http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Lee, Sang-Hoon,Ahsan, Nagib,Lee, Ki-Won,Kim, Do-Hyun,Lee, Dong-Gi,Kwak, Sang-Soo,Kwon, Suk-Yoon,Kim, Tae-Hwan,Lee, Byung-Hyun G. Fischer 2007 Journal of plant physiology Vol. No.
<P><B>Summary</B></P><P>To mitigate the oxidative damage inflicted by biotic or abiotic stresses, plants have evolved complex anti-oxidative defense mechanisms that involve induction of antioxidant and anti-oxidative enzymes, such as superoxide dismutase (SOD) and ascorbate peroxidase (APX). To determine whether overexpression of the genes encoding copper–zinc SOD (CuZnSOD) and APX in plants is capable of decreasing reactive oxygen species (ROS) produced in response to abiotic stresses, we generated transgenic tall fescue plants expressing the CuZnSOD and APX genes in chloroplasts under the control of the oxidative stress-inducible promoter, sweet potato peroxidase anionic 2 (SWPA2). Transgenic plants were generated by <I>Agrobacterium</I>-mediated genetic transformation, and genotypes were confirmed by DNA blot analysis. Transgenic plants were exposed to several ROS-generating abiotic stresses, such as methyl viologen (MV), H<SUB>2</SUB>O<SUB>2</SUB>, and the heavy metals copper, cadmium, and arsenic, and their tolerance was evaluated. High levels of CuZnSOD and APX gene transcripts in the transgenic plants under these treatments suggested that the transgenes were functionally expressed. Compared to transgenic plants, higher amounts of ROS were generated in the leaves of control plants exposed to abiotic stresses, resulting in increased thiobarbituric acid reactive substances (TBARS), ion leakage, and chlorophyll degradation. These parameters were significantly lower in transgenic plants. Enzyme activity assays and native polyacrylamide gel electrophoresis (PAGE) showed that total SOD and APX were highly active in transgenic plants under the abiotic stresses examined. We conclude that one of the mechanisms of increased anti-oxidative defense in transgenic tall fescue plants is overexpression of the CuZnSOD and APX genes, which are utilized in scavenging ROS and thus provide improved tolerance to abiotic stresses.</P>
Expression of Heat Shock Protein and Antioxidant Genes in Rice Leaf Under Heat Stress
Lee, Dong-Gi,Ahsan, Nagib,Kim, Yong-Goo,Kim, Kyung-Hee,Lee, Sang-Hoon,Lee, Ki-Won,Rahman, Md. Atikur,Lee, Byung-Hyun The Korean Society of Grassland and Forage Science 2013 한국초지조사료학회지 Vol.33 No.3
We have previously investigated the proteome changes of rice leaves under heat stress (Lee et al. in Proteomics 2007a, 7:3369-3383), wherein a group of antioxidant proteins and heat shock proteins (HSPs) were found to be regulated differently. The present study focuses on the biochemical changes and gene expression profiles of heat shock protein and antioxidant genes in rice leaves in response to heat stress ($42^{\circ}C$) during a wide range of exposure times. The results show that hydrogen peroxide and proline contents increased significantly, suggesting an oxidative burst and osmotic imbalance under heat stress. The mRNA levels of chaperone 60, HSP70, HSP100, chloroplastic HSP26, and mitochondrial small HSP responded rapidly and showed maximum expression after 0.5 or 2 h under heat stress. Transcript levels of ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and Cu-Zn superoxide dismutase (Cu-Zn SOD) showed a rapid and marked accumulation upon heat stress. While prolonged exposure to heat stress resulted in increased transcript levels of monodehydroascorbate reductase, peroxidase, glyoxalase 1, glutathione reductase, thioredoxin peroxidase, 2-Cysteine peroxiredoxin, and nucleoside diphosphate kinase 1, while the transcription of catalase was suppressed. Consistent with their changes in gene expression, the enzyme activities of APX and DHAR also increased significantly following exposure to heat stress. These results suggest that oxidative stress is usually caused by heat stress, and plants apply complex HSP- and antioxidant-mediated defense mechanisms to cope with heat stress.
A proteomic approach in analyzing heat-responsive proteins in rice leaves
Lee, Dong-Gi,Ahsan, Nagib,Lee, Sang-Hoon,Kang, Kyu Young,Bahk, Jeong Dong,Lee, In-Jung,Lee, Byung-Hyun WILEY-VCH 2007 Proteomics Vol. No.
