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Nguyen QTC, Lee SJ, Choi SW, Na YJ, Song MR, Hoang QTN, Sim SY, Kim MS, Kim JI, Soh MS, Kim SY. Arabidopsis Raf-Like Kinase Raf10 Is a Regulatory Component of Core ABA Signaling. Mol Cells 2019; 42:646-660. [PMID: 31480825 PMCID: PMC6776158 DOI: 10.14348/molcells.2019.0173] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 08/09/2019] [Indexed: 11/27/2022] Open
Abstract
Abscisic acid (ABA) is a phytohormone essential for seed development and seedling growth under unfavorable environmental conditions. The signaling pathway leading to ABA response has been established, but relatively little is known about the functional regulation of the constituent signaling components. Here, we present several lines of evidence that Arabidopsis Raf-like kinase Raf10 modulates the core ABA signaling downstream of signal perception step. In particular, Raf10 phosphorylates subclass III SnRK2s (SnRK2.2, SnRK2.3, and SnRK2.6), which are key positive regulators, and our study focused on SnRK2.3 indicates that Raf10 enhances its kinase activity and may facilitate its release from negative regulators. Raf10 also phosphorylates transcription factors (ABI5, ABF2, and ABI3) critical for ABAregulted gene expression. Furthermore, Raf10 was found to be essential for the in vivo functions of SnRK2s and ABI5. Collectively, our data demonstrate that Raf10 is a novel regulatory component of core ABA signaling.
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Affiliation(s)
- Quy Thi Cam Nguyen
- Department of Biotechnology and Kumho Life Science Laboratory, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186,
Korea
| | - Sun-ji Lee
- Department of Biotechnology and Kumho Life Science Laboratory, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186,
Korea
| | - Seo-wha Choi
- Department of Biotechnology and Kumho Life Science Laboratory, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186,
Korea
| | - Yeon-ju Na
- Department of Biotechnology and Kumho Life Science Laboratory, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186,
Korea
| | - Mi-ran Song
- Department of Biotechnology and Kumho Life Science Laboratory, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186,
Korea
| | - Quyen Thi Ngoc Hoang
- Department of Biotechnology and Kumho Life Science Laboratory, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186,
Korea
| | - Seo Young Sim
- Department of New Biology, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988,
Korea
| | - Min-Sik Kim
- Department of New Biology, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988,
Korea
| | - Jeong-Il Kim
- Department of Biotechnology and Kumho Life Science Laboratory, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186,
Korea
| | - Moon-Soo Soh
- Department of Molecular Biology, Sejong University, Seoul 05006,
Korea
| | - Soo Young Kim
- Department of Biotechnology and Kumho Life Science Laboratory, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186,
Korea
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Choi J, Eom S, Shin K, Lee RA, Choi S, Lee JH, Lee S, Soh MS. Identification of Lysine Histidine Transporter 2 as an 1-Aminocyclopropane Carboxylic Acid Transporter in Arabidopsis thaliana by Transgenic Complementation Approach. Front Plant Sci 2019; 10:1092. [PMID: 31572413 PMCID: PMC6749071 DOI: 10.3389/fpls.2019.01092] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 08/09/2019] [Indexed: 05/17/2023]
Abstract
1-Aminocyclopropane-1-carboxylic acid (ACC), a biosynthetic precursor of ethylene, has long been proposed to act as a mobile messenger in higher plants. However, little is known about the transport system of ACC. Recently, our genetic characterization of an ACC-resistant mutant with normal ethylene sensitivity revealed that lysine histidine transporter 1 (LHT1) functions as a transporter of ACC. As amino acid transporters might have broad substrate specificity, we hypothesized that other amino acid transporters including LHT1 paralogs might have the ACC-transporter activity. Here, we took a gain-of-function approach by transgenic complementation of lht1 mutant with a selected set of amino acid transporters. When we introduced transgene into the lht1 mutant, the transgenic expression of LHT2, but not of LHT3 or amino acid permease 5 (AAP5), restored the ACC resistance phenotype of the lht1 mutant. The result provides genetic evidence that some, if not all, amino acid transporters in Arabidopsis can function as ACC transporters. In support, when expressed in Xenopus laevis oocytes, both LHT1 and LHT2 exhibited ACC-transporting activity, inducing inward current upon addition of ACC. Interestingly, the transgenic expression of LHT2, but not of LHT3 or AAP5, could also suppress the early senescence phenotypes of the lht1 mutant. Taking together, we propose that plants have evolved a multitude of ACC transporters based on amino acid transporters, which would contribute to the differential distribution of ACC under various spatiotemporal contexts.
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Affiliation(s)
- Jungki Choi
- Division of Integrative Bioscience and Biotechnology, College of Life Science, Sejong University, Seoul, South Korea
| | - Sanung Eom
- Departments of Biotechnology, Chonnam National University, Gwangju, South Korea
| | - Kihye Shin
- Division of Integrative Bioscience and Biotechnology, College of Life Science, Sejong University, Seoul, South Korea
| | - Rin-A Lee
- Division of Integrative Bioscience and Biotechnology, College of Life Science, Sejong University, Seoul, South Korea
| | - Soobin Choi
- Division of Integrative Bioscience and Biotechnology, College of Life Science, Sejong University, Seoul, South Korea
| | - Jun-Ho Lee
- Departments of Biotechnology, Chonnam National University, Gwangju, South Korea
| | - Sumin Lee
- Division of Integrative Bioscience and Biotechnology, College of Life Science, Sejong University, Seoul, South Korea
- *Correspondence: Sumin Lee, ; Moon-Soo Soh,
| | - Moon-Soo Soh
- Division of Integrative Bioscience and Biotechnology, College of Life Science, Sejong University, Seoul, South Korea
- *Correspondence: Sumin Lee, ; Moon-Soo Soh,
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Abstract
Light is an important environmental cue, causing a high degree of developmental plasticity in higher plants. The outcome of light-regulated developmental response is determined by not only photo-sensory systems but also endogenous physiological contexts in plants. KARRIKIN-INSENSITIVE2 (KAI2) functions as a receptor of karrikin and endogenous, as yet to be identified, KAI2 ligand (KL). The loss-of-function of KAI2 caused light-hyposensitive photomorphogenesis, affecting the expression light-responsive genes under the light conditions. However, it remains still unclear how KAI2-KL signaling interacts with light-signaling. Here, we show that the ply2 mutation, a severe loss-of-function allele of KAI2 affected the expression of a subset of light-responsive genes, irrespectively of light condition. The results implied that the overlapping set of light- and KAI2-responsive genes may serve as an integrating node between light- and KAI2-KL signaling. Further, the results of double mutant analyses between the ply2 mutant and mutants of CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) or LONG HYPOCOTYL IN FAR-RED (HFR1) implicated that KAI2-KL signaling acts at downstream of COP1, largely independently of HFR1. Together, these results suggest that KAI2-KL signaling intersects with a subset of the light-regulatory network, by which plants adjust their photomorphogenic development.
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Affiliation(s)
- Inhye Lee
- Division of Integrative Bioscience and Biotechnology, College of Life Science, Sejong University, Seoul, Republic of Korea
| | - Soobin Choi
- Division of Integrative Bioscience and Biotechnology, College of Life Science, Sejong University, Seoul, Republic of Korea
| | - Sumin Lee
- Division of Integrative Bioscience and Biotechnology, College of Life Science, Sejong University, Seoul, Republic of Korea
- Sumin Lee Division of Integrative Bioscience and Biotechnology, College of Life Science, Sejong University, Seoul 143-747, Republic of Korea
| | - Moon-Soo Soh
- Division of Integrative Bioscience and Biotechnology, College of Life Science, Sejong University, Seoul, Republic of Korea
- CONTACT Moon-Soo Soh
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Lee I, Kim K, Lee S, Lee S, Hwang E, Shin K, Kim D, Choi J, Choi H, Cha JS, Kim H, Lee RA, Jeong S, Kim J, Kim Y, Nam HG, Park SK, Cho HS, Soh MS. A missense allele of KARRIKIN-INSENSITIVE2 impairs ligand-binding and downstream signaling in Arabidopsis thaliana. J Exp Bot 2018; 69:3609-3623. [PMID: 29722815 PMCID: PMC6022639 DOI: 10.1093/jxb/ery164] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 04/24/2018] [Indexed: 05/26/2023]
Abstract
A smoke-derived compound, karrikin (KAR), and an endogenous but as yet unidentified KARRIKIN INSENSITIVE2 (KAI2) ligand (KL) have been identified as chemical cues in higher plants that impact on multiple aspects of growth and development. Genetic screening of light-signaling mutants in Arabidopsis thaliana has identified a mutant designated as ply2 (pleiotropic long hypocotyl2) that has pleiotropic light-response defects. In this study, we used positional cloning to identify the molecular lesion of ply2 as a missense mutation of KAI2/HYPOSENSITIVE TO LIGHT, which causes a single amino acid substitution, Ala219Val. Physiological analysis and genetic epistasis analysis with the KL-signaling components MORE AXILLARY GROWTH2 (MAX2) and SUPPRESSOR OF MAX2 1 suggested that the pleiotropic phenotypes of the ply2 mutant can be ascribed to a defect in KL-signaling. Molecular and biochemical analyses revealed that the mutant KAI2ply2 protein is impaired in its ligand-binding activity. In support of this conclusion, X-ray crystallography studies suggested that the KAI2ply2 mutation not only results in a narrowed entrance gate for the ligand but also alters the structural flexibility of the helical lid domains. We discuss the structural implications of the Ala219 residue with regard to ligand-specific binding and signaling of KAI2, together with potential functions of KL-signaling in the context of the light-regulatory network in Arabidopsis thaliana.
