The aim of the present study was to compare two different serum-free media, modified synthetic oviduct fluid (mSOF) and modified potassium simplex optimization medium (mKSOM) containing 20% RD (RPMI1640 + DMEM, 1:1 v/v) (RD-mKSOM), for in vitro culture (IVC) of bovine embryos. After in vitro maturation and fertilization, the presumptive zygotes were cultured in two different serum-free conditions for 7 days and 9 days to evaluate blastocyst formation and hatching, respectively. Serum supplemented conventional CR2 medium was used as control. After 7 day of culture, there was no significant difference in cleavage and blastocyst formation rates among three groups (mSOF, 59.3 and 30.1%; RD-mKSOM, 65.0 and 41.5%; control, 51.6 and 38.0%, respectively). Hatching rate was significantly higher in control (69.0%) than other experimental groups (mSOF, 22.0%; RD-mKSOM, 39.5%) (P＜0.0001 and P＜0.001, respectively). Although both serum-free conditions showed lower hatching rates than serum-added control, in serum-free groups, RD-mKSOM showed significantly higher hatching rate than mSOF (P＜0.001). In addition, one-step using RD-mKSOM may facilitate IVC procedure than two-step culture system. In conclusion, the results indicate that one-step RD-mKSOM is more suitable defined culture system for IVC of bovine embryos than two-step mSOF.

This study was carried out to investigate the effects of tissue inhibitor of matalloproteinase-1 (TIMP-1), Activin A and Heparin binding epidermal growth factor (HB-EGF) on in vitro production of bovine embryos. In experiment 1, presumptive zygotes were cultured in the medium supplemented with TIMP-1 (0.5 μg/ml), Activin A (100 ng/ml), or HB-EGF (100 ng/ml) at 39 ℃ in a humidified atmosphere of 5% (v/v) CO2, 5% (v/v) O2 and 90% (v/v) N2. In experiment 2, TIMP-1 + HB-EGF or Activin A + HB-EGF combinations were supplemented in the culture medium. The developmental rate to blastocysts, hatching rate and total cell numbers of the blastocysts were evaluated in both experiments. The embryos cultured in medium without growth factor supplementation was used as control group. In experiment 1, the embryos cultured in medium supplemented with TIMP-1 and Activin A showed significantly higher developmental rate to blastocysts than those cultured with HB-EGF and control (36.9%, 34.1%, 21.2% and 23.1%, respectively) (P<0.0001). However, the hatching rate of blastocyst was significantly higher in embryos with HB-EGF than those with TIMP-1, Actvin A and Control groups (84.4%, 58.8%, 51.4% and 49.3%, respectively) (P<0.001). Total cell number per blastocyst was also significantly higher in embryos with HB-EGF group (174.3±2.5) than those with TIMP-1, Activin A (149.7 and 150.0, respectively) (P<0.05) and Control (119.0) (P<0.001). In experiment 2, embryos cultured with combined treatment of Activin A and HB-EGF resulted in significantly higher rates of blastocysts formation (48.0%), hatching rate (89.7%) and total cell number in blastocyst (182.3±2.1) than those with TIMP-1 and HB-EGF combination group (32.0%, P<0.001; 76.6%, P<0.05; 165.7±4.2, P<0.001, respectively). Our data demonstrate that in vitro production of bovine embryos could be improved by combined supplementation of Activin A and HB-EGF in culture medium.

This study was carried out to assess the effect of vitamin E against the reactive oxygen species (ROS) on chemical activation of in vitro matured oocytes. Bovine oocytes were aspirated from slaughtered ovaries and transferred to maturation medium with or without vitamin E (). After 22 hours of culture, oocytes with polar bodies were selected and submitted to activation treatments with or without vitamin E. After activation, oocytes were cultured in mSOF medium and rate of development was monitored. For ROS () detection, in vitro matured and activated oocytes were selected and stained with DCFDA and observed under fluorescence microscope. The ROS contents were not significant differences in IVM rate, activation process and embryonic development to blastocysts with or without vitamin E. The cell number of blastocyst showed significant difference (p<0.05) in embryos matured and activated with vitamin E. The results of the present study demonstrated that the exposure of vitamin E in IVM and activation process improved the quality of embryos evaluated by the cell number of blastocysts.

본 연구에서는 결과 중심의 평가에서 학습 지향적 평가로의 변화에 부응하기 위해서 국어교 과를 중심으로 국외의 온라인 형성평가 사례를 살펴보고, 우리나라 국어과 온라인 형성평가 시 스템의 발전 방향에 관한 시사점을 도출하고자 하였다. 이를 위해 Ⅱ장에서는 최근 학생평가 패러다임인 ‘학습을 위한 평가’와 ‘학습으로서의 평가’에 대해서 탐색하고, 이러한 평가 패러다 임에서의 온라인 형성평가 시스템의 필요성을 살펴보았다. Ⅲ장에서는 우리나라 온라인 형성평 가 시스템의 개발 현황을 살펴보고, 그 한계점을 살펴보았다. 이러한 내용을 바탕으로 하여, Ⅳ 장에서는 향후 국어과 온라인 형성평가 시스템의 발전 방향을 두 가지 측면에서 논의하였다. 향후 국어과 온라인 형성평가 시스템은 다음과 같은 측면에 중점을 두어 개발되어야 한다. 첫째는 국어과 온라인 형성평가 시스템은 국어과의 세부 학습요소별로 문항을 제공해야 한다 는 것이고, 둘째는 학습순서도 및 학습요소별 강약점 피드백을 통해서 학생의 자기주도적 학습 을 지원할 수 있어야 한다는 것이다. 이 연구가 학급당 학생 수가 많은 우리나라 공교육 상황 에서 질 높고 만족도가 높은 학생 맞춤형 국어 교육으로 나아가기 위해 보다 실효성 있는 방 안을 마련하는 데에 기여할 수 있기를 기대한다.