• 한국수정란이식학회지
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• 제30권3호
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• pp.207-211
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• 2015

미세주입법에 의한 형질전환 마우스 제작에는 대량의 전핵기란을 필요로 한다. 본 실험에서는 심플한 형질전환 마우스 제작방법을 확립하기 위해 초급속 동결한 전핵기란을 공시했다. 초급속 동결법으로 동결한 전핵기 체외수정란 139개를 융해 후 공시하고, ${\beta}-actin/luc^+$ 융합유전자를 미세주입하였다. 주입 조작 후, 형태학적으로 정상적인 수정란 101개(72.6%)를 5마리의 수란암컷 마우스에 이식하였다. 그 결과, 이식한 모든 마우스가 임신하고, 최종적으로 15마리(14.8%)의 산자가 태어났다. 한편, 450개의 체외수정란에 대해 동일한 배아조작 후에 338개(75.1%)가 생존하고 14마리의 수란암컷 마우스에 이식 하였다. 그 중에 78%의 수정암컷 마우스가 임신하고, 54마리(19.1%)의 산자가 태어났다. 태어난 산자에 대해서는 southern blot 법에 의해 염색체 내의 도입유전자의 도입을 확인한 결과, 동결수정란 처리구와 체외수정란구에서 각각 6.6%(1/15), 5.5% (3/54)의 마우스에서 도입유전자의 도입이 확인되었다. 더욱이 두 처리구 전부의 형질전환 마우스의 미부조직에서 도입유전자인 루시페라제 유전자의 발현이 관찰되었다. 이상의 결과에 의해 체외수정란 초급속 동결보존법을 사용한 Tg 마우스 제작방법의 확립을 확인하였고, 이러한 결과들로부터 실험기간의 단축과 작업의 간소화에 크게 이바지할 것으로 사료된다.

• 한국수정란이식학회지
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• 제29권1호
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• pp.51-57
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• 2014

본 연구는 돼지 정자의 동결 건조 시 동결 보호제인 trehalose의 효과와 동결 건조 시간과 동결 건조 후 저장 기간에 따라 정자의 생존성과 체외 성숙 난자 내 동결 건조 정자를 직접 주입한 후 전핵 형성율, 난할율 그리고 배발달 성적을 조사하였다. 동결 건조 후 정자의 생존율은 trehalose 무첨가구에 비해 trehalose를 첨가한 처리구에서 높은 생존율을 보였으며, 75 mM의 trehalose를 첨가하여 동결 건조한 정자들의 생존율이 가장 높은 것으로 나타났다. 또한, 동결 건조 후 저장 기간이 길어질수록 생존율이 낮아지는 경향이었다. 체외 성숙 난자 내 동결 건조 정자를 직접 주입 후 전핵 형성율은 trehalose 첨가구에서 유의적으로 높았으며(p<0.05), 난할율과 배발달 성적도 trehalose 첨가구에서 유의적으로 높았고(p<0.05), 정자의 동결 건조 시간이 짧을수록 높은 난할율과 배발달율을 보였다.

• Clinical and Experimental Reproductive Medicine
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• 제24권1호
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• pp.111-118
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• 1997

Intracytoplasmic sperm injection (ICSI) recently has been utilized widely as the most successful technique to overcome the unfertilization problem in cases of severe male infertility in couples who could not be treated by conventional IVF. Recently, indications of ICSI have been extended further and more fertilized oocytes become available. Thus, it is necessary to examine the efficiency of freezing the surplus embryos obtained from ICSI. We compared the survival rate and the future outcome of cryopreserved embryos obtained either after conventional IVF or ICSI during the same period. After ICSI or IVF, five best-quality embryos from each patient were transferred in the stimulation cycle and the surplus pronuclear (PN) stage oocytes or multicellular embryos were cryopreserved by slow freezing protocol with 1,2-propanediol (PROH) as a cryoprotectant. A total of 792 embryos from ICSI trial were thawed and 65.2% (516/792) survived. The survival rates of PN stage oocyte, multicellular embryo and PN + multicellular embryo were 63.5%, 68.2%, 64.0%, respectively. After 111 transfers, 34 pregnancies were achieved, corresponding to a clinical pregnancy rate of 30.6% per transfers. We thawed 1033 embryos from IVF trials and 57.5% (594/1033) survived. In IVF cycle, the survival rates of PN stage oocyte, multicellular embryo and PN + multicellular embryo were 58.2%, 65.2%, 40.2%, respectively. Thirty eight clinical pregnancies were established after 134 transfers, corresponding to a pregnancy rate of 28.4% per transfer. The cleavage rate of thawed PN stage oocytes from ICSI trial (61.3%) was significantly higher than those from conventional IVF (53.4%). The developmental rates of good embryo (${\geqq}$ grade II) in thawed PN stage oocytes obtained from conventional IVF and ICSI were 63% and 65%, respectively. We concluded that PN stage oocytes, multicellular embryos resulting from ICSI procedure can be successfully frozen/thawed with reasonable clinical pregnancy rates comparable to those of IVF.