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Affiliation(s)
- Inhye Lee
- Division of Integrative Bioscience and Biotechnology, School of Life Science, Sejong University, Seoul, Republic of Korea
| | - Kuglae Kim
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Sumin Lee
- Division of Integrative Bioscience and Biotechnology, School of Life Science, Sejong University, Seoul, Republic of Korea
| | - Seungjun Lee
- Division of Integrative Bioscience and Biotechnology, School of Life Science, Sejong University, Seoul, Republic of Korea
| | - Eunjin Hwang
- Division of Integrative Bioscience and Biotechnology, School of Life Science, Sejong University, Seoul, Republic of Korea
| | - Kihye Shin
- Division of Integrative Bioscience and Biotechnology, School of Life Science, Sejong University, Seoul, Republic of Korea
| | - Dayoung Kim
- Division of Integrative Bioscience and Biotechnology, School of Life Science, Sejong University, Seoul, Republic of Korea
| | - Jungki Choi
- Division of Integrative Bioscience and Biotechnology, School of Life Science, Sejong University, Seoul, Republic of Korea
| | - Hyunmo Choi
- Division of Integrative Bioscience and Biotechnology, School of Life Science, Sejong University, Seoul, Republic of Korea
| | - Jeong Seok Cha
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Hoyoung Kim
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Rin-A Lee
- Division of Integrative Bioscience and Biotechnology, School of Life Science, Sejong University, Seoul, Republic of Korea
| | - Suyeong Jeong
- Center for Plant Aging Research, Institute for Basic Science (IBS), Daegu, Republic of Korea
| | - Jeongsik Kim
- Center for Plant Aging Research, Institute for Basic Science (IBS), Daegu, Republic of Korea
| | - Yumi Kim
- Center for Plant Aging Research, Institute for Basic Science (IBS), Daegu, Republic of Korea
| | - Hong Gil Nam
- Center for Plant Aging Research, Institute for Basic Science (IBS), Daegu, Republic of Korea
- Department of New Biology, DGIST, Daegu, Republic of Korea
| | - Soon-Ki Park
- School of Applied Biosciences, Kyungpook National University, Daegu, Republic of Korea
| | - Hyun-Soo Cho
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Moon-Soo Soh
- Division of Integrative Bioscience and Biotechnology, School of Life Science, Sejong University, Seoul, Republic of Korea
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Nguyen TD, Moon S, Oo MM, Tayade R, Soh MS, Song JT, Oh SA, Jung KH, Park SK. Application of rice microspore-preferred promoters to manipulate early pollen development in Arabidopsis: a heterologous system. Plant Reprod 2016; 29:291-300. [PMID: 27796586 DOI: 10.1007/s00497-016-0293-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 10/23/2016] [Indexed: 06/06/2023]
Abstract
Rice microspore-promoters. Based on microarray data analyzed for developing anthers and pollen grains, we identified nine rice microspore-preferred (RMP) genes, designated RMP1 through RMP9. To extend their biotechnological applicability, we then investigated the activity of RMP promoters originating from monocotyledonous rice in a heterologous system of dicotyledonous Arabidopsis. Expression of GUS was significantly induced in transgenic plants from the microspore to the mature pollen stages and was driven by the RMP1, RMP3, RMP4, RMP5, and RMP9 promoters. We found it interesting that, whereas RMP2 and RMP6 directed GUS expression in microspore at the early unicellular and bicellular stages, RMP7 and RMP8 seemed to be expressed at the late tricellular and mature pollen stages. Moreover, GUS was expressed in seven promoters, RMP3 through RMP9, during the seedling stage, in immature leaves, cotyledons, and roots. To confirm microspore-specific expression, we used complementation analysis with an Arabidopsis male-specific gametophytic mutant, sidecar pollen-2 (scp-2), to verify the activity of three promoters. That mutant shows defects in microspore development prior to pollen mitosis I. These results provide strong evidence that the SIDECAR POLLEN gene, driven by RMP promoters, successfully complements the scp-2 mutation, and they strongly suggest that these promoters can potentially be applied for manipulating the expression of target genes at the microspore stage in various species.
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Affiliation(s)
- Tien Dung Nguyen
- School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Korea
| | - Sunok Moon
- Graduate School of Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin, 17104, Korea
| | - Moe Moe Oo
- School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Korea
| | - Rupesh Tayade
- School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Korea
| | - Moon-Soo Soh
- Department of Molecular Biology, Sejong University, Seoul, 143-747, Korea
| | - Jong Tae Song
- School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Korea
| | - Sung Aeong Oh
- School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Korea
| | - Ki Hong Jung
- Graduate School of Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin, 17104, Korea.
| | - Soon Ki Park
- School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Korea.
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Nguyen TD, Moon S, Nguyen VNT, Gho Y, Chandran AKN, Soh MS, Song JT, An G, Oh SA, Park SK, Jung KH. Genome-wide identification and analysis of rice genes preferentially expressed in pollen at an early developmental stage. Plant Mol Biol 2016; 92:71-88. [PMID: 27356912 DOI: 10.1007/s11103-016-0496-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 05/23/2016] [Indexed: 06/06/2023]
Abstract
Microspore production using endogenous developmental programs has not been well studied. The main limitation is the difficulty in identifying genes preferentially expressed in pollen grains at early stages. To overcome this limitation, we collected transcriptome data from anthers and microspore/pollen and performed meta-expression analysis. Subsequently, we identified 410 genes showing preferential expression patterns in early developing pollen samples of both japonica and indica cultivars. The expression patterns of these genes are distinguishable from genes showing pollen mother cell or tapetum-preferred expression patterns. Gene Ontology enrichment and MapMan analyses indicated that microspores in rice are closely linked with protein degradation, nucleotide metabolism, and DNA biosynthesis and regulation, while the pollen mother cell or tapetum are strongly associated with cell wall metabolism, lipid metabolism, secondary metabolism, and RNA biosynthesis and regulation. We also generated transgenic lines under the control of the promoters of eight microspore-preferred genes and confirmed the preferred expression patterns in plants using the GUS reporting system. Furthermore, cis-regulatory element analysis revealed that pollen specific elements such as POLLEN1LELAT52, and 5659BOXLELAT5659 were commonly identified in the promoter regions of eight rice genes with more frequency than estimation. Our study will provide new sights on early pollen development in rice, a model crop plant.
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Affiliation(s)
- Tien Dung Nguyen
- School of Applied Biosciences, Kyungpook National University, Daegu, 702-701, Republic of Korea
| | - Sunok Moon
- Graduate School of Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin, 446-701, Republic of Korea
| | - Van Ngoc Tuyet Nguyen
- Graduate School of Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin, 446-701, Republic of Korea
| | - Yunsil Gho
- Graduate School of Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin, 446-701, Republic of Korea
| | - Anil Kumar Nalini Chandran
- Graduate School of Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin, 446-701, Republic of Korea
| | - Moon-Soo Soh
- Department of Molecular Biology, Sejong University, Seoul, 143-747, Republic of Korea
| | - Jong Tae Song
- School of Applied Biosciences, Kyungpook National University, Daegu, 702-701, Republic of Korea
| | - Gynheung An
- Graduate School of Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin, 446-701, Republic of Korea
| | - Sung Aeong Oh
- School of Applied Biosciences, Kyungpook National University, Daegu, 702-701, Republic of Korea
| | - Soon Ki Park
- School of Applied Biosciences, Kyungpook National University, Daegu, 702-701, Republic of Korea.
| | - Ki-Hong Jung
- Graduate School of Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin, 446-701, Republic of Korea.
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Jeong S, Kim JY, Choi H, Kim H, Lee I, Soh MS, Nam HG, Chang YT, Lim PO, Woo HR. Rootin, a compound that inhibits root development through modulating PIN-mediated auxin distribution. Plant Sci 2015; 233:116-126. [PMID: 25711819 DOI: 10.1016/j.plantsci.2015.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 12/31/2014] [Accepted: 01/09/2015] [Indexed: 06/04/2023]
Abstract
Plant roots anchor the plant to the soil and absorb water and nutrients for growth. Understanding the molecular mechanisms regulating root development is essential for improving plant survival and agricultural productivity. Extensive molecular genetic studies have provided important information on crucial components for the root development control over the last few decades. However, it is becoming difficult to identify new regulatory components in root development due to the functional redundancy and lethality of genes involved in root development. In this study, we performed a chemical genetic screen to identify novel synthetic compounds that regulate root development in Arabidopsis seedlings. The screen yielded a root growth inhibitor designated as 'rootin', which inhibited Arabidopsis root development by modulating cell division and elongation, but did not significantly affect shoot development. Transcript analysis of phytohormone marker genes revealed that rootin preferentially altered the expression of auxin-regulated genes. Furthermore, rootin reduced the accumulation of PIN1, PIN3, and PIN7 proteins, and affected the auxin distribution in roots, which consequently may lead to the observed defects in root development. Our results suggest that rootin could be utilized to unravel the mechanisms underlying root development and to investigate dynamic changes in PIN-mediated auxin distribution.
