• Animal cells and systems
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• 제13권2호
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• pp.235-245
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• 2009

Embryonic stem (ES) cells have a capability to generate all types of cells. However, the mechanism by which ES cells differentiate into specific cell is still unclear. Using microarray technology, the differentiation process in mouse embryonic stem cells was characterized by temporal gene expression changes of mouse ES cells during differentiation in a monolayer culture. A large number of genes were differentially regulated from 1 day to 14 days, and less number of genes were differentially expressed from 14 days to 28 days. The number of up-regulated genes was linearly increased throughout the 28 days of in vitro differentiation, while the number of down-regulated genes reached the plateau from 14 days to 28 days. Most differentially expressed genes were functionally classified into transcriptional regulation, development, extra cellular matrix (ECM),cytoskeleton organization, cytokines, receptors, RNA processing, DNA replication, chromatin assembly, proliferation and apoptosis related genes. While genes encoding ECM proteins were up-regulated, most of the genes related to proliferation, chromatin assembly, DNA replication, RNA processing, and cytoskeleton organization were down-regulated at 14 days. Genes known to be associated with embryo development or transcriptional regulation were differentially expressed mostly after 14 days of differentiation. These results indicate that the altered expression of ECM genes constitute an early event during the spontaneous differentiation, followed by the inhibition of proliferation and lineage specification. Our study might identify useful time-points for applying selective treatments for directed differentiation of mouse ES cells.

• 한국수정란이식학회지
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• 제30권2호
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• pp.99-107
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• 2015

The aim of the present study was to identify coat color associated genes that are differentially expressed in mature Korean brindle cattle (KBC) with different coat colors and in Hanwoo cows. KBC calves, before and after coat color appearance, were included. Total cellular RNA was isolated from the tail hair cells and used for microarray. The number of expressed coat color associated genes/probes was 5813 in mature KBC and Hanwoo cows. Among the expressed coat color associated genes/probes, 167 genes were the coat color associated genes listed in the Gene card database and 125 genes were the pigment and melanocyte genes listed in the Gene ontology_bovine database. There were 23 genes/probes commonly listed in both databases and their expressions were further studied. Out of the 23 genes/probes, MLPH, PMEL, TYR and TYRP1 genes were expressed at least two fold higher (p<0.01) levels in KBC with brindle color than either Hanwoo or KBC with brown color. TYRP1 expression was 22.96 or 19.89 fold higher (p<0.01) in KBC with brindle color than either Hanwoo or KBC with brown color, respectively, which was the biggest fold difference. The hierarchical clustering analysis indicated that MLPH, PMEL, TYR and TYRP1 were the highly expressed genes in mature cattle. There were only a few genes differentially expressed after coat color appearance in KBC calves. Studies on the regulation and mechanism of gene expression of highly expressed genes would be next steps to better understand coat color determination and to improve brindle coat color appearance in KBC.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권5호
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• pp.432-443
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• 2005

Microarray technology has contributed Significantly to the understanding of bacterial genetics and transcriptional regulation. One neglected aspect of this technology has been optimization of microarray-generated signals and quality of generated information. Full genome microarrays were developed for Clostridium acetobutylicum through spotting of PCR products that were designed with minimal homology with all other genes within the genome. Using statistical analyses it is demonstrated that Signal quality is significantly improved by increasing the hybridization volume. possibly increasing the effective number of transcripts available to bind to a given spot, while changes in labeled probe amounts were found to be less sensitive to improving signal quality. In addition to Q-RT-PCR, array validation was tested by examining the transcriptional program of a mutant (M5) strain lacking the pSOL1 178-gene megaplasmid relative to the wildtype (WT) strain. Under optimal conditions, it is demonstrated that the fraction of false positive genes is 1% when considering differentially expressed genes and 7% when considering all genes with signal above background. To enhance genomic-scale understanding of organismal physiology, using data from these microarrays we estimated that $40{\sim}55%$ of the C. acetobutylicum genome is expressed at any time during batch culture, similar to estimates made for Bacillus subtilis.