• Clinical and Experimental Reproductive Medicine
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• 제30권3호
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• pp.193-202
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• 2003

Objective: To evaluate the difference of implantation rate (IR) and clinical pregnancy rate (CPR) between two protocols of endometrial preperation in women undergoing frozen-thawed embryo transfer (FET) cycles. Methods: This study was performed during the different time periods: A retrospective study from January 2000 to June 2001 (phase I) and a prospective study from July 2001 to March 2002 (phase II). All the patients received estradiol valerate (6 mg p.o. daily) starting from day 1 or 2 of the menstrual cycle without pituitary down regulation. Progesterone was administered around day 14 after sonographic confirmation of endometrial thickness $\geq$7 mm and no growing follicle. In Group A (n=88, 99 cycles) of phase I, progesterone was administered i.m. at a dose of 50 mg daily from one day prior to thawing of pronuclear (PN) stage frozen embryo or three days prior to thawing of 6-8 cell stage frozen embryo and then each stage embryos were trasnsferred 2 days or 1 day later after thawing. In Group B (n=246, 299 cycles) of phase I, patients recieved progesterone 100 mg i.m. from one day earlier than group A; two days prior to PN embryo thawing, four days prior to of 6-8 cell embryo thawing. During the phase II, to exclude any differences in embryo transfer procedures, in Group 1 (n=23, 28 cycles) of phase II embryo was transfered by one who have used the progesterone protocol since the phase I. In Group 2 (n=122, 139 cycles) of phase II embryo was transfered by one who use the progesterone protocol from the phase II. Results: When compared across the phase and group, there were no significant differences in the characteristics. During the phase I, there were significant increase in IR (14.4% vs 5.9%, p=0.001) and CPR (28.3% vs 14.5%, p=0.000) in group A. During the phases II, IR (11.8% vs 10.6%) and CPR (27.6% vs 27.3%) show no differences between two groups. Conclusions: In FET cycles, IR and CPR are increased significantly by the change of dosage and timing of progesterone administraton. And the timing is considered to be more important factor because the dosage of progesterone did not affect implantation window in previous studies. Therefore, we suggest that progesterone administration in FET cycle should begin from one day prior to PN stage embryo thawing and three days prior to 6-8 cell stage embryo thawing.

• 한국가축번식학회지
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• 제16권1호
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• pp.55-62
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• 1992

Bovine oocytes obtained from ovarian(2 to 5mm in diameter) of slaughtered cows were cultured in TCM 199 with 10~20% estrous-cow-serum(ECS) for 24~25hr at 39$^{\circ}C$ in 5% CO2-95% air. After culture, some oocytes were examined their maturation. The remainder were used to assess the fertilizability with frozen-thawed spermatozoa in a medium containing caffeine and heparin, and subsequent development in media with bovien cumulus cells(BCC) or bovine oviduct epithelial cells(BOEC). The results obtained were summarized as follows ; 1. The maturation rate of the oocytes in TCM199 with 15% ECS group(76.5%) was higher than that of 10% ECS(69.2%) or 20% ECS group(64.8%). 2. The proportions of the oocytes penetrated and the pronuclear oocytes in the presence of caffeine and heparin were 72.1%(62/86) and 93.5%(58/62), respectively. The rate of polyspermy in the fertilized oocytes was 8.1%. 3. When 73 oocytes recovered from fertilization drop were cultured in TC-199 medium with 10% fetal calf serum(FCS), 41 oocytes(56%) cleaved to 2-cell and further stages of embryos. Among these only one embryo developed upto morula stage. 4. The rate of the cleaved oocytes was higher in medium with BCC(80%:59/74) than BOEC(76%:58/76). However, the rate of developed morulae and blastocysts was higher in the medium with BOEC(40%;23/58) than with BCC(34;20/59).