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Affiliation(s)
- Suyeong Jeong
- Department of Life Sciences, POSTECH, Hyojadong, Pohang, Gyeongbuk 790-784, Republic of Korea
| | - Jun-Young Kim
- Department of Chemistry, NUS & Singapore Bioimaging Consortium, A*STAR, Singapore 117543, Singapore
| | - Hyunmo Choi
- Department of Integrative Bioscience and Biotechnology, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, Republic of Korea
| | - Hyunmin Kim
- Department of Life Sciences, POSTECH, Hyojadong, Pohang, Gyeongbuk 790-784, Republic of Korea
| | - Ilhwan Lee
- Department of Life Sciences, POSTECH, Hyojadong, Pohang, Gyeongbuk 790-784, Republic of Korea
| | - Moon-Soo Soh
- Department of Integrative Bioscience and Biotechnology, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, Republic of Korea
| | - Hong Gil Nam
- Center for Plant Aging Research, Institute for Basic Science (IBS), Republic of Korea; Department of New Biology, DGIST, Daegu 711-873, Republic of Korea
| | - Young-Tae Chang
- Department of Chemistry, NUS & Singapore Bioimaging Consortium, A*STAR, Singapore 117543, Singapore.
| | - Pyung Ok Lim
- Department of New Biology, DGIST, Daegu 711-873, Republic of Korea.
| | - Hye Ryun Woo
- Department of New Biology, DGIST, Daegu 711-873, Republic of Korea.
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Shin K, Lee S, Song WY, Lee RA, Lee I, Ha K, Koo JC, Park SK, Nam HG, Lee Y, Soh MS. Genetic Identification of
ACC-RESISTANT2
Reveals Involvement of
LYSINE HISTIDINE TRANSPORTER1
in the Uptake of 1-Aminocyclopropane-1-Carboxylic Acid in
Arabidopsis thaliana. ACTA ACUST UNITED AC 2014; 56:572-82. [DOI: 10.1093/pcp/pcu201] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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9
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Oo MM, Bae HK, Nguyen TD, Moon S, Oh SA, Kim JH, Soh MS, Song JT, Jung KH, Park SK. Evaluation of rice promoters conferring pollen-specific expression in a heterologous system, Arabidopsis. Plant Reprod 2014; 27:47-58. [PMID: 24550073 DOI: 10.1007/s00497-014-0239-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 02/10/2014] [Indexed: 06/03/2023]
Abstract
Promoters can direct gene expression specifically to targeted tissues or cells. Effective with both crop species and model plant systems, these tools can help researchers overcome the practical obstacles associated with transgenic protocols. Here, we identified promoters that allow one to target the manipulation of gene expression during pollen development. Utilizing published transcriptomic databases for rice, we investigated the promoter activity of selected genes in Arabidopsis. From various microarray datasets, including those for anthers and pollen grains at different developmental stages, we selected nine candidate genes that showed high levels of expression in the late stages of rice pollen development. We named these Oryza sativa late pollen-specific genes. Their promoter regions contained various cis-acting elements that could be responsible for anther-/pollen-specific expression. Promoter::GUS-GFP reporters were constructed and introduced into Arabidopsis plants. Histochemical GUS staining revealed that six of the nine rice promoters conferred strong GUS expression that was restricted to the anthers in Arabidopsis. Further analysis showed that although the GUS signals were not detected at the unicellular stage, they strengthened in the bicellular or tricellular stages, peaking at the mature pollen stage. This paralleled their transcriptomic profiles in rice. Based on our results, we proposed that these six rice promoters, which are active in the late stages of pollen formation in the dicot Arabidopsis, can aid molecular breeders in generating new varieties of a monocot plant, rice.
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Affiliation(s)
- Moe Moe Oo
- School of Applied Biosciences, Kyungpook National University, Daegu, 702-701, Republic of Korea
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Shin K, Lee RA, Lee I, Lee S, Park SK, Soh MS. Genetic identification of a second site modifier of ctr1-1 that controls ethylene-responsive and gravitropic root growth in Arabidopsis thaliana. Mol Cells 2013; 36:88-96. [PMID: 23740431 PMCID: PMC3887932 DOI: 10.1007/s10059-013-0097-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 05/02/2013] [Accepted: 05/08/2013] [Indexed: 01/01/2023] Open
Abstract
Ethylene controls myriad aspects of plant growth throughout developmental stages in higher plants. It has been well established that ethylene-responsive growth entails extensive crosstalk with other plant hormones, particularly auxin. Here, we report a genetic mutation, named 1-aminocyclopropane carboxylic acid (ACC) resistant root1-1 (are1-1) in Arabidopsis thaliana (L.) Heynh. The CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) encodes a Raf-related protein, functioning as an upstream negative regulator of ethylene signaling in Arabidopsis thaliana. We found that the ctr1-1, a kinase-inactive allele exhibited slightly, but significantly, longer root length, compared to ACC-treated wild-type or ctr1-3, a null allele. Our genetic studies unveiled the existence of are1-1 mutation in the ctr1-1 mutant, as a second-site modifier which confers root-specific ethylene-resistance. Based on well-characterized crosstalk between ethylene and auxin during ethylene-responsive root growth, we performed various physiological analyses. Whereas are1-1 displayed normal sensitivity to synthetic auxins, it showed modest resistance to an auxin transport inhibitor, 1-Nnaphthylphthalamic acid. In addition, are1-1 mutant exhibited ectopically altered DR5:GUS activity upon ethylenetreatment. The results implicated the involvement of are1-1 in auxin-distribution, but not in auxin-biosynthesis, -uptake, or -sensitivity. In agreement, are1-1 mutant exhibited reduced gravitropic root growth and defective redistribution of DR5:GUS activity upon gravi-stimulation. Taken together with genetic and molecular analysis, our results suggest that ARE1 defines a novel locus to control ethylene-responsive root growth as well as gravitropic root growth presumably through auxin distribution in Arabidopsis thaliana.
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Affiliation(s)
- Kihye Shin
- Department of Molecular Biology, College of Life Science, Sejong University, Seoul 143-747,
Korea
| | - Rin-A Lee
- Department of Molecular Biology, College of Life Science, Sejong University, Seoul 143-747,
Korea
| | - Inhye Lee
- Department of Molecular Biology, College of Life Science, Sejong University, Seoul 143-747,
Korea
| | - Sumin Lee
- Department of Molecular Biology, College of Life Science, Sejong University, Seoul 143-747,
Korea
| | - Soon Ki Park
- School of Applied Biosciences, Kyungpook National University, Daegu 702-701,
Korea
| | - Moon-Soo Soh
- Department of Molecular Biology, College of Life Science, Sejong University, Seoul 143-747,
Korea
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12
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Lee S, Shin K, Lee I, Song HR, Noh YS, Lee RA, Lee S, Kim SY, Park SK, Lee S, Soh MS. Genetic identification of a novel locus, ACCELERATED FLOWERING 1 that controls chromatin modification associated with histone H3 lysine 27 trimethylation in Arabidopsis thaliana. Plant Sci 2013; 208:20-27. [PMID: 23683925 DOI: 10.1016/j.plantsci.2013.03.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Revised: 03/11/2013] [Accepted: 03/12/2013] [Indexed: 06/02/2023]
Abstract
Flowering on time is a critically important for successful reproduction of plants. Here we report an early-flowering mutant in Arabidopsis thaliana, accelerated flowering 1-1D (afl1-1D) that exhibited pleiotropic developmental defects including semi-dwarfism, curly leaf, and increased branching. Genetic analysis showed that afl1-1D mutant is a single, dominant mutant. Chromosomal mapping indicates that AFL1 resides at the middle of chromosome 4, around which no known flowering-related genes have been characterized. Expression analysis and double mutant studies with late flowering mutants in various floral pathways indicated that elevated FT is responsible for the early-flowering of afl1-1D mutant. Interestingly, not only flowering-related genes, but also several floral homeotic genes were ectopically overexpressed in the afl1-1D mutants in both FT-dependent and -independent manner. The degree of histone H3 Lys27-trimethylation (H3K27me3) was reduced in several chromatin including FT, FLC, AG and SEP3 in the afl1-1D, suggesting that afl1-1D might be involved in chromatin modification. In support, double mutant analysis of afl1-1D and lhp1-4 revealed epistatic interaction between afl1-1D and lhp1-4 in regard to flowering control. Taken together, we propose that AFL1 regulate various aspect of development through chromatin modification, particularly associated with H3K27me3 in A. thaliana.
