• 미생물학회지
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• 제52권1호
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• pp.116-119
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• 2016

텔로미어를 안정적으로 유지하는 것은 세포의 증식과 생존에 필수적이다. 비록 텔로미어 유지에는 telomerase가 가장 중요한 수단이지만 재조합도 텔로미어 유지를 위한 또 다른 중요한 과정으로 작용한다. 본 연구에서는 효모의 텔로미어 내부에 존재하는 $TG_{1-3}$ 반복서열을 이용하여 텔로미어 재조합을 관찰할 수 있는 유전학적 방법을 개발하였다. 관찰된 재조합 빈도는 내부 $TG_{1-3}$ 반복서열의 존재 여부에 영향을 받았으며, 생성된 $FOA^rCan^r$ 콜로니로부터 추출한 유전체 DNA를 사용하여 URA3와 CAN1 marker 근처 부위를 PCR 증폭한 결과, 각 콜로니들은 marker를 포함한 염색체 말단 부위가 결손 된 것으로 나타났다. 뿐만 아니라, 더 긴 내부 $TG_{1-3}$ 반복서열을 사용하였을 때 재조합 빈도는 더 증가하였다. 이러한 결과는 $FOA^rCan^r$ 콜로니 형성이 내부와 말단의 $TG_{1-3}$ 반복서열 사이의 재조합에 기인한다는 것을 의미한다.

• BMB Reports
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• 제51권11호
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• pp.578-583
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• 2018

Telomeres are specialized nucleoprotein complexes that function to protect eukaryotic chromosomes from recombination and erosion. Several telomere binding proteins (TBPs) have been characterized in higher plants, but their detailed in vivo functions at the plant level are largely unknown. In this study, we identified and characterized OsTRFL1 (Oryza sativa Telomere Repeat-binding Factor Like 1) in rice, a monocot model crop. Although OsTRFL1 did not directly bind to telomere repeats $(TTTAGGG){_4}$ in vitro, it was associated with telomeric sequences in planta. OsTRFL1 interacted with rice TBPs, such as OsTRBF1 and RTBP1, in yeast and plant cells as well as in vitro. Thus, it seems likely that the association of OsTRFL1 with other TBPs enables OsTRFL1 to bind to telomeres indirectly. T-DNA inserted OsTRFL1 knock-out mutant rice plants displayed significantly longer telomeres (6-25 kb) than those (5-12 kb) in wild-type plants, indicating that OsTRFL1 is a negative factor for telomere lengthening. The reduced levels of OsTRFL1 caused serious developmental defects in both vegetative and reproductive organs of rice plants. These results suggest that OsTRFL1 is an essential factor for the proper maintenance of telomeres and normal development of rice.

• Molecules and Cells
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• 제26권1호
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• pp.93-99
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• 2008

Transcriptional silencing is regulated by promoter methylation and histone modifications such as methylation and acetylation. We constructed a Schizosaccaromyces pombe reporter strain, KCT120a, to identify modifiers of transcriptional silencing, by inserting the $ura4^+$ gene into a heterochromatic telomere region. Two compounds inhibited the activity of histone deacetylases, induced acetylation of histone H3 and caused apoptotic cell death in HeLa cells. Expression of gelsolin and $p21^{waf1/cip1}$ also increased, as it does in response to HDAC inhibitors such as TSA. Therefore, these compounds appear to be potent inhibitors of HDACs, and hence potential anti-cancer drugs. Our observations suggest that a yeast cell-based assay system for transcriptional silencing may be useful for identifying histone deacetylase inhibitors and other agents affecting chromatin remodeling.

• BMB Reports
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• 제52권3호
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• pp.175-180
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• 2019

Telomeres are nucleoprotein complexes at the physical ends of linear eukaryotic chromosomes. They protect the chromosome ends from various external attacks to avoid the loss of genetic information. Telomeres are maintained by cellular activities associated with telomerase and telomere-binding proteins. In addition, epigenetic regulators have pivotal roles in controlling the chromatin state at telomeres and subtelomeric regions, contributing to the maintenance of chromosomal homeostasis in yeast, animals, and plants. Here, we review the recent findings on chromatin modifications possibly associated with the dynamic states of telomeres in Arabidopsis thaliana.

• 생명과학회지
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• 제26권6호
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• pp.646-650
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• 2016

본 연구는 염색체 가공기술(chromosome manipulation technique)을 이용하여 다양한 개수의 염색체를 가진 균주들의 세포 성장속도 및 life span을 비교하여 염색체 수의 증가가 세포 생리에 미치는 영향을 조사하였다. 16개의 염색체를 가지는 숙주세포 FY833 균주와 18개의 염색체를 가지는 YKY18 및 YKY18R 균주, 24개의 염색체를 가지는 YKY24 균주와 30개의 염색체를 가지는 YKY30 균주를 사용하여 specific growth rate를 비교해 본 결과, YKY18 균주와 YKY24 균주는 세포성장의 변화가 거의 없었으나, YKY18R 균주와 YKY30 균주에서는 숙주세포에 비해 각각 25%와 40% 이상 성장이 감소됨을 확인 할 수 있었다. 또한 염색체 수와 노화의 관계를 알아보기 위해 replicative life span을 조사해 본 결과, YKY24균주와 YKY30 균주에서 숙주세포에 비해 약 14%와 45% 정도로 life span이 감소했음을 알 수 있었다. 노화인자로 알려져 있는 telomere의 길이도 인공염색체의 수가 증가될수록 점점 다양해지고 길이가 짧아짐을 확인 할 수 있었다. 따라서 염색체 수의 증가도 새로운 노화원인이 될 수 있다는 가능성을 제시하였고, 본 연구 결과가 다양한 인공염색체를 가진 산업용 균주의 안정적인 개량을 위한 기초 자료로 활용될 수 있을 것이라 기대한다.

