• Economic and Environmental Geology
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• v.43 no.1
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• pp.53-66
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• 2010

We report petrologic characteristics including $^{40}Ar-^{39}Ar$ absolute ages of the subsurface lavas recovered from borehole cores in two islets, Marado and Gapado, off the southwestern coast of Jeju in southernmost Korea and discuss on the volcanism in the region. The lavas in Gapado are apparently divided into one unit with bright colored, aphanitic texture and sheet jointed, and another unit with dark colored and massive. The outcrops often show differentially weathered pattern due to textural difference. While, the lavas in Marado have vesicular and glomerporphyric texture, even though each lava flow unit in Marado has slight unique texture with variation of vesicularity and phenocrysts. The chemical composition of rock core samples from Gapa borehole and Mara borehole shows that the lavas from Gapado and Marado are classified into basaltic trachyandesite($SiO_2$ 52.6-53.6 wt%, $Na_2O+K_2O$ 7.3-7.5 wt%) and tholeiitic andesite($SiO_2$ 51.7-52.8 wt%, $Na_2O+K_2O$ 3.6-4.1 wt%), respectively. The measured $^{40}Ar-^{39}Ar$ plateau ages range from $824{\pm}32\;Ka$(MSL -69 m) to $758{\pm}\;Ka$(MSL 19 m) for core samples of Gapa borehole and $259{\pm}168\;Ka$(MSL -26 m) for a core sample of Mara borehole, respectively. The absolute age of Gapado basaltic trachyandesite is well correlated with that of Sanbangsan trachyte(Won et al., 1986). Meanwhile, the age of a sample in Marado has $259{\pm}168\;Ka$(MSL -26 m) with poor plateau age formation and high error range. We report the data in caution but the rock composition and absolute age of Marado tholeiitic andesite are relatively correlated with those of lava units from Duksu and Sangmo-2 boreholes, indicating the volcanism during 260-150 Ka. On the basis of interpretation of occurrences of exposed and subsurface volcanic rocks of the study area, stratigraphic relationship with adjacent borehole cores and the bathymetry chart of surrounding area, it indicates that the lavas in Gapado were formed around 800 Ka during relatively early stage of volcanic activity in Jeju Island. Meanwhile, Marado may have originated around 260-150 Ka during relatively young stage of volcanism in Jeju Island. It is inferred that the volcanisms have originated in land and these islets were individual ancient volcanoes. The apparent topography has been re-shaped by tidal erosion due to transgression.

• Economic and Environmental Geology
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• v.50 no.6
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• pp.477-486
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• 2017

In this study, we analyze precise seabed geomorphology and conditions for comparing the nearshore areas of the Dongdo(East Island) and the Seodo(West Island) using detailed bathymetry data and seafloor backscattering images, in Dokdo, the East Sea. We have been obtained the detailed bathymetry data and the seafloor backscattering data. The survey range is about $250m{\times}250m$ including land of islets to the nearshore areas of the southern part of the Dongdo and the Seodo. As a result of bathymetry survey, the southern area of the Dongdo(~50 m) is deeper than the Seodo(~30 m) in the water depth. The survey areas are consist of extended bedrocks from land of the Dongdo and the Seodo. The underwater rock region of the Seodo is larger than the Dongdo. In spite of similar extended rocks features from islets, there are some distinctive seabed characteristics between the southern nearshore areas of the Dongdo and the Seodo. The Talus-shaped seafloor environment formed by gravel and underwater rocks originating from the land of the Dongdo is up to about 15 m depth. And the boundary line of between extended bedrocks and seabottom is unclear in the southern nearshore of the Dongdo. On the other hand, the southern coast of the Seodo is characterized by relatively large scale underwater rocks and evenly distributed sediments, which clearly distinguish the boundary of between extended bedrocks and seafloor. This is because the tuff layers exposed to the coastal cliffs of the Dongdo are weak against weathering and erosion. It is considered that there are more influences of the clastic sediments carried from the land of the Dongdo compared with the Seodo. Particularly, the land of the Dongdo has been undergoing construction activities. And also a highly unstable ground such as faults, joints and cracks appears in the Dongdo. In previous study, there are dissimilar features of the massive tuff breccia formations of the Dongdo and the Seodo. These conditions are thought to have influenced the different seabed characteristics in the southern nearshore areas of the Dongdo and the Seodo.

