• 한국발생생물학회:학술대회논문집
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• 한국발생생물학회 2003년도 제3회 국제심포지움 및 학술대회
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• pp.81-81
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• 2003

DNA methylation is a covalent modification of DNA that can modulate gene expression and is now recognized as a major component of the epigenome. During evolution, the dinucleotide CpG has been progressively eliminated from the genome of higher eukaryotes and is present at only 5% to 10% of its predicted frequency. Approxymately 80% of the remaining CpG sites contain methylated cytosines in most vertebrates and they are distributed in a pattern that is unique in each tissue and is inversely correlated with gene expression. The pattern of methylation is faithfully maintained during cell division by the enzyme Dnmt1, the maintenance DNA methyltransferase, which catalyzes the transfer of a methyl group from S-adenosyl-methionine to the 5'-position of the cytosine ring. We have been identified bovine Dnmt1 cDNA full-length recently (AY173048) Little is known on the functions of Dnmt1 in bovine preimplantation embryos. Thus, we analyzed the specific pattern of Dnmt1 in in vitro derived/nuclear transfer bovine and in vivo derived mouse embryos to monitor the epigenetic reprogramming process. We investigated these process by using indirect immunofluresence with an antibody to Dnmt1. According to other studies, Dnmt1 accumulates in nuclei of early growing oocytes but is sequestered in the cytoplasm of mature oocytes. In 2-cell and 4-cell embryos, Dnmt1 is cytoplasmic, but at the 8-cell stage, it is present only in the nucleus. By the blastocyst stage, Dnmt1o is again found only in the cytoplasm. Thus, nuclear localization of Dnmt1o in preimplantation embryos is limited to the 8-cell stages After implantation, Dnmt1 is localized in the nucleus in mouse. However, we have found different patterns of Dnmt1 nuclear localization. Though we used the common antibody, immune-localization data revealed that Dnmt1 antibody have been detected at the nucleus in 1-cell to blastocyst embryos. Therefore, maybe we think that the functions of Dnmt1 between bovine and mice are different. In order to Identify the mechanisms that regulate DNA methylation in bovine preimplantation embryo, we have plans on using bovine oocyte and somatic specific Dnmt1 antibodies.

• Clinical and Experimental Reproductive Medicine
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• 제27권1호
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• pp.47-57
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• 2000

Objective: The effects of cryopreservation with or without coculture on the in vitro development of blastomere-biopsied 8-cell mouse embryos were investigated. This experimental study was originally designed for the setup of a preclinical mouse model for the preimplantation genetic diagnosis (PGD) in human. Methods: Eight-cell embryos were obtained after in vitro fertilization (IVF) from F1 hybrid mice (C57BL(표현불가)/CBA(표현불가)). Using micromanipulation, one to four blastomeres were aspirated through a hole made in the zona pellucida by zona drilling (ZD) with acid Tyrode's solution (ATS). A slow-freezing and rapid-thawing protocol with 1.5M dimethyl sulfoxide (DMSO) and 0.1M sucrose as cryoprotectant was used for the cryopreservation of blastomere- biopsied 8-cell mouse embryos. After thawing, embryos were cultured for 110 hours in Ham's F-10 supplemented with 0.4% bovine serum albumin (BSA). In the coculture group, embryos were cultured for 110 hours on the monolayer of Vero cells in the same medium. The blastocyst formation was recorded, and the embryos developed beyond blastocyst stage were stained with 10% Giemsa to count the total number of nuclei in each embryo. Results: The survival rate of embryos after cryopreservation was significantly lower in the blastomere-biopsied (7/8, 6/8, 5/8, and 4/8 embryos) groups than in the non-biopsied, zona intact (ZI) group. Without the coculture, the blastocyst formation rate of embryos after cryopreservation was not significantly different among ZI, the zona drilling only (ZD), and the balstomere-biopsied groups, but it was significantly lower than in the non-cryopreserved control group. The mean number of cells in embryos beyond blastocyst stage was significantly higher in the control group ($50.2{\pm}14.0$) than in 6/8 ($26.5{\pm}6.2$), 5/8 ($25.0{\pm}5.5$), and 4/8 ($17.8{\pm}7.8$) groups. With the coculture using Vero cells, the blastocyst formation rate of embryos after cryopreservation was significantly lower in 5/8 and 4/8 groups, compared with the control, 7/8, and 6/8 groups. The mean number of cells in embryos beyond blastocyst stage was also significantly lower in 4/8 group ($25.9{\pm}10.2$), compared with the control ($50.2{\pm}14.0$), 7/8 ($56.0{\pm}22.2$), and 6/8 ($55.3{\pm}25.5$) groups. Conclusion: After cryopreservation, blastomere-biopsied mouse embryos have a significantly impaired developmental competence in vitro, but this detrimental effect might be prevented by the coculture with Vero cells in 8-cell mouse embryos biopsied one or two blastomeres. Biopsy of mouse embryos after ZD with ATS is a safe and highly efficient preclinical model for PGD of human embryos.