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Affiliation(s)
- Sumin Lee
- Department of Molecular Biology, College of Life Science, Sejong University, Seoul 143-747, Republic of Korea
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Abstract
SUMMARY
This study examined the effects of food-simulating liquid (FSL) on the hardness and roughness of giomer restoratives based on pre-reacted glass ionomer (PRG) technology. The materials investigated included a regular (Beautifil II [BT]) and a recently introduced injectable (Beautifil Flow Plus F00 [BF]) hybrid PRG composite. A direct hybrid composite (Filtek Z250 [ZT]) and an indirect hybrid composite (Ceramage [CM]) were used for comparison. The materials were placed into customized square molds (5 mm × 5 mm × 2.5 mm), covered with Mylar strips, and cured according to manufacturers' instructions. The materials were then conditioned in air (control), distilled water, 50% ethanol solution, and 0.02 N citric acid at 37°C for seven days. Specimens (n=6) were then subjected to hardness testing (Knoop) and surface profilometry. Data were analyzed using one-way analysis of variance and post hoc Scheffe test (p<0.05). Mean Knoop hardness values for the control group (air) ranged from 53.4 ± 3.4 (BF) to 89.5 ± 5.2 (ZT), while mean surface roughness values values ranged from 0.014 ± 0.002 (ZT) to 0.032 ± 0.001 (BT). All materials were significantly softened by FSL. The degree of softening by the different FSLs was material dependent. The hardness of giomers was most affected by citric acid and ethanol. The smoothest surface was generally observed with the control group. Giomer restoratives were significantly roughened by citric acid.
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Affiliation(s)
- TJM Kooi
- Terence Jun Ming Kooi, NA, Faculty of Dentistry, National University of Singapore, Singapore
| | - QZ Tan
- Qing Zhen Tan, NA, Faculty of Dentistry, National University of Singapore, Singapore
| | - AUJ Yap
- Adrian UJ Yap, PhD, MSc, BDS, Grad Dip Psychotherapy, Raffles Hospital; Faculty of Dentistry, National University of Singapore, Singapore; School of Science and Technology, SIM University, Singapore
| | - W Guo
- Weidi Guo, NA, Faculty of Dentistry, National University of Singapore, Singapore
| | - KJ Tay
- Koong Jiunn Tay, NA, Faculty of Dentistry, National University of Singapore, Singapore
| | - MS Soh
- Mui Siang Soh, PhD, MSc, BSc, Institute of Materials Research and Engineering, Singapore
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14
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Abstract
Polymerase chain reaction (PCR) is a powerful technique in molecular biology and is widely used in various fields. By amplifying DNA fragments, PCR has facilitated gene cloning procedures, as well as molecular genotyping. However, the extraction of DNA from samples often acts as a limiting step of these reactions. In particular, the extraction of PCR-compatible genomic DNA from higher plants requires complicated processes and tedious work because plant cells have rigid cell walls and contain various endogenous PCR inhibitors, including polyphenolic compounds. We recently developed a novel solution, referred to as AnyDirect, which can amplify target DNA fragments directly from whole blood without the need for DNA extraction. Here, we developed a simple lysis system that could produce an appropriate template for direct PCR with AnyDirect PCR buffer, making possible the direct amplification of DNA fragments from plant leaves. Thus, our experimental procedure provides a simple, convenient, non-hazardous, inexpensive, and rapid process for the amplification of DNA from plant tissue.
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Affiliation(s)
- Young Geun Yang
- Department of Biochemistry, College of Science, Yonsei University, Seoul 120-749, Korea
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15
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Lee S, Lee S, Yang KY, Kim YM, Park SY, Kim SY, Soh MS. Overexpression of PRE1 and its Homologous Genes Activates Gibberellin-dependent Responses in Arabidopsis thaliana. ACTA ACUST UNITED AC 2006; 47:591-600. [PMID: 16527868 DOI: 10.1093/pcp/pcj026] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Gibberellins control various aspects of growth and development. Here, we identified a gene, designated paclobutrazol resistance1 (PRE1), by screening Arabidopsis activation-tagged lines. PRE1 encodes a helix-loop-helix protein and belongs to a small gene family. Physiological and genetic analysis indicated that overexpression of PRE1 altered various aspects of gibberellin-dependent responses such as germination, elongation of hypocotyl/petiole, floral induction and fruit development, and suppressed gibberellin-deficient phenotypes of the ga2 mutant. Expression of some gibberellin-responsive genes was also affected by PRE1. Expression of PRE1 was shown to be early gibberellin inducible in the wild-type plants and under control of SPY and GAI, upstream negative regulators of gibberellin signaling. The shortened hypocotyl length phenotype of the gai-1 mutant was suppressed by PRE1 overexpression. Ectopic overexpression of each of the four PRE1-related genes conferred pleiotropic phenotypes similar to PRE1 overexpression, indicative of overlapping functions among the PRE gene family. Our results of gain-of-function studies suggest that PRE genes may have a regulatory role in gibberellin-dependent development in Arabidopsis thaliana.
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Affiliation(s)
- Sumin Lee
- Department of Molecular Biology, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, Republic of Korea
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16
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Yap AUJ, Soh MS. Curing efficacy of a new generation high-power LED lamp. Oper Dent 2005; 30:758-63. [PMID: 16382599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This study investigated the curing efficacy of a new generation high-power LED lamp (Elipar Freelight 2 [N] 3M-ESPE). The effectiveness of composite cure with this new lamp was compared to conventional LED/halogen (Elipar Freelight [F], 3M-ESPE; Max [M], Dentsply-Caulk) and high-power halogen (Elipar Trilight [T], 3M-ESPE; Astralis 10 [A], Ivoclar Vivadent) lamps. Standard continuous (NS, FS, TS; MS), turbo (AT) and exponential (NE, FE, TE) curing modes of the various lights were examined. Curing efficacy of the various lights and modes were determined by measuring the top and bottom surface hardness of 2-mm thick composite specimens (Z100, 3M-ESPE) using a digital microhardness tester (n=5; load=500 g; dwell time=15 seconds) one hour after light polymerization. The hardness ratio was computed by dividing HK (Knoops Hardness) of the bottom surface by HK of the top surface. The data was analyzed using one-way ANOVA/Scheffe's test and Independent Samples t-test at significance level 0.05. Results of the statistical analysis were as follows: HK top--E, FE, NE > NS and NE > AT, TS, FS; HK bottom--TE, NE > NS; Hardness ratio--NS > FE and FS, TS > NE. No significant difference in HK bottom and hardness ratio was observed between the two modes of Freelight 2 and Max. Freelight 2 cured composites as effectively as conventional LED/halogen and high-power halogen lamps, even with a 50% reduction in cure time. The exponential modes of Freelight 2, Freelight and Trilight appear to be more effective than their respective standard modes.
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Affiliation(s)
- Adrian U J Yap
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore.
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17
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Neo BJ, Soh MS, Teo JW, Yap AUJ. Effectiveness of composite cure associated with different light-curing regimes. Oper Dent 2005; 30:671-5. [PMID: 16382588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This study investigated the use of various light-curing regimens with standardized light energy density on the effectiveness of cure of a visible light activated resin composite (Z100, 3M-ESPE). A light-cure unit (Variable Intensity Polymerizer (VIP), BISCO Inc) which permitted individual control over time and intensity, was used. The five light-curing modes investigated include Pulse Delay (PD), Pulse Cure (PC), Soft-start (SS), Turbo (T) and Control (C). Effectiveness of cure was established by measuring the top and bottom Knoop hardness of 2-mm thick composite specimens using a digital microhardness tester (n=5, load=500g; dwell time=15 seconds) immediately and at one-day post-polymerization. Data obtained was analyzed using one-way ANOVA/Scheffe's post hoc test and Independent Samples t-tests (p<0.05). Top KHN observed immediately after polymerization with C was significantly lower than PD. At one day post-polymerization, the top KHN obtained with C was significantly lower than PD, SS and T. No significant difference in bottom KHN was observed among the different curing modes immediately after curing. At one day post-polymerization, the bottom KHN obtained with C was significantly lower than SS and T. Regardless of curing regimens, top and bottom values at one day were significantly higher than those observed immediately after light polymerization. No significant difference in mean hardness ratio was observed among the different curing regimens immediately and one day later. Effectiveness of the cure at the bottom surfaces of composites may be increased by soft-start and turbo polymerization regimens.
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Affiliation(s)
- B J Neo
- Faculty of Dentistry, National University of Singapore
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18
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Chye CH, Yap AUJ, Laim YC, Soh MS. Post-gel polymerization shrinkage associated with different light curing regimens. Oper Dent 2005; 30:474-80. [PMID: 16130868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
This study compared post-gel polymerization shrinkage associated with five different light curing regimens of similar light energy density. A light-cure unit (VIP, BISCO) that allowed for independent command over time and intensity was used. The five regimens investigated were pulse delay (PD), soft-start (SS); pulse cure (PC), turbo cure (TC) and standard continuous cure (C) [control]. With the exception of TC, the light energy density for all curing regimens was fixed at 16 J/cm2. A strain-monitoring device and test configuration were used to measure the linear polymerization shrinkage of 2-mm thick composite specimens (Z100, 3M ESPE) during and post-light polymerization up to 60 minutes. Five samples were made for each curing mode. The results were analyzed using ANOVA/Scheffee's post-hoc test at significance level 0.05. Post-gel shrinkage ranged from 0.30% to 0.46 % at 60 minutes. The use of PD resulted in significantly lower shrinkage compared to PC, TC, SS and C. Shrinkage associated with SS was, in general, significantly lower than C. No significant difference in shrinkage was observed between PC, TC and C at all time intervals. The use of pulse delay and soft-start regimens decreased post-gel polymerization shrinkage.
