• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.280-280
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• 2014

We report the fabrication and electroluminescent characteristics of GaN/InxGa1-xN microdonut-shaped light-emitting diode (LED) microarrays as variable-color emitters. The diameter, width, height, and period of the GaN microdonuts were controlled by their growth parameters and the geometrical factors of the growth mask patterns. For the fabrication of microdonut LEDs, p-GaN/p-AlxGa1-xN/u-GaN/u-InxGa1-xN heteroepitaxial layers were coated on the entire surface of n-GaN microdonuts. The microdonut LED arrays showed strong light emission, which could be seen with the unaided eye under normal room illumination. Additionally, magnified optical images of microdonut LED arrays exhibited microdonut-shaped light emissions having spatially resolved blue and green colors. Their electroluminescence spectra had two dominant peaks at 460 and 560 nm. With increasing applied voltage, the intensity of the blue emission peak increased much faster than that of the green emission peak, indicating that the color of the LEDs is tunable. We also demonstrated that EL spectra of the devices could be controlled by changing the size of microdonut LEDs. What we want to emphasize here with the microdonut LEDs is that they have additional inner sidewall facets which did not exist for other typical three-dimensional structures including nanopyramids and nanorods, and that InxGa1-xN single quantum well formed on the inner sidewall facets had unique thickness and chemical composition, which generated additional EL color. The origin of the electroluminescence peaks was investigated by structural characterizations and chemical analyses.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 2003년도 추계국제학술대회
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• pp.173-173
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• 2003

With the introduction of DNA microarrays, a high throughput analysis of gene expression is now possible as a replacement to the traditional time-consuming Southern-blot analysis. This cDNA microarray should be ahighly favored technology in the area of molecular toxicology or analysis of environmental stresses.In this study, therefore, we developed a novel cDNA microarray for analyzing stress-specific responses in japanese Medaka fish. In the design and fabrication of this stress specific functional cDNA microarray, 123 different genes in Medaka fish were selected from eighteen different stress responsive groups and spotted on a 25${\times}$75 mm glass surface. After exposure of the fish to bisphenol A which is the one of the well-known endocrine disrupting chemicals (EDCs), over 1 or 10 days, the responses of the DNA chip were found to show distinct expression patterns according to the mode of toxic actions from environmental toxicants. As a results, they showed specific gene expression pattern to bisphenol A, additionally, the chemical spesific biomarkers could be suggested based on the chip analysis data. Therefore, this chip can be used to monitor stress responses of unknown and/or known toxic chemicals using Medaka fish and may be used for the further development of biomarkers by utilizing the gene expression patterns for known contaminants.

• 대한두경부종양학회지
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• 제21권2호
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• pp.121-125
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• 2005

Objectives: To investigate the role of MMP-2 and TIMP-2 in the invasion and metastasis of thyroid papillary microcarcinomas. Materials and Methods: We performed immunohistochemical study on MMP-2 and its tissue inhibitor (TIMP-2) using tissue microarrays containing 2 cores of 40 microPTC and 8 non-neoplastic thyroid tissue. The expression intensity was semiquantitatively scored as -, ${\pm}$, +1, +2, and +3. Results: Both MMP-2 and TIMP-2 expression was observed in all tumors(100%) and in 1 of 8 non-neoplastic tissue(12.5%), and the positive staining was restricted to the epithelial cells. In 17 and 23 tumors with or without extrathyroid invasion, respectively, 8(47%) and 10(43%) cases showed moderate to strong(+23) positivity for MMP-2. TIMP-2 expression was moderate to strong in 13 cases(76%) and 16 cases(70%) in each group. In multifocal and solitary tumors, 3 of 6(50%) and 11 of 21(52%) cases showed moderate to strong MMP-2 expression, and 5/6(83%) and 15/21(71%) showed moderate to strong TIMP-2 expression. Conclusion: There is no relationship between MMP-2 or TIMP-2 expression and extrathyroid invasion or tumor multifocality in papillary microcarcinoma of the thyroid gland.