• Clinical and Experimental Reproductive Medicine
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• 제51권1호
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• pp.57-62
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• 2024

Objective: The purpose of this study was to use a mouse model to investigate the blastocyst formation rate in vitrified-warmed embryos derived from vitrified-warmed oocytes. Methods: Metaphase II oocytes obtained from BDF1 mice were vitrified and warmed, followed by fertilization with epididymal sperm. On day 3, a total of 176 embryos, at either the eight-cell or the morula stage, were vitrified-warmed (representing group 1). For group 2, 155 embryos at the same developmental stages were not vitrified, but rather were directly cultured until day 5. Finally, group 3 included day-5 blastocysts derived from fresh oocytes, which served as fresh controls. The primary outcome measured was the rate of blastocyst formation per day-3 embryo at the eight-cell or morula stage. Results: The rates of blastocyst formation per day-3 embryo were comparable between groups 1 and 2, at 64.5% and 69.7%, respectively (p>0.05). The formation rates of good-quality blastocysts (expanded, hatching, or hatched) were also similar for groups 1 and 2, at 35.5% and 43.2%, respectively (p>0.05). For the fresh oocytes (group 3), the blastocyst formation rate was 75.5%, which was similar to groups 1 and 2. However, the rate of good-quality blastocyst formation in group 3 was 57.3%, significantly exceeding those of group 1 (p=0.001) and group 2 (p=0.023). Conclusion: Regarding developmental potential to the blastocyst stage, vitrified-warmed day-3 embryos originating from vitrified-warmed oocytes demonstrated comparable results to non-vitrified embryos from similar oocytes. These findings indicate that day-3 embryos derived from vitrified-warmed oocytes can be effectively cryopreserved without incurring cellular damage.

• 한국가축번식학회지
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• 제13권2호
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• pp.113-120
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• 1989

In order to determine the sex of preimplantation embryos prior to transfer in cattle, a series of experiments were carried out using 45 Holstein donor cows to examine the ovarian response on the gonadotropin and PGF2${\alpha}$, and the morphology of fresh embryos or frozen/thawed embryos after deep freezing at -196$^{\circ}C$. The sexing of embryos treated with the medium containing H-Y antiserum(10%, v/v) and FITC anti-mouse IgG(10%, v/v) were analysed by chromosomal analysis, and the sex of the embryos which survived were ascertain after delivering the pups. The results obtained were summarized as follows ; 1. The average number of developed follicle and corpus luteum per cow were 13.5 and 8.1, and the ovalation rate was 60.1%. 2. Of 220-ova recovered, 75(34.1%) were morula and 91(41.4%) were blastocyst, and the morphological normal and abnormal rate of ova recovered were 75.5% and 24.5%, respectively. 3. Of 39 frozen/thawed embryos, the scores of normal morula and blastocyst, after thawing were 79.2%(19/24) and 73.3%(11/15). The average rate of frozen/thawed embryos which appeared morphologically normal post thawing was 76.9%(30/39). 4. The sex ratio was measured using the embryos treated with immunofluorescence assay to examine the relationship between embryo developmental stage, sex ratio of morula stage embryo was 42.2%(19/45) fluorescing and 57.8%(26/45) non-fluorescing, on the other hand, the ratio switched to 46.8%(29/62) fluorescing and 53.2%(33/62) non-fluorescing embryo in blastocyst stage. The sex ratio was also measured between fresh and frozen/thawed embryos, fresh and frozen/thawed treated embryos were indicated 45.8%(38/83) fluorescing, 54.2%(45/83) non-fluorescing and 41.7%(10/24) fluorescing, 58.3%(14/24) non-fluorescing. This trend indicated the approximal sex ratio was 1 : 1. 5. The result of karyotype test showed the successful rate of sexing embryo is fluorescing and non-fluorescing was 21.2%(7/33) and 29.6%(8/27). The female to male ratio within 33 fluorescing was 28.6 : 71.4, and the ratio of 27 non-fluorescing embryos was 87.7 : 12.5. 6. Of the embryo transferred after assignment of H-Y phenotype, five of the fluorescing embryos survived to term, all was males. Whereas six non-fluorescing embryos also survived to term and the sexes of the calves were 1 male 5 female.