<P>The present study investigated rice leaf proteome in response to heat stress. Rice seedlings were subjected to a temperature of 42°C and samples were collected 12 and 24 h after treatment. Increased relative ion leakage and lipid peroxidation suggested that oxidative stress frequently was generated in rice leaves exposed to high temperature. 2-DE, coupled with MS, was used to investigate and identify heat-responsive proteins in rice leaves. In order to identify the low-abundant proteins in leaves, samples were prefractionated by 15% PEG. The PEG supernatant and the pellet fraction samples were separated by 2-DE, and visualized by silver or CBB staining. Approximately 1000 protein spots were reproducibly detected on each gel, wherein 73 protein spots were differentially expressed at least at one time point. Of these differentially expressed proteins, a total of 34 and 39 protein spots were found in the PEG supernatant and pellet fractions, respectively. Using MALDI-TOF MS, a total of 48 proteins were identified. These proteins were categorized into classes related to heat shock proteins, energy and metabolism, redox homeostasis, and regulatory proteins. The results of the present study show that a group of low molecular small heat shock proteins (sHSPs) were newly induced by heat stress. Among these sHSPs, a low molecular weight mitochondrial (Mt) sHSP was validated further by Western blot analysis. Furthermore, four differentially accumulated proteins that correspond to antioxidant enzymes were analyzed at the mRNA level, which confirmed the differential gene expression levels, and revealed that transcription levels were not completely concomitant with translation. The identification of some novel proteins in the heat stress response provides new insights that can lead to a better understanding of the molecular basis of heat-sensitivity in plants.</P>
Modeling of RC shear walls strengthened by FRP composites
Mohammed A. Sakr,Saher R. El-khoriby,Tarek M. Khalifa,Mohammed T. Nagib 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.3
RC shear walls are considered one of the main lateral resisting members in buildings. In recent years, FRP has been widely utilized in order to strengthen and retrofit concrete structures. A number of experimental studies used CFRP sheets as an external bracing system for retrofitting of RC shear walls. It has been found that the common mode of failure is the debonding of the CFRP-concrete adhesive material. In this study, behavior of RC shear wall was investigated with three different micro models. The analysis included 2D model using plane stress element, 3D model using shell element and 3D model using solid element. To allow for the debonding mode of failure, the adhesive layer was modeled using cohesive surface-to-surface interaction model at 3D analysis model and node-to-node interaction method using Cartesian elastic-plastic connector element at 2D analysis model. The FE model results are validated comparing the experimental results in the literature. It is shown that the proposed FE model can predict the modes of failure due to debonding of CFRP and behavior of CFRP strengthened RC shear wall reasonably well. Additionally, using 2D plane stress model, many parameters on the behavior of the cohesive surfaces are investigated such as fracture energy, interfacial shear stress, partial bonding, proposed CFRP anchor location and using different bracing of CFRP strips. Using two anchors near end of each diagonal CFRP strips delay the end debonding and increase the ductility for RC shear walls.
식물생장조절물질이 페레니얼 라이그래스 (Lolium perenne L.)의 캘러스 유도와 식물체 재분화에 미치는 영향
이기원(Ki-Won Lee),이동기(Dong-Gi Lee),Nagib Ahsan,원성혜(Sung-Hye Won),이상훈(Sang-Hoon Lee),김기용(Ki-Yong Kim),최기준(Gi Jun Choi),서성(Sung Seo),이병현(Byung-Hyun Lee) 한국초지조사료학회 2007 한국초지조사료학회지 Vol.27 No.4
페레니얼 라이그래스의 최적 조직배양조건을 확립하기 위하여 성숙종자로부터 배발생 캘러스 유도 및 효율적인 식물체 재분화조건을 체계적으로 확립하였다. 배발생 캘러스 유도시 첨가되는 auxin으로는 2,4-D가 가장 효율적이었으며, 9 ㎎/L 2,4-D와 0.1 ㎎/L BA가 첨가된 MS 배지에서 배발생 캘러스가 가장 높은 빈도로 유도되었다. 식물체 재분화는 배발생 캘러스를 1 ㎎/L 2,4-D와 5 ㎎/L BA가 첨가된 N6 배지에서 배양했을 때 58.3%의 높은 재분화율을 나타내었다. 본 연구를 통하여 확립된 단기간의 효율적인 재분화 시스템은 분자육종을 통한 신품종 페레니얼 라이그래스 개발에 유용하게 응용되어질 수 있을 것이다. Optimum tissue culture conditions for an efficient induction of embryogenic callus from mature seeds of perennial ryegrass (Lolium perenne L.) and regeneration of plants from callus tissues were investigated. MS medium containing 3 ㎎/L 2,4-D and 0.1 ㎎/L BA was optimal for embryogenic callus induction from mature seeds. The highest plant regeneration frequency (58.3%) was observed when the embryogenic callus tissues were cultured on N6 medium supplemented with 1 ㎎/L 2,4-D and 3 ㎎/L BA. Regenerated plants were grown normally when shoots transplanted to the soil. A short tissue culture period and high-frequency regeneration system would be helpful for molecular breeding of perennial ryegrass through Agrobacteriummediated genetic transformation.