• Korean Journal of Veterinary Pathology
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• v.6 no.1
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• pp.41-48
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• 2002

Oval cell is considered as facultative precursor cells for both hepatocytes and biliary cells, as well as origin of hepatocellar and cholangiocellular carcinoma (CCC) during carcinogenesis or toxic liver injury. To clarify the cellular origin or differentiation of cholagiocarcinogensis, the fate of carcinogen-induced oval cells was pathologically and phenotypically chased in Syrian golden hamster liver after Clonorchis sinensis (CS) infection which would give rise to a promoting effect. Two week treatment of hamsters with 0.005% diethylnitrosamine (DEN) followed by 2 week treatment of 1% 2-acetylaminofluorene (AAF) under choline deficient diet resulted in massive proliferation of BrdU labeleed and PCNA positive oval cells showing various distinct morphology, histochemical and immunohistochemical phenotypes for GGT, cytokeratin 19 and OV-6. Oval cells also frequently form ductular-like structures or phenotypically show hepatocyte-like characteristics. After CS infection, the oval cells showed sequential morphological changes to atypicl proliferating bile ductules and all hamsters thereafter developed well differentiated and anaplastic CCC at 16 week after CS infection. In electron microscopy, some bile ductules were constructed by intermediate oval cells and bile ductular cells surrounded by basement membrane. The results of this study strongly suggest that CCC developed in the present study were originated from hepatic stem-like oval cells, supporting the theory of stem cell origin of cancers. In addition, this hamster model would be valuable for the molecular mechanistic study during chemical-triggered cholangiocarcinogenesis.

• Korean journal of applied entomology
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• v.7
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• pp.27-32
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• 1969

The purplish stem borer (Sesamia inferens Walker). which was infested in southern part of Korea. attack rice plant. and its damage appear quite serious in some districts. This study was conducted to investigate the life history. seasonal abundance and control of the insect pest. The pest overwinter as larvae and it seems to have 2-3 generations in a year. It takes 56.6 days in the shortest one while the longest one takes 74.6 days. Three peaks of moth appearance are May-June. end of July and end of August, respectively. The effectivencess of insecticides was compared with EPNec $45\%$ and the different granular insecticides in pot experiment. In the result. M. Parathion G. EPNec, Diazinon G and Lebaycid G showed good control of the pest. with the infestation of $12.0,\; 22.9\%,\; 24.7\%,\; and\; 27.3\%$ respectively, while the untreated has $62.6\%$

• Journal of Veterinary Clinics
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• v.30 no.3
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• pp.186-188
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• 2013

This study investigated the prevalence of ectoparasite infestations in the pet rabbits of Daejeon area, Korea. The authors used tape strip test, hair coat combing and otoscopy for diagnosis. Only three species were detected. Cheyletiella parasitovorax was found in 152/251 rabbits (60.6%), Psoroptes cuniculi was found in 7/251 rabbits (2.8%) and Ornithonyssus bacoti was found in 5/251 rabbits (1.9%). C parasitovorax is the highest prevalence among the three species. Co-infection of C. parasitovorax with P. cuniculi was found in 3/251(1.2%). Co-infection of C. parasitovorax with O. bacoti was found in 5/251(1.9%). This study is the first large scale survey of C. parasitovorax, P. cuniculi and O. bacoti in the pet rabbits of Daejeon area, Korea.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.482-489
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• 1996

Dried-red pepper, whole and powdered types, was subjected to a storage-study by investigation the effects of packaging methods (polycloth & polyethylene/polycloth, whole dried-red pepper; nylon/polyethylene-lam-inated film, red pepper powder), temperature (ambient, $5{\sim}10^{\circ}C$) and gamma irradiation doses (0-10 kGy). After 6 months storage in polyclith sack at ambient temperature, all whole dried-red pepper showed quality deterioration, such as weight change, insect infestation, discoloration and chemical changes, After 2 years storage in combined packaging with polyethylene/polycloth sack of 5-7.5 kGy irradiated whole dried-red pepper at ambient temperature, however, quality deterioration was not observed. Gamma-irradiated red pepper powder (7.5-10kGy) showed a good quality in hygienic, physicochemical and organoleptic evaluation after 2 years of storage at ambient temperature.

• Journal of Korean Society of Forest Science
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• v.86 no.4
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• pp.407-414
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• 1997

The resistance of a non-transgenic poplar clone, 'Ogy' and three transgenic poplar lines to the cottonwood leaf beetle, Chrysomela scripta F., was evaluated by in vitro feeding. The lines were transformed with neomycin phosphotransferase II(NPT II) as a selectable marker, proteinase inhibitor II(pin2) as a resistance gene, and CaMV 35S as a promoter. An efficient method of sterilizing the beetle eggs and introducing them into plant tissue cultures was developed. The resistance of the transgenic lines was investigated in terms of effects tin leaf area consumed, insect weight, insect developmental stages, and plantlet root dry weight after feeding. Also, leaf area consumed was examined by leaf age as measured through leaf plastochron index(LPI). The leaf area consumed and insect weight were highly significant between transformants and control, and insect development in vitro was significant among the transgenic lines. Larval infestation was the most severe around LPI 4 to 5 which were young leaves. The system provided a quick, highly controlled method to screen developing transgenic plantlets directly.

