• Educational Technology International
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• 제9권2호
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• pp.123-142
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• 2008

The purpose of this study was to examine how computer conferencing might facilitate collaborative learning for students to engage in meaningful discussion. The participants in this study consisted of the instructor and the students in a graduate level course. Different sources of evidence were used to triangulate the data: in-depth interviews, content analysis of transcripts of discussion, and other archival data including course syllabus, presentation materials, and lecture notes. Participants perceived web-based learning as collaborative process, providing opportunities to share the idea, respect and evaluate different perspectives, and co-construct new insights. Analysis of the data revealed several challenges related collaboration in a web-based learning environment: absence of a sense of community, technical problems, adaptability to different types of learner, and managing the discussion. The data also indicated that a variety of strategies were used to facilitate learning: building a sense of community, technical support, developing instructional methodologies, class size, and design of the content.

• 생명과학회지
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• 제19권4호
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• pp.549-552
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• 2009

유전자의 융합으로 인한 돌연변이는 염색체 재배열, 트랜스 스플라이싱, 유전자간 스플라이싱으로 인하여 야기된다고 알려져 있다. 우리는 두 개의 서로 다른 유전자의 pre-mRNA의 융합으로 인하여 만들어지는 트랜스 스플라이싱의 전사 산물에 관심을 가져, 인간의 태아 줄기 세포에서 이러한 돌연변이 양상을 분석하였다. 배아줄기세포의 mRNA에서 트랜스 스플라이싱 전사체 70개를 탐지해 내고, 이들의 융합되는 패턴에 따라 5'UTR-5'UTR, 5'UTR-3'UTR, 3'UTR-3'UTR, 5'UTR- CDS, 3'UTR-CDS, CDS-CDS의 6개의 유형으로 분류하여 분석하였다. 두 유전자의 융합되는 영역은 UTR영역보다 CDS에서 풍부하였는데, 이러한 이유는 많은 인트론 수로 인해 야기되는 것으로 추정된다. 융합되는 유전자의 염색체상의 위치분석 결과, 17번과 19번 염색체가 융합유전자의 활성화를 나타내었다. 이러한 연구결과는 향후 융합유전자와 인간의 질병 연구에 크게 기여할 것으로 사료된다.

• Parasites, Hosts and Diseases
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• 제33권4호
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• pp.357-364
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• 1995

이질아메바에 의한 장염 환자의 조직 또는 이질아메바를 실험적으로 감염시킨 동물의 조직 검사에서 호중구의 침윤이 특징적으로 관찰된다. 그러나 이와같은 호중구의 침윤을 설명할 수 있는 기전에 대한 연구는 매우 미흡하다. 따라서 본 연구자들은 아메바 감염 초기에 인체 대장상피 세포에서 interleukin-8(IL-8)이 유도되어 호중구 침윤과 같은 염증반응이 유발될 것이라는 가설을 설정하였다. 이를 위하여 인체 대장상피세포주인 HT-29에 이질아메바 영양형을 실험적으로 노출시킨 뒤 발현되는 IL-S mRNA를 역전사 중합효소법(reverse transcriptional polymerase chain reaction, RT-PCR)으로 검사함과 퐁시에 발현된 IL-8 mRNA를 인공적으로 합성시킨 표준 RNA와 RT-PCR법을 이용하여 정량하였다. 실험 결과 이질아메바 영양형에 노출된 30분 후 부터 IL-8 mRAN가 발현되기 시작하였다 그리고 그 발현 분자수는 노출 시간의 증가에 따라 계속 증가하여 3시간 대에는 $3.1{\;}{\times}{\;}10^7{\;}molecules/\mu\textrm{g}$ total RNA를 나타내었다. 동시에 IL-8 mRNA의 발현은 노출시킨 이질아메바 영양형의 수에 비례하였다. 즉 HT-29/아메바 영양형의 비율이 10:1인 경우 IL-8 mRNA의 발현 분자수는 $1.2{\;}{\times}{\;}10^7{\;}molecules/\mu\textrm{g}$ total RNA로 나타났다. 이와같은 IL-8 mRNA의 발현은 IL-8 단백질 분비로 이어짐을 ELISA 검사로 확인할 수 있었다. 한편 이질아메바 파쇄액(Iysate)도 대장상피세포군인 Caco-2에서 IL-8 mRNA발현을 유도하였다. 결론적으로 본 실험은 이질아메바 감염 초기에 대장상피세포로 부터 IL-8이 발현되며, 이에 의하여 염증반응이 촉발될 가능성이 있음을 시사해 준다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권6호
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• pp.3503-3507
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• 2013

