• Reproductive and Developmental Biology
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• 제29권2호
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• pp.127-131
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• 2005

The objective of this study was to examine the effect of EGF on meiotic maturation and pronuclear (PN) formation of porcine oocytes. Prepubertal gilt cumulus-oocyte-complexes (COCs) aspirated from $2\~6mm$ follicles of abbatoir ovaries were matured in TCM199 containing 0.1mg/ml cysteine, $0.5{\mu}/ml$ FSH and LH, and EGF (0, 5, 10, 20, 40 ng/ml) for 22 hr at $39^{\circ}C$ in a humidified atmosphere of $5\%$ $CO_2$ in air. They were then cultured for an additional 22hr without hormones. In Experiment 1, to examine the nuclear maturation at 44hr of culture, the expanded cumulus cells were removed by vortexing for 1 min in 3 mg/ml hyaluronidase. The oocytes were fixed in acetic acid: methanol (1:3, v/v) at least for 48 hr and stained with $1\%$ orcein solution for 5 min. Nuclear status was classified as germinal vesicle (GV), germinal vesicle breakdown (GVBD), prophase-metaphase I (PI-MI), and PII-MII under microscope. In Experiment 2, to investigate PN formation, oocytes were fertilized with Percoll-treated freshly ejaculated sperm $(1\times10^5\; cells/ml)$ in mTBM with $0.3\%$ BSA and 2mM caffeine for 5hr, and cultured in NCSU-23 medium with $0.4\%$ BSA. At 6hr of culture, the embryos were fixed in $3.7\%$ formaldehyde for 48hr and stained with 10ug/ml propidium iodide for 30 min. PN status was classified as no or one PN (unfertilized), 2 PN (normal fertilized) and $\geq3$ PN (polyspermy). Differences between groups were analyzed using one-way ANOVA after arc-sine transformation of the proportional data. The rate of oocytes that had reached to PII-MII were significantly (P<0.05) higher in all groups added EGF than that of non-treated group $(67\%)$, but it did not differ among the all added groups $(86\%,\;85\%,\;79\%\;and\;81\%$, in 5, 10, 20 and 40 ng/ml EGF, respectively). No differences on the incidence of 2PN were observed in all treated groups $(25\%,\;30\%,\;33\%,\;29\%\;and\;29\%$, in 0, 5, 10, 20 and 40 ng/ml EGF, respectively), however, in non-treated group, polyspermy tended to be increased ($66\%\;vs\;. 58\%,\;54\%,\;52\%\;and\;55\%$, 0 vs. 5, 10, 20, 40 ng/ml EGF, respectively). These results suggest that EGF can be effectively used as an additive for enhancing oocyte maturation and reducing the incidence of polyspermy in pig.

• 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.

• 한국가축번식학회지
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• 제25권4호
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• pp.305-315
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• 2001

본 연구의 목적은 외래 EGFP 유전자를 분화이전의 웅성생식세포에 도입한 후 이를 난모세포내에 미세주입하여 형질전환동물을 생산하는 기술을 개발하는 데에 있다. 이를 위하여 반수체 정자세포에서 특이적으로 발현하는 생쥐의 mTP1과 햄스터의 hPrm2 유전자 발현 시기를 RT-PCR로 조사한 결과 그시기는 생쥐와 햄스터에서 각각 18일령과 20일령으로 확인되었다. 이에 따라 외래 유전자의 침입이 용이한 감수분열 직전단계인 17일령의 생쥐와 19일령의 햄스터 정자세포를 EGFP 유전자가 포함된 배양액에 부유시킨 다음, 전기자극을 부여한 결과 0.18 ㎸/cm의 전기자극을 가한 후 72시간 배양한 정자세포의 28.5%와 32.1%에서 EGFP 유전자가 발현되는 것으로 확인되었다. EGFP유전자가 도입된 반수체 정자의 수정 및 발달 능력을 검증하기 위하여, 이들 정자세포를 햄스터 난자 내에 미세주입 하였으나, 형광현미경하에서는 EGFP유전자의 발현은 관찰할 수 없었다. 이에 이들 난자를 공시하여 PCR분석을 실시한 결과, 약 44%의 수정란에서 EGFP 유전자의 존재가 확인되었다. 이러한 결과로 보아 반수체 정자세포는 외래 유전자를 난자 내에 도입하기 위한 운반체로 이용될 수 있을 것으로 생각된다.

