Tae Kwon Ryu

Jinju National University, Gyeongju, North Gyeongsang, South Korea

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Publications (6)7.33 Total impact

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    ABSTRACT: Hypoxia is an issue that affects ocean coastal waters worldwide. It has severe consequences for marine organisms, including death and rapid adaptive changes in metabolic organization. Although some aquatic animals are routinely exposed and resistant to severe environmental hypoxia, others such as sea urchins (Strongylocentrotus nudus) have a limited capacity to withstand this stress. In this study, hypoxia induced a significant increase in the number of red spherule cells among coelomocytes, which function as immune cells. This suggests that sea urchin immune cells could be used as a biological indicator of hypoxic stress. In the current study, we used cDNA microarrays to investigate the differential expression patterns of hypoxia-regulated genes to better understand the molecular mechanisms underlying the response of immune cells to hypoxia. Surprisingly, the predominant major effect of hypoxia was the widespread suppression of gene expression. In particular, the expression of RNA helicase and GATA-4/5/6 was decreased significantly in response to hypoxia, even in field conditions, suggesting that they could be utilized as sensitive bioindicators of hypoxic stress in the sea urchin.
    Ecotoxicology and Environmental Safety 11/2014; 109:63–69. · 2.20 Impact Factor
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    ABSTRACT: Triclosan (TCS, 2,4,4'-trichloro-2'-hydroxydiphenyl ether), a broad-spectrum antibacterial agent, is commonly found in the aquatic environment. In this study, we investigated TCS toxicity with pertaining to gamete viability, fertilization, and embryogenesis up to pluteus stage of the sea urchin, (Strongylocentrotus nudus). When the sperm and eggs were exposed to TCS (0-3.0μM), the viability of sperm was significantly decreased at molarities higher than 1μM of TCS. In addition, for exposure of 2.0μM TCS the viability of eggs was not influenced and none of the sperm was viable. Fertilization rate was significantly decreased when sperm were exposed to 0.5 and 1μM of TCS (p<0.001) and no fertilization was observed for the exposure of 1.5μM of TCS. In embryonic development, embryos are treated with higher than 1.0μM levels of TCS displayed arrested development. For TCS, the EC50 and LOECs values were 1.8, 1.49 and 0.99μM and 0.53, 0.62 and 0.39μM for sperm viability, fertilization rate, and larval development to pluteus, respectively. In the recovery test regarding normal development of arrested embryos based upon TCS exposure time, it was observed that embryos exposed to 1μM TCS for 15h were normally recovered for normal development, while embryos with more than 30h exposure were not recovered to normal larvae. Overall, the results of this study strongly suggest that the gametes and embryos of S. nudus can provide the basis for an effective bioassay, with a fast and sensitive means of evaluating TCS contamination in the marine ecosystem.
    Ecotoxicology and Environmental Safety 01/2014; · 2.20 Impact Factor
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    ABSTRACT: Bioassays and biomarkers have been previously developed to assess the effects of heavy metal contaminants on the early life stages of the sea urchin. In this study, malformation in the early developmental processes was observed in sea urchin (Strongylocentrotus intermedius) larvae exposed to 10 ppm Ni for over 30 h. The most critical stage at which the triggering of nickel effects takes place is thought to be the blastula stage, which occurs after fertilization in larval development. To investigate the molecular-level responses of sea urchin exposed to heavy metal stress and to explore the differentially expressed genes that are induced or repressed by nickel, differential display polymerase chain reaction (DD-PCR) was used with sea urchin mRNAs. The malformation-related genes expressed in the early life stages of the sea urchin were cloned from larvae exposed to 10 ppm of nickel for 15 h, and accessed via DD-PCR. Sequence analysis results revealed that each of the genes evidenced high homology with EGF2, PCSK9, serine/threonine protein kinase, apolipophorin precursor protein, and MGC80921 protein/transcript variant 2. This result may prove useful in the development of novel biomarkers for the assessment of heavy metal stresses on sea urchin embryos.
    Ecotoxicology and Environmental Safety 07/2012; 84:18-24. · 2.20 Impact Factor
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    ABSTRACT: Prorocentrum minimum is a common bloom- forming photosynthetic dinoflagellate found along the southern coast of Korea. To investigate the adaptive responses of P. minimum to high light stress, we measured growth rate, and generation of reactive oxidative species (ROS), superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) in cultures exposed to normal (NL) and high light levels (HL). The results showed that HL (800 µmol m −2 s −1 ) inhibited growth of P. minimum , with maximal inhibition after 7-9 days. HL also increased the amount of ROS and MDA, suggesting that HL stress leads to oxidative damage and lipid peroxidation in this species. Under HL, we first detected superoxide on day 4 and H2O2 on day 5. We also detected SOD activity on day 5 and CAT activity on day 6. The level of lipid peroxidation, an indicator of cell death, was high on day 8. Addition of diphenyleneiodonium (DPI), an NAD(P)H inhibitor, decreased the levels of superoxide generation and lipid peroxidation. Our results indicate that the production of ROS which results from HL stress in P. minimum also induces antioxidative enzymes that counteract oxidative damage and allow P. minimum to survive.
    Ocean Science Journal 12/2009; 44(4):199-204.
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    ABSTRACT: Acute toxicity and oxidative stress caused by exposure of titanium dioxide nanoparticles (TiO2-NPs) in juvenile common carp (Cyprinus carpio) were investigated. TiO2-NPs solution was prepared using deionized water and dispersed by sonication. Juvenile carp were exposed to different concentrations (5, 10, 20, 40, and 80 mg/L) of TiO2-NPs. TiO2-NP characteristics (particle morphology, size distribution, and zetapotential) were analyzed using transmission electron microscopy (TEM) and dynamic light scattering (DLS). Different tissue samples (skin, liver, brain, and gill) of fish were dissected, and the biochemical responses (catalase [CAT] and glutathione S-transferase [GST] activities) were measured. The results showed that acute exposure to TiO2-NPs induced GST and CAT levels to vary in all observed organs. The effective concentration of TiO2-NPs was 20 mg/L in the liver and brain and 40 mg/L in the gill. Histopathological changes were as follows: (1) skin: hypertrophy and increased number of mucous cells and thickening of the epidermal layer; (2) gill: hypertrophy of chloride cells, degeneration of mucous cells, and increased acidification of mucous cells; and (3) liver: hyperplasia and cytoplasm vacuolation of hepatic cells. No lethal effects were observed during the acute test. Our results show that there is a potential risk of TiO2-NP exposure to aquatic organisms in the environment.
    Molecular and Cellular Toxicology 8(4). · 0.72 Impact Factor