• 한국발생생물학회지:발생과생식
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• 제10권2호
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• pp.105-113
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• 2006

세포의 대사과정에서 생성되는 활성산소종(reactive oxygen species : ROS)은 세포의 성숙과 발생 과정을 저해하며, 인간의 생식 수관에서 불임의 원인이 된다. 많은 세포생물학적 연구를 통해 ROS에 대한 세포 내의 보호 기작이 밝혀지고 있다. Activating transcription factor 4(ATF4)는 세포 내에서 산화적 스트레스를 비롯한 여러 스트레스 요인으로부터 세포를 보호하는 기작에 관여하는 중요한 인자로서, 스트레스에 의한 세포 사멸을 유도하는 유전자의 활성화와 관련이 있다고 알려져 있다. 본 연구에서는 착상 전 초기 배아의 발생 단계에서 ROS에 의한 산화적 스트레스가 배아의 발생에 영향을 준다는 보고와 관련하여 생쥐 초기배아에 산화적 스트레스 요인인 $H_2O_2$(hydrogen peroxide)를 처리한 후 ATF4 유전자의 발현 변화를 추적하였으며, ROS 방어에 관여하는 SOD1 유전자와 apoptosis 유전자인 Bax의 발현 양상을 함께 비교하였다. 또한 면역형광염색법을 이용하여 착상전 초기배아의 ATF4 단백질 발현 부위를 조사하였다. $H_2O_2$를 0.1 mM 농도로 처리한 2-세포기 배아에서는 처리 8시간 후인 4-세포기 단계부터 발생율이 감소하기 시작하였으며, 0.5 mM과 1.0 mM 농도에서는 배아의 발생이 진행되지 않았다. RT-PCR결과 SOD1 유전자의 발현은 $H_2O_2$를 처리한 모든 그룹에서 처리 1시간째인 2-세포기 배아단계에서 대조군보다 증가하였으며, ATF4 유전자 역시 2-세포기 배아단계에서 발현이 증가하였다. Bax 유전자도 통일한 시기에 발현이 증가하였다. ATF4 단백질의 배아 세포 내 발현부위는 스트레스 방어 기작이 주로 일어나는 세포질에서 많이 발현이 되었으며 포배기 배아에서는 내세포괴(inner cell mass)부위 보다는 영양외배엽(trophectoderm)에서 발현됨을 확인하였다. 2-세포기 배아에서 ATF4 immunoreactivity는 모든 $H_2O_2$농도 처리군에서 대조군보다 증가하였다. 이상의 결과에서, 착상 전 초기 배아에서 ROS에 의해 ATF4 발현이 유도됨을 확인하였다. 따라서 산화적 스트레스에 대해 배아를 보호하기 위한 방어 기작에 ATF4가 관여하는 것으로 사료되며, 세포 사멸 유전자의 발현과도 밀접한 관련이 있는 것으로 사료된다.

• Clinical and Experimental Reproductive Medicine
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• 제19권1호
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• pp.1-8
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• 1992

A fluorescence microscopy technique using flurescein diacetateCFDA) as a substract has been tested for the evaluation of the viability of early mouse embryos. Embryos were incubated in T6 containing FDA concentrations of 2.5 to $50{\mu}g/ml$ for 1 to 5min. Embryos were then examined by reflected light fluorescence using a KP 490 and 520 barrier filter in a Nicon Diaphot microscopy. The results were as follow. 1. The rate of fluorescein accumulation increased on the concentration on FDA from $2.5{\times}10^{-6}M$ to $20{\times}10^{-6}M$ 2. The rate at which intracellular fluorescein was lost from embryos was depended on the temperature at which are stored. 3. Embryos with 3 min exposure to FDA have the most intensity of fluorescence. 4. Exposure of 2 cell embryos to FDA ($2.5-5{\mu}g/ml$) for 1 min did not alter their ability to delope normally in vitro.

• 한국발생생물학회지:발생과생식
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• 제5권1호
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• pp.17-21
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• 2001