• 한국수정란이식학회지
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• 제30권4호
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• pp.299-303
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• 2015

KO mice provide an excellent tool to determine roles of specific genes in biomedical filed. Traditionally, knockout mice were generated by homologous recombination in embryonic stem cells. Recently, engineered nucleases, such as zinc finger nuclease, transcription activator-like effector nuclease and clustered regularly interspaced short palindromic repeats (CRISPR), were used to produce knockout mice. This new technology is useful because of high efficiency and ability to generate biallelic mutation in founder mice. Until now, most of knockout mice produced using engineered nucleases were C57BL/6 strain. In the present study we used CRISPR-Cas9 system to generate knockout mice in FVB strain. We designed and synthesized single guide RNA (sgRNA) of CRISPR system for targeting gene, Abtb2. Mouse zygote were obtained from superovulated FVB female mice at 8-10 weeks of age. The sgRNA was injected into pronuclear of the mouse zygote with recombinant Cas9 protein. The microinjected zygotes were cultured for an additional day and only cleaved embryos were selected. The selected embryos were surgically transferred to oviduct of surrogate mother and offsprings were obtained. Genomic DNA were isolated from the offsprings and the target sequence was amplified using PCR. In T7E1 assay, 46.7% among the offsprings were founded as mutants. The PCR products were purified and sequences were analyzed. Most of the mutations were founded as deletion of few sequences at the target site, however, not identical among the each offspring. In conclusion, we found that CRISPR system is very efficient to generate knockout mice in FVB strain.

• 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.

• 한국수정란이식학회지
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• 제31권2호
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• pp.117-121
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• 2016

Although piglets have been delivered by embryo transfer (ET) with in vitro produced (IVP) embryos and blastocysts, a success rate has still remained lower level. Unlike mouse, human, and bovine, it is difficult to a production of piglets by in vitro fertilization (IVF) because of an inappropriate in vitro culture (IVC) system in pig. Therefore, the present study was conducted to investigate whether minimized exposure time in IVC can improve the pregnancy and delivery rates of piglets. Immediately after IVM, the oocytes were denuded and co-incubated with freshly ejaculated boar semen for 3.5 to 4 hours at $38.5^{\circ}C$ under 5% $CO_2$ in air. To avoid long-term exposure to in vitro state, we emitted IVC step after IVF. After that the presumptive zygotes were transferred into both oviducts of the surrogate on the same day or 1 day after the onset of estrus. Pregnancy was diagnosed on day 28 after ET and then was checked regularly every month by ultrasound examination. The 3 out of 4 surrogates were determined as pregnant (75%) and a total of 5 piglets (2 females and 3 males) were delivered at $118.3{\pm}2.5$ days of pregnancy period. In conclusion, a short-term exposure time may be an important factor in the production of IVP-derived piglets. It can be apply to the in vitro production system of transgenic pig by IVF, cloning, and pronuclear microinjection methods.

• BMB Reports
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• 제40권5호
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• pp.656-661
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• 2007

In this report, we describe an optimized method for generation of ephA8 BAC transgenic mice expressing the lacZ reporter gene under ephA8 regulatory sequences. First, we constructed a targeting vector that carries a 1.2 kb ephA8 DNA upstream of its first exon, a lacZ expression cassette, a kanamycin cassette, and a 0.7 kb ephA8 DNA downstream of its first exon. Second, the targeting vector was electroporated into cells containing the ephA8 BAC and pKOBEGA, in which recombinases induce a homologous recombination between the ephA8 BAC DNA and the targeting vector. Third, the FLP plasmid expressing the Flipase was electroporated into these bacteria to eliminate a kanamycin cassette from the recombinant BAC DNA. The appropriate structures of the modified ephA8 BAC DNA were confirmed by Southern analysis. Finally, BAC transgenic mouse embryos were generated by pronuclear injection of the recombinant BAC DNA. Whole mount X-gal staining revealed that the lacZ reporter expression is restricted to the anterior region of the developing midbrain in each transgenic embryo. These results indicate that the ephA8 BAC DNA contains most, if not all, regulatory sequences to direct temporal and spatial expression of the lacZ gene in vivo.

• 한국가축번식학회지
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• 제16권1호
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• pp.15-20
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• 1992

These experiments were undertaken to investigate the rate of in vitro fertilization of bovine follicular oocytes treated with glycosaminoglycans(GAGs). Bovine follicular oocytes were obtained from the ovary of slaughtered animal and matured in media containing the various concentrations of hydluronic acid, chondroitin sulfate or heparin for 26 hours. Epididymal spermatozoa were capacitated and insemination was made by introducing about 10~15 matured oocytes into the suspension of spermatozoa. Six hour after insemination the eggs were transferred to TCM-199 supplemented with FCS(10%) and then examined the embryo development. After in vitro insemination, percentages of ova fertilized were 61.3 or 48.3%, respectively, for the cumulus intact or removed in the percentages of GAGs. However, in case of cumulus-free oocytes treated with GAGs, the fertilization rates were 58.8, 62.1, 58.8, and 61.8%, respectively, showing significant effect compared to 48.3% in cumulus-free oocytes. Our findings suggest that cnondroitin sulfate and heparin are superior to hyaluronic acid in the fertilizatin and pronuclear formation of bovine oocytes.