• 응용통계연구
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• 제22권5호
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• pp.1059-1072
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• 2009

마이크로어레이 극소수 샘플(array) 자료의 분석에서는 유의한 발현수치를 나타내는 유전자를 검정통계량에 의해 결정하는 것이 주요과제이다. 이 때 수 천 또는 수 만개인 유전자의 발현수치로부터 귀무분포(null distribution)의 생성이 필수적이며, 극소수 샘플 자료의 경우에는 순열방법(permutation methods)에 의해 귀무분포를 생성하는 것이 가장 바람직하다. 본 논문에서는 귀무분포 생성에 사용될 수 있는 매우 단순한 검정통계량을 제시하면서 더불어 귀무분포 생성에 적절한 순열방법도 제안한다. 모의실험으로 기존의 검정통계량으로 생성된 귀무분포와 본 논문에서 제안하는 검정통계량의 귀무분포를 비교하며, 실제 자료에 적용하여 유의 유전자를 탐색한다.

• Journal of Plant Biotechnology
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• 제45권1호
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• pp.45-54
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• 2018

This research was conducted to study the gene expression of coffee (Coffea arabica L.) seedlings under salt stress condition. A solution of five percent ($2.3dS\;m^{-1}$) deep sea water was used for the salt treatment, and it was thereby compared to normal irrigation water ($0.2dS\;m^{-1}$) used for the control treatment. The mRNA was extracted from the leaves of the coffee seedlings for a comprehensive analysis. In this study, a total of 19,581 genes were identified and aligned to the reference sequences available in the coffee genome database. The gene ontology analysis was performed to estimate the number of genes associated with the identified biological processes, cellular components and molecular functions. Among the 19,581 genes, 7369 (37.64%) were associated with biological processes, 5909 (30.18%) with cellular components, and 5325 (27.19%) with molecular functions. The remaining 978 (4.99%) genes were therefore grouped as unclassified. A differential gene expression analysis was performed using the DESeq2 package to identify the genes that were differentially expressed between the treatments based on fold changes and p-values. Namely, a total of 611 differentially expressed genes were identified (treatment/control) in that case. Among these, 336 genes were up-regulated while 275 of the genes were down-regulated. Of the differentially expressed genes, 60 genes showed statistically significant (p < 0.05) expression, 44 of which were up-regulated and 16 which were down-regulated. We also identified 11 differentially expressed transcription factor genes, 6 of which were up-regulated and rest 5 genes were down-regulated. The data generated from this study will help in the continued interest and understanding of the responses of coffee seedlings genes associated with salinity stress, in particular. This study will also provide important resources for further functional genomics studies.

• 생명과학회지
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• 제23권1호
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• pp.8-14
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• 2013

고추 탄저병균의 포자 발아 단계에서 발현되는 유전자를 파악하기 위해 포자 발아단계cDNA library를 제작하고, 임의로 선택된 cDNA clone들에 대한 EST sequencing을 실시하였다. 총 983개 EST를 확보하여 contig assembly를 실시한 결과, 197개 contigs와 267개 singletons으로 조합되어, 최종적으로 464개의 유전자를 동정하였다. 464개 유전자 서열에서 유추한 아미노산 서열을 이용한 상동유전자 검색을 통해 절반의 유전자가 GenBank에 기존 등록된 유전자와 유의성 있는 유사성을 보였다. 가장 높은 빈도로 발현된 유전자는 elongation factor, histone protein, ATP synthease, 14-3-3 protein, clock controlled protein을 암호화하는 유전자들이었다. 그리고 고추 탄저병균의 세포 발달과정에 관여 하는것으로 추정되는 GTP-binding protein, MAP kinase, transaldolase, ABC transporter 유전자들도 검출되었다. 또한 고추탄저병균의 병원성에 영향을 미치는 것으로 파악되는 ATP citrate lyase, CAP20, manganese-superoxide dismutase 유전자들도 검출되어, EST sequencing 을 통한 세포 발달 단계 발현 유전자 탐색이 효과적임을 알 수 있었다.

