• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.123-139
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• 1985

The present survey was undertaken to observe the geographical distibution of matacercaria among the sweetfish, Plecoglossus altivelis, the most important second intermediate host of Metagonimus yokegawai, which were collected during the period from 1983 to 1984 in south-eastern coastal areas of Korea. The results obtained were summarized as follow: 1. A total of 668 sweetfish collected from 70 chins (=streams) in the above coastal arcus was examined for the metacercariae, and 432 (64.7%) among them were infected with metacercariae of M. yokogawai. The mean number of metacercariae in a fish was in the range from 0 to 29,604 and the mean number of the metacercariae in a fish was 640.3. 2. It was observed that the mean infection rate showed 46.45 in Gangweon-Do (=province) . The infection rates varied from stream to stress showing 100% in Namdae stream(Gangnun-city) , Obsib stream (Samchok-gun) and Dongmak, 95.0% in Hosan stream, 90.0% in Gungchin stream, and Namdae stream (Yangyang-fp) ,80.0% in Hwasang stream,50.0% in Daebong stream,45.0% in Yonghwa stream, 30.0% in sangchsn stream and Sachsn stream, 20.0% in Munam stream and Okgyoe stream, 15.0% in Imweon stream, 10.0% in Namchsn stream. And no metacercarial infections in their fish host were found in the areas of Mulchi stream, Sangun stream, Gosamun stream, Jonchon stream and Gagok stream. 3. It was observed that the mean infection rate showed 50.9% in Kyangsangbuk-Do (=province). The infection rates also varied from stream to stream showing 100% in Songchon stream, Osib stream (Yongdok-gun) and Daejong stream,60.0% in Pyanghae stream and Gunmu stream,50.0% in Buhwung stream and stream, 25.0% in Nagok stream, 20.0% in Oangbi stream, 10.0% in Namhodong stream. And no metacercarial infections in their fish host were found in the areas of Namdae stream (Uljinup) and Chaksan stream. 4. It was observed that the mean infection rate showed 67.6% in Kyangsangnam-Do(=province). The infection rates varied from stream to stream showing 100% in Taehwa river, Hwiya river, Inchfn stream, Miryang river, Nam river, Hwagae stream, Koha stream, Sosang stream, and Tongchon stream,90.9% in Yancho stream,90.0% in Hoihwa stream,80.0% in Chindong stream, 66. YoA in Chingyo stream, 40.0% in Hoyam river. And no metacercarial infections in their fish host were found in the areas of Chinjon stream, Sanchan stream and Jukch6n stream. 5. It was observed that the mean infection rate showed 94.6"A in 0h511anam-Do(=province). The infection rates varied from stream to stream showing 100% in DongchEn stream, Isachon stream, Somjin river(GoksEng-gun) , Ssmjin river(Kurye-gun) , S6si stream, Gokchsn stream, Kohung stream, Kwansan stream, Youi stream, stream, Unj6n stream and Apnae stream, 92.3% in Tamjin river, 90.9% in Okkok stream, 84.6% in Songgen stream. And no metacercarial infections in their fish host were found in the area of Ypmgpl stream. 6. On the other hand, the infection rate showed 100% in Inchsn river of Chollabuk Do (=province) (=province) and Kangsn stream of Cheju-Do(=province) .

• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.432-441
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• 2016

Machaerium cuspidatum, a canopy liana, is a species of genus legume in the Fabaceae family and contributes to the total species richness in the tropical rain forests. In the present study, we investigated the antioxidative and anti-cancer effects of M. cuspidatum and its mode of action. The methanol extract of M. cuspidatum (MEMC) exhibited anti-oxidative activity with an $IC_{50}$ value of $1.66{\mu}g/ml$, and this was attributable to its 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity. MEMC also exhibited a cytotoxic effect and induced morphological changes in a dose-dependent manner in several cancer cell lines including human lung adenocarcinoma A549 cells, human hepatocellular carcinoma HepG2 cells, and human colon carcinoma HT29 cells. Moreover, MEMC treatment induced the accumulation of subG1 population, which is indicative of apoptosis in A549 and HepG2 cells. MEMC-induced apoptosis was confirmed by the increase in Annexin V-positive apoptotic cells and apoptotic bodies using Annexin-V staining and DAPI staining, respectively. Further investigation showed that MEMC-induced apoptosis was associated with the increase in p53 and Bax expression, and the decrease in Bcl-2 expression. In addition, MEMC treatment led to proteolytic activation of caspase-3, 8, and 9 and degradation of poly-ADP ribose polymerase (PARP). Taken together, these results suggest that MEMC may exert a beneficial anti-cancer effect by inducing apoptosis via both the extrinsic and intrinsic pathways in A549 and HepG2 cells.

