Hyokyoung Won

Korea Institute of Ocean Science and Technology, Sŏul, Seoul, South Korea

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Publications (10)8.65 Total impact

  • Seungshic Yum · Seonock Woo · Aekyung Lee · Hyokyoung Won · Junghee Kim
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    ABSTRACT: The need for nonmammalian and nonvertebrate experimental systems for toxicology is increasing because of growing concern about animal welfare. Hydra, a genus of freshwater cnidarian, has been used in classical toxicology for more than 40 years and has been recommended as a standard model for ecotoxicology. Functional assays using Hydra homologues of the signal molecules and transcription factors of other metazoans have demonstrated that Hydra shares the common molecular mechanisms for pattern formation with bilaterian animals. The availability of the Hydra genome and mRNA information has meant that it can be used as a model organism in biological sciences. The purpose of this review is to explore recent developments in our understanding of the molecular aspects of axis formation, bud formation, regeneration, and the nervous system in Hydra and to introduce Hydra as an alternative animal model in environmental toxicogenomics for predicting the toxicity of environmental pollutants at the molecular level.
    No preview · Article · Dec 2015 · Molecular and Cellular Toxicology
  • Hyokyoung Won · Seonock Woo · Seungshic Yum
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    ABSTRACT: Differential gene expression profiling of the liver tissue of the marine medaka fish, Oryzias javanicus, was performed with a cDNA microarray after exposure to 4-nonylphenol (4-NP, 20 μg/L for 48 h), which is used in detergents, pesticides, and as an antioxidant in plastics and rubber. We identified 218 differentially expressed genes; the expressions of 117 genes were upregulated and those of 101 genes were downregulated (P<0.05). Among them, the expression levels of two genes, vitellogenin 1 and choriogenin L, were found to be upregulated. Both of which are representative environmental estrogen-responsive gene. The upregulated and downregulated genes were assembled into 21 and 20 functional groups, respectively, based mainly on the eukaryotic orthologous groups (KOG) classification. The same tendencies in gene expression were observed in the results of a real-time quantitative reverse transcription-PCR (qRT-PCR) analysis, which was conducted to examine 32 selected genes. The genes differentially expressed in response to 4-NP were associated with estrogenic signaling, immune responses, nerve cell maturation, cellular stress and detoxification, tumor transformation, glucose metabolism, RNA processing, lipid biosynthesis, and iron metabolism. These differentially expressed genes could be used as molecular biomarkers of biological responses to environmental pollutants, especially endocrinedisrupting chemicals.
    No preview · Article · Jun 2014 · Molecular and Cellular Toxicology
  • Hyokyoung Won · Seonock Woo · Aekyung Lee · Seungshic Yum
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    ABSTRACT: Differential gene expression profiling was carried out using cDNA microarray hybridization on hepatic tissue from marine medaka (Oryzias javanicus) after exposure to benzo[a]pyrene (BaP), a representative polycyclic aromatic hydrocarbon classified as a persistent organic pollutant. Forty-one differentially expressed candidate genes were identified; 18 were induced and 23 were repressed (P/0.05). The genes were assembled into 18 groups based mainly on the Eukaryotic Orthologous Groups classification. These differentially expressed gene candidates could have great potential as molecular biomarkers for identifying environmental stressors and prognosis for the biological effects of BaP. The candidate genes isolated in this study were grouped into endocrine disruption, cardiovascular disease, tumorigenesis, immune response, detoxification, energy production and conversion, and other biological responses. Our results could allow future studies to assess the molecular mechanisms of BaP toxicity and to develop a systems biology approach to environmental stress biology.
    No preview · Article · Sep 2013 · Toxicology and Environmental Health Sciences
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    ABSTRACT: Differential gene expression profiling was performed using cDNA microarray hybridization on the hepatic tissue of the marine medaka (Oryzias javanicus) after exposure to toxaphene, which is classified as a persistent organic pollutant. Ninety-seven differentially expressed candidate genes were identified; 40 were induced and 57 were repressed (P<0.05). The genes were assembled into 18 groups based mainly on the Eukaryotic Orthologous Groups classification. These isolated gene candidates were differentially expressed and therefore have great potential as molecular biomarkers for identifying environmental stressors and prognosis for the biological effects of the toxicant. Some of the genes were closely related to endocrine disruption, renal and cardiovascular disease, tumorigenesis, immune responses, and detoxification. Our results will allow future studies to assess the molecular mechanisms of toxaphene toxicity and to develop a systems biology approach to environmental stress biology.
