• Journal of Korean Society on Water Environment
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• v.34 no.3
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• pp.285-292
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• 2018

This study was performed in order to identify the red tide-causing organism and to understand the characteristics of the water quality during the winter of 2015 and 2016 in the Oncheon stream, a tidal river in Busan, where red tide often occurs in the wintertime. Two sites were selected on the stream and the surface water was sampled a total of 28 times during the experimental period. Twelve water quality characteristics, including water temperature, pH, DO, COD, total-N (T-N), total-P (T-P), and salinity were analyzed in order to test water quality. The cell numbers of cryptomonads were counted directly by microscopic observation. The nucleotide sequences of the partial 28S rRNA gene and psbA gene from metagenomic DNA, derived from each sampling site, were analyzed. According to the results, the alga most responsible for the bloom was identified as Teleaulax OC1 sp., which belongs to the cryptomonads. Three items of chl-a, pH, and DO were positively correlated with the cell numbers of the cryptomonads counted at the upper stream of the tidal area (St 1) while eight items of chl-a, TOC, BOD, total-N, COD, SS, pH, and DO were positively correlated with the cells located at the junction between the stream and Su-young river (St 2) in the order.

• Journal of fish pathology
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• v.7 no.1
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• pp.1-5
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• 1994

Nuclear polyhedrosis virus was successfully infected the continuous Sf cell line. At 12hrs post-infectio(P.I), the cell lost the motility and the nuclei of the cells were hypertrophied. At 24hrs P.I, the cells were somewhat abnormal form and PIB formation was observed. At 48hrs, the PIBs formed in all cells. PIBs in the nuclei were released in the culture media at 72hrs P.I. By the observation of NPV morphogenesis by electron microscopy at 13hrs P. I, the virogenic stroma formed in the nucleus, and nucleocapsids formed. At 48hrs P.I, many nucleocapsids were bundled and then occluded in PIB, and PIBs were matured. PIB shapes were mostly tetragonal and a polyhedron was about $3{\sim}10{\mu}m$ in size. Virions were rod shape. nucleocapsids ranging in size $30{\sim}40{\times}300{\sim}400nm$.

• Korean journal of food and cookery science
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• v.21 no.4 s.88
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• pp.528-535
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• 2005

This paper aims to compare and evaluate the quality of beef jerky made with Korean beef meat, Korean beef cattle and imported beef meat from Australia and New Zealand through sensory evaluation, measurement of hardness, thickness and contents of the moisture and crude lipid, and microscopic texture observation (SEM). According to the sensory evaluation, beef jerky made with Korean beef meat recorded the highest score in overall acceptability; New Zealand beef meat, the lowest. The preference of beef jerky made with Korean beef meat was shown in the appearance, smell, and texture, and especially in the taste. Whereas Korean beef jerky scored highest in color, glaze and palatability, New Zealand beef meat showed the lowest score. Korean beef meat showed the lowest in hardness, but New Zealand beef meat showed the highest as shown in the result of technical evaluation through rheometer. The evaluation through colormeter concluded that New Zealand beef meat had the highest scores in L and a values, but that Korean beef meat showed the lowest score. When it comes to the color difference compared with Korean beef meat, New Zealand beef meat showed the biggest difference. Although the moisture contents of jerky made with different beef meat showed little difference, the content of the crude lipid of jerky made with Korean beef meat and Australian beef meat was lower than that of Korean beef cattle and New Zealand beef meat. When the beef jerky is dry, fat contained in the beef meat is dissolved, which causes the glaze on the outside. Scanning electron micrographs showed that Korean and Australian beef jerky had larger gaps than Korean beef cattle and New Zealand beef jerky. It was concluded that this affected the hardness of beef jerky.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.408-412
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• 1998