Background: Although the majority of investigations concerned with TP53 and its protein have focused on coding regions, recently a set of studies highlighted significant roles of regulatory elements located in p53 mRNA, especially 5'UTR. The wrap53${\alpha}$ transcript is one of those that acts as a natural antisense agent, forming RNA-RNA hybrids with p53 mRNA and protecting it from degradation. Materials and Methods: In this study, we focused on the mutation status of exon $1{\alpha}$ of the WRAP53 gene (according to exon 1 of p53) in 160 breast tumor tissue samples and conducted a bioinformatics search for probable miRNA binding site in the p53/wrap53 overlapping region. Mutations were detected, using single stranded conformation polymorphism (SSCP) and sequencing. We applied the miRBase database for prediction of miRNAs which target overlapping region of p53/wrap53 transcripts. Results: Our results showed all samples to have wild type alleles in exon 1 of TP53 gene. We could detect a novel and unreported intronic mutation (IVS1+56, G>C) outside overlapping regions of p53/wrap53 genes in breast cancer tissues and also predict the presence of a binding site for miR-4732-5p in the 5'UTR of Wrap53 mRNA. Conclusions: From our findings we propose designing further studies focused on overexpression of miRNA-4732-5p and introducing different mutations in the overlapping region of wrap53 and p53 genes in order to study their effects on p53 and its ${\Delta}N$ isoform (${\Delta}$40p53) expression. The results may provide new pieces in the p53 targeting puzzle for cancer therapy.

• 한국초지조사료학회지
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• 제26권1호
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• pp.1-8
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• 2006

조사료로서 소화율을 향상시킨 신품종 형질 전환 오차드그래스를 개발할 목적으로 lignin 합성경로에 있어서 중요한 효소 유전자 중의 하나인 COMT 유전자를 cloning하여 그 특성을 해명하였다. 오차드그래스의 COMT 유전자는 식물체의 전 조직에서 발현되고 있었으며, 특히 줄기와 뿌리조직에서 높은 발현량을 나타냄으로서 목질화에 크게 관여하는 lignin 생합성 유전자일 것으로 판단되었다. Dgcomt 유전자의 발현을 억제시킨 형질전환 오차드그래스를 개발하기 위하여 Dgcomt 유전자를 RNAi 발현벡터에 도입한 후, Agrobacterium 형질전환시스템을 이용하여 오차드그래스에 도입하였다. PCR, Southern 및 Northern 분석 결과 RNAi 발현벡터가 genome에 도입되었으며, Dgcomt 유전자의 발현이 상당한 수준으로 저하되었음을 확인하였다. Dgcomt 유전자의 발현억제는 식물체의 목질화와 더불어 증가되는 lignin의 축적량을 감소시킬 것으로 기대되며 향후 소화율이 증가된 고품질 신품종 목초의 개발에 유용하게 활용될 것으로 판단된다.