    Full-text · Article · Jun 2013 · Molecular and Cellular Toxicology
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    Seonock Woo · Hyokyoung Won · Aekyung Lee · Seungshic Yum
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    ABSTRACT: Transcriptional changes in the expression of stress-related genes (catalase, glutathione peroxidase, glutathione S-transferase, glutathione reductase, metallothionein, and ubiquitin) in intestinal, liver and muscle tissues of Javanese medaka (Oryzias javanicus) exposed to 17-estradiol (E2) were investigated using real-time quantitative PCR. The lipid peroxidation levels and superoxide dismutase activity in liver tissues was also examined at various exposure concentrations. In fish exposed to 10, 100 and 1000 g/L E2 the level of catalase mRNA increased significantly in intestinal and muscle tissues, while expression of the glutathione peroxidase gene showed the opposite trend in liver and muscle tissues. Expression of the glutathione S-transferase gene increased in a dose-dependent manner in liver and muscle tissues of fish exposed to E2, relative to the non-exposed control group. The level of glutathione reductase mRNA increased markedly in the liver tissues of all fish exposed to 100 and 1000 g/L E2, but decreased in intestinal tissues. The metallothionein gene was strongly downregulated in intestinal and liver tissues of fish exposed to E2, but slightly upregulated in muscle tissues. In all fish exposed to 100 and 1000 g/L E2 expression of the ubiquitin gene increased markedly in liver and muscle tissue, but not in intestinal tissues. Lipid peroxidation and superoxide dismutase activities increased significantly in all 17-estradiol treatment groups, and were correlated to the exposure concentration. Thus, E2 exposure differentially affected the transcription of a range of stress-related genes in various tissues of Javanese medaka, suggesting that analysis of transcriptional changes in these genes could be used as a rapid assay of the effects of E2 exposure.
    Preview · Article · Sep 2012 · Molecular and Cellular Toxicology
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    ABSTRACT: Differential gene expression profiling was performed by heterologous hybridization using a medaka cDNA microarray on the hepatic tissue of the marine medaka (Oryzias javanicus) after exposure to Arochlor 1260, a polychlorinated biphenyl (PCB), which is classified as a persistent organic pollutant. Twenty-eight differentially expressed candidate genes were identified; one was induced and 27 were repressed (P<0.01). The genes were assembled into 10 groups based mainly on the Eukaryotic Othologous Groups classification. These isolated gene candidates were differentially expressed and therefore have great potential as molecular biomarkers for identifying environmental stressors. The results obtained in this study will allow future studies to assess the molecular mechanisms of Arochlor 1260 toxicity and to develop a systems biology approach to PCB stress biology.
    Full-text · Article · Jun 2012 · Toxicology and Environmental Health Sciences
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    ABSTRACT: We evaluated toxaphene-induced acute toxicity in Hydra magnipapillata. The median lethal concentrations of the animals (LC(50)) were determined to be 34.5 mg/L, 25.0 mg/L and 12.0 mg/L after exposure to toxaphene for 24 h, 48 h and 72 h, respectively. Morphological responses of hydra polyps to a range of toxaphene concentrations suggested that toxaphene negatively affects the nervous system of H. magnipapillata. We used real-time quantitative PCR of RNA extracted from polyps exposed to two concentrations of toxaphene (0.3 mg/L and 3 mg/L) for 24 h to evaluate the differential regulation of levels of transcripts that encode six antioxidant enzymes (CAT, G6PD, GPx, GR, GST and SOD), two proteins involved in detoxification and molecular stress responses (CYP1A and UB), and two proteins involved in neurotransmission and nerve cell differentiation (AChE and Hym-355). Of the genes involved in antioxidant responses, the most striking changes were observed for transcripts that encode GPx, G6PD, SOD, CAT and GST, with no evident change in levels of transcripts encoding GR. Levels of UB and CYP1A transcripts increased in a dose-dependent manner following exposure to toxaphene. Given that toxaphene-induced neurotoxicity was not reflected in the level of AChE transcripts and only slight accumulation of Hym-355 transcript was observed only at the higher of the two doses of toxaphene tested, there remains a need to identify transcriptional biomarkers for toxaphene-mediated neurotoxicity in H. magnipapillata. Transcripts that respond to toxaphene exposure could be valuable biomarkers for stress levels in H. magnipapillata and may be useful for monitoring the pollution of aquatic environments.