생쥐 초기배아의 체외배양 시 부화에 관련된 단백질 분해효소의 발현 시기와 존재부위를 알아보고 trypsin억제제 benzamidine을 배양액에 첨가하여 부화효소의 역할을 살펴보았다. 부화 효소로 제안되고 있는 trypsin 유사효소의 발현부위를 확인하기 위해 rhodamine이 부착되어 있는 Trypsin subsfrate probe를 이용하여 형광염색하였다. 생쥐 배아의 발생과정에서 trypsin 유사효소의 발현은 후기 상실 배아에서부터 관찰되었으며, 포배기 배아에서는 영양배엽 표면에서 전체적으로 관찰되었다. 특히, 부화가 진행되고 있는 배아의 부화 개시 부위 (blebbing)에서 그 염색 정도가 상대적으로 강함을 확인할 수 있었다. 생쥐 4-세포기 배아의 체외배양 시 배양액에 trypsin 억제제인 benzamidine을 ImM 농도로 첨가하였을 때 포배기로의 발생률은 영향을 받지 않았지만, 부화율은 15.8%로 대조군의 83.0%에 비해 유의하게 (p<0.02) 낮게 나타났다. 배아의 발생단계에 따라 5mM의 benzamidine을 12시간 동안 처리한 경우 부화율이 8.7%로 대조군의 83.0%에 비해 유의하게(p<0.01)낮았다. 결론적으로, trypsin 유사효소는 초기 포배기에서부터 발현되기 시작하며 특히, 후기 포배기에서 그 효소의 작용이 부화 과정에 커다란 영향을 미치는 것이 확인되었다. 또한 배양중 부화 과정에서는 배아 자체에서 분비되는 trypsin 유사효소의 역할만으로도 부화할 수는 있지만 생체 내에서는 배아와 자궁내막 상피와의 상승적 상호 작용에 의해 부화과정이 더 활발히 진행되는 것으로 생각된다.

• 한국가축번식학회지
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• 제24권3호
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• pp.263-268
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• 2000

본 연구는 2-, 4- 또는 8-세포기 생쥐 수정란으로부터 분리된 단일 할구의 발달 및 완만동결 후 생존능력을 조사하기 위하여 실시하였다. 2-, 4-또는 8-세포기 생쥐 수정란에서 각각 223개, 60개, 188개의 할구를 분리하여 96시간 배양하였는데 이중 2-세포기 수정란으로부터 분리된 할구는 111개(49.8%)가 배반포기까지 발육하였으며, 4-세포기와 8-세포기 수정란으로부터 분리된 할구는 각각 12개(20.0%)와 31개(16.5%)가 배반포기까지 발육하였다. 분리된 할구를 완만 동결한 후 융해하여 배양했을 때 배반포기까지의 발육율은 2-세포기 할구는 27.1%(16/50), 4-세포기 할구는 36.4%(4/11) 그리고 8-세포기 할구는 17.6%(3/17)였으며, 융해 후 할구 회수율은 각각 54.2%(65/120), 46.4%(13/28), 24.3%(17/70)을 나타냈다. 2-세포기 할구를 동결 융해한 후 동기화시킨 생쥐 자궁에 이식하여 정상적으로 발달한 태아를 생산하였다. 본 실험의 결과로 완만동결방법이 생쥐의 할구를 동결 보존하는데 이용될 수 있음을 확인하였다.

• Clinical and Experimental Reproductive Medicine
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• 제33권1호
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• pp.25-33
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• 2006

목 적: 본 연구에서는 착상전 생쥐 배아에서 분리한 할구를 이용하여 배아줄기세포주를 확립하고 그 효용성과 특성을 살펴보고자 하였다. 연구방법: 생쥐 (C57BL/6J)의 2- 또는 4-세포기 배아에서 투명대를 제거하고 할구를 분리하여 지지세포와 공동배양한 후 할구로부터 형성된 내세포괴를 분리하여 계대배양을 실시하였다. 계대배양 중인 세포주의 특성을 확인하기 위해 alkaline phosphatase 활성도와 표지 인자 및 관련 유전자 발현을 세포면역화학적 염색과 RT-PCR 방법으로 살펴보았다. 또한, 계대배양 중인 배아줄기 세포주의 염색체 분석을 실시하였다. 결 과: 전체적으로 2-세포기에서 분리한 할구와 4-세포기에서 분리한 할구에서 각각 3.0% (1/33)와 4.0% (1/25)의 효율로 배아줄기세포주를 확립할 수 있었다. 이는 4-세포기의 배아를 사용하였을 때의 16.7% (5/30)에 비해 현저하게 낮았다. 분리된 할구로부터 확립된 배아줄기세포주에서 SSEA-l 과 Oct-4의 발현을 관찰하였고, 이들에서 분화된 배아체에서 삼배엽성 분화 관련 유전자들의 발현도 확인할 수 있었다. 결 론: 본 연구에서는 동물모델을 이용하여 착상전 초기 배아에서 분리한 할구를 이용하여 배이줄기세포를 확립할 수 있음을 확인하였다. 지속적인 관련 연구를 통해 인간의 체외수정 및 배아이식술에서 배아의 파괴 또는 발생 능력에 손상을 주지 않고 새로운 인간 배아줄기세포주를 생산할 수 있는 방법을 개발하고 실용화할 수 있을 것으로 사료된다.

• Reproductive and Developmental Biology
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• 제33권2호
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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.