• Reproductive and Developmental Biology
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• 제31권4호
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• pp.267-272
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• 2007

Human embryonic stem (ES) cells are derived from the inner cell mass of the preimplantation embryo and have the capacity to differentiate into various types of cells in the body. Hence, these cells may potentially be an indefinite source of cells for cell therapy in various degenerative diseases including neuronal disorders. For clinical applications of human ES cells, directed differentiation of these cells would be necessary. The objective of this study is to develop the culture condition for the expansion of neural precursor cells derived from human ES cells. Human ES cells were able to differentiate into neural precursor cells upon a stepwise culture condition. Neural precursor cells were propagated up to 5000-fold in cell numbers over 12-week period of culture and evaluated for their characteristics. Expressions of sox1 and pax6 transcripts were dramatically up-regulated along the differentiation stages by RT-PCR analysis. In contrast, expressions of oct4 and nanog transcripts were completely disappeared in neural precursor cells. Expressions of nestin, pax6 and sox1 were also confirmed in neural precursor cells by immunocytochemical analysis. Upon differentiation, the expanded neural precursor cells differentiated into neurons, astrocytes, and oligodendrocytes. In immunocytochemical analysis, expressions of type III ${\beta}$-tubulin and MAP2ab were observed Presence of astrocytes and oligodendrocytes were also confirmed by expressions of GFAP and O4, respectively. Results of this study demonstrate the feasibility of long-term expansion of human ES cell-derived neural precursor cells in vitro, which can be a potential source of the cells for the treatment of neurodegenerative disorders.

• 한국산학기술학회논문지
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• 제17권11호
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• pp.443-452
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• 2016

본 논문은 예체능 및 놀이문화 형성 프로그램 중심의 '2016 여름방학 대학생 돌봄교실 봉사'에 참여한 예비유아교사를 연구 참여자로 선정하여, 이들이 봉사과정을 통해 겪은 경험의 의미를 질적으로 분석하고자 하였다. 연구 참여자들은 예비유아교사 6명으로 이들은 봉사프로그램의 계획, 예산편성, 재료구입, 실천, 평가까지 일련의 모든 과정을 스스로 해결해야하는 자기 주도적 봉사의 취지를 수용하고 참의의사를 밝힌 상황에서, 방학 중 40시간 이상 초등학교 저학년(1~2학년) 돌봄교실을 방문하여 봉사프로그램을 실시하였다. 연구자료로는 연구참여자저널, 개인면담 및 단체면담 전사본, 전화통화 전사본, 메일, 차수별 자체평가 기록지 등을 활용하였으며, 연구의 신뢰성과 타당성을 높이기 위해 삼각측정, 구성원검토작업, 전문가의 조언과 검토 등이 이루어졌다. 연구결과, 자기 주도적 봉사에 참여한 예비유아교사들의 봉사경험관련 의미는 '생각하는 힘이 자라요', '소통의 중요성을 깨달아가요', '함께 하는 자체가 중요해요', '자원 정보 활용능력이 필요해요' 등으로 이루어진 '역량을 갖춘 전문적인 교사 되어가기'와 '유초연계교육의 필요성을 알아가요', '유초연계교육에 대해 배우고 싶어요' 등으로 세분화된 '유초연계교육에 대한 안목 키워가기'로 크게 범주화되었다.

• IMMUNE NETWORK
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• 제2권4호
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• pp.217-222
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• 2002

Background: Scid.adh is a recently developed murine thymic lymphoma cell line, which has been used as in vitro model for the study of double negative stage III thymocytes. In this study, we compared the expression profile of a number of genes and proteins, which are tightly related to T cell development and apoptosis, in thymic lymphoma cell lines, R1.1, EL-4, and Scid.adh for the developmental staging. Methods: We examined the expression of development marker genes and proteins in three lymphoma cell lines by flow cytometry and RT-PCR. In addition, the expression of apoptosis-related molecules including bcl-2, bax and Fas was also investigated. Results: As previously reported, Scid.adh cell line expressed CD8 and CD25 but not TCR ${\alpha}$ chain, while R1.1 cells expressed TCR ${\alpha}$ chain and both CD4 and CD8 transcripts. These suggest that R1.1 might be in double positive stage, and low level of CD44 expression and the absence of CD25 support this suggestion. In contrast, EL-4 cells showed high level of TCR ${\alpha}$ chain transcript, and low-level of CD4 expression, suggesting that EL-4 is in more mature stage than R1.1. Further, this suggestion was supported by the lack of mT-20 in EL-4 cells, which is expressed in the immature thymocytes, and Scid.adh and R1.1 cell lines, but not in the terminally differentiated thymocytes and peripheral T cells. Among the apoptosis-related gene, transcripts of bcl-2 gene were detected in both R1.1 and EL-4 but not in Scid.adh cells, while bax was expressed in all cell lines. Fas expression was the highest in EL-4 cells and low in Scid.adh cell line. Conclusion: R1.1 cell may represent double positive stage, and EL-4 is more differentiated cell line. In addition, Scid.adh and EL-4 cell lines are suspected to be useful for the study of function of bcl-2 family and Fas during the thymocyte development, respectively.