• Parasites, Hosts and Diseases
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• v.32 no.4
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• pp.249-258
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• 1994

Recently, the importance of toxoplasmosis is raised as a complication in immunosuppressed or AIDS patients. Our study focused on the identification of a variety of Toxoplasma antigens by immunoblotting. Rabbits and BALB/c mice were immunized with Toxoplosmo Iysate (RH strain) , frozen tachyzoites (RH strain) or cysts (Beverly and Fukaya strain) . Blood were collected from ear vein, heart or orbital plexus for detecting the serum antibody levels. For excretory-secretory (E.S) antigens, T gondii (RH) tachyzoite were cultured in CHL (Chinese hamster lung) cells with MEM containing of 5% FCS. After 72hrs, culture supernatant was collected. BALB/c mice were inoculated with RH tachyzoite intraperitoneally and peritoneal fluids were extracted three days later. E.S antigens were detected in culture supernatant and infected mouse peritoneal fluid by EITB. Serum IgG levels in rabbit were 1 :512 of 10 days after primary immunization, 1 : 2,048 of 10 days after secondary immunization, 1: 1,024 of 20 days after secondary immunization by IFAT, respectively. Serum IgG levels of immunized mice were 1:128 after 7 weeks. Tachyzoite antigens of the RH strain were detected 25 protein bands ranging 10 kDa-220 kDa of molecular weights with Coomassie blue stain. Toxoplcsma major antigens corresponding to n of 24 kDa, 27 kDa,30 kDa, 35 kDa, 38 kDa were recognized by IgG and IgM antibodies. Excretory-secretory antigens present in culture supernatant with M. W. of 20, 30 kDa and in infected mouse peritoneal fluid with M.W. of 33 (P30), 45 kDa. When RH tachyzoite antigen was probed with different mice sera immunized with 2 strains of T gondii, the IgG antibody bud of Fukaya and Beverly strain (8 week-serum) is identical to those of RH strain. It is considered that the 30 kDa polypeptide detected in excretory- secretory materials and Iysate was important major antigen of T gondii (RH).

• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.47-60
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• 2020

To assess the characteristics of phytoplankton community structures related to environmental factors, seasonal surveys were conducted in the vicinity of Dokdo. In 2019, phytoplankton of four phyla and 69 species were observed. During winter, unidentified nanoflagellates dominated, with an average of 3.19×10⁴ cells L^-1. In spring, unidentified nanoflagellates occupied about 50% of the composition and a variety of dinoflagellates appeared. The summer phytoplankton population showed very low abundance. In autumn, various species of Chaetoceros appeared, along with diatoms, such as Bacteriastrum spp., Guinardia striata, and Pseudo-nitzschia spp. In addition, tropical species Amphisolenia sp. and Ornithocercus sp. were observed in both 2018 and 2019. The diversity was high in the summer of 2018 and the winter of 2019 and the characteristics of each index varied. Cluster analysis was divided into four groups according to species and population characteristics regardless of the season. The stratification of spring was particularly weak. In the autumn of 2018, the water mass was stabilized in the same way as in the summer, which is considered a suitable condition for phytoplankton growth. However, in 2019, the water masses were mixed, resulting in a low population. In a phytoplankton comparison, the dominant group showed seasonal differences, except for summer when the population was low, and the difference was most pronounced in autumn. Therefore, the waters surrounding Dokdo have different environmental and ecological characteristics from the East Sea, but the seasonal characteristics of each year are considered to be different depending on the topography, various currents, the island effect, and other factors.

• Parasites, Hosts and Diseases
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• v.33 no.1
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• pp.45-54
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• 1995

Two-day-old chickens{\;}and{\;}mallards were orally inoculated with one of % doses varying from $2{\;}{\times}{\;}10^2{\;}to{\;}2{\;}{\times}{\;}10^6$ of C. bailevi oocysts per individual. Generally, the more oocysts Inoculated were, the longer the patent periods were, and the more oocysts shedding were. Meanwhile increasing the inoculative dose, the prepatent periods were shortened except that mallards inoculated with $2{\;}{\times}{\;}10^2and{\;}2{\;}{\times}{\;}10^3$ oocysts foiled to produce the oocysts. The more parasites involving oocysts appeared from the chicken in comparison to the mallard. In the chickens challenged with a single dose of $2{\;}{\times}{\;}10^6$ oocysts, a small number of oocysts were detected from feces on days 4-14 after challenge infection (ACI) in all of carrageenan administered groups and in the control groups inoculated with $2{\;}{\times}{\;}10^2{\;}and{\;}2{\;}{\times}{\;}10^3$ oocysts. In the mallards, a few oocysts were also recognized on days 5-15 ACI in all of carrageenan treated groups and in the control groups inoculated with $2{\;}{\times}{\;}10^2,{\;}2{\;}{\times}{\;}10^3{\;}and{\;}2{\;}{\times}{\;}10^4$ oocysts. Just prior to challenge infection, phagocytic activity of peritoneal macrophages (Me) and the number of peripheral Mc in both birds were significantly decreased in the carrageenan treated groups as compared to the control groups. Mild challenge inection in both birds denoted that the immunogenicity of C. bailelli to the birds was very strong, despite MB blocker carrageenan administration.