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Affiliation(s)
- C H Chye
- Faculty of Dentistry, National University of Singapore, Republic of Singapore
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19
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Kim JI, Shen Y, Han YJ, Park JE, Kirchenbauer D, Soh MS, Nagy F, Schäfer E, Song PS. Phytochrome phosphorylation modulates light signaling by influencing the protein-protein interaction. Plant Cell 2004; 16:2629-40. [PMID: 15377754 PMCID: PMC520960 DOI: 10.1105/tpc.104.023879] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Accepted: 07/06/2004] [Indexed: 05/20/2023]
Abstract
Plant photoreceptor phytochromes are phosphoproteins, but the question as to the functional role of phytochrome phosphorylation has remained to be elucidated. We investigated the functional role of phytochrome phosphorylation in plant light signaling using a Pfr-specific phosphorylation site mutant, Ser598Ala of oat (Avena sativa) phytochrome A (phyA). The transgenic Arabidopsis thaliana (phyA-201 background) plants with this mutant phyA showed hypersensitivity to light, suggesting that phytochrome phosphorylation at Serine-598 (Ser598) in the hinge region is involved in an inhibitory mechanism. The phosphorylation at Ser598 prevented its interaction with putative signal transducers, Nucleoside Diphosphate Kinase-2 and Phytochrome-Interacting Factor-3. These results suggest that phosphorylation in the hinge region of phytochromes serves as a signal-modulating site through the protein-protein interaction between phytochrome and its putative signal transducer proteins.
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Affiliation(s)
- Jeong-Il Kim
- Kumho Life and Environmental Science Laboratory, Gwangju 500-712, Korea
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20
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Soh MS, Yap AUJ, Yu T, Shen ZX. Analysis of the degree of conversion of LED and halogen lights using micro-Raman spectroscopy. Oper Dent 2004; 29:571-7. [PMID: 15470880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
This study determined the degree of conversion of two LED (light-emitting diodes) (Elipar FreeLight [FL], 3M ESPE; GC e-Light [EL], GC), a high intensity (Elipar TriLight [TL], 3M ESPE) and a very high intensity (Astralis 10 [AS], Ivoclar Vivadent) halogen light. The degree of conversion of these lights was compared to a conventional halogen light (Max [MX] (control), Dentsply-Caulk). Ten different light curing regimens, including pulse (EL1), continuous (FL1, EL2, TL1), turbo (EL3, AS1) and soft-start (FL2, EL4, TL2) modes of various lights were also investigated. Composite specimens of dimensions 3 x 3 x 2 mm were cured with the 10 different light curing regimens investigated. Micro-Raman spectroscopy was used to determine the degree of conversion at the top and bottom surfaces of a composite restorative (Z100, [3M ESPE]) at 60 minutes post-light polymerization. Five specimens were made for each cure mode. The results were analyzed using ANOVA/Scheffe's post-hoc test and Independent Samples t-tests at significance level 0.05. The degree of conversion ranged from 55.98 +/- 2.50 to 59.00 +/- 2.76% for the top surface and 51.90 +/- 3.36 to 57.28 +/- 1.56% for the bottom surface. No significant difference in degree of conversion was observed for the 10 light curing regimens when compared to MX (control). The curing efficiency of LED lights was comparable to halogen lights regardless of curing modes.
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Affiliation(s)
- M S Soh
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore
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21
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Yap AUJ, Soh MS, Han TTS, Siow KS. Influence of curing lights and modes on cross-link density of dental composites. Oper Dent 2004; 29:410-5. [PMID: 15279480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
This study investigated the influence of curing lights and modes on the cross-link density of dental composites. Four LED/halogen curing lights (LED-Elipar Freelight [FL], 3M-ESPE and GC e-light [EL], GC; high intensity halogen-Elipar Trilight [TL], 3M-ESPE; very high intensity halogen-Astralis 10 [AS], Ivoclar Vivadent) were selected for this study. Pulse (EL1), continuous (FL1, EL2, TL1), turbo (EL3, AS) and soft-start (FL2, EL4, TL2) curing modes of the various lights were examined. A conventional, continuous cure halogen light (Max [MX], Dentsply-Caulk) was used for comparison. Six composite (Z100, 3M-ESPE) specimens were made for each light-curing mode combination. After polymerization, the specimens were stored in air at 37 degrees C for 24 hours and subjected to hardness testing using a digital microhardness tester (load=500 g; dwell time=15 seconds). The specimens were then placed in 75% ethanol-water solution at 37 degrees C for 24 hours and post-conditioning hardness was determined. Mean hardness (HK)/change in hardness (deltaHK) was computed and the data subjected to analysis using one-way ANOVA/Scheffe's test and Independent Samples t-test (p<0.05). Softening upon storage in ethanol (deltaHK) was used as a relative indication of cross-link density. Specimens polymerized with AS, TL2 and all modes of both LED lights were significantly more susceptible to softening in ethanol than specimens cured with MX. No significant difference in cross-link density was observed among the various modes of EL and FL. For TL, curing with continuous mode resulted in specimens with significantly higher cross-link density than curing with the soft-start mode.
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Affiliation(s)
- Adrian U J Yap
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore.
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22
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Yap AUJ, Han VTS, Soh MS, Siow KS. Elution of leachable components from composites after LED and halogen light irradiation. Oper Dent 2004; 29:448-53. [PMID: 15279486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
This study investigated the influence of curing lights and modes on the elution of leachable components from dental composites. Four LED/halogen curing lights (LED-Elipar Freelight [FL], 3M-ESPE and GC e-light [EL], GC; high intensity halogen-Elipar Trilight [TL], 3M-ESPE; very high intensity halogen-Astralis 10 [AS], Ivoclar Vivadent) were selected for this study. Pulse (EL1), continuous (FL1, EL2, TL1), turbo (EL3, AS) and soft-start (FL2, EL4, TL2) curing modes of the various lights were examined. A conventional continuous cure halogen light (Max [MX], Dentsply-Caulk) was used for comparison. Three composite (Z100, 3M-ESPE) specimens (6.5 mm in diameter and 1-mm thick) were made for each curing light-mode combination. After polymerization, the specimens were stored in air at 37 degrees C for 24 hours and incubated in acetonitrile at 37 degrees C for 24 hours. BisGMA and TEGDMA extracts were isolated by high performance liquid chromatography (HPLC). Data were subjected to analysis using one-way ANOVA/Scheffe's post-hoc test and Independent Samples t-test at significance level 0.05. The total monomer (BisGMA and TEGDMA) eluted ranged from 8.75 to 27.97 ppm for FL1 and AS, respectively. Significantly more unreacted monomers were leached from composites cured with all modes of EL and AS when compared to MX. No significant difference in the total monomer eluted was observed between the two modes of FL/TL and MX Although composites cured with EL2 released significantly less monomer than EL1, 3 and 4, no significant difference in the total monomer eluted was observed between the continuous and soft-start modes of FL and TL. The elution of leachable components from composites appears to be curing light specific rather than light source (LED or halogen) and curing mode specific.
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Affiliation(s)
- Adrian U J Yap
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore.
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23
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Soh MS, Yap AUJ, Siow KS. Post-gel shrinkage with different modes of LED and halogen light curing units. Oper Dent 2004; 29:317-24. [PMID: 15195733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
This study compared the post-gel shrinkage of two LED (light-emitting diodes) lights (Elipar FreeLight [FL], 3M ESPE; GC e-Light [EL], GC), a high intensity (Elipar TriLight [TL], 3M ESPE) and a very high intensity (Astralis 10 [AS], Ivoclar Vivadent) halogen light to a conventional (Max [MX] (control), Dentsply-Caulk) halogen light. Ten light curing regimens were investigated. These included continuous (FL1, EL2, MX, TL1 and AS1), soft-start (FL2, EL4, TL2), pulse activation (EL1) and turbo (EL3) modes. A strain-monitoring device and test configuration was used to measure the linear polymerization shrinkage of a composite restorative (Z100, [3M ESPE]) during and post-light polymerization up to 60 minutes when cured with the different modes. Five specimens were made for each cure mode. Results were analyzed using ANOVA/Scheffe's post-hoc test and independent sample t-tests at significance level 0.05. Shrinkage associated with the various modes of EL was significantly lower than MX immediately after light polymerization and at one-minute post-light polymerization. No significant difference between MX and the various lights/cure modes was observed at 10, 30 and 60-minutes post-light polymerization. At all time intervals, post-gel shrinkage associated with continuous light curing mode was significantly higher than the soft-start light curing mode for FL and TL.
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Affiliation(s)
- M S Soh
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore.
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Soh MS, Yap AUJ. Influence of curing modes on crosslink density in polymer structures. J Dent 2004; 32:321-6. [PMID: 15053916 DOI: 10.1016/j.jdent.2004.01.012] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2003] [Revised: 12/03/2003] [Accepted: 01/12/2004] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE This study investigates the influence of curing modes on the crosslinking density of dental composites. METHODS A light-cure unit (BISCO VIP) that allowed for independent command over time and intensity was selected. Four different light-curing modes with constant light energy density were investigated (control (C), pulse delay (PD), soft-start (SS) and pulse cure (PC)). The degree of crosslinking was assessed directly by measuring the glass transition temperature of 1 mm thick composite (Z100, 3M-ESPE) specimens using differential scanning calorimetry (DSC 2920). Polymer softening in ethanol was used as an indirect method for assessing the degree of crosslinking. After light-curing, specimens were stored in air at 37 degrees C for 24 h and subjected to hardness testing using a digital microhardness tester (n = 6, load=500 g; dwell time=15 s). The specimens were then placed in 75% ethanol-water solution at 37 degrees C for 24 h and post-conditioning hardness was determined. Mean hardness (KHN)/hardness deterioration (DeltaKHN) was computed and data was subjected to analysis using one-way ANOVA/Scheffe's test. RESULTS Ranking of degree of crosslinking density by DSC was as follows: C>PC>SS>PD. For the indirect method of determining crosslinking density, DeltaKHN ranged from 10.8 to 12.9 and ranking was PC>SS>C>PD. CONCLUSIONS Specimens polymerized with PD were significantly more susceptible to softening in ethanol than specimens cured with PC. Results of this study suggest that polymerization with PD resulted in a lower crosslink density and gave rise to polymers with an increased susceptibility to softening in ethanol.