• Korean Journal of Environment and Ecology
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• v.34 no.2
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• pp.99-105
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• 2020

Migratory birds use a variety of breeding and wintering sites, and it is particularly important to understand more information on breeding and feeding sites for the conservation and management of endangered species. Black-faced spoonbills (Platalea minor) are an international endangered species distributed in East Asia. The majority of black-faced spoonbills breed on uninhabited islets off the west coast of the Korean Peninsula during the breeding season, and they are distributed in East Asia such as Taiwan, Hong Kong, southern China, Japan, and Jeju island during the winter season. In this study, we used a wild animal location tracking system to analyze and compare home ranges of three black-faced spoonbills spending the post-fledging stage in Gujido islet in Incheon and Chilsando islet in Yeonggwang each in 2015. The tree black-faced spoonbills in Guji islet showed a home range in coastal areas in Hwanghaenam-do and Gangneung-gun. The home range size (mean±SD) was estimated to be 425.49±116.95 ㎢ using 100% MCP, 43.61±18.51 ㎢ using KDE 95%, and 7.46±3.68 ㎢using KDE 50%. The tree black-faced spoonbills in Chilsando islet showed a home range in the Baeksu tidal flat and the Buan Saemangeum area with a size of 99.38±55.29 ㎢ using 100% MCP, 19.87±6.05 ㎢ using KDE 95%, and 1.16±0.53 ㎢ using KDE 50%. The figured indicated that the tree black-faced spoonbills breeding in Gujido islet had a wider home range than those breeding in Chilsando islet. During the post-fledging stage, the home ranges of black-faced spoonbills were mostly breeding in mudflats. Therefore, it is necessary to minimize human intervention, such as the construction of roads and structures and the human access, to protect the habitats during the period.

• Microbiology and Biotechnology Letters
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• v.45 no.1
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• pp.63-70
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• 2017

A functional screen of 60,672 fosmid metagenomic clones amplified from marine sediment obtained from the Dokdo islets in Korea identified the gene EstES1, whose product, EstES1, displayed lipolytic properties on tributyrin-supplemented media. EstES1 is a 576 amino acid protein with a predicted molecular weight of 59.4 kDa including 37 N-terminal leader amino acids. EstES1 exhibited the highest sequence similarity (44%) to a carboxylesterase found in Haliangium ochraceum DSM14365. Phylogenetic analysis indicated that EstES1 belongs to a currently uncharacterized family of lipases. Within the conserved domain, EstES1 retains the catalytic triad that consists of the consensus penta-peptide motif, GESAG. EstES1 demonstrated a broad substrate specificity toward the long acyl group of ethyl esters (C2-C12), and its optimal activity was recorded toward p-Nitrophenyl butyrate (C4) at pH 9.0 and $40^{\circ}C$ (specific activity of 255.4 U/mg). The enzyme remained stable in the ranges of $60-65^{\circ}C$ and pH 9.0-10.5 and in the presence of methanol, ethanol, isopropanol, and dimethyl sulfoxide. Therefore, EstES1 has potential for use in industrial applications involving high temperature, organic solvents, and/or alkaline conditions.

• Journal of Ecology and Environment
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• v.33 no.1
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• pp.23-36
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• 2010

The Cat Ba Islands in Hai Phong City, northern Vietnam, consist of a large limestone island with a maximum height of 322 m above sea level and 366 small limestone islets with a total area of about $180\;km^2$. The islands are relicts of karst limestone mountains that became submerged during the Holocene transgression 7000 - 8000 year ago. The combination of the longtime karst process and recent marine processes in the monsoonal tropical zone has created a very diversity landscape on the Cat Ba Islands that can be divided into 3 habitat types with 16 forms. The first habitat type is the karst mountains and hills, including karst mountains and hills, karst valleys and dolines, karst lakes, karst caves, and old marine terraces. The second habitat type is the limestone island coast, including beaches, mangrove marshes, tidal flats, rocky coasts, marine notch caves, marine karst lakes, and bights. The third habitat type is karst plains submerged by the sea, including karst cones (fengcong) and towers (fengling), bedrock exposed on the seabed, sandy mud seabed, and submerged channels. Like the landscape, the biodiversity is also high in ecosystems composed of scrub cover - bare hills, rainy tropical forests, paddy fields and gardens, swamps, caves, beaches, mangrove forests, tidal flats, rocky coasts, marine krast lakes, coral reefs, hard bottoms, seagrass beds and soft bottoms. The ecosystems on the Cat Ba Islands that support very high species biodiversity include tropical evergreen rainforests, soft bottoms; coral reefs, mangrove forests, and marine karst lakes. A total of 2,380 species have been recorded in the Cat Ba Islands, included 741 species of terrestrial plants; 282 species of terrestrial animals; 30 species of mangrove plants; 287 species of phytoplankton; 79 species of seaweed; 79 species of zooplankton; 196 species of marine fishes; 154 species of corals; and 538 species of zoobenthos. Many of these species are listed in the Red Book of Vietnam as endangered species, included the white-headed or Cat Ba langur (Trachypithecus poliocephalus), a famous endemic species. Human activities have resulted in significantly changes to the landscape end ecosytems of the Cat Ba islands; however, many natural aspects of the islandsd have been preserved. For this reason, the Cat Ba Islands were recognized as a Biological Reserved Area by UNESCO in 2004.

