheasant testicular germline cells into spermatids appears to offer extremely attractive potential for the conservation of endangered birds and treatment of male infertility.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2004.10a
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• pp.26-31
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• 2004

This work was undertaken in order to study the developmental competence of nuclear transfer cat embryo with fetal fibroblast and adult skin fibroblast as donor nuclei. Oocytes wererecovered by mincing the ovaries in Hepes-buffered TCM199 and selected the cumulus oocyte complexes (COCs) with compact cumulus cell mass and dark. Homogenous ooplasm were cultured for maturation in TCM199 + 10% fetal bovine serum (FBS) for 12 hours and used as a source of recipient cytoplast for exogenous somatic nuclei. In Experiment 1, we evaluated the effect donor cell types on the reconstruction and development of cloned embryos. Fusion, first cleavage and blastocyst developmental rate was not different between fetal fibroblast and adult skin cell (71.2 vs. 66.8; 71.0 vs. 57.6; 4.0 vs. 6.1 %, P<0.05). In Experiment 2, cloned embryos were surgically transferred into the oviducts of recipient queens. One of seven recipient queens was delivered naturally 2healthy cloned cats and 1 stillborn from fetal fibroblast cell of male origin after 65 days embryo transfer. One of three recipient queens was delivered naturally 1 healthy cloned cat from adult skin cell of female after 65 days embryo transfer. The cloned cats showed genotypes identical to the donor cell lines, indicating that adult somatic cells can be used for feline cloning.