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Affiliation(s)
- M S Soh
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, 5 Lower Kent Ridge Road, Singapore, Singapore 119074.
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25
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Yap AUJ, Soh MS. Post-gel polymerization contraction of "low shrinkage" composite restoratives. Oper Dent 2004; 29:182-7. [PMID: 15088730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
This study compared the post-gel contraction of two "low-shrinkage" composites (InTen-S [IS], Ivoclar-Vivadent; Aelite LS [AL], BISCO Inc) and an ormocer (Admira [AM], Voco) to two conventional mini-filled composites (Renew [RN], BISCO; Z100 [ZO], 3M ESPE). A strain-monitoring device and test configuration were used to measure the linear polymerization shrinkage associated with the various composites (A2 shade) during and up to 60 minutes post light polymerization. Each specimen was irradiated for 40 seconds using a halogen curing light (Max, Dentsply-Caulk) with an intensity of 401 mW/cm2. Five specimens were made for each composite. Data was analyzed using one-way ANOVA/Scheffe's post-hoc test at significance level 0.05. The linear percentage shrinkage immediately after light polymerization and at 60 minutes post light polymerization ranged from 0.10 +/- 0.02 to 0.40 +/- 0.02% and 0.22 +/- 0.02 to 0.60 +/- 0.05%, respectively. Post-gel shrinkage ranking of the materials was as follows: immediately after light polymerization - IS < AL < AM < ZO < RN and at 60 minutes post light polymerization - IS < AL = AM < ZO < RN. The shrinkage associated with IS, AL and AM was significantly lower than for ZO and RN immediately after light polymerization and at 1, 10, 30 and 60 minutes post light polymerization. The post-gel polymerization shrinkage of IS, AL and AM was significantly lower than conventional mini-filled composites.
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Affiliation(s)
- A U J Yap
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore.
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26
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Soh MS, Yap AUJ, Siow KS. Comparative depths of cure among various curing light types and methods. Oper Dent 2004; 29:9-15. [PMID: 14753326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
This study evaluated the depth of cure associated with commercial LEDs (light-emitting diodes) (Elipar FreeLight [FL], 3M-ESPE; GC e-Light [EL], GC), high intensity (Elipar TriLight [TL], 3M-ESPE) and very high intensity (Astralis 10 [AS], Ivoclar Vivadent) Quartz Tungsten Halogen (QTH) curing lights. Depth of cure of the various lights/curing modes were compared to a conventional QTH light (Max [Mx], Dentsply-Caulk). Ten exposure regimens were investigated: FL1 - 400 mW/cm2 [40 seconds]; FL2 - 0-400 mW/cm2 [12 seconds] --> 400 mW/cm2 [28 seconds]; EL1 - 750 mW/cm2 [10 pulses x 2 seconds], EL2 - 350 mW/cm2 [40 seconds]; EL3 - 600 mW/cm2 [20 seconds]; EL4 - 0 - 600 mW/cm2 [20 seconds] --> 600 mW/cm2 [20 seconds]; TL1 - 800 mW/cm2 [40 seconds]; TL2 - 100- 800 mW/cm2 [15 seconds] --> 800 mW/cm2 [25 seconds]; AS1 - 1200 mW/cm2 [10 seconds]; MX - 400 mW/cm2 [40 seconds]. Depth of cure was determined by penetration, scraping and microhardness techniques. The results were analyzed using one-way ANOVA/Scheffe's post-hoc test and Pearson's correlation at significance level 0.05 and 0.01, respectively. All light curing regimens met the ISO depth of cure requirement of 1.5 mm with the exception of EL1-EL3 with the microhardness technique. Curing with most modes of EL resulted in significantly lower depths of cure than the control [MX]. No significant difference in depth of cure was observed among the control and the two modes of FL. Curing with TL1 resulted in significantly greater depth of cure compared to MX with all testing techniques. No significant difference in depth of cure was observed between the control and AS1 for all testing techniques except for the penetration technique. The depth of composite cure is light unit and exposure mode dependent. Scraping and penetration techniques were found to correlate well but tend to overestimate depth of cure compared to microhardness.
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Affiliation(s)
- M S Soh
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore
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Yang KY, Kim YM, Lee S, Song PS, Soh MS. Overexpression of a mutant basic helix-loop-helix protein HFR1, HFR1-deltaN105, activates a branch pathway of light signaling in Arabidopsis. Plant Physiol 2003; 133:1630-42. [PMID: 14645731 PMCID: PMC300719 DOI: 10.1104/pp.103.029751] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2003] [Revised: 08/05/2003] [Accepted: 09/13/2003] [Indexed: 05/23/2023]
Abstract
The HFR1, a basic helix-loop-helix protein, is required for a subset of phytochrome A-mediated photoresponses in Arabidopsis. Here, we show that overexpression of the HFR1-deltaN105 mutant, which lacks the N-terminal 105 amino acids, confers exaggerated photoresponses even in darkness. Physiological analysis implied that overexpression of HFR1-deltaN105 activated constitutively a branch pathway of light signaling that mediates a subset of photomorphogenic responses, including germination, de-etiolation, gravitropic hypocotyl growth, blocking of greening, and expression of some light-regulated genes such as CAB, DRT112, PSAE, PSBL, PORA, and XTR7, without affecting the light-responsiveness of anthocyanin accumulation and expression of other light-regulated genes such as CHS and PSBS. Although the end-of-day far-red light response and petiole elongation were suppressed in the HFR1-deltaN105-overexpressing plants, flowering time was not affected by HFR1-deltaN105. In addition, the HFR1-deltaN105-overexpressing plants showed hypersensitive photoresponses in the inhibition of hypocotyl elongation, dependently on phytochrome A, FHY1, and FHY3 under FR light or phyB under R light, respectively. Moreover, our double mutant analysis suggested that the hypersensitive photoresponse is due to functional cooperation between HFR1-deltaN105 and other light-signaling components including HY5, a basic leucine zipper protein. Taken together, our results of gain-of-function approach with HFR1-deltaN105 suggest the existence of a complex and important basic helix-loop-helix protein-mediated transcriptional network controlling a branch pathway of light signaling and provide a useful framework for further genetic dissection of light-signaling network in Arabidopsis.
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Affiliation(s)
- Ki-Young Yang
- Kumho Life and Environmental Science Laboratory, 1 Oryong-Dong, Buk-Gu, Gwangju 500-712, Republic of Korea
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Soh MS, Yap AUJ, Siow KS. The effectiveness of cure of LED and halogen curing lights at varying cavity depths. Oper Dent 2003; 28:707-15. [PMID: 14653284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
This study compared the effectiveness of cure of two LED (light-emitting diodes) lights (Elipar FreeLight [FL], 3M-ESPE and GC e-Light [EL], GC) to conventional (Max [MX] (control), Dentsply-Caulk), high intensity (Elipar TriLight [TL], 3M-ESPE) and very high intensity (Astralis 10 [AS], Ivoclar Vivadent) halogen lights at varying cavity depths. Ten light curing regimens were investigated. They include: FL1-400 mW/cm2 [40 seconds], FL2-0-400 mW/cm2 [12 seconds] --> 400 mW/cm2 [28 seconds], EL1-750 mW/cm2 [10 pulses x 2 seconds], EL2-350 mW/cm2 [40 seconds], EL3-600 mW/cm2 [20 seconds], EL4-0-600 mW/cm2 [20 seconds] --> 600 mW/cm2 [20 seconds], TL1-800 mW/cm2 [40 seconds], TL2-100-800 mW/cm2 [15 seconds] --> 800 mW/cm2 [25 seconds], AS1-1200 mW/cm2 [10 seconds], MX-400 mW/cm2 [40 seconds]. The effectiveness of cure of the different modes was determined by measuring the top and bottom surface hardness (KHN) of 2-mm, 3-mm and 4-mm thick composite (Z100, [3M-ESPE]) specimens using a digital microhardness tester (n = 5, load = 500 g; dwell time = 15 seconds). Results were analyzed using ANOVA/Scheffe's post-hoc test and Independent Samples t-Test (p < 0.05). For all lights, effectiveness of cure was found to decrease with increased cavity depths. The mean hardness ratio for all curing lights at a depth of 2 mm was found to be greater than 0.80 (the accepted minimum standard). At 3 mm, all halogen lights produced a hardness ratio greater than 0.80 but some LED light regimens did not; and at a depth of 4 mm, the mean hardness ratio observed with all curing lights was less than 0.80. Significant differences in top and bottom KHN values were observed among different curing regimens for the same light and between LED and halogen lights. While curing with most modes of EL resulted in significantly lower top and bottom KHN values than the control (MX) at all depths, the standard mode of FL resulted in significantly higher top and bottom KHN at a depth of 3 mm and 4 mm. The depth of composite cure with LED LCUs was, therefore, product and mode dependent.
