In the present study, performances of several in vitro maturation (IVM) systems for porcine follicular oocytes were evaluated, and an efficient chemically defined IVM system for porcine oocytes was proposed. The proposed one-step culture system supplemented with polyvinylalcohol (PVA) gave competitive efficiencies in terms of oocyte maturation and blastocyst development after parthenogenetic activation and in vitro culture, compared with the conventional two-step culture system by a supplementation of porcine follicular fluid (pFF). Additionally, it is identified that the proposed chemically defined one-step culture system yielded the comparable level of blastocyst production to the conventional maturation system in porcine somatic cell nuclear transfer (SCNT). Therefore, one can eliminate un-expected effects accompanied by supplementation of pFF. No medium replacement during whole maturation period is an additional benefit by applying this new system. Thus, these data support that the developed PVA supplemented chemically defined one-step IVM system for porcine follicular oocyte might be used in porcine SCNT program.

Methods for activation of reconstructed oocytes were examined for the production of nuclear transfer (NT) rat embryos using fetal neural stem cells as donor. Neural stem cells were isolated from Day 14.5 rat fetuses, and the oocytes for recipient cytoplasm were recovered from 4-week old Sprague Dawley rats. After enucleation and nuclear injection, the reconstructed oocytes were immediately exposed to activation medium consisting of 10 mM SrCl₂ for 4 h (immediate activation after injection; IAI), or cultured in vitro for 2~3 h before activation treatment (injection before activation; IBA). Pre-activated oocytes were also used for NT to test reprogramming potential of artificially activated oocytes. The oocytes were grouped as IIA (immediate injection after activation) and ABI (activation 2~3 h before injection). Following NT, the oocytes were cultured in vitro. Development of the NT embryos was monitored at 44 and 119 h after activation. The embryos in groups IAI, mA, and IIA were cleaved to the 2-cell stage at the rates of 36.6%(15/41), 39.5% (17/43) and 46.3% (25/54), respectively. However, in the ABI group, only one embryo (1.8%, 1/55) was cleaved after activation. After in vitro culture, two NT embryos from IAI group had developed to the morula stage (4.9%, 2/41). However, no morula or blastocyst was obtained in the other groups. These results suggest that immediate activation after injection (IAI) method may be used for the production of rat somatic cell NT embryos.

본 연구는 재래산양에서 복제 수정란의 생산효율을 향상시키기 위한 기초 자료를 제시하고자 체세포 핵이식을 실시하여 공핵세포의 종류, 핵이식란의 활성화 처리 방법 및 수핵난자의 조건이 체외발달율에 미치는 영향을 조사, 검토하여 핵이식란 생산을 위한 최적의 조건을 규명하고자 실시하였다. 공핵세포의 종류에 따른 핵이식란의 체외발달율은 융합이 이루어진 핵이식란의 활성화 처리 후 분할율은 귀 유래 섬유아세포를 공핵세포로 사용하였을 때가 로서 태아 유래 섬유아세포를

This study was conducted to investigate nuclear remodeling and developmental rate following nuclear transfer of fetal fibroblast cells, ear skin cells and oviduct epithelial cells into porcine recipient oocytes. To test par-thenogenetic activation, oocytes were treated with a 6-dimethylaminopurine (6-DMAP), a single DC-pulse (DC), calcium ionomycin (ionomycin), DC+6-DMAP and ionomycin + 6-DMAP after in vitro maturation. For nuclear transfer, in vitro matured oocytes were enucleated, and donor cells were transferred into oocytes. Cloned embryos were fused and stimulated with 6-DMAP for 4 h and cultured in vitro for 6 days. Among treatments for parthenogenesis, the activation rate of DC +6-DMAP treatment was significantly higher than that of single treatment roups (p<0.01), except for DC treatment group. However, the difference was not significant in activation rate compared to other complex treatment groups. Nuclear swelling of the cloned embryos was initiated at 60 min after stimulation and increased afterwards. Fusion rates were not different among different donor cells. Cleavage rates of DC treatment groups were significantly higher than those of DC+6-DMAP treatment groups (p<0.05) in case that fetal fibroblast and ear cells were used for nuclear donor. The cloned embryos from developed to blastocysts in oviduct epithelial cell nuclear transfer with DC+6-DMAP treatment was significantly higher compared to those with DC only treatment (p<0.05). However, no blastocyst was developed from nuclear transfer of fetal fibroblast and ear cells regardless of activation treatments. Based on these results, a proper activation stimulation may be necessary to increase the activation rate and the development to blastocyst in cloned porcine embryos.