• 생명과학회지
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• 제30권9호
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• pp.819-825
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• 2020

모든 생명체는 연령이 증가함에 따라 생체 내에서 노화된 세포수가 축적되면서 피부주름 형성, 근육퇴화, 백내장 및 모발의 백발화 과정 같은 노화의 특성을 나타낸다. 이러한 노화의 핵심적인 원인으로 알려진 세포노화는 세포가 외부 및 내부요인에 의하여 늙어서 결국 세포의 증식이 정지됨으로 생물체의 노화와 직접적으로 밀접하게 연관되어 있다. 이러한 현상에 대한 보다 심층적인 연구로부터 세포노화의 원인이 텔로미어가 세포 분열에 따라 점차적으로 짧아짐으로, 텔로미어의 길이에 의해서 결정된다는 것이다. 최근에는 유전자 발현에 영향을 줄 수 있는 히스톤 디아세틸레이즈 유전자가 효모에서 뿐만 아니라 예쁜 꼬마 선충 및 사람의 항노와 기전에 깊숙히 관여하고 있다는 것이 밝혀졌다. 한편, 최근에는 늙은 세포가 노화 현상에 결정적인 역할을 한다는 것이 발견하여 이러한 노화세포를 채내로부터 제거함으로써 젊은 세포의 증식을 촉진하여 노화를 지연 할 수 있다는 것이 보고되었다. 그러므로 향후 잠재적인 항노화제를 개발하기 위해서는 텔로머레이즈 활성화제, 서르튜언 활성화제, 세노릭틱스에 대한 심층연구로부터 시작되어야 한다고 판단되어, 최근에 각광 받고 있는 위와 관련된 항노화 후보물질에 대한 최근 연구에 대하여 기술한다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권1호
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• pp.1-6
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• 2000

For the rapid selection of higher recombinant hirudin producing strain in a methylotrophic yeast Hansenula polymorpha, a multiple gene integration and dose-dependent selection vector, based on a telomere-associated ARS and a bacterial aminoglycoside 3-phosphotransferase (aph) gene, was adopted. Two hirudin expression cassettes (HV1 and HV2) were constructed using the MOX promoter of H. polymorpha and the mating factor $\alpha$ secretion signal of S. cerevisiae. Multiple integrants of a transforming vector containing hirudin expression cassettes were easily selected by using an antibiotic, G418. Hirudin expression level and integrated plasmid copy number of the tested transformants increased with increasing the concentration of G418 used for selection. The expression level of HV1 was consistently higher than that of HV2 under the similar conditions, suggesting that the gene context might be quite important for the high-level gene expression in H. polymorpha. The highest hirudin producing strain selected in this study produced over 96 mg/L of biologically active hirudin in a 500-mL flask and 165 mg/L in a 5-L fermentor.

• 식물조직배양학회지
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• 제25권6호
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• pp.453-475
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• 1998

During the 100 years since the initial discovery of meiotic phenomenon many brilliant aspects have been elucidated, but further researches based on light microscopy alone as an experimental tool have been found to have some limits and shortcomings. By the use of electron microscopy and armed with the advanced knowledges on modern genetics and biochemistry it has been possible to applu molecular technology in gaining information on the detailed aspects of meiosis. As synapsis takes place, a three-layered proteinous structure called the synatonemal complex starts to form in the space between the homologous chromosomes. To be more precise, it begins to form along the paired chromosomes early in the prophase I of meiotic division. The mechanism that leads to precise point-by-point pairing between homologous chromocomes division. The mechamism that leads to precise point-by-point pairing between homologous chromosomes remains to be ascertained. Several items of information, however, suggest that chromsome alignment leading to synapsis may be mediated somehow by the nuclear membrane. Pachytene bivalents in eukaryotes are firmly attached to the inner niclear membrane at both termini. This attached begins with unpaired leptotene chromosomes that already have developed a lateral element. Once attached, the loptotene chromosomes begin to synapse. A number of different models have been proposed to account for genetic recombination via exchange between DNA strands following their breakage and subsequent reunion in new arrangement. One of the models accounting for molecular recombination leading to chromatid exchange and chiasma formation was first proposed in 1964 by Holliday, and 30 years later still a modified version of his model is favored. Nicks are made by endomuclease at corresponding sites on one strant of each DNA duplex in nonsister chromatid of a bivalent during prophase 1 of meiosis. The nicked strands loop-out and two strands reassociate into an exchanged arrangement, which is sealed by ligase. The remaining intact strand of each duplex is nicked at a site opposite the cross-over, and the exposed ends are digested by exonuclease action. Considerable progress has been made in recent years in the effort to define the molecular and organization features of the centromere region in the yeast chromosome. Centromere core region of the DNA duplex is flanked by 15 densely packed nucleosomes on ons side and by 3 packed nucleosomes on the other side, that is, 2000 bp on one side and 400 400 bp in the other side. All the telomeres of a given species share a common DNA sequence. Two ends of each chromosome are virtually identical. At the end of each chromosome there exist two kinds of DNA sequence" simple telpmeric sequences and telpmere-associated sequencies. Various studies of telomere replication, function, and behabior are now in progress, all greatly aided by molecular methods. During nuclear division in mitosis as well as in meiosis, the nucleili disappear by the time of metaphase and reappear during nuclear reorganizations in telophase. When telophase begins, small nucleoli form at the NOR of each nucleolar-organizing chromosome, enlarge, and fuse to form one or more large nucleoli. Nucleolus is a special structure attached top a specific nucleolar-organizing region located at a specific site of a particular chromosome. The nucleolus is a vertical factory for the synthesis of rRNAs and the assenbly of ribosome subunit precursors.sors.