• Molecules and Cells
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• 제21권3호
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• pp.343-355
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• 2006

Stem cells are unique cell populations with the ability to undergo both self-renewal and differentiation, although a wide variety of adult stem cells as well as embryonic stem cells have been identified and stem cell plasticity has recently been reported. To identify genes implicated in the control of the stem cell state as well as the characteristics of each stem cell line, we analyzed the expression profiles of genes in human embryonic, hematopoietic ($CD34^+$ and $CD133^+$), and mesenchymal stem cells using cDNA microarrays, and identified genes that were differentially expressed in specific stem cell populations. In particular we were able to identify potential hESC signature-like genes that encode transcription factors (TFAP2C and MYCN), an RNA binding protein (IMP-3), and a functionally uncharacterized protein (MAGEA4). The overlapping sets of 22 up-regulated and 141 down-regulated genes identified in this study of three human stem cell types may also provide insight into the developmental mechanisms common to all human stem cells. Furthermore, our comprehensive analyses of gene expression profiles in various adult stem cells may help to identify the genetic pathways involved in self-renewal as well as in multi-lineage specific differentiation.

• Journal of Animal Science and Technology
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• 제48권2호
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• pp.169-190
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• 2006

최근 가축에 있어서 DNA marker를 이용하여 경제적으로 유용한 유전자를 찾아내는 연구가 활발히 진행되고 있다. 소의 경우 생산성을 향상시키기 위하여 경제형질관련 양적 형질좌위에 존재하는 후보 유전자를 선발한 후 형질변이의 원인이 되는 염기서열을 찾아 표지인자로 이용을 하고 있다. 본 연구는 소의 중요 경제형질인 육질 및 육량과 관련된 분자 유전학적 연구와 더불어 경제형질관련 후보유전자를 찾아내기 위하여 최근에 많이 이용되고 있는 microarray에 대하여 고찰하였다. 특히 microarray의 경우 cDNA microarray에서 oligoarray를 제작하여 이용함으로서 실험의 오차를 최대한 줄이는 방향으로 연구가 진행되고 있다. 소의 형질 관련 유전자에 관한 연구는 bovine genome sequencing이 끝난 현 시점에서 연구의 속도가 가속화될 것으로 생각되며 경제형질 원인 유전자의 분석 뿐 아니라 질병 저항성과 환경에 영향을 많이 받는 유전자를 확인하여 선발에 이용하기 위한 연구가 계속될 것으로 생각된다.

• Genomics & Informatics
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• 제17권3호
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• pp.28.1-28.9
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• 2019

Bar-code (tag) microarrays of yeast gene-deletion collections facilitate the systematic identification of genes required for growth in any condition of interest. Anti-sense strands of amplified bar-codes hybridize with ~10,000 (5,000 each for up-and down-tags) different kinds of sense-strand probes on an array. In this study, we optimized the hybridization processes of an array for fission yeast. Compared to the first version of the array (11 ㎛, 100K) consisting of three sectors with probe pairs (perfect match and mismatch), the second version (11 ㎛, 48K) could represent ~10,000 up-/ down-tags in quadruplicate along with 1,508 negative controls in quadruplicate and a single set of 1,000 unique negative controls at random dispersed positions without mismatch pairs. For PCR, the optimal annealing temperature (maximizing yield and minimizing extra bands) was 58℃ for both tags. Intriguingly, up-tags required 3× higher amounts of blocking oligonucleotides than down-tags. A 1:1 mix ratio between up- and down-tags was satisfactory. A lower temperature (25℃) was optimal for cultivation instead of a normal temperature (30℃) because of extra temperature-sensitive mutants in a subset of the deletion library. Activation of frozen pooled cells for >1 day showed better resolution of intensity than no activation. A tag intensity analysis showed that tag(s) of 4,316 of the 4,526 strains tested were represented at least once; 3,706 strains were represented by both tags, 4,072 strains by up-tags only, and 3,950 strains by down-tags only. The results indicate that this microarray will be a powerful analytical platform for elucidating currently unknown gene functions.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2004년도 Annual Meeting BioExibition International Symposium
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• pp.258-265
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• 2004

Numerous genes of Escherichia coli have been shown to growth phase-dependent expression throughout growth. The global patterns of growth phase-dependent gene expression of E. coli throughout growth using oligonucleotide microarrays containing a nearly complete set of 4,289 annotated open reading frames. To determine the change of gene expression throughout growth, we compared RNAs taken from timecourses with common reference RNA, which is combined with equal amount of RNA pooled from each time point. The hierarchical clustering of the conditions in accordance with timecourse expression revealed that growth phases were clustered into four classes, consistent with known physiological growth status. We analyzed the differences of expression levels at genome level in both exponential and stationary growth phase cultures. Statistical analysis showed that 213 genes are shown to, growth phase-dependent expression. We also analyzed the expression of 256 known operons and 208 regulatory genes. To assess the global impact of RpoS, we identified 193 genes coregulated with rpoS and their expression levels were examined in the isogenic rpoS mutant. The results revealed that 99 of 193 were novel RpoS-dependent stationary phase-induced genes and the majority of those are functionally unknown. Our data provide that global changes and adjustments of gene expression are coordinately regulated by growth transition in E. coli.

