• The Korean Journal of Zoology
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• v.31 no.1
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• pp.1-10
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• 1988

A syrnpatnc sample of Rana nigrnmaculata sand R plancyi (Anura) from Kwangu, Korea was investigated to clarify their taxonornic status and to estimate the degree of genic variation, genetic relatedness, and reproductive isolation between them, based on electrophoretic analysis, marphometric data, mating call, mating season, and habitat. All the characters measured including morphometric, genetic, behavioral, and ecological suggest that they are distinct species and R nigrnmaculata might have originated from R plancyi (tropical form about three and a half million years ago. An adult female was found to be Fl hybrid between two species The hybrid female possessed fettile eggs and morphologically intermediate to the parental species in head parts, hind limb, and web characters. The differences in mating call, mating behavior, breeding season, and habitat strongly suggest that postmating isolating mechanism is operating, even though very rare hybrid is found.

• Korean Journal of Veterinary Research
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• v.44 no.4
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• pp.561-569
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• 2004

To detect viral agents and isolate porcine circovirus 2 (PCV2), 60 samples of lung and lymph node were collected from 5 to 12 week-old pigs that had showed clinical signs of postweaning multisystemic wasting syndrome (PMWS). Polymerase chain reactions (PCRs) were conducted to identify the viral pathogens including PCV1, PCV2, porcine parvovirus (PPV) and porcine reproductive and respiratory syndrome virus (PRRSV) that have been considered to be the causal agents of PMWS. Among 60 samples, PCV 2 was detected from 57 samples but no PCV 1 was detected. PRRSV and/or PPV were also detected from 27 (47.4%) samples and 1 (1.8%) sample of these 57 PCV 2-positive samples, respectively. Tissue homogenates were inoculated onto PCV-free PK-15 cell monolayers. Seven isolates were confirmed as PCV 2 by multiplex PCR, indirect immunofluorescence assay, and transmissible electron microscopy. These date suggest that PRRSV is a major cofactors causing PMWS in pigs that were infected with PCV2 in Korea.

• Korean Journal of Veterinary Research
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• v.34 no.1
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• pp.77-83
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• 1994

Three viral strains, causing CPE in porcine alveolar macrophage cell, were isolated from aborted fetus, serum from young pig showing blue-ear sign and lung of suspected pig, respectively. The differential diagnostic results showed no characteristics of Aujeszky's disease virus(ADV), hog cholera virus (HCV), Japanese encephalitis virus(JEV), porcine parvovirus(PPV) and encephalomyocarditis virus (EMCV). However, positive reactions were demonstrated by IFA using monospecific porcine antibodies against Lelystad virus. When the paired sera of experimentally inoculated swine with one of isolate, KPRRSV-l were tested by IPMA, the result indicated that the isolate was related to United States isolate than European LV.

• Korean Journal of Medicinal Crop Science
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• v.13 no.2
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• pp.69-74
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• 2005

Kalopanax pictus is a long-lived woody species mostly distributed in East Asia. K. pictus has been regarded as medically and ecologically important species in Korea. Thornless castor aralia variant, local name 'Cheongsong' is an endemic to Cheongsong province in Korea. Random amplified polymorphic DNA (RAPD) was used to investigate the genetic variation and structure of Korean populations of two species. A high level of genetic variation was found in six K. pictus populations. Twelve primers revealed 49 loci, of which 29 were polymorphic (59.2%). Nei's gene diversity for K.pictus and K. pictus variant were 0.119 and 0.098, respectively. Mean of genetic diversity in K. pictus was higher than average values for species with similar life history traits. The asexual and sexual reproduction, perennial habitat, and longevity are proposed as possible factors contributing to high genetic diversity. An indirect estimate of the number of migrants per generation (Nm=0.857) indicated that gene flow was not extensive among Korean populations of K.pictus. It is suggested that the isolation of geographical distance and reproductive isolation between K.pictus and K.pictus variant populations may have played roles in shaping the population structure of this species.

