• Journal of Embryo Transfer
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• v.12 no.1
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• pp.21-27
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• 1997

The studies were carried out to investigate the effects of bisection method and with and without-zona pellucida of embryos on in vitro developmental rate bisected embryos by micromanipulator, micropipette and pipetting. The ovaries were obtained from slaughtered Korean native cows. The follicular oocytes were cultured in TCM-199 mediurn containing 10 IU /ml의 PMSG(Sigma, USA), 10 IU /ml의 hCG, 1$\mu$g /ml의 $\beta$-estradiol(Sigma, USA) and 10% FCS for 24~48 hrs in incubator with 5% $CO_2$ in air at 38.5$^{\circ}C$ and then, matured oocytes were again cultured for 12~ 18 hrs with motile capacitated sperm by preincubation of heparin. Bisected embryos cultured for 1~5 days in 20% FCS + TCM-199 medium. Survival rate was defined as developmental rate on in vitro culture or FDA-test. The results are summarized as follows :1. The survival rates of bisected bovine embryos by micromanipulator and micropipett were 29.2% and 19.1%, respectively. The rates of non-bisection embryos(46.7%) were significantly higher than those of bisection embryos. 2. The in vitro developmental rates of bisected bovine embryos by micromanipulator, micropipett and pipetting method were 32.4%, 19.4% and 25.6%, respectively.3. The in vitro developmental rates of with and without-zona pellucida of bisected bovine embryos by raicromanipulator were 30.8% and 25.0%, respectively. The rates of nonbisection embryos(53.1%) were significantly higher than those of bisection embryos.

• Korean Journal of Animal Reproduction
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• v.20 no.3
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• pp.307-313
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• 1996

This study was conducted to investigate the effect of S-phase synthronized nuclear transfer on the development of nuclear transplant bovine embryos. A blastomere derived from the 16~32 cell stage bovine embryos was transferred into an enucleated metaphase II(MII) oocytes or activated S-phase eggs. From the MII-phase and S-phase nuclear transfer, 6.3%(4/63) and 13.8%(9/65) of nuclear transplant embryos developed to the blastocyst stage, respectively. In the S-phase nuclear transfer, maximal proportion of embryos developed to the blastocyst stage(16.6%) was obtained after the recipient cell was activated 8 h prior to receving a donor nucleus. MII-phase nuclear transplant embryos showed the PCC state of their nuclear at 1.5~2 h after fusion, whereas, S-phase nuclear transplant embryos did not undergo PCC. The result of this study suggests that if blastomeres of unknown cell-cycle-stage are used, S-phase nuclear transplantation through the activation of enucleated oocytes prior to fusion enhances development of nuclear transplant embryos. This result also suggests that the interval time from oocyte activation to cell fusion may affect the development of nuclear transplant embryos.

• Journal of Embryo Transfer
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• v.15 no.2
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• pp.157-165
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• 2000

The efficiency of transgenic livestock production could be improved by early screening of transgene-integration and sexing of embryos at preimplantational stages before trasferring them into recipients. We examined the effciency of multiplex PCR analysis for the simultaneous confirmation of the trasgene and sex during the preimplantational development of bovine embryos and the possibility of green fluorescent protein(GFP) gene as a non-invasive marker for the early screening of transgenic embryos. The GFP gene was microinjected into the male pronuclei of bovine zygotes produced in vitro. The injected zygotes were co-cultured in TCM-199 containing 10% FCS with boving oviductal epithelial cells in a 5% CO2 incubator. Seventeen(13.0%) out of 136 gene-injected bovine zygotes developed by multiplex PCR analysis and the expression of GFP was detected by observing green fluorescence in embryos under a fluorescent microscope. Eight(67%) of 12 embryos at 2-cell to blastocyst stage were positive in the PCR analysis, but only two(11.8%) of 17 blastocysts expressed the GFP gene. Their sex was determined as 7 female and 5 male embryos by the PCR analysis. The results indicate that the screening of GFP gene and sex in bovine embryos by PCR analysis and fluorescence detection could be a promisible method for the preselection of transgenic embryos.

• Korean Journal of Animal Reproduction
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• v.20 no.2
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• pp.191-196
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• 1996