본 연구에서는 체세포를 이용한 돼지 복제수정란의 생산효율을 높이는 최적의 방법을 구명코자 핵이식 수정란에 각기 다른 조건들의 전기적 자극에 의한 융합과 활성화를 유도하여 융합율, 분할율, 후기배로의 발달율 및 배반포기배의 할구수를 비교ㆍ조사하여 다음과 같은 결과를 얻었다. 핵이식 복제 수정란과 전기자극에 의한 단위발생란과의 체외배양후 분할율을 비교한 결과 두 처리간에 유의적인 차이를 나타내지 않았으나, 배양7일째 배반포기배로의 발달율에 있어서는 복제수정

본 연구는 이종간 핵이식란의 생산성 향상에 기여하기 위한 기초연구로서 핵이식 수정란의 융합과 활성화 과정에 있어서 수핵난자 및 전기적 융합조건이 핵이식 수정란의 융합 및 체외 발달에 미치는 요인들을 조사하기 위하여 실시하였다. 도축되어지는 소 및 돼지의 난소에서 난포란을 채취하여 TCM-199 및 NCSU-23에 혈청 및 호르몬을 첨가하여 39℃, 5% CO₂ 배양기내에서 24 및 48시간 체외성숙을 실시하여 수핵난자를 준비하고, 공여세포의 준비는 산양의 귀세포를 채취하여 0.25% Trypsin-EDTA의 처리로 세포를 분리, 배양하여 사용하였으며, 계대배양과 함께 세포는 TCM-199 ＋ 10% FBS ＋ 10% DMSO로 동결을 실시하였다. 핵이식은 성숙된 난자의 극체 및 전핵을 laser system으로 투명대를 drilling 하여 제거하고 준비된 공여세포를 핵이 제거된 난자에 주입하여 전기적 자극으로 융합을 실시하여 융합된 난자는 전기적 자극으로 활성화를 유도하였다. 활성화가 이루어진 복제 수정란은 수핵란이 소난자의 경우 monolayer가 형성된 10% FBS가 첨가된 TCM199 배양액에서 7∼9일 동안 체외배양하였으며, 수핵란이 돼지의 경우 10% FBS가 첨가된 NCSU-3 배양액으로 6∼8일 동안 체외배양을 실시하여 배반포기로 유도하였다. 본 연구에서 얻은 결과를 요약하면 다음과 같다. 전기자극의 세기를 1.95 kv/cm와 2.10 kv/cm로 주었을 때 수핵란이 소 난자의 경우 융합율은 47.7및 44.6%였으며, 분할율도 41.9 및 54.5%로써 차이가 없었다. 수핵란이 돼지 난자인 경우는 융합율은 51.3 및 46.1%로써 차이가 없었으며, 분할율도 75.0및 84.9%로써 차이가 없었다. 전기자극 시간을 30 또는 60μsec, 횟수는 1 또는 2회 주었을 때 수핵란이 소 난자의 경우 융합율은 30 μsec 1회(50.8%) 와 2회(31.0%) 간에 차이가 없었으나, 60μsec 1회(19.3%)가 가장 낮았다(P＜0.05). 융합란의 분할율은 30μsec 1회(53.3%)와 2회(50.0%) 간에 차이가 없었으나, 60μsec 1회(18.2%)보다 유의적(P＜0.05)으로 높게 나타났다. 돼지 난자의 경우 융합율은 30μsec 1회(48.1%), 2회(45.2%)및 60μsec 1회(48.6%)간에 차이가 없었으며, 분할율은 30μsec 1회(78.4%)와 60μsec 1회 (79.4%)간에 차이가 없었으나, 30μsec 2회(53.6%)보다 유의적(P＜0.05)으로 높게 나타났다. 이종간 핵이식란의 체외발달에 있어서 수핵란이 소 난자의 경우 상실배와 배반포기로의 발달율이 22.6%로써 단위발생란 30.6%와 차이가 없었으며, 돼지 난자의 경우는 이종간 핵이식란이 5.1%로써 단위발생란 37.4%보다 유의적(P＜0.05)으로 낮게 나타났다. 이상의 실험결과로 보아 산양의 체세포를 이용한 이종간 핵이식 복제수정란의 생산을 위하여 수핵란으로 소와 돼지를 사용하여 복제수정란의 발달을 확인할 수 있었으며, 이종간 핵이식에 있어서 수핵란, 공여세포, 융합, 활성화 및 배양조건 등 아직 초보 수준에 있으며, 앞으로 보다 많은 연구를 통하여 이러한 문제들이 해결되면 멸종위기 상태에 있는 동물들의 종 보존에도 활용이 가능할 것으로 생각된다.

