Light signaling to flowering

Lee, Ilha,Oh, Ml-Jin,Hyun, Youbong,Lee, Sun-joo 이화여자대학교 세포신호전달연구센터 2003 고사리 세포신호전달 심포지움 Vol. No.5

In plants, light is used as a signal to sense their environment as well as energy source. Light affects plant development throughout the life cycle such as seed germination, seedling growth, and transition to flowering. It is well known that phytochrome, a red! far-red light photoreceptor and cryptochrome, a blue light photoreceptor are involved in the regulation of flowering but the signal cascades are largely unknown. To elucidate the signalling mechanism from light to flowering, we adopted molecular genetic approaches and identified signaling components that mediate photoreceptors and physiological responses including flowering. From activation tagging mutagenesis, which randomly inserts 35S enhancer into Arabidopsis chromosome to cause overexpression of a gene in the vicinity of the insertion, we isolated two mutants that show early flowering and long hypocotyl phenotype. Because phytochrome B(phyB) mutant and cryptochrome(cry) mutant also show long hypocotyl phenotype under white light, the specificity of two mutants were determined by checking seedling growth under monochromatic light source such as red, far-red and blue light. One mutant, named as dhy1(dominant long hypocotyl) showed exactly the same phenotype with phyB mutant such as long hypocotyl under continuous red light, petiole elongation and early flowering. On the contrary, phytochrome A(phyA) specific responses such as induction of germination under far-red light, inhibition of hypocotyl elongation under far-red light, and far-red-preconditioned blocking of greening were normal, suggesting dhy1 is phyB specific downstream regulator. Although phyB also affects on the circadian rhythm, dhy1 mutant did not show any effects on the circadian rhythm, suggesting phyB affects flowering time of plants independently of circadian rhythm. Other mutant, named as dbi(dominant blue light insensitive) showed defect in inhibition of hypocotyl length under blue light but not under red or far-red light, suggesting DBI acts in blue light signalling mechanism. The two mutants, dhy1 and dbi are dominant, suggesting both wild type genes function as negative regulators for light signal transduction. The cloning of the genes are now in progress.

SOC1 translocated to the nucleus by interaction with AGL24 directly regulates <i>LEAFY</i>

Lee, Jungeun,Oh, Mijin,Park, Hanna,Lee, Ilha Blackwell Publishing Ltd 2008 The Plant journal Vol.55 No.5

<P>Summary</P><P><I>SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1</I> (<I>SOC1</I>) is one of the flowering pathway integrators and regulates the expression of <I>LEAFY</I> (<I>LFY</I>), which links floral induction and floral development. However, the mechanism by which SOC1, a MADS box protein, regulates <I>LFY</I> has proved elusive. Here, we show that SOC1 directly binds to the distal and proximal region of the <I>LFY</I> promoter where critical <I>cis</I>-elements are located. Intragenic suppressor mutant analysis shows that a missense mutation in the MADS box of SOC1 causes loss of binding to the <I>LFY</I> promoter as well as suppression of the flowering promotion function. The full-length SOC1 protein locates in the cytoplasm if expressed alone in protoplast transient expression assay, but relocates to the nucleus if expressed with AGAMOUS-LIKE 24 (AGL24), another flowering pathway integrator and a MADS box protein. The domain analysis shows that co-localization of SOC1 and AGL24 is mediated by the MADS box and the intervening region of SOC1. Finally, we show that <I>LFY</I> is expressed only in those tissues where <I>SOC1</I> and <I>AGL24</I> expressions overlap. Thus, we propose that heterodimerization of SOC1 and AGL24 is a key mechanism in activating <I>LFY</I> expression.</P>

Hollow nanotubular toroidal polymer microrings

Lee, Jiyeong,Baek, Kangkyun,Kim, Myungjin,Yun, Gyeongwon,Ko, Young Ho,Lee, Nam-Suk,Hwang, Ilha,Kim, Jeehong,Natarajan, Ramalingam,Park, Chan Gyung,Sung, Wokyung,Kim, Kimoon Nature Publishing Group, a division of Macmillan P 2014 Nature chemistry Vol.6 No.2

Despite the remarkable progress made in the self-assembly of nano- and microscale architectures with well-defined sizes and shapes, a self-organization-based synthesis of hollow toroids has, so far, proved to be elusive. Here, we report the synthesis of polymer microrings made from rectangular, flat and rigid-core monomers with anisotropically predisposed alkene groups, which are crosslinked with each other by dithiol linkers using thiol-ene photopolymerization. The resulting hollow toroidal structures are shape-persistent and mechanically robust in solution. In addition, their size can be tuned by controlling the initial monomer concentrations, an observation that is supported by a theoretical analysis. These hollow microrings can encapsulate guest molecules in the intratoroidal nanospace, and their peripheries can act as templates for circular arrays of metal nanoparticles.