The objective of this study were to investigate the effects of culture media and additives on the development of bovine in vitro matured(IVM) and in vitro fertilized(IVF) oocytes. In experiment 1, bovine oocytes were cultured in droplets of TC 199 supplemented with 10% fetal bovine serum(FBS) with or without hormones (5$\mu\textrm{g}$/ml FSH, 5$\mu\textrm{g}$/ml LH, 1$\mu\textrm{g}$/ml E2). Cleavage rates of embryos cultured for 40~44hrs after IVF were higher when embryos were cultured in TC 199 supplemented hormones (68.1%, 921/35) than without hormones (52.7%, 77/146), but the percentages of development beyond morulae stage were not difference (20.7%, 19.4%). In experiment 2, the effects of various media such as TC 199, synthetic oviduct fluid(SOF), CR1aa with different energy source (fatal bovine serum, FBS; bovine serum albumin, BSA) on developmental capacity of IVM/IVF bovine embryos were investigated. The developmental rates into morulae and blastocysts were 27.1, 10.7, 6.3 and 0%, respecitvely, in CR1aa plus 3mg/ml BSA, SOF plus 10% FBS, TC 199 plus 10% FBS, SOF plus 3mg/ml BSA. In experiment 3, the comparisons of bovine embryos developed to morulae and blastocysts in different culture media (TC 199, SOF, CR1aa, Menezo's B2) were investigated. The developmental capacity beyond morulae stage were 32.9, 26.6, 11.1 and 7.1%, respectively, in Menezo's B2 plus BSA, CR1aa plus BSA, SOF plus BSA, TC 199 plus FBS medium. The cell numbers of the blastocyst were not different in different cultrue media. In experiment 4, bovine embryos were co-cultured with vobine oviduct epithelial cells(BOEC) in TC 199 plus FBS, SOF plus BSA, CR1aa plus BSA, Menezo's B2 plus BSA. The morula and blastocyst rates were 44.7, 32.9, 26.0 and 23.3%, respectively, in CR1aa TC 199, SOF, and Menezo's B2 medium. The cell numbers of the blastocyst were similar to those of blastocyst developed in different culture media.

• Korean Journal of Animal Reproduction
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• v.24 no.3
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• pp.299-309
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• 2000

This study was performed 1) to establish the optimal PCR condition of sex determination in Hanwoo IVM/IVF embryos, 2) to examine the sex determination and sex ratio to the developmental stages of Hanwoo IVM/IVF embryos by two-step PCR method. The sexing of bovine IVF embryos were accurately determined by PCR methods using Y chromosome specific DNA primer(BOV 97M, 141bp) and bovine specific DNA primer(216bp). The fregment size were shown at 141 and 216 base pairs(bp) in male, and 216 bp in female. Two-steps PCR method in which the samples were amplified by 15 cycles with Y chromosome specific DNA primer and then amplified by additional 30 cycles with bovine specific DNA primer was effective in the sexing of bovine IVF embryos. The zona-free embryos were more effective than zona-intact embryos in bovine IVF embryo sexing. The appearance of Y chromosome specific band was 45.2% in embryos treated with protease K and 53.3% in embryos treated with freezing and thawing repeatedly. The optimun volume of DNA for sexing of Hanwoo IVF embryos were 2 to 10 $\mu$1 in Zona-free embryos and 12 to 13 $\mu$1 in zona-intact embryos. The sexing rate of bovine IVF embryos by PCR was 96.0% and questionable rate not identified sex was 4.0%, respectively. Among the sexed embryos, the percentage of male and female was 49.7% and 46.3%, respectively, the sex ratio was 1: 1.1. The successful rate of embryo sexing was increased to the developmental stages.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.114-114
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• 2003

Epidermal growth factor (EGF) induces well-documented mitogenic and differentiating effects on murine and bovine preimplantation embryos. However, the effects of EGF on apoptosis and implantation-related gene expression in bovine embryos developing in vitro have not been evaluated. The objective of this study was to determine the effects of exogenous EGF in the presence and absence of BSA on the preimplantation development of bovine embryos. In addition, we measured cell number, apoptosis, and expression of apoptosis and implantation-related genes of the blastocysts that developed in these culture conditions. In vitro produced bovine embryos were randomly cultured in the same medium containing 0 or 10 ng/ml EGF in the presence and absence of 0.8% BSA. More 2-cell embryos developed into blastocysts at day 7 when BSA was present than when BSA was absent. The addition of 10 ng/$m\ell$ EGF into the medium did not significantly increase the developmental rate and the cell numbers per blastocyst. However, addition of EGF in the presence of 0.8% BSA significantly reduced the degree of apoptosis in the blastocysts (P<0.01). To investigate whether EGF modulates mRNA expression of apoptosis-related genes, mRNA was prepared from single blastocysts and each preparation was subjected to RT-PCR for Bcl-2 and Bax transcripts. EGF did not alter the relative abundance of Bax gene expression in the presence of BSA, but increase Bcl-2 (P<0.01) The relative abundance of Interferon tau expression was increased by EGF treatment in the presence of BSA. These results suggest that EGF and BSA synergistically enhance Bcl-2 and interferone tau gene expression, which may result in a net increase in viability in bovine embryos.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.99-99
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• 2003