    No preview · Article · Apr 2012 · Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology
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    Hyokyoung Won · Seungshic Yum · Seonock Woo
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    ABSTRACT: The construction of a subtractive cDNA library of organisms and the analysis thereof have proven meaningful in the search for clones whose expressions are regulated by exterior changes. The principal objective of this study was to identify the differentially expressed genes of marine medaka fish (Oryzias javanicus) under benzo[a]pyrene exposure conditions. Medaka fish were exposed to 100 μg/L of benzo[a]pyrene for 24 hr and its hepatic RNA was extracted; RNA from the livers of non-exposed medaka fish was also extracted. Both RNAs were employed in the construction of the subtractive cDNA library and the nucleotide sequences of differentially expressed clones were analyzed. Twenty-eight genes of the total differentially expressed clones were considered significant; in particular, the transcription of the cytochrome P450 1A gene was upregulated in a dose-dependent manner under various benzo[a]pyrene concentration exposure conditions. The 28 genes were then divided into 4 categories: (1) information storage and processing, (2) cellular processes and signaling, (3) metabolism, and (4) poorly characterized. The data reported herein provide general information regarding the effects of benzo[a]pyrene contamination on marine organisms, and constitute a primary step in the development of novel biomarkers for marine environmental pollution. KeywordsMarine medaka– Oryzias javanicus –Benzo[a]pyrene–Subtractive cDNA library–Differentially expressed genes
    Preview · Article · Mar 2011 · Toxicology and Environmental Health Sciences
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    Seonock Woo · Hyokyoung Won · Jae-Chun Ryu · Seungshic Yum
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    ABSTRACT: Differential gene expression profiling was performed in the hepatic tissue of marine medaka fish (Oryzias javanicus) after exposure to an organophosphorous pesticide (OPP), Iprobenfos (IBP), a widely used pesticide in agri- and fish-culture, by heterologous hybridization using a medaka cDNA microarray. Fifty differentially expressed candidate genes, of which 10 induced and 40 repressed (P<0.01), were identified. The genes were assembled into 19 groups mainly based on Eukaryotic Othologous Groups (KOG) classification. These isolated gene candidates were differentially expressed and therefore have great potential as molecular biomarkers for the identification of environmental stressors. The results obtained in this study will allow future studies to assess the molecular mechanisms of IBP toxicity and the development of a systems biology approach to the stress biology of organophosphorous pesticide. KeywordsMarine medaka– Oryzias javanicus –Heterologous hybridization–Organophosphorus pesticide–Iprobenfos (IBP)–Differential gene expression profile
    Preview · Article · Feb 2010 · Toxicology and Environmental Health Sciences
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    ABSTRACT: Differential gene expression profiling was performed in the hepatic tissue of marine medaka fish (Oryzias javanicus) after exposure to benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon (PAH), by heterologous hybridization using a medaka cDNA microarray. Thirty-eight differentially expressed candidate genes, of which 23 were induced and 15 repressed (P⁄0.01), were identified and found to be associated with cell cycle, development, endocrine/reproduction, immune, metabolism, nucleic acid/protein binding, signal transduction, or non-categorized. The presumptive physiological changes induced by BaP exposure were identified after considering the biological function of each gene candidate. The results obtained in this study will allow future studies to assess the molecular mechanisms of BaP toxicity and the development of a systems biology approach to the stress biology of organic chemicals.
    Full-text · Article · Dec 2009 · Molecular and Cellular Toxicology