Analysis of transcription factor HY5 genomic binding sites revealed its hierarchical role in light regulation of development.

Lee, Jungeun,He, Kun,Stolc, Viktor,Lee, Horim,Figueroa, Pablo,Gao, Ying,Tongprasit, Waraporn,Zhao, Hongyu,Lee, Ilha,Deng, Xing Wang American Society of Plant Physiologists 2007 The Plant cell Vol.19 No.3

<P>The transcription factor LONG HYPOCOTYL5 (HY5) acts downstream of multiple families of the photoreceptors and promotes photomorphogenesis. Although it is well accepted that HY5 acts to regulate target gene expression, in vivo binding of HY5 to any of its target gene promoters has yet to be demonstrated. Here, we used a chromatin immunoprecipitation procedure to verify suspected in vivo HY5 binding sites. We demonstrated that in vivo association of HY5 with promoter targets is not altered under distinct light qualities or during light-to-dark transition. Coupled with DNA chip hybridization using a high-density 60-nucleotide oligomer microarray that contains one probe for every 500 nucleotides over the entire Arabidopsis thaliana genome, we mapped genome-wide in vivo HY5 binding sites. This analysis showed that HY5 binds preferentially to promoter regions in vivo and revealed >3000 chromosomal sites as putative HY5 binding targets. HY5 binding targets tend to be enriched in the early light-responsive genes and transcription factor genes. Our data thus support a model in which HY5 is a high hierarchical regulator of the transcriptional cascades for photomorphogenesis.</P>

적층 압전액츄에이터 소자의 온도에 따른 전기적 특성

이갑수(Kabsoo Lee),이일하(Ilha Lee),류주현(Juhyun Yoo) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.10

In this paper, multilayer piezoelectric actuator was fabricated in order to develop ultrasonic linear motor. Multilayer actuator showed a high density of 7.78[g/㎤], a large effective electromechanical coupling factor(k<SUB>eff</SUB>) of 0.259, a high mechanical quality factor(Qm') of 1301, and high capacitance(c) of 19.32[㎋l Curie temperature was 343[℃]

EFFECT OF Nb SUBSTITUTION ON THE PIEZOELECTRIC AND DIELECTRIC PROPERTIES OF 0.95(K0.5Na0.5) NbO3-0.05Li (Sb1 - xNbx)O3 CERAMICS

YOO, JUHYUN,KIM, DOHYUNG,LEE, YUHYEONG,LEE, ILHA,LEE, SANGHO,KIM, INSUNG,SONG, JAESUNG Taylor Francis 2009 Integrated ferroelectrics Vol.105 No.1

<P> In this study, lead-free 0.95(K0.5Na0.5)NbO3-0.05Li(Sb1 - xNbx)O3 system ceramics were fabricated according to the amount of Nb substitution for Sb site of LiSbO3 ceramics and their dielectric and piezoelectric characteristics were investigated. With increasing the amount of Nb substitution, electromechanical coupling factor (kp), density and piezoelectric constant (d33) increased up to 1mol% Nb and decreased above 1mol% Nb. With increasing the amount of Nb substitution, dielectric constant linearly decreased and Curie temperature increased. At the 1mol% Nb substitution composition ceramics sintered at 1040°C, electromechanical coupling factor (kp), density, dielectric constant (&epsis;r), piezoelectric constant (d33) and Curie temperature (Tc) showed the optimal value of 0.41, 4.35 g/cm3, 789, 206 pC/N and 395°C, respectively for piezoelectric device application.</P>

A molecular basis behind heterophylly in an amphibious plant, <i>Ranunculus trichophyllus</i>