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Affiliation(s)
- M S Soh
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore
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Soh MS, Yap AUJ, Siow KS. Effectiveness of composite cure associated with different curing modes of LED lights. Oper Dent 2003; 28:371-7. [PMID: 12877422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
This study compared the effectiveness of cure of two LED (light-emitting diodes) lights (Elipar FreeLight [FL], 3M-ESPE; GC e-Light [EL], GC) to conventional (Max [MX], Dentsply-Caulk [control]), high intensity (Elipar TriLight [TL], 3M-ESPE) and very high intensity (Astralis 10 [AS], Ivoclar Vivadent) halogen lights. The 10 light-curing regimens investigated were: FL1 400 mW/cm2 [40 seconds], FL2 0-400 mW/cm2 [12 seconds] --> 400 mW/cm2 [28 seconds], EL1 750 mW/cm2 [10 pulses x 2 seconds], EL2 350 mW/cm2 [40 seconds], EL3 600 mW/cm2 [20 seconds], EL4 0-600 mW/cm2 [20 seconds] --> 600 mW/cm2 [20 seconds], TL1 800 mW/cm2 [40 seconds], TL2 100-800 mW/cm2 [15 seconds] --> 800 mW/cm2 [25 seconds], AS1 1200 mW/cm2 [10 seconds], MX 400 mW/cm2 [40 seconds]. Effectiveness of cure with the different modes was determined by measuring the top and bottom surface hardness (KHN) of 2-mm thick composite (Z100, [3M-ESPE]) specimens using a digital microhardness tester (n=5, load=500 g; dwell time=15 seconds). Results were analyzed using one-way ANOVA/Scheffe's post-hoc test and Independent Samples t-test (p<0.05). At the top surface, the mean KHN observed with LED lights ranged from 55.42 +/- 1.47 to 68.54 +/- 1.46, while that of halogen lights was 62.64 +/- 1.87 to 73.14 +/- 0.97. At the bottom surface, the mean KHN observed with LED and halogen lights ranged from 46.90 +/- 1.73 to 66.46 +/- 1.18 and 62.26 +/- 1.93 to 70.50 +/- 0.87, respectively. Significant differences in top and bottom KHN values were observed between different curing regimens for the same light, and between LED and halogen lights. Although curing with most modes of EL resulted in significantly lower top and bottom KHN values than the control, no significant difference was observed for the different modes of FL. Hence, the effectiveness of composite cure with LED LCUs is product dependent.
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Affiliation(s)
- M S Soh
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore
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Abstract
We report the characterization of a semi-dominant mutation fin5-1 (far-red insensitive 5-1) of Arabidopsis, which was isolated from genetic screening of phytochrome A (phyA) signaling components. Plants with the fin5-1 mutation exhibited a long hypocotyl phenotype when grown under far-red (FR) light, but not under red light. Physiological analyses implied that FIN5 might be differentially involved in diverse responses that are regulated by phyA under continuous FR light. Anthocyanin accumulation, gravitropic response of hypocotyl growth, and FR light-preconditioned blocking of greening were also impaired in the fin5-1 mutant, whereas photoperiodic floral induction was not, if at all, significantly affected. Moreover, light-regulated expression of the CHS, PORA and PsbS genes was attenuated in fin5-1 mutant plants, while the light-induced expression of CAB was normal. The mutation exhibited semi-dominance regarding control of hypocotyl growth in FR light. We suggest that FIN5 defines a novel branch in the network of phyA signaling in Arabidopsis.
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Affiliation(s)
- Dae-Shik Cho
- Department of Life Science and School of Environmental Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Nam-Gu, Pohang, Kyungbuk, 790-784 Republic of Korea
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Yap AUJ, Soh MS. Thermal emission by different light-curing units. Oper Dent 2003; 28:260-6. [PMID: 12760697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
This study quantified and compared the thermal emission of different light curing units (LCU). Three LED (Elipar Freelight [3M]; GC e-light [GC]; Coolblu [Dentalsystems.com]) and three halogen (Max [Dentsply-Caulk]; Elipar Trilight [3M]; Astralis 10 [Ivoclar-Vivadent]) lights were selected for the study. Thermal emission of the LCUs, when used in various curing modes, was assessed using a K-type thermocouple and a digital thermometer at distances of 3 mm and 6 mm compared to the conventional halogen LCU (Max). The temperature profiles and mean maximum temperature change (n = 7) generated by each LCU were obtained. Data was subjected to ANOVA/Scheffe's post-hoc test and Independent Samples t-test at significance level 0.05. At 3 mm, temperature rise observed with LED lights ranged from 4.1 degrees C to 12.9 degrees C, while halogen lights ranged from 17.4 degrees C to 46.4 degrees C. At 6 mm, temperature rise ranged from 2.4 degrees C to 7.5 degrees C and 12.7 degrees C to 25.5 degrees C for LED and halogen lights, respectively. Thermal emission of LED lights was significantly lower than halogen lights. Significant differences in temperature rise were observed between different curing modes for the same light and between different LED/halogen lights.
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Affiliation(s)
- Adrian U J Yap
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore.
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Kim YM, Woo JC, Song PS, Soh MS. HFR1, a phytochrome A-signalling component, acts in a separate pathway from HY5, downstream of COP1 in Arabidopsis thaliana. Plant J 2002; 30:711-719. [PMID: 12061902 DOI: 10.1046/j.1365-313x.2002.01326.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
HFR1, a basic helix-loop-helix protein, is known to be required for a subset of phytochrome A (phyA)-dependent photoresponses. To investigate the role of HFR1 in light signalling, we have examined the genetic interaction between HFR1 and HY5, a positive regulator of light signalling, and COP1, a repressor of photomorphogenesis. Double mutant analysis suggests that HFR1 mediates phyA-dependent inhibition of hypocotyl elongation independently of HY5. HFR1 was shown to be necessary for a subset of cop1-triggered photomorphogenic phenotypes in the dark, including inhibition of hypocotyl elongation, gravitropic hypocotyl growth, and expression of the light-inducible genes CAB and RBCS. Phenotypic analysis of the triple mutant cop1hy5hfr1 indicated that both HFR1 and HY5 are required for cop1-mediated photomorphogenic seedling development in darkness, consistent with their additive roles in phyA-dependent signalling. Taken together, these results suggest that HFR1 might act downstream of COP1, in a separate pathway from HY5, to mediate photomorphogenesis in Arabidopsis.
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Affiliation(s)
- Young-Mi Kim
- Kumho Life & Environmental Science Laboratory, 1 Oryong-Dong, Buk-Gu, Gwangju 500-712, Republic of Korea
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Yap AUJ, Soh MS, Siow KS. Post-gel shrinkage with pulse activation and soft-start polymerization. Oper Dent 2002; 27:81-7. [PMID: 11822366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
This study investigated the influence of pulse activation and soft-start polymerization regimens on the post-gel shrinkage of a visible light-activated composite resin (Z100). A light-cure unit (BISCO VIP) that allowed for independent command over time and intensity was used. The six light-curing modes that were examined include: Control (C)-400 mW/cm2 [40 seconds]; Pulse Delay I (PDI)-100 mW/cm2 [3 seconds], delay [3 minutes], 500 mW/cm2 [30 seconds]; Pulse Delay II (PDII)-200 mW/cm2 [20 seconds], delay [3 minutes], 500 mW/cm2 [30 seconds]; Soft-start (SS)-200 mW/cm2 [10 seconds], 600 mW/cm2 [30 seconds]; Pulse Cure I (PCI)--two 400 mW/cm2 [10 seconds] and one 400 mW/cm2 [20 seconds] pulses with 10 seconds interval between; and Pulse Cure II (PCII)-two 400 mW/cm2 [20 seconds] pulses with 20 seconds interval between. A strain-monitoring device measured the linear polymerization shrinkage associated with the various cure modes during and post light polymerization up to 60 minutes. Five specimens were made for each cure mode. Data was analyzed using one-way ANOVA and Scheffe's post-hoc test at significance level 0.05. Post-gel shrinkage associated with PDI was significantly lower than with PDII, SS and PCI immediately post light-polymerization. At one-minute post light polymerization, PDI had significantly lower shrinkage compared to PDII and SS. Significant differences in shrinkage were observed between PDI and SS only at 10, 30 and 60 minutes. At all time intervals, no significance in post-gel shrinkage was observed between the control and all-pulse activation/soft-start polymerization regimens.