• Molecules and Cells
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• 제25권2호
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• pp.279-288
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• 2008

The analysis of microarray data is essential for large amounts of gene expression data. In this review we focus on clustering techniques. The biological rationale for this approach is the fact that many co-expressed genes are co-regulated, and identifying co-expressed genes could aid in functional annotation of novel genes, de novo identification of transcription factor binding sites and elucidation of complex biological pathways. Co-expressed genes are usually identified in microarray experiments by clustering techniques. There are many such methods, and the results obtained even for the same datasets may vary considerably depending on the algorithms and metrics for dissimilarity measures used, as well as on user-selectable parameters such as desired number of clusters and initial values. Therefore, biologists who want to interpret microarray data should be aware of the weakness and strengths of the clustering methods used. In this review, we survey the basic principles of clustering of DNA microarray data from crisp clustering algorithms such as hierarchical clustering, K-means and self-organizing maps, to complex clustering algorithms like fuzzy clustering.

• Communications for Statistical Applications and Methods
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• 제29권5호
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• pp.591-601
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• 2022

In gene set analysis with microarray expression data, a group of genes such as a gene regulatory pathway and a signaling pathway is often tested if there exists either differentially expressed (DE) or differentially co-expressed (DC) genes between two biological conditions. Recently, a statistical test based on covariance estimation have been proposed in order to identify DC genes. In particular, covariance regularization by hard thresholding indeed improved the power of the test when the proportion of DC genes within a biological pathway is relatively small. In this article, we compare covariance thresholding methods using four different regularization penalties such as lasso, hard, smoothly clipped absolute deviation (SCAD), and minimax concave plus (MCP) penalties. In our extensive simulation studies, we found that both SCAD and MCP thresholding methods can outperform the hard thresholding method when the proportion of DC genes is extremely small and the number of genes in a biological pathway is much greater than a sample size. We also applied four thresholding methods to 3 different microarray gene expression data sets related with mutant p53 transcriptional activity, and epithelium and stroma breast cancer to compare genetic pathways identified by each method.

• Asian-Australasian Journal of Animal Sciences
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• 제18권8호
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• pp.1080-1087
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• 2005

By screening specific genes related to the muscle growth of swine using cDNA microarray technology, a total of 5 novel genes (GF (growth factor) I, II, III, IV and V) were identified. Results of southern blotting to investigate the number of copies of these genes in the genome of swine indicated that GF I, GF III, and GF V existed as one copy and GF II, and GF IV existed as more than two copies. It was suggested that there are many isoforms of these genes in the genome of swine. Also, results of northern blotting to investigate whether these genes were expressed in grown muscle, using GF I, III, and V indicated that all the genes were much more expressed in the muscle of swine with body weight of 90 kg. Expression patterns of these genes in other organs, namely muscle and propagation and fat tissues, were investigated by extracting RNA from the tissues. These genes were not expressed in the propagation and fat tissues, but were expressed in the muscle tissue. To determine the mechanism of muscle growth, further studies should be preceded using the 3 specific genes related to muscle growth, that is GF I, III, and V.

• Radiation Oncology Journal
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• 제23권1호
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• pp.43-50
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• 2005

목적 : 자경경부암세포에서 polymeric chain reaction (PCR)원리를 이용한 suppression subtractive hybridization (SSH) 방법으로 방사선조사 시 차등 발현되는 유전자를 동정하고자 하였다. 대상 및 방법 : 자궁경부암세포주인 HeLa세포주에 방사선조사 전과 후 총 RNA와 poly $(A)^+$ mRNA를 분리였다. SSH방법으로 forward 및 reverse-subtracted cDNA libraries를 만들었다. 차등 발현된 유전자를 screening하기 위해 reverse Northern blotting (dot blot analysis)을 이용하여 각각의 library에서 88개의 클론을 선택하였고 Nothern blotting으로 확인 후 sequencing하였다. 결과 : screening상 176개 클론 중 forward-subtracted library에서 10개의 유전자가 reverse-subtracted library에서 9개의 유전자가 동정되었다. forward-subtracted library로부터 3개의 유전자가 Northern blotting에 의하여 확인되었고 이중 telomerase catalytic subunit and sodium channel-like protein 유전자와 1개의 ESTs (expressed sequence tags) 유전자가 방사선선량에 따라 증가하쳐다. 결론 : 본 연구를 통해 자궁경부암세포주에서 방사선에 의해 유도되는 유전자를 SSH 방법을 통해 동정할 수 있었다. 그러나 이러한 유전자가 어떤 생물학적인 기능을 갖고 있는지에 대한 계속적인 연구가 필요하다