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DNA Strand Breaks in Mitotic Germ Cells of Caenorhabditis elegans Evaluated by Comet Assay
Byungchan Ahn,Sojin Park,Seoyun Choi 한국분자세포생물학회 2016 Molecules and cells Vol.39 No.3
DNA damage responses are important for the maintenance of genome stability and the survival of organisms. Such responses are activated in the presence of DNA damage and lead to cell cycle arrest, apoptosis, and DNA repair. In Caenorhabditis elegans, double-strand breaks induced by DNA damaging agents have been detected indirectly by antibodies against DSB recognizing proteins. In this study we used a comet assay to detect DNA strand breaks and to measure the elimination of DNA strand breaks in mitotic germline nuclei of C. elegans. We found that C. elegans brc-1 mutants were more sensitive to ionizing radiation and camptothecin than the N2 wild-type strain and repaired DNA strand breaks less efficiently than N2. This study is the first demonstration of direct measurement of DNA strand breaks in mitotic germline nuclei of C. elegans. This newly developed assay can be applied to detect DNA strand breaks in different C. elegans mutants that are sensitive to DNA damaging agents.
Byungchan Han(한병찬) 한국표면공학회 2022 한국표면공학회 학술발표회 초록집 Vol.2022 No.6
A nanocatalyst is at the central position as a promoter of various chemical. Innovative design of highly functional catalyst materials has been, however, delayed. In molecular level computational electrochemistry new research paradigm has been established, which substantially incorporates IT-based artificial intelligence (AI) technology into machine learning algorism. Using the new computational methodology high-throughput screening of promising nanoparticle candidates has been attempted for various desired applications. Whether the frontier approach is successful or not is significantly controlled by the reliability and accuracy of input database. It is true that substantial amounts of the data are come by previous literatures and often ab-initio calculations with idealized model systems. The conditions in which the data were generated may be so different from the operando circumstances of the target materials. To secure extreme-level integrity of the database the in-situ measurement of nanoparticle structures should be carried out, from which the reliable correlation of the structure-performance-design principle can be identified. Using first-principles calculations we studied nanoparticles with adsorbate ligands in liquid solution to establish three-dimensional (3D) structure and property database, which are, then, analyzed through AI-based neural-network approach with high speed and accuracy. The information includes sizes, lattice distortions, and defects with picometer resolution under non-vacuum conditions. The computational outcomes are rigorously validated from the 3D liquid-cell electron microscopy. The approach is indeed ‘knowledge-based’ AI, which can be expected to make groundbreaking ways toward the quantum nanoarchitecture for hybrid interface materials.
A Performance Evaluation for applying e-navigation on Wibro in Marine Environment
ByungChan Kim,SungHoon Jung,GyuSik Yang 한국멀티미디어학회 2009 한국멀티미디어학회 국제학술대회 Vol.2009 No.-
This paper presents a performance evaluation in order to show the possibility of e-navigation application on Wibro communication system in marine environment. For this purpose, we had experimented Wibro system on the commercial passenger ship, while Wibro base station transmitting signals toward the ship side.
Impedance Learning for Robotic Contact Tasks Using Natural Actor-Critic Algorithm
Byungchan Kim,Jooyoung Park,Shinsuk Park,Sungchul Kang IEEE 2010 part B Vol.40 No.2
<P>Compared with their robotic counterparts, humans excel at various tasks by using their ability to adaptively modulate arm impedance parameters. This ability allows us to successfully perform contact tasks even in uncertain environments. This paper considers a learning strategy of motor skill for robotic contact tasks based on a human motor control theory and machine learning schemes. Our robot learning method employs impedance control based on the equilibrium point control theory and reinforcement learning to determine the impedance parameters for contact tasks. A recursive least-square filter-based episodic natural actor-critic algorithm is used to find the optimal impedance parameters. The effectiveness of the proposed method was tested through dynamic simulations of various contact tasks. The simulation results demonstrated that the proposed method optimizes the performance of the contact tasks in uncertain conditions of the environment.</P>
Chromatin Remodeling Facilitates DNA Incision in UV-damaged Nucleosomes
Byungchan Ahn,Kyungeun Lee,김덕룡 한국분자세포생물학회 2004 Molecules and cells Vol.18 No.1
The DNA repair machinery must locate and repair DNA damage all over the genome. As nucleosomes inhibit DNA repair in vitro, it has been suggested that chromatin remodeling might be required for efficient repair in vivo. To investigate a possible contribution of nucleosome dynamics and chromatin remodeling to the repair of UV-photoproducts in nucleosomes, we examined the effect of a chromatin remodeling complex on the repair of UV-lesions by Micrococcus luteus UV endonuclease (ML-UV endo) and T4-endonuclease V (T4- endoV) in reconstituted mononucleosomes positioned at one end of a 175-bp long DNA fragment. Repair by ML-UV endo and T4-endoV was inefficient in mononucleosomes compared with naked DNA. However, the human nucleosome remodeling complex, hSWI/SNF, promoted more homogeneous repair by ML-UV endo and T4-endo V in reconstituted ucleosomes. This result suggests that recognition of DNA damage could be facilitated by a fluid state of the chromatin resulting from chromatin remodeling activities.
Byungchan Han(한병찬),박정윤,이종민,오진우 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
인공지능형 머신러닝기법을 통해 제일원리 전산으로 구축된 빅데이터를 분석하여 연구한 유전자 조작 M13 박테리오파지 수용체 설계 기술을 소개한다. M13 파지는 유전 성질에 따라 수십억 개 이상의 고유한 표면 화학 반응성을 구현할 수 있으며, 그 표면 화학 특성은 유전자 가위로 DNA를 조작하는 방식으로 제어가 가능하다. 본 발표에서는 파지 전자코가 가시광선 영역에서 다양한 휘발성 유기물질을 센싱할 수 있음을 규명한다. 이 연구의 주요 성과는 M13 파지가, 기존 센서로는 검출이 어려운 화학물질을 육안으로 판별할 수 있는 색깔 패턴으로 쉽게 탐지할 수 있는 휴대용 생체 센서로 개발할 수 있는 과학적인 근거를 마련했다는 점이다. 이 결과를 바탕으로, 폭발성 유기 화합물에 반응하는 최적의 M13 파지 수용체를 실험으로 직접 제적하여 파지 전자코를 구현하는데 성공하고 그 소자의 성능 테스트 결과, 화학적 특성이 크게 다른 방향족/지방족 구별은 물론, 같은 화학적 분류에 속하는 유사한 화합물을 1 ppb레벨의 정확도로 판별할 수 있음이 관측된다.