In order to illustrate the role of conidia of Mycosphaerella nawae as a secondary inoculum in nature, pseudothecial development on persimmon leaves was investigated microscopically. The fungal ascospores have been believed as the primary or only inoculum source in nature, however, pseudothecia were readily formed on persimmon leaves infected naturally and artificially by conidia. The pseudothecia of M. nawae were found to form in the tissues of infected leaves while the leaves were still hanging on the trees. The size of pseudothecia were approximately 51.0~122.4$\times$51.0~112.2 ${\mu}{\textrm}{m}$ (82.8 $\times$72.5 ${\mu}{\textrm}{m}$in average), the shapes were spherical, ovoid or occidental pear type. The sizes of asci were approximately 30.6~61.2$\times$8.2~10.2 ${\mu}{\textrm}{m}$(46.6$\times$9.4 ${\mu}{\textrm}{m}$ in average) and the shapes were cylinder or banana. The ascospores were mostly spindle type, and the sizes were 10.2~12.2$\times$3.1~4.1 ${\mu}{\textrm}{m}$ (11.4$\times$3.2 ${\mu}{\textrm}{m}$ in average)-like. The pseudothecial formation was initiated before defoliation and morphological characteristics of the pseudothecia, ascus and ascospores on the infected leaves were fully illustrated in this study. Results indicated that conidia of M. nawae induce circular leaf spot of persimmon as much as ascospores, and might play an important role of the disease epidemics in nature.

• International Journal of Industrial Entomology and Biomaterials
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• v.23 no.1
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• pp.107-113
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• 2011

Infection effect of $Nosema$ $bombyics$ on the midgut of silkworm $Bombyx$ $mori$ and subsequent appearance of spores and the performance of larvae was studied. Autopsy of larvae showed white pustules on the surface of midgut at 5 days of post infection (pi). At later stage, important organs like midgut, silk gland and gonads reduced in size and all these organs showed white pustules. Light microscope observation of pustules revealed enormous spores. Spore multiplication was at a faster rate in young larvae. Infection of the adult larvae resulted in pebrinized pupa and moths. Larval weight, cocoon weight and cocoon shell ratio reduced as the post infection period increased. Transverse sections of midgut showed $N.$ $bombycis$ infection limited to a few columnar cells at 3-5 days of pi. At 7 days pi, cell volume increased, cells were swollen and elongated. Heavily infected cells looked like sacks filled with parasite and the apical region of certain cells were bulging into the gut lumen. Later at 8-9 days of pi, spores or its developing stages leaked into the lumen either freely or enclosed within the globules of host cytoplasm. Besides columnar cells, development of $N.$ $bombycis$ was observed in the regenerative cells and rarely in goblet cells. Development of $N.$ $bombycis$ was also observed in both longitudinal and circular muscles at the late pi period. The histopathological changes, deformities and spore production time in the host were all influenced by the spore dosage and age of the host.

• Parasites, Hosts and Diseases
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• v.42 no.1
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• pp.27-34
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• 2004

We investigated the optimal culture conditions for Cryptosporidium muris in a human stomach adenocarcinoma (AGS) cell line by determining the effects of medium pH and of selected supplements on the development of C. muris. The optimum pH of the culture medium required for the development of C. muris was determined to be 6.6. The number of parasites significantly increased during cultivation for 72 hr (p < 0.05) at this level. On the other hand, numbers decreased linearly after 24 hr of incubation at pH 7.5. When cultured in different concentrations of serum, C. muris in media containing 5% FBS induced 4-7 times more parasites than in 1% or 10% serum. Of the six medium supplements examined, only 1 mM pyruvate enhanced the number of C. muris in vitro. Transmission electron microscopic observation showed the developmental stages of C. muris in the cytoplasm of the cells, not in an extracytoplasmic location. The growth of C. muris in AGS cells provides a means of investigating its biological characteristics and of testing its response to therapeutic agents. However, a more optimized culture system is needed for the recovery of oocysts on a large scale in vitro.

