• Environmental Mutagens and Carcinogens
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• v.8 no.1
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• pp.1-12
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• 1988

The effects of aphidicolin (APC), an inhibitor of DNA polymerase alpha, or 2', 3'-dideoxythymidine 5'-triphosphate (ddTTP), an inhibitor of DNA polymerase beta, on the repair of DNA damage induced by ethyl methanesulfonate (EMS) or bleomycin (BLM) were investigated in Chinese hamster ovary (CHO)-K1 cells. Three assays were employed in this study: unscheduled DNA synthesis, alkaline elution and alkaline sucrose gradient sedimentation. It was shown that APC or ddTTP inhibited DNA induced by EMS, and thus, the post-treatment with APC or ddTTP following EMS treatment was resulted in the more amount of unscheduled DNA synthesis, and the more accumulation of DNA single-stand breaks than the cells post-incubated without APC or ddTTP. While, in the BLM induced DNA repair, only ddTTP inhibited DNA repair induced by BLM. And thus, the groups post-incubated with or without APC after BLM treatment had the same value in the amount of unscheduled DNA synthesis and of DNA single-strand breaks, while post-treatment with ddTTP was resulted in the increased amount of unscheduled DNA synthesis and the increased DNA sin -strand breaks than the group without ddTTP. These results suggested that both of DNA polymerase $\alpha$ and $\beta$ participated in the repair of DNA damage induced by EMS, but in BLM-induced DNA repair, polymerase $\beta$ participated.ipated.

• Journal of Veterinary Clinics
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• v.28 no.2
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• pp.232-235
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• 2011

Clostridium (C) difficile has been recognized as an important emerging pathogen in both humans and animals. The prevalence of C. difficile in rectal feces and frozen colons of 132 pigs with diarrhea from the Jeju Island was investigated by polymerase chain reaction (PCR) to detect C. difficile toxin A and B genes. PCR findings revealed toxin A and B in 5 pigs (3.8%), including 2 suckling pigs, 2 weaned pigs and 1 growing pig. The result of PCR was closely matched histopathologic lesions of C. difficile in large intestines of pigs. Histopathologically, the cecum and colons of C. difficile toxin-positive pigs had severe submucosal and mesocolonic edema. Mucosal lesions ranged from random single cell necrosis and exfoliation to segmental, transmural necrosis of the cecum and colon. According to bacteriology, 4 C. difficile-positive pigs (80%) were co-infected with Salmonella typhimurium.

• Animal Systematics, Evolution and Diversity
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• v.11 no.4
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• pp.409-416
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• 1995

Forty samples of common rats (Rattus norvegicus caraco) from Cheongu, Korea, were used for the analyses of mitochondrial DNA (mtDNA) fragment patterns resulted from the digestion with eight restriction enzymes. A total of 36 fragments were recognized and six mtDNA clones were revealed . The nucleotide-sequence divergences (p) among six mtDNA clones ranged from 0.35% to 2.73%. moreover, the six clones were grouped into three major subgroups ; the first, second , and third subgroup were composed of 29 samples of three clones, ten samples of two clones, and one sample of one clone, respectively. The second and third subgroups were different in their mtDNa genotype of Pvu II from the first subgroup, and the third subgroup differed in the genotype of Dra I from other two subgroups. Futhermore, the maximum divergence among common rats from Korea in this study is greater than that among common rats from the United States and Japan by Brown and Simpson (1981). Further analyses with additional sample from other localities in Korea appeared to be necessary in order to clarify the taxnomic status of the distinct mtDNA subgroups.

• Applied Microscopy
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• v.26 no.1
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• pp.67-77
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• 1996

Pancreases obtained from native Korean goats were used, and examined by immunoelectron microscopy using several antisera. Five types cells, glucagon (A), insulin (B), somatostatin (D), and pancreatic polypeptide (PP-I and PP-II) cells, were identified in the pancreatic islets. The morphologies of A, B, and D cells corresponded to the typical charateristics described in previous reports on other mammals. Serotonin immunoreactivity was observed in the D cells on the basis of the granular profiles. Two types of PP cells could be distinguished on the basis of the granular profile: the first type was formed by round, homogeneous secretory granules ($220{\sim}400nm$) having a narrow halo between the dense core and limiting membrane, while the other type consisted of cells whose secretory granules ($240{\sim}440\;nm$ in the major axis, $150{\sim}200nm$ in the minor axis) were pleomorphic, having a dense core and a closely fitting limiting membrane. From these results, we suggest that the pancreatic islets of the native Korean goat consist of five types of endocrine cells, A, B, D, PP-I and PP-II cells. Among these, PP-I type cells may correspond to the classical PP of other mammalian pancreases, while PP-II type cells may correspond to the enterochromaffin cells in other species.