• Korean Journal of Veterinary Research
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• v.45 no.1
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• pp.105-111
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• 2005

Canine sarcoptic mite (Sarcoptes scabiei var. canis) is ectoparasite which burrow usually in the stratum corneum of the skin of dogs. Antigens from the burrowing mites induce humoral and cellmediated immune responses in the hosts. The effect of antigenecity induced by somatic antigens of house dust mite (Dermatophagoides pteronyssinus) isolated by continuous elution has been evaluated in canine sarcoptic mites infestation. Continuous elution was carried out in 7.5% SDS-PAGE to isolate proteins of common antigens from somatic antigens of house dust mite. These eluted proteins from somatic antigens of house dust mite were confirmed by Western blotting in 7.5% SDS-PAGE, and eluted proteins (65, 60 kDa) were isolated. To evaluate the antigenetic effect of eluted proteins, eight dogs were divided as 4 groups such as non-vaccinated and non-challenged control (Group I), challenged control (Group II), vaccinated (Group III), and vaccinatedandchallenged (Group IV) groups. Group II and IV were artificially infested canine sarcoptic mites. Group III and IV were immunized with eluted proteins (65, 60 kDa). At the 6th week of the vaccination, the antibody titers of Group of IV were statistically significant higher than those of Group II (p<0.05). And antibody titers of Group III were also statistically significant higher than those of Group I (p<0.05). From these result, it is possible to replace somatic antigens of canine sarcoptic mites with eluted proteins from somatic antigens of house dust mites in order to diagnose and prevent the canine sarcoptic mite infestations.

• Korean journal of applied entomology
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• v.30 no.1
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• pp.58-64
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• 1991

This study was carried out to investigate the occurrence of bug species around bank and paddy field and its peckey rice in four different districts of Kyonggi Area, and then to observe the distribution of bug species causing pee key rice. The results obtained were as follows; Thirty one bug species were collected around bank and its dominant species were Eyarcoris parvus, Nabis stenoferus, Stictopleurus crassicornis and each constituted 35.9, 20.2, 6.5 %, respectively. On the other hand, 11 bug species in paddy field were identified and the dominant species among them were Nabis stenoferus, Adelphocoris triannulatus, Eyarcoris parvus. Pee key rice induced by the infestation of bug species was 34.7% in Eyarcoris parvus and 2.7% in Aeschynteles maculatus. The occurrence of pecked rice injured by bugs was severe on milk ripe stage through heading stage to yellow ripe stage of rice growth period. Peckey rice among rice varieties was higher in Sobaekbyeo, extremely early mature variety, and Taebaegbyeo, early mature variety. The occurrence of peckey rice was higher in mountainous area such as Pocheon culturing early mature rice varieties.

• Korean journal of applied entomology
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• v.31 no.2
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• pp.174-181
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• 1992

Early, mid, and late maturing soybean varieties were artificially infested with larvae of Delia platura at seeding, and then later development and productivity of soybeans were studied. In addition, in hope to utilize as possible tactics in the management of D. platura in soybeans, cultural factors such as contents of organic matter in soil, soil types, and the use of plastic mulching on the degree of damage to soybean plants by D. platura were examined. Primary leaf damage by the larva delayed the forthcoming vegetative growth but not the blooming which is initiated by the change in day length. Degree of delay in growth was more severe where leaf damage was induced by insect infestation than where artificially excised, apparently owing to simultaneous damage in stems and roots besides primary leaves. Productivity of soybeans also dropped significantly in plants with 25 % or more loss in the primary leaf area by the larva. Both transparent and black plastic mulchings shortened the period from seeding to emergence of soybean thus reducing the chance of possible attack by the larva. Soybean seedlings grown in clay loam or clay were attacked less by the larva than those in other types of soil. High organic matter content in the soil enhanced speed of emergence resulting in less larval damage to the seedling.

• Korean journal of applied entomology
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• v.23 no.3 s.60
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• pp.153-157
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• 1984

The present work was designed to study the yield loss on rice at different appearance days of hopperburn caused by the brown planthopper(BPH), Nilaparvata lugens Stal, when rice plants were infested with BPH on booting and heading stages. Dead plants were colleted from 23 days after heading stage with intervals of 5 days. Yield losses by the initation of BPH infestation was greater at tooting than at heading stage. Compared to the uninfested plot, there was a reduction in 1,000 grain weight and filled grain percentage at both stages. Positive relationship was observed between rice yield(Y) and the number of days from heading to the appearance of the hopper-burn. Regression equations calculated were; for BPH feeding from booting $\hat{Y}(g)=10.145X-16.374(r=0.9726^{**})$, and for BPH feeding from heading $\hat{Y}(g)=9.792X+26.936(r=0.8850^{**})$.

• Applied Biological Chemistry
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• v.31 no.2
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• pp.143-146
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• 1988

The effect of gamma irradiation on controlling infestation of insects on rice grain were investigated. The egg and larva stages of rice weevil (Sitophilus oryzae) were more radiosensitive than the pupal and adult stages. The complete mortal dose of the first two stages was 0.05kGy, while it was 0.5kGy in the second two stages. In indian-meal moth (plodia interpuctella Hubner), sterile doses of egg, larva, pupa and adult were 0.04 to 0.05, 0.05 to 0.06 and 0.2 to 0.25kGy, respectively. Therefore, the irradiation dose within 1.0kGy was considered to be effective for rice storage so far as reinfestation was prevented. Attractiveness of indian-meal moth toward the rice irradiated at 1.0 to 5.0kGy was non-significant in F-test.