Kim, Juhyun,Joo, Youngsung,Kyung, Jinseul,Jeon, Myeongjune,Park, Jong Yoon,Lee, Ho Gyun,Chung, Doo Soo,Lee, Eunju,Lee, Ilha Public Library of Science 2018 PLoS genetics Vol.14 No.2

<▼1><P><I>Ranunculus trichophyllus</I> is an amphibious plant that produces thin and cylindrical leaves if grown under water but thick and broad leaves if grown on land. We found that such heterophylly is widely controlled by two plant hormones, abscisic acid (ABA) and ethylene, which control terrestrial and aquatic leaf development respectively. Aquatic leaves produced higher levels of ethylene but lower levels of ABA than terrestrial leaves. In aquatic leaves, their distinct traits with narrow shape, lack of stomata, and reduced vessel development were caused by <I>EIN3</I>-mediated overactivation of abaxial genes, <I>RtKANADIs</I>, and accompanying with reductions of <I>STOMAGEN</I> and <I>VASCULAR-RELATED NAC-DOMAIN7</I> (<I>VDN7</I>). In contrast, in terrestrial leaves, ABI3-mediated activation of the adaxial genes, <I>RtHD-ZIPIIIs</I>, and <I>STOMAGEN</I> and <I>VDN7</I> established leaf polarity, and stomata and vessel developments. Heterophylly of <I>R</I>.<I>trichophyllus</I> could be also induced by external cues such as cold and hypoxia, which is accompanied with the changes in the expression of leaf polarity genes similar to aquatic response. A closely-related land plant <I>R</I>. <I>sceleratus</I> did not show such heterophyllic responses, suggesting that the changes in the ABA/ethylene signaling and leaf polarity are one of key evolutionary steps for aquatic adaptation.</P></▼1><▼2><P><B>Author summary</B></P><P>Evolutionary adaptation into aquatic environment is widely observed in diverse clades of land plants. To understand the molecular basis behind such adaptation, we analyzed <I>Ranunculus trichophyllus</I>, an amphibious plant producing different leaf shape depending on the growth conditions. Aquatic leaves of this plant produce higher levels of ethylene, which causes overactivation of genetic circuits composed of <I>EIN3</I>, an ethylene signaling transducer, and abaxial genes that suppress genes regulating stomata and xylem development. In contrast, terrestrial leaves produce higher levels of ABA, which activates adaxial genes and causes activation of stomata and xylem developments. Such changes in the ABA/ethylene signaling and leaf polarity after submergence were not observed in the closely-related land plant <I>R</I>. <I>sceleratus</I>, indicating that they are key evolutionary steps towards aquatic adaptation.</P></▼2>

Anisotropic change in THz resonance of planar metamaterials by liquid crystal and carbon nanotube.

Woo, J H,Choi, E,Kang, Boyoung,Kim, E S,Kim, J,Lee, Y U,Hong, Tae Y,Kim, Jae H,Lee, Ilha,Lee, Young Hee,Wu, J W Optical Society of America 2012 Optics express Vol.20 No.14

<P>THz metamaterials are employed to examine changes in the meta-resonances when two anisotropic organic materials, liquid crystal and carbon nanotubes, are placed on top of metamaterials. In both anisotropic double split-ring resonators and isotropic four-fold symmetric split-ring resonators, anisotropic interactions between the electric field and organic materials are enhanced in the vicinity of meta-resonances. In liquid crystal, meta-resonance frequency shift is observed with the magneto-optical coupling giving rise to the largest anisotropic shift. In carbon nanotube, meta-resonance absorptions, parallel and perpendicular to nanotube direction, experience different amount of broadening of Lorentzian oscillator of meta-resonance. Investigation reported here opens the application of metamaterials as a sensor for anisotropic materials.</P>

세계 고무산업의 현황과 동향

이원선,일하의치,Lee, Won-Seon,IlHa Ui-Chi 대한타이어공업협회 1996 타이어 Vol.182 No.-

Piezoelectric and dielectric properties of low temperature sintering Pb(Mn1/3Nb2/3)O3-Pb(Zn1/3Nb2/3)O3-Pb(Zr0.48Ti0.52)O3 ceramics with variation of sintering time

Yoo, Juhyun,Lee, Ilha,Paik, Dong Soo,Park, Yong-Wook Springer-Verlag 2009 Journal of electroceramics Vol.23 No.2