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Affiliation(s)
- A U J Yap
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore
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Yap AUJ, Soh MS, Siow KS. Effectiveness of composite cure with pulse activation and soft-start polymerization. Oper Dent 2002; 27:44-9. [PMID: 11822365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
The study investigated the effectiveness of composite cure with pulse activation and soft-start polymerization. A light-cure unit (BISCO VIP, BISCO Dental Products, Schaumburg, IL 60193, USA) that allowed for independent command over time and intensity was used. The six light-curing modes examined were: Control (C)-400 mW/cm2 [40 seconds]; Pulse Delay I (PDI) -100 mW/cm2 [3 seconds] --> delay [3 minutes] --> 500 mW/cm2 [30 seconds]; Pulse Delay II (PDII) - 200 mW/cm2 [20 seconds] --> delay [3 minutes] --> 500 mW/cm2 [30 seconds]; Soft-start (SS) - 200 mW/cm2 [10 seconds] --> 600 mW/cm2 [30 seconds]; Pulse Cure I (PCI) - 400 mW/cm2 [10 seconds] --> delay [10 seconds] --> 400 mW/cm2 [10 seconds] --> delay [10 seconds] --> 400 mW/cm2 [20 seconds]; and Pulse Cure II (PCII) - 400 mW/cm2 [20 seconds] --> delay [20 seconds] --> 400 mW/cm2 [20 seconds]. Effectiveness of cure with the different modes was determined by measuring the top and bottom surface hardness of 2 mm thick composite (Z100) specimens using a digital microhardness tester (load=500 gf; dwell time=15 seconds). The effectiveness of cure of the bottom surface of the composite was also established by Fourier Transform Infrared (FTIR) spectroscopy using the KBr technique. Data obtained was analyzed using one-way ANOVA/Scheffe's post-hoc test (p<0.05). No significant difference in top Knoops Hardness Number KHN wa s observed except for PDIand PDII. At the bottom surfaces, KHN obtained with the control was significantly greater than with PDII, SS and PCII. FTIR results ranked well with the hardness of the bottom surfaces. The absorbance ratio of carbon double bonds to aromatic ring obtained with the control group was significantly greater than with PDII and PCII. Effectiveness of the cure at the bottom surfaces of composites may be reduced by some pulse activation and soft-start polymerization regimens.
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Affiliation(s)
- A U J Yap
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore
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Soh MS, Kim YM, Han SJ, Song PS. REP1, a basic helix-loop-helix protein, is required for a branch pathway of phytochrome A signaling in arabidopsis. Plant Cell 2000; 12:2061-74. [PMID: 11090209 PMCID: PMC150158 DOI: 10.1105/tpc.12.11.2061] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2000] [Accepted: 09/19/2000] [Indexed: 05/18/2023]
Abstract
Phytochromes are primary photoreceptors mediating diverse responses ranging from induction of germination to floral induction in higher plants. We have isolated novel recessive rep1 (reduced phytochrome signaling 1) mutants, which exhibit a long-hypocotyl phenotype only under far-red light but not under red light. Physiological characterization showed that rep1 mutations greatly reduced a subset of phytochrome A-regulated responses, including the inhibition of hypocotyl elongation, cotyledon expansion, modulation of gravitropic growth of hypocotyl, and induction of the CAB (encoding chlorophyll a/b binding protein) gene, without affecting the accumulation of anthocyanin, far-red-preconditioned blocking of greening, induction of germination, and induction of CHS (encoding chalcone synthase) and FNR (encoding ferredoxin-NADP(+) oxidoreductase) genes. These results suggest that REP1 is a positive signaling component, functioning in a branch of the phytochrome A signaling pathway. Molecular cloning and characterization of the REP1 gene revealed that it encodes a light-inducible, putative transcription factor containing the basic helix-loop-helix motif.
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Affiliation(s)
- M S Soh
- Kumho Life and Environmental Science Laboratory, 1, Oryong-Dong, Puk-Gu, Kwangju 500-712, Republic of Korea.
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Choi G, Yi H, Lee J, Kwon YK, Soh MS, Shin B, Luka Z, Hahn TR, Song PS. Phytochrome signalling is mediated through nucleoside diphosphate kinase 2. Nature 1999; 401:610-3. [PMID: 10524631 DOI: 10.1038/44176] [Citation(s) in RCA: 194] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Because plants are sessile, they have developed intricate strategies to adapt to changing environmental variables, including light. Their growth and development, from germination to flowering, is critically influenced by light, particularly at red (660 nm) and far-red (730 nm) wavelengths. Higher plants perceive red and far-red light by means of specific light sensors called phytochromes(A-E). However, very little is known about how light signals are transduced to elicit responses in plants. Here we report that nucleoside diphosphate kinase 2 (NDPK2) is an upstream component in the phytochrome signalling pathway in the plant Arabidopsis thaliana. In animal and human cells, NDPK acts as a tumour suppressor. We show that recombinant NDPK2 in Arabidopsis preferentially binds to the red-light-activated form of phytochrome in vitro and that this interaction increases the activity of recombinant NDPK2. Furthermore, a mutant lacking NDPK2 showed a partial defect in responses to both red and farred light, including cotyledon opening and greening. These results indicate that NDPK2 is a positive signalling component of the phytochrome-mediated light-signal-transduction pathway in Arabidopsis.
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Affiliation(s)
- G Choi
- Kumho Life and Environmental Science Laboratory, Kwangju, Korea.
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37
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Park DH, Somers DE, Kim YS, Choy YH, Lim HK, Soh MS, Kim HJ, Kay SA, Nam HG. Control of circadian rhythms and photoperiodic flowering by the Arabidopsis GIGANTEA gene. Science 1999; 285:1579-82. [PMID: 10477524 DOI: 10.1126/science.285.5433.1579] [Citation(s) in RCA: 371] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Photoperiodic responses in plants include flowering that is day-length-dependent. Mutations in the Arabidopsis thaliana GIGANTEA (GI) gene cause photoperiod-insensitive flowering and alteration of circadian rhythms. The GI gene encodes a protein containing six putative transmembrane domains. Circadian expression patterns of the GI gene and the clock-associated genes, LHY and CCA1, are altered in gi mutants, showing that GI is required for maintaining circadian amplitude and appropriate period length of these genes. The gi-1 mutation also affects light signaling to the clock, which suggests that GI participates in a feedback loop of the plant circadian system.
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Affiliation(s)
- D H Park
- Department of Life Science, Pohang University of Science and Technology, Pohang, Kyungbuk, 790-784, Korea
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Soh MS, Hong SH, Hanzawa H, Furuya M, Nam HG. Genetic identification of FIN2, a far red light-specific signaling component of Arabidopsis thaliana. Plant J 1998; 16:411-419. [PMID: 9881161 DOI: 10.1046/j.1365-313x.1998.00307.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Phytochrome A (PhyA) mediates most, if not all, various plant responses to far-red (FR) light. Here, we report a novel genetic mutation that impairs a variety of responses in the PhyA-signaling pathway of Arabidopsis thaliana. The mutation was isolated by screening seedlings that show reduced sensitivity to continuous far-red (FRc) light irradiation, but not to continuous red (Rc) light irradiation. The mutation named fin2-1 is not allelic to a PHYA mutation. Furthermore, immunoblot analysis indicated that the amount of the phytochrome A apoprotein in the fin2-1 mutant was comparable to that in wild type. Seedling of the fin2-1 mutant showed defects in hypocotyl growth inhibition and apical hook and cotyledon opening in FRc light but not in Rc light. The results showed that the mutation occurred in a downstream signaling component potentially specific to PhyA. Other PhyA-mediated responses such as FR-preconditioned blocking of greening, anthocyanin accumulation, reduction of gravitropic response, and expression of the CAB and CHS genes were impaired by the fin2-1 mutation: the degree of the mutant effect on the responses was variable. However, FR light-mediated seed germination and photoperiodic flowering responses were not affected significantly in the mutant. These results showed that FIN2 defines an upstream branch point in the PhyA signaling pathway.
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Affiliation(s)
- M S Soh
- Department of Life Science and School of Environmental Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk, South Korea
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39
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Kim BC, Soh MS, Hong SH, Furuya M, Nam HG. Photomorphogenic development of the Arabidopsis shy2-1D mutation and its interaction with phytochromes in darkness. Plant J 1998; 15:61-8. [PMID: 9744095 DOI: 10.1046/j.1365-313x.1998.00179.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We previously reported a photomorphogenic mutation of Arabidopsis thaliana, shy2-1D, as a dominant suppressor of a hy2 mutation. Here, we report that shy2-1D confers various photo-responsive phenotypes in darkness and the dark phenotypes of the mutant are affected by phytochrome deficiency. Dark-grown seedlings of the mutant developed several photomorphogenic characteristics such as short hypocotyls, cotyledon expansion and opening, and partial differentiation of plastids. When grown further in darkness, the mutant plant underwent most of the developmental stages of a light-grown wild-type plant, including development of foliar leaves, an inflorescence stem with cauline leaves, and floral organs. In addition, two light-inducible genes, the nuclear-encoded CAB and the plastid-encoded PSBA genes, were highly expressed in the dark-grown mutant seedlings. Furthermore, reduced gravitropism, a phytochrome-modulated response, was observed in the mutant hypocotyl in darkness. Thus, shy2-1D is one of the most pleiotropic photomorphogenic mutations identified so far. The results indicate that SHY2 may be a key component regulating photomorphogenesis in Arabidopsis. Surprisingly, double mutants of the shy2-1D mutant with the phytochrome-deficient mutants hy2, hy3(phyB-1) and fre1-1(phyA-201) showed reduced photomorphogenic response in darkness with a longer hypocotyl, a longer inflorescence stem, and a lower level expression of the CAB gene than the shy2-1D single mutant. These results showed that phytochromes function in darkness in the shy2-1D mutant background. The implications of these results are discussed.
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Affiliation(s)
- B C Kim
- Department of Life Science and School of Environmental Engineering, Pohang University of Science and Technology, Kyungbuk, Korea
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