• Journal of Microbiology and Biotechnology
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• 제20권12호
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• pp.1637-1646
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• 2010

The bacterium Deinococcus radiodurans is one of the most resistant organisms to ionizing radiation and other DNA-damaging agents. Although, at present, 30 Deinococcus species have been identified, the whole-genome sequences of most species remain unknown, with the exception of D. radiodurans (DRD), D. geothermalis, and D. deserti. In this study, comparative genomic hybridization (CGH) microarray analysis of three Deinococcus species, D. radiopugnans (DRP), D. proteolyticus (DPL), and D. radiophilus (DRPH), was performed using oligonucleotide arrays based on DRD. Approximately 28%, 14%, and 15% of 3,128 open reading frames (ORFs) of DRD were absent in the genomes of DRP, DPL, and DRPH, respectively. In addition, 162 DRD ORFs were absent in all three species. The absence of 17 randomly selected ORFs was confirmed by a Southern blot. Functional classification showed that the absent genes spanned a variety of functional categories: some genes involved in amino acid biosynthesis, cell envelope, cellular processes, central intermediary metabolism, and DNA metabolism were not present in any of the three deinococcal species tested. Finally, comparative genomic data showed that 120 genes were Deinococcus-specific, not the 230 reported previously. Specifically, ddrD, ddrO, and ddrH genes, previously identified as Deinococcus-specific, were not present in DRP, DPL, or DRPH, suggesting that only a portion of ddr genes are shared by all members of the genus Deinococcus.

• Journal of Plant Biotechnology
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• 제33권3호
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• pp.161-169
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• 2006

식물대사체학은 식물세포, 조직, 기관, 혹은 개체수준에서 주어진 시간과 조건에서 발견되는 모든 대사물질을 밝히고, 시간의 경과 혹은 조건의 변화에 따른 metabolic profiling의 변화를 연구하는 식물학 분야이다. 식물대사체학은 생물에 대한 전체론적 접근을 위한 가장 최근에 발달된 omics분야의 하나로서 일종의 시스템 생물학이다. 전체론적 접근과 이해를 위해서 대사체학은 metabolic profiling의 계량화학 혹은 다변량분석 방법을 자주 사용한다. 식물학분야에서 대사체학은 애기장대나 벼와 같은 모델식물에 tag를 도입하여 형질전환시킨 돌연변이체에 대해 DNA microarray와 함께 사용하여 유전자의 기능을 밝히는데 유용하게 사용된다. 본 총설에서는 식물대사체학의 기본 개념과 1H NMR 혹은 FTIR으로 얻은 metabolic profiling의 다변량분석에 대한 실용적인 사용법을 소개하고자 하였다.

• Genomics & Informatics
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• 제3권4호
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• pp.154-158
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• 2005

Germ-line mutations of the BRCA1 gene confer an increased risk for breast and ovarian cancers. BRCA1 in female cells is directly related with the maintenance of the inactive X chromosome (Xi). The effect by the loss of the BRCA1 function on the X chromosome gene expression remains unclear in cancer cells. We attempted to investigate the expression pattern of the X-linked genes by performing BRCA1 knockdown via RNA interference in the MCF7 breast cancer cell line. The transcriptional and translational levels of BRCA1 were decreased over 95% in the MCF7 cells after BRCA1 knockdown. The expression patterns of one hundred ninety X-linked genes were profiled by the X chromosome-specific cDNA arrays. A total of seven percent of the X-linked genes (14/190) were aberrantly expressed by over 2-fold in the MCF7-BRCA1 knockdown cells, which contained two up-regulated genes (2/190, 1 %) and 12 down-regulated genes (12/190, 6.3%). It is interesting that 72% of the aberrantly expressed X-linked genes were located on the Xq (10/14,) region. Our data suggests that BRCA1 may not be important to maintain X chromosome inactivation in cancer because the BRCA1 knockdown did increase the expression of the only one percent of X-linked genes in the human breast cancer cells.