• 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.

• BMB Reports
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• 제47권11호
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• pp.609-618
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• 2014

DNA methylation at cytosines (5mC) is a major epigenetic modification involved in the regulation of multiple biological processes in mammals. How methylation is reversed was until recently poorly understood. The family of dioxygenases commonly known as Ten-eleven translocation (Tet) proteins are responsible for the oxidation of 5mC into three new forms, 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). Current models link Tet-mediated 5mC oxidation with active DNA demethylation. The higher oxidation products (5fC and 5caC) are recognized and excised by the DNA glycosylase TDG via the base excision repair pathway. Like DNA methyltransferases, Tet enzymes are important for embryonic development. We will examine the mechanism and biological significance of Tet-mediated 5mC oxidation in the context of pronuclear DNA demethylation in mouse early embryos. In contrast to its role in active demethylation in the germ cells and early embryo, a number of lines of evidence suggest that the intragenic 5hmC present in brain may act as a stable mark instead. This short review explores mechanistic aspects of TET oxidation activity, the impact Tet enzymes have on epigenome organization and their contribution to the regulation of early embryonic and neuronal development.

• Asian-Australasian Journal of Animal Sciences
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• 제4권1호
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• pp.73-78
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• 1991

Sixty-one 5-11 month-old California, Chinchilla and New Zealand White rabbit were employed in this investigation. Thirty-three does were superovulated by injecting FSH/HCG subcutaneously or intravenously and then sacrificed at different hours after mating. The ova were collected from the fallopian tubes with Ham's F-10 medium supplemented with 0.4% bovine serum albumin (BSA) and 1% pregnant rabbit serum (PRS). Embryos were examined under an inverted DIC microscopy for observing the stage of development. We have found that the fertilized ova formed pronuclei at 19 - 20 hr postcoitus. Approximately at 26, 64 - 78 and 84 - 88 hr after mating, the fertilized ova cleaved further to 2-cell, morulae and blastocyst stage respectively. Another 28 does were allocated to the gene transfer study. Fourteen of the 28 does were sacrificed at 19 - 20 hr to donate the pronuclear stage ova for gene injection. The other 14 does were induced to pseudopreganacy by injection of 100 IU HCG intravenous as recipients. Four hundreds and seventeen ova were injected totally and 212 gene injected zygotes were transferred into the recipient oviducts. Five recipients became pregnant and 10 fetuses were obtained. Eight of the 10 fetuses were analysed for gene incorporation, but none of them were transgenic.

• Clinical and Experimental Reproductive Medicine
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• 제25권2호
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• pp.233-237
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• 1998

We demonstrated that the normal pregnancy and delivery by round spermatid injection (ROSI) into oocytes was achieved from nonobstructive azoospermia patient. In this case, the normal fertilization rate was 50%. All of the two pronuclear stage embryos cleaved and were transferred to the patient's uterus. A singleton pregnancy was achieved and resulted in the birth of normal female infant. This resuJt show that intracytoplasraic injection of round spermatid seems to be new treatment of nonobstmctive azoospermia male infertility. Further research is needed to evaluate the required culture conditions to induce progression of the round spermatid into a more elongated stage.