• Journal of Soil and Groundwater Environment
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• v.20 no.4
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• pp.73-82
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• 2015

Despite significant effects on macroscopic migration and distribution of CO₂ injected during geological sequestration, only limited information is available on wettability in microscopic scCO₂-brine-mineral systems due to difficulties in pore-scale observation. In this study, a micromodel had been developed to improve our understanding of how scCO₂ flooding and residual characteristics of porewater are affected by the wettability in scCO₂-water-glass bead systems. The micromodel (a transparent pore structure made of glass beads and glass plates) in a pressurized chamber provided the opportunity to visualize scCO₂ spreading and porewater displacement. CO₂ flooding followed by fingering migration and dewatering followed by formation of residual water were observed through an imaging system. Measurement of contact angles of residual porewater in micromodels were conducted to estimate wettability in a scCO₂-water-glass bead system. The measurement revealed that the brine-3M NaCl solution-is a wetting fluid and the surface of glass beads is water-wet. It is also found that the contact angle at equilibrium decreases as the pressure decreases, whereas it increases as the salinity increases. Such changes in wettability may significantly affect the patterns of scCO₂ migration and porewater residence during the process of CO₂ injection into a saline aquifer at high pressures.

• Molecular & Cellular Toxicology
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• v.1 no.4
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• pp.275-280
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• 2005

Carbon tetrachloride ($CCl_4$) is well known hepatotoxicant. Its overdose cause severe centrilobular hepatic necrosis in human and experimental animals. We administered $CCl_{4}$ at low (0.2 mL/kg p.o.) and high (2 mL/kg p.o.) doses to mice. Mice were sacrificed at 24 h after administration. We evaluated liver toxicity by serum AST and ALT level and by microscopic observation. Using cDNA chip, we conducted gene expression analysis in liver. Mean serum activities of the hepatocellular leakage enzymes, ALT and AST, were significantly increased compare to control, respectively, in the low and high dose groups. H&E evaluation of stained liver sections revealed $CCl_{4}-related$ histopathological findings in mice. Moderate centrilobular hepatocellular necrosis was present in all $CCl_{4}$ treated mice. We found that gene expression pattern was very similar between low and high dose group. However, some stress related genes were differently expressed. These results could be a molecular signature for the degree of liver injury. Our data suggest that the degree of severity could be figure out by gene expression profiling.

• Korean Journal of Microbiology
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• v.37 no.4
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• pp.289-293
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• 2001

Incidence of infectious viruses is ensuing throughout the world and threatening the health of children as well as adults. The outbreaks of viral diseases of alimentary tract in Pusan from 1998 to 2000 were detected. Viruses were isolated from stool specimens, cerebrospinal fluid and throat swabs from suspicious patients and confirmed by cell culture, latex agglutination test, indirect immunofluorescent test and electron microscopic observation. The average isolation rate was 12.5% from the suspected specimens. From this work, 2 cases of enteric adenoviruses, 23 cases of echovirus, 31 cases of coxsackivirus 36 cases of rotavirus, 45 cases of SRSV, and 7 cases of poliovirus were detected. The major serotypes of coxsackievirus were B2, B3, B4, B6 and echovirus of serotypes 6, 9, 11, 25, and 30 were examined. Two cases of enteric adenovirus type 41 were also confirmed. The incidence of SRSV was mostly concentrated between December through following March, April through October with echovirus and coxsackievirus, and January through April with rotavirus, respectively. Electron micrograph of negative-stained viruses showed typical appearance with 30-80 nm in diameter.

• Journal of Animal Science and Technology
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• v.48 no.2
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• pp.191-202
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• 2006

In addition to the removal of dying or dead lutein cells by phagocytosis in many species, macrophages exert both luteotropic effect during maturation period and luteolytic effect during degenerative period via mediating autocrine/paracrine actions of self-producing cytokines in the corpus luteum. In this experiment, immunohistochemical and transmission electron microscopic (TEM) studies were performed to observe the morphologic changes of luteal macrophages during luteolysis. A small number of macrophages and low immunoreactivity were present at the mature stage. The number of macrophages and immunoreactivity gradually increased along the advance of luteolysis. Two subtypes of macrophages could be observed through TEM observation. One type of macrophage located between the large lutein cells contained no lipid droplets in their cytoplasm at mature stage. The other type of macrophage located near the blood vessels contained many lipid droplets in their cytoplasm during luteolysis. Particularly, no phagocytic macrophages were observed, which suggested the macrophages in the porcine corpus luteum did not involve in the phagocytotic elimination of dying lutein cells.