• Nutrition Research and Practice
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• v.9 no.1
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• pp.22-29
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• 2015

BACKGROUND/OBJECTIVES: Recently, anthocyanins have been reported to have various biological activities. Furthermore, anthocyanin-rich purple corn extract (PCE) ameliorated insulin resistance and reduced diabetes-associated mesanginal fibrosis and inflammation, suggesting that it may have benefits for the prevention of diabetes and diabetes complications. In this study, we determined the anthocyanins and non-anthocyanin component of PCE by HPLC-ESI-MS and investigated its anti-diabetic activity and mechanisms using C57BL/KsJ db/db mice. MATERIALS/METHODS: The db/db mice were divided into four groups: diabetic control group (DC), 10 or 50 mg/kg PCE (PCE 10 or PCE 50), or 10 mg/kg pinitol (pinitol 10) and treated with drugs once per day for 8 weeks. During the experiment, body weight and blood glucose levels were measured every week. At the end of treatment, we measured several diabetic parameters. RESULTS: Compared to the DC group, Fasting blood glucose levels were 68% lower in PCE 50 group and 51% lower in the pinitol 10 group. Furthermore, the PCE 50 group showed 2-fold increased C-peptide and adiponectin levels and 20% decreased HbA1c levels, than in the DC group. In pancreatic islets morphology, the PCE- or pinitol-treated mice showed significant prevention of pancreatic ${\beta}$-cell damage and higher insulin content. Microarray analyses results indicating that gene and protein expressions associated with glycolysis and fatty acid metabolism in liver and fat tissues. In addition, purple corn extract increased the phosphorylation of AMP-activated protein kinase (AMPK) and decreased phosphoenolpyruvate carboxykinase (PEPCK), glucose 6-phosphatase (G6pase) genes in liver, and also increased glucose transporter 4 (GLUT4) expressions in skeletal muscle. CONCLUSIONS: Our results suggested that PCE exerted anti-diabetic effects through protection of pancreatic ${\beta}$-cells, increase of insulin secretion and AMPK activation in the liver of C57BL/KsJ db/db mice.

• Biomolecules & Therapeutics
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• v.19 no.3
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• pp.348-356
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• 2011

Liriope platyphylla is a medical herb that has long been used in Korea and China to treat cough, sputum, neurodigenerative disorders, obesity and diabetes. The aims of this study were to study the antidiabetic effects of the aqueous extract of L. platyphylla (AEtLP) through pancreatic and extrapancreatic actions. AEtLP were orally administrated to ICR mice once a day for 7 days. Of three different concentrations of AEtLP, only 10% AEtLP were low toxic to liver, based on body weight and serum biochemical analyses. However, 10% AEtLP-treated mice displayed signifi cant reduction of the glucose concentration and increased insulin concentration; no changes were noted using 5% and 15% AEtLP. Also, the increase of glucose transporter (Glut)-1 expression in liver was dependent on the concentration of AEtLP, and was regulated by the phosphorylation of Akt. The lowest expression of Glut-3 was observed in 15% AEtLP treated mice, followed by 10% AEtLP- and 5% AEtLP-treated mice. This pattern of Glut-3 expression was roughly in accord with the phosphorylation of c-Jun N-teminal kinase (JNK) in the mitogen-activated protein kinase (MAPK) pathway. Furthermore, a signifi cant rise of the superoxide dismutase activity (SOD) was detected in AEtLP-treated mice. The fi ndings suggest that AEtLP should be considered as a diabetes therapeutic candidate to induce insulin secretion from pancreatic ${\beta}$-cells and glucose uptake in liver cells.