• Atmosphere
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• v.28 no.3
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• pp.305-315
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• 2018

This study investigates the characteristic spatial patterns and dynamic processes associated with the summertime extreme temperature events in South Korea during the last 20 years (1995~2014) using Self-Organizing Map (SOM). The classified SOM patterns commonly have high temperature and anticyclonic circulation anomalies over South Korea. The two major teleconnection patterns are identified: one is from the subtropical western North Pacific (WNP) affecting to the north and the other is from the North Atlantic (NA) affecting downstream region. The meridional teleconnection pattern is related to the forcing of positive sea surface temperature (SST) anomaly over the WNP. The northward propagating Rossby wave generates the East Asia-Pacific (EAP) pattern to form an anticyclonic circulation anomaly over South Korea. On the other hand, NA SST anomalies generate an eastward Rossby wave train across the Eurasian continent, leading to the development of an anticyclonic circulation anomaly over South Korea. The EAP pattern occurs more frequently in July and August, whereas the midlatitude teleconnection pattern associated with NA SST anomalies develops more frequently in early summer (June).

• Parasites, Hosts and Diseases
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• v.29 no.3
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• pp.245-258
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• 1991

In order to determine the antigenic localization in the tissues of the adult Metagonimus yokegawai, immunogoldlabeling method was applied using serum immunoglobulins (IgG) of cats which were infected with isolated metacercariae from Plecoglossus altivelis. The sectioned worm tissue was embedded in Lowicryl HM 20 medium and stained with infected serum IgG and protein A gold complex (particle size: 12 nm) , It was observed by electron microscopy at each tissue of the worm. The gold particles were observed on the tegumental syncytium as well as cytoplasm of tegumental cells and epithelial lamella of the caecum. The gold particles were not observed on the basal lamina of the tegument, interstitial matrix of the parenchyma, the muscle tissue and mitochondria of the tegument. The gold particles were specifically labeled in the secretory granules in the vitelline cells. They were also labeled on the lumen of bladder and egg shell. The above findings showed that antigenic materials in the tissue of adult worms were specifically concentrated on the tegumental syncytium as well as cytoplasm of tegumental cells and epithelial lamella of the caecum.

• Economic and Environmental Geology
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• v.56 no.3
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• pp.343-363
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• 2023

Sulawesi island, as a global producer of nickel resources, is leading the rapid growth of nickel industry of Indonesia. Nickel laterite deposits in Sulawesi was formed by lateritization of the world-scale East Sulawesi Ophiolite (ESO) under the active tectonic setting and tropical rainforest climate. In this paper, exploration cases for nickel laterite deposits in five regions of Sulawesi are reported. Regional characteristics on nickel laterite deposits in Sulawesi are understood based on various exploration activities such as outcrop, trench and pit survey, petrological observation, geochemical analysis, and interpretation of drilling data, etc.. In the northeastern part of 'Southeast-Arm', which is a strategic location for nickel industry of Indonesia, ESO is extensively exposed to the surface. In the Morombo and Morowali regions, typical high-grade saprolite-type orebodies with a thickness of 10 to 20 m occur. The cases showed that topographic relief tends to regulate Ni-grade distribution and orebody thickness, and that high grade intervals tend to occur in places where joints and garnierite veins are dense. In the Tinanggea and South Palangga regions in the southern part of the Southeast-Arm, overburden composed of Neogene to Quaternary deposits is a major factor affecting the preservation and profitability of nickel laterite deposits. Despite the overburden, high-grade saprolite-type orebodies composed of Ni-bearing serpentine with garnierite veins occur in a thickness of around 10 m to secure economic feasibility. In contrast, in the Ampana region in the northern part of 'East-Arm', low-grade nickel laterite deposits with immature laterite profile was identified, which is thought to be the result of active denudation due to tectonic uplift. Exploration cases in this paper will help to understand characteristics and controlling factors on nickel laterite deposits in Sulawesi, Indonesia.