• Asian-Australasian Journal of Animal Sciences
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• 제17권2호
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• pp.164-167
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• 2004

This study was carried out to investigate in vitro fertilization and development of in vitro matured pig oocytes inseminated with the Duroc boar sperm by different sperm washing media after thawing of the 5 ml frozen straws. Immature follicular oocytes (30-40) were transferred into each well of a Nunc 4-well multidish containing $500{\mu}l$ mTCM199 maturation medium. The sperm rich portion of ejaculates was collected into a 250 ml insulated vacuum bottle and gradually cooled 22 to $24^{\circ}C$ over a 2 h period. Semen was centrifuged at 800 g for 10 min and the seminal plasma discarded. Sperm were esuspended in a lactose-egg yolk and N-acetyl-Dglucosamine (LEN) diluent to contain $1{\times}10^{9}$ sperm/ml and cooled to $5^{\circ}C$ over a 2 h period. Immediately before freezing, semen was rediluted with an equal volume of LEN+4% glycerol and packed into 5 ml straws. After thawing of the 5 ml straw, the 5 ml semen was diluted with 20 ml Beltsville thawing solution (BTS) at room temperature. Oocytes were inseminated with untreated (unwashed and nonpreincubated) or treated sperm (washed two times in BTS, mTLP-PVA and mTBM media, respectively and nonpreincubated) with $2{\times}10^{7}$ sperm concentration. Oocytes were coincubated for 6 h in $500{\mu}l$ mTBM fertilization. At 6 h after IVF, oocytes were transferred into $500{\mu}l$ NCSU-23 culture medium for further culture of 6 h. Sperm penetration, polyspermy and male pronuclear formation of oocytes at 12 h after IVF and developmental ability of oocytes at 48 h after IVF were evaluated. Sperm penetration rate, male pronuclear formation and rate of cleaved embryos were higher in the BTS, mTLP-PVA and mTBM treatments than the unwashed treatment (p<0.05). The rate of blastocysts from the cleaved oocytes (2-4 cell stage) were higher in the mTLP-PVA treatment than in the unwashed, BTS and mTBM treatments. In conclusion, we recommend the washing of frozen-thawed sperm with mTLP-PVA medium before in vitro fertilization of oocytes in mTBM medium.

• Clinical and Experimental Reproductive Medicine
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• 제24권3호
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• pp.281-292
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• 1997

The objective of this study was to compare retrospectively the survival and pregnancy rates(PR) of cryopresered-thawed embryos obtained from intracytoplasmic sperm injection (ICSI) or conventional in vitro fertilization (IVF). Ninety-six cycles of cryopresered-thawed embryo transfer (ET) were performed in 79 patients from June, 1996 to September, 1997 and grouped as followings: 20 cycles (16 patients) inseminated by ICSI (ICSI Group) and 76 cycles (63 patients) by conventional IVF (IVF Group). Slow-freezing and rapid-thawing protocol was used with 1.5M propanediol (PROH) and 0.1M sucrose as cryoprotectant. All embryos were frozen-thawed at the two pronuclear (2 PN) stage excluding four cycles in which the early cleavage stage embryos were frozen, and allowed to cleave in vitro for one day before ET. The duration from freezing to thawing was comparable in both groups ($mean{\pm}SD$, $112.1{\pm}80.0$ vs. $124.8{\pm}140.1$ days). The age of female ($31.2{\pm}3.4$ vs. $32.6{\pm}3.3$ years) and the endometrial thickness prior to progesterone injection ($9.4{\pm}2.0$ vs. $9.3{\pm}1.8$ mm) were also comparable in both groups. There was no significant difference in the outcomes of cryopreserved-thawed ET between two groups: survival rate ($85.2{\pm}16.1%$ vs. $82.2{\pm}19.7%$), cleavage rate ($96.9{\pm}6.7%$ vs. $94.7{\pm}13.0%$), cumulative embryo score (CES, $54.5{\pm}31.1$ vs. $49.0{\pm}20.0$), preclinical loss rate (5.0% vs. 5.3%), clinical miscarriage rate (0% vs 29.4%), clinical PR per transfer (35.0% vs. 22.4%), implantation rate (9.9% vs. 5.6%), and multifetal PR (42.9% vs. 17.6%). In conclusion, human embryos resulting from ICSI can be cryopreserved-thawed and transferred successfully, and the survival rate and PR are comparable to conventional IVF.

• 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).