• YAKHAK HOEJI
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• v.53 no.5
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• pp.286-292
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• 2009

In this study, we investigated the anti-obese activity of HPJ extract in C57BL/6J mice. The C57BL/6J mice were randomly divided into five groups: normal control group (Con), high fat diet control group (HFD), treatment groups with HPJ at 125 mg/kg (HPJ125), 250 mg/kg (HPJ250), or 500 mg/kg (HPJ500). To induce an obesity, mice were fed by a high fat diet for 6 weeks, and mice were administered with HPJ extract once a day for 8 weeks. At the end of treatment, we examined the effect of HPJ extract on body weight, plasma lipid, and lipogenic enzymes. HPJ extract was found to lower whole body and epididymal adipose tissue weights and lowered plasma levels of glucose, insulin, triglyceride (TG), total cholesterol (TC), non-esterified fatty acid (NEFA) and leptin, compared to those in HFD group. Histological analyses of the liver and fat tissues of mice treated with HPJ extract revealed significantly decreased number of lipid droplets and decreased size of adipocytes compared to the HFD group. In addition, HPJ extract preserved the morphological integrity of pancreatic islets. To elucidate an action mechanism of HPJ extract, Western blot and RT-PCR were performed using epididymal adipose tissues. HPJ extract up-regulated the levels of phosphorylated adenosine monophosphate-activated protein kinase (AMPK) and its substrate, acetyl-CoA carboxylasse (ACC). HPJ extract also attenuated lipogenic gene expressions of sterol regulatory element-binding protein $1{\alpha}$ (SREBP$1{\alpha}$), fatty acid synthase (FAS), sterol-CoA desaturase 1 (SCD1) and glycerol-3-phosphate acyltransferase (GPAT) in dose-dependent manners. In contrast, expressions of lipolytic genes such as peroxisome proliferator-activated receptor-$\alpha$ (PPAR-${\alpha}$) and CD36, and fatty acid $\beta$-oxidation gene, carnitine palmitoyltransferase-1 (CPT-1) were increased. These results suggest that HPJ extract ameliorates obesity through inhibiting synthesis of lipogenic enzymes as well as stimulating fatty acid oxidation resulting from activation of AMPK, and HPJ extract could be developed as a potential therapeutic agent for obese patients.

• Korean Journal of Pharmacognosy
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• v.47 no.2
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• pp.158-164
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• 2016

This study was conducted to verify the potential of Allium hookeri to control blood glucose metabolism in diabetes model. We fed the experimental diets(ALE, ARE) supplemented with the extract of Allium hookeri leaf or root at 1% of diet to the diabetic mice (C57BLKS/J, db/db) for 8 weeks. Hetero and control mice were fed the control diet without any extract of Allium hookeri leaf or root. At 8th week of feeding the diets, we measured body weight, blood glucose, HbA1c, and plasma insulin levels and conducted an oral glucose tolerance test (OGTT) and staining insulin immunoreactive cells in islets of pancreas. ARE group treated with the root of A. hookeri showed significantly lower blood glucose levels than the Cont group at 120 min in the OGTT. However, HbA1c level was significantly reduced in both ALE and ARE groups, and higher serum insulin levels and increased density of insulin immunoreactive cells compared with the Cont group were found in these 2 groups. Based on these results, A. hookeri is considered to be effective in improving glucose tolerance by partially affecting insulin secretion and it may be used to prevent and treat diabetic disease.

• Korean Journal of Pharmacognosy
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• v.46 no.1
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• pp.78-83
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• 2015

This study was conducted to verify the potential of Allium hookeri to control glucose metabolism in a diabetes model. We fed the experimental diets (AL, AR, Dex) supplemented with the powder of leaf, root, or dextrin as a positive control, respectively at 3% of diet to the diabetic mice (C57BLKS/J, db/db) for 8 weeks. Control mice were fed with the diet supplemented with cornstarch (Cont) at 3% level of diet. At 8th week of feeding the diets, we measured body weight, blood glucose, HbA1c, and plasma insulin levels and conducted an oral glucose tolerance test (OGTT) and staining insulin immunoreactive cells in islets of pancreas. AL group treated with the leaf of A. hookeri showed significantly lower blood glucose and HbA1c levels, higher plasma insulin levels, and increased density of insulin immunoreactive cells compared with the Cont group. During the OGTT, AL group showed lower blood glucose levels than the Cont group for 120 min. Based on these results, leaf of A. hookeri is considered to be effective in improving glucose tolerance by partially affecting insulin secretion and it may be used to prevent and treat diabetic disease.