This study was conducted to investigate the developmental ability of caprine embryos after somatic cell interspecies nuclear transfer. Donor cells were obtained from an ear-skin biopsy of a caprine, digested with 0.25% trypsin-EDTA in PBS, and primary fibroblast cultures were established in TCM-199 with 10% FBS. After maturation, expanded cumulus cells were removed by vigorous pipetting in the presence of 0.3% hyaluronidase. The matured oocytes were dipped in D-PBS plus 10% FBS＋7.5 ㎍/ml cytochalasin B and 0.05 M sucrose. The reconstructed oocytes were electrically fused with donor cells in 0.3 M mannitol fusion medium. After the electofusion, embryos were activated by electric stimulation. Interspecies nuclear transfer embryos with bovine cytoplasts were cultured in TCM-199 medium supplemented with 10% FBS including bovine oviduct epithelial cells for 7∼9 day. On the other hand, the NT embryos with porcine cytoplasts were cultured in NCSU-23 medium supplemented with 10% FBS for 6∼8 day at 39℃, 5% CO₂ in air. In caprine-bovine NT embryos, the cleavage(2-cell) rate was 36.8% in confluence and 43.8% in serum starvation. The developmental rate of morula- and blastocyst-stage embryos was 0.0% in confluence and 18.8% in serum starvation. In caprine-porcine NT embryos, the cleavage(2-cell) rate was 76.7% in confluence and 66.7% in serum starvation. The developmental rate of morula and blastocyst stage embryos was 3.3% in confluence and 3.0% in serum starvation, and no significant difference was observed in synchronization treatment between donor cells. In caprine-bovine NT embryos, the cleavage(2-cell) rate of cultured donor cells was 30.8% and 17.6% in 5∼9 and 10∼14 passage(P＜0.05). The developmental rate of morula and blastocyst stage embryos were significantly higher(P＜0.05) in 5∼9 passage(23.1%) than in 10∼14 passage(0.0%) of cultured donor cells. In caprine-porcine NT embryos, the cleavage rate was significantly higher(P＜0.05) in 5∼9 passage(86.7%) than in 10∼14 passage(50.0%) of cultured donor cells. The developmental rate of morula and blastocyst stage embryos were 3.3 and 0.0% in 5∼9 and 10∼14와 passage of cultured donor cells. In caprine-bovine NT embryos, the developmental rate of morula and blastocyst stage embryos were 22.6% in interspecies nuclear transfer, 33.9% in in vitro fertilization and 28.1% in parthenotes, which was no significant differed. The developmental rate of morula and blastocyst stage embryos with caprine-porcine NT embryos were lower(P＜0.05) in interspecies nuclear transfer(5.1%) than in vitro fertiltzation(26.9%) and parthenotes(37.4%).

본 연구는 체세포의 종류, 세포 제공 개체, 계대배양 수 및 세포의 trypsin 처리시간이 소 체세포 핵이식란의 체외발육에 미치는 영향을 검토하였다. 세 종류의 체세포(피부, 근육 및 난구세포) 와 암소 3 개체를 실험에 공시하였으며, 한 개체 유래의 피부세포는 5∼30회 계대배양하였고, 핵이식 전에 1∼3분간 trypsin처리하여 핵이식에 사용하였다. 핵이식과정은 상법에 따라 전기융합법을 이용하였다. 핵이식란의 배반포 발육율은 세포의 종류(16.5∼23.9%)나 개체 간(16.4∼19.5%)에 차이가 없으나, 30회 계대 배양한 세포를 사용한 경우(5.8%)에는 5회(25.3%) 또는 15회(23.5%) 계대 배양한 세포를 사용한 경우에 비해 유의적으로 낮았다(P＜0.05). 또한, 1분간 trypsinization 한 세포를 사용한 경우(30.7%)는 3분간 trypsinization 한 경우에 비해 배반포 발육율이 유의적으로 높게 나타났다(P＜0.05). 본 연구의 결과는 소 체세포 핵이식란의 발육이 체세포의 종류 및 세포 제공 개체에 따라서는 영향을 받지 않으나, passage 수 및 체세포의 trypsinization 시간에 따라서는 영향을 받을 수 있음을 시사한다.