• Molecules and Cells
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• 제38권3호
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• pp.259-266
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• 2015

The regulation of flowering time has crucial implications for plant fitness. MicroRNA156 (miR156) represses the floral transition in Arabidopsis thaliana, but the mechanisms regulating its transcription remain unclear. Here, we show that two AGAMOUS-like proteins, AGL15 and AGL18, act as positive regulators of the expression of MIR156. Small RNA northern blot analysis revealed a significant decrease in the levels of mature miR156 in agl15 agl18 double mutants, but not in the single mutants, suggesting that AGL15 and AGL18 co-regulate miR156 expression. Histochemical analysis further indicated that the double mutants showed a reduction in MIR156 promoter strength. The double mutants also showed reduced abundance of pri-miR156a and pri-miR156c, two of the primary transcripts from MIR156 genes. Electrophoretic mobility shift assays demonstrated that AGL15 directly associated with the CArG motifs in the MIR156a/c promoters. AGL18 did not show binding affinity to the CArG motifs, but pull-down and yeast two-hybrid assays showed that AGL18 forms a heterodimer with AGL15. GFP reporter assays and bimolecular fluorescence complementation (BiFC) showed that AGL15 and AGL18 co-localize in the nucleus and confirmed their in vivo interaction. Overexpression of miR156 did not affect the levels of AGL15 and AGL18 transcripts. Taking these data together, we present a model for the transcriptional regulation of MIR156. In this model, AGL15 and AGL18 may form a complex along with other proteins, and bind to the CArG motifs of the promoters of MIR156 to activate the MIR156 expression.

• Molecules and Cells
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• 제41권11호
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• pp.979-992
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• 2018

Potato (Solanum tuberosum L.) is the third most important food crop, and breeding drought-tolerant varieties is vital research goal. However, detailed molecular mechanisms in response to drought stress in potatoes are not well known. In this study, we developed EMS-mutagenized potatoes that showed significant tolerance to drought stress compared to the wild-type (WT) 'Desiree' cultivar. In addition, changes to transcripts as a result of drought stress in WT and drought-tolerant (DR) plants were investigated by de novo assembly using the Illumina platform. One-week-old WT and DR plants were treated with -1.8 Mpa polyethylene glycol-8000, and total RNA was prepared from plants harvested at 0, 6, 12, 24, and 48 h for subsequent RNA sequencing. In total, 61,100 transcripts and 5,118 differentially expressed genes (DEGs) displaying up- or down-regulation were identified in pairwise comparisons of WT and DR plants following drought conditions. Transcriptome profiling showed the number of DEGs with up-regulation and down-regulation at 909, 977, 1181, 1225 and 826 between WT and DR plants at 0, 6, 12, 24, and 48 h, respectively. Results of KEGG enrichment showed that the drought tolerance mechanism of the DR plant can mainly be explained by two aspects, the 'photosynthetic-antenna protein' and 'protein processing of the endoplasmic reticulum'. We also divided eight expression patterns in four pairwise comparisons of DR plants (DR0 vs DR6, DR12, DR24, DR48) under PEG treatment. Our comprehensive transcriptome data will further enhance our understanding of the mechanisms regulating drought tolerance in tetraploid potato cultivars.