Epidermal growth factor (EGF) induces well-documented mitegenic and differentiating effects on murine and bovine preimplantation embryos. However, the effects of EGF on apoptosis and implantation-related gene expression in bovine embryos developing in vitro have not been evaluated. The objective of this study was to determine the effects of exogenous EGF in the presence and absence of BSA on the preimplantation development of bovine embryos. In addition, we measured cell number, apoptosis, and expression of apoptosis and implantation-related genes of the blastocysts that developed in these culture conditions. In vitro produced bovine embryos were randomly cultured in the same medium containing 0 or 10 ng/$m\ell$ EGF in the presence and absence of 0.8% BSA. More 2-cell embryos developed into blastocysts at day 7 when BSA was present than when BSA was absent. The addition of 10 ng/$m\ell$ EGF into the medium did not significantly increase the developmental rate and the cell numbers per blastocyst. However, addition of EGF in the presence of 0.8% BSA significantly reduced the degree of apoptosis in the blastocysts (P< 0.01). To investigate whether EGF modulates mRNA expression of apoptosis-related genes, mRNA was prepared from single blastocysts and each preparation was subjected to RT-PCR for Bcl-2 and Bax transcripts. EGF did not alter the relative abundance of Bax gene expression in the presence of BSA, but increase Bcl-2 (P < 0.01). The relative abundance of Interferon tau expression was increased by EGF treatment in the presence of BSA. These results suggest that EGF and BSA synergistically enhance Bcl-2 and interferone tau gene expression, which may result in a net increase in viability in bovine embryos.

• Korean Journal of Veterinary Research
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• v.33 no.1
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• pp.179-188
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• 1993

The developmental capacity of bovine oocytes under three different culture systems was investigated in this experiment ; One was culture in TCM199 with bovine oviductal epithelial cells(BOEC) for in vitro culture, another was culture in TCM199 with BOEC for 2 days and then transfer of 4~8cell embryos to rabbit oviduct(RO) and the other was transfer of 1 or 2cell embryos to RO for in vivo culture. And the other concern of this experiment was to investigate the effect of culture period and transfer site on recovery. Immature bovine oocytes were cultured in TCM199 with granulosa cells for 22-24hrs and then fertilized in vitro using frozen-thawed semen treated with BO-caffine and BO-BSA. Fifteen to 18hrs after in vitro fertilization oocytes were cultured in TCM199 with BOEC or transferred to RO for 5 days. The rate of development to the morula or blastocyst was higher in transfer of 1 or 2cell embryos to RO(23.1%) than culture in TCM199 with BOEC(11.7%). But, there was no difference between transfer of 1 or 2cell embryos and transfer of 4~8cell embryos to RO(12.8%). Recovery under different culture periods in RO was significantly higher in 90~95hrs(70.1%) than 122~125hrs(50.9%, p<0.05) and recovery significantly increased when oocytes were transferred deeper in RO(2.5cm>, 47.7% ; 2.5~4.5cm, 63.9% ; 4.5cm<, 77.3%, p<0.05). The results show that transfer of 1 or 2cell embryos to RO is an effective means of supporting the further development of in vitro matured and fertilized bovine oocytes than culture in TCM199 with BOEC or transfer of 4~8cell embryos to RO, and recovery from RO increases when oocytes are transferred deeper and incubated shorter in RO.

• 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.

• Korean Journal of Animal Reproduction
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• v.15 no.2
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• pp.141-147
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• 1991

This stduy was carried out in order to investigate the effects of cryoprotective concentration and equilibration time on survival rate of ultrarapidly frozen in vitro fertilized bovine embryos. In vitro fertilized bovine embryos, following dehydration by cryoprotective agents and sucorese were directly plunged into liquid nitrogen and thawed in 38$^{\circ}C$ water. Survival rate was defined by development rate to the morula and blaqstocyst stage after in vitro culture of by FDA test. The results are summarized as follows : 1. The survival rates of in vitro fertilized bovine embryos after ultrarapid frozen-thawing in the freezing medium of 0.25M sucroese added 2.0M, 2.5M, 3.0M, 3.5M, 4.0M glycerol were 75.0%, 72.0%, 67.6%, 44.8% and 18.3% respectively. 2. The survival rates of in vitro fertilized bovine embryos after ultrarapid frozen-thawing in the freezing medium of 0.25M sucrose added 2.0M, 2.5M, 3.0M, 3.5M, 4.0M DMSO were 64.0%, 66.7%, 70.8%, 52.7% and 18.6, respectively. 3. The survival rates of in vitro fertilized bovine embryos after ultrarapid frozen-thawing in the freezing medium of 0.25M sucrose added 2.0M, 2.5M, 3.0M, 3.5M, 4.0M propanediol were 68.4%, 64.9%, 63.2%, 62.2% and 34.7%, respectively. 4. The survival rates of in vitro fertilized bovine embryos after ultrarapid frozen-thawing in the freezing medium of 2.50M glycerol added 0.1M, 0.25M, 0.5M, 0.75M, sucrose were 60.5%, 72.2%, 70.1% and 54.9%, respectively. The survival rate of in vitro fertilized embryos after ultrarapid frozen-thawing in the freezing medium of 2.5M glycerol added 0.25M sucrose were higher than concentration of 0.10M, 0.50M and 0.75M sucrose. 5. The equilibration time on the survival rate of in vitro fertilized bovine embryos was attained after short period of time(2.5~5min.) in the freezing medium added 0.25M sucrose and 3.0M DMSO higher than long period time(1~20min.).