• Animal Systematics, Evolution and Diversity
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• v.14 no.4
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• pp.327-334
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• 1998

Four external and 27 cranial characters of three subspecies of striped field mice (Apodemus agrarius) from 15 regions in far eastern Asia(South Korea, North Korea, northeastern China, and far eastern Russia) were analyzed by multivariate methods in order to determine taxonomic status of striped field mice from North Korea. Three subgroups were recognized: a large-size form from two localities in South Korea(Cheju Island, Wando Island): a medium-size form from eight localities in South Korea and North Korea(Jindo Island, Kunsan, Mt. Chirisan, Cheongju, Mt. Weoleksan, Mt. taebaksan; Haeju, Sineuiju); a small-size form from five localities in North Korea, northeastern China, and far eastern Russia (Mt. Kumkangsan, Mt. Myohyangsan; Jirin, Yichun; Vladivostok). It is confirmed that the large-size form, the medium-size form, and the small-size form are subspecies chejuensis, coreae, and manchuricus, respectively, as noted by Koh et al.(1997). It is revealed that striped field mice(the medium-size form) from western region of North Korea (Haeju, Sineuiju) is classified into A. agrarius coreae, as noted by Thomas(1908), but striped field mice(the small-size form) from eastern region of North Korea(Mt. Kumkangsan, Mt. Myohyangsan) is A. agrarius manchuricus.

• Korean Journal of Animal Reproduction
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• v.26 no.2
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• pp.193-199
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• 2002

This study was conducted to investigate the optimal physiologic mating time in Hanwoo for protection to decrease of reproductivity and improvement of production of offspring. We observed 32 cows that were devide into 4 parts of treatment : T1(12 months of age and 0.5kg daily gain), T2(12 months of age and 0.8kg daily gain), T3(15 months of age and 0.5kg daily gain) and T4(18 months and 0.5kg daily gain). The first heat of treated cows was 263.3$\pm$6.4 days and average weight was 181.1$\pm$11.3kg. It was revealed the conception rates of first insemination were 25%(T1), 75%(T4) and number of insemination of T3 and T4(both 1.5) was lower than T1 and T2(2.3 and 2.4). In return of estrus after heifer's first parturition, they(T1, T2, T3 and T4) showed 66.2 days, 76.7 days, 62.4 days and 68.5 days respectively and the average was 65.7 days. Plasma progesterone(P4) concentration was nearly the same during the observation periods of treated cows and P4 was released just after 12 months. Only 5 cows (15.6%) in 32 were showed normal estrus cycle and ovulation before 12 months. Before and after parturition, P4 concentration was decreased fastly and then there was no detection of P4 from after parturition to 40 days after milking. P4 would be released again on 45 day after parturition. The results were summarized as that the optimal mating time of Hanwoo heifers was decided by the 14 months of age, 110 cm height and 265kg weight.

• Animal Systematics, Evolution and Diversity
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• v.14 no.4
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• pp.341-355
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• 1998

Thirty one morphometric characters of specimens in 15 subspecies of striped field mouse(Apodemus agrarius Pallas) from Eurasia were analyzed to clarify taxonomic status of these subspecies. Five major subgroups in A. agrarius were revealed: I, a largest-size form, specimens from two southern from other six localities in Korea, subspecies coreae and pallescens; III, the other large-size from, specimens from Astrachan in western Russia, subspecies volgensis; IV, a medium-size form, specimens from 16 localities in eastern Asia(North Korea, China, and eastern Russia), subspecies coreae, manchuricus, pallidior, ningpoensis, and insulaemus; V, a small-size form, specimens from 16 localities in western Asia and Europe (Kazakhstan, Russia, Lithuania, and Ukraine), subspecies tianschanicus, ognevi, agrarius, septentrionalis, nikolski, caucasicus, and karelicus. From this morphometric analyses, the followings are concluded: subspecies chejuensis is a larger-size form, as noted by Johnson and Jones(1955): subspecies pallescens is the synonym of subspecies agrarius, as suggested by Koh(1986): subspecies coreae from Korea is a large-size form and is idistinct from other 12 subspecies in Eurasia: the eastern form of subspecies ningpoensis by Corbet(1978) is a medium-size form o subspecies manchuricus, pallidior, ningpoensis, and insulaemus from eastern Asia (China and eastern Russia), and it includea North Korea specimens: a small-size form from western Asia and Europe(subspecies tianschanicus, ognevi, agrarius, septentrionalis, nikolski, caucasicus, and karelicus) is the western form of subspecies agrarius by Corbet(1978); the other large-size form of subspecies volgensis from western Russia is a distinct subspecies, which differs from the western subspecies agrarius. Therefore, it is concluded that 15 subspecies of A. agrarius can be classifed into five subspecies (chejuensis, coreae, ningpoensis, agrarius, and volgensis), although it is necessary to measure and analyze morphometric characters of specimens of other seven subspecies(albostriatus, maculatus, rubens, kahmanni, henrici, gloveri, and harti) for the complete reclassification of this species).