• Journal of Life Science
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• v.17 no.6 s.86
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• pp.805-810
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• 2007

Inter simple sequence repeat (ISSR) markers were performed in order to analyse the phylogenetic relationships of eight Hypericum electum populations in Korea. The six primers were produced 37 reproducible ISSR bands. Analysis of ISSR from individual plants of Korean H. erectum resulted in 22 polymorphic bands with 59.5%. Across populations, the mean number of alleles per locus was 1.348 and Shannon's information index was 0.203.Population Mt. Gyeryong had the highest expected genetic diversity (0.175) among all populations. When species were grouped by eight populations, within group diversity was 0.140 (Hs), while among group diversity was 0.472 (G$_{ST}$) on a per locus basis. The estimated gene flow (Nm) for H. erectum was very low (0.561). It is suggested that reproductive isolation by the isolation of geographical distance among H. electum populations and genetic drift may have played roles in shaping the population structure of this species. In phonetic tree, all populations were well separated from each other. Thus, ISSR markers are very effective in classifying natural population levels of genus Hypericum in Korea.

• Korean Journal of Veterinary Research
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• v.37 no.4
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• pp.793-807
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• 1997

We tried to develop detection system of porcine reproductive and respiratory syndrome virus(PRRSV) by in situ hybridization(ISH) in the piglets experimentally infected with KPRRS-2, the Korean isolate(12 piglets) or Mn-1b, the American isolate(4 piglets), and in the natural infection suspected 6 piglets. Twelve 30-days-old piglets(two pigs per each inoculated group) were inoculated by nasal instillation of KPRRS-2 virus(total dose $10^{4.5}TCID_{50}$), Six piglets(one pig per each group) were induced contact infection with inoculated piglets, during the experiment, and two piglets were used as control. Inoculated or contacted piglets were euthanized at 1, 3, 5, 7, 14 and 21 days postinoculation(DPI). The respiratory signs such as coughing and nasal discharge were observed on day 3 DPI, and ear cyanosis were on day 5 DPI, including contacted piglets. Through the necropsy, purple discolorization of dorsal part of lung, and hypertrophy of local lymph nodes were observed. The histopathological lesions of lung were interstitial pneumonia characterized by type 2 pneumocyte hyperplasia. We prepared the probe for ISH by RNA isolation from KPRRS-2, RT-PCR, and biotin labeling. We performed the ISH within only 1~2 hours using $Microprobe^{TM}$ capillary action system. As the results, the strong red specific positive signals, means PRRSV distribution, was mainly observed in the cytoplasm of alveolar macrophages. And also signals were detected in some type 2 pneumocytes and bronchiolar epithelium of lung, myocardium, liver, kidney, tonsil, spleen, gastrointestinal mucosa, testis and lymph nodes.

• Reproductive and Developmental Biology
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• v.33 no.3
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• pp.133-137
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• 2009

Pluripotent embryonic stem (ES) cells isolated from inner cell mass (ICM) of blastocyst-stage embryos are capable of differentiating into various cell lineages and demonstrate germ-line transmission in experimentally produced chimeras. These cells have a great potential as tools for transgenic animal production, screening of newly-developed drugs, and cell therapy. Miniature pigs, selectively bred pigs for small size, offer several advantages over large breed pigs in biomedical research including human disease model and xenotransplantation. In the present study, factors affecting primary culture of somatic cell nuclear transfer blastocysts from miniature pigs for isolation of ES cells were investigated. Formation of primary colonies occurred only on STO cells in human ES medium. In contrast, no ICM outgrowth was observed on mouse embryonic fibroblasts (MEF) in porcine ES medium. Plating intact blastocysts and isolated ICM resulted in comparable attachment on feeder layer and primary colony formation. After subculture of ES-like colonies, two putative ES cell lines were isolated. Colonies of putative ES cells morphologically resembled murine ES cells. These cells were maintained in culture up to three passages, but lost by spontaneous differentiation. The present study demonstrates factors involved in the early stage of nuclear transfer ES cell isolation in miniature pigs. However, long-term maintenance and characterization of nuclear transfer ES cells in miniature pigs are remained to be done in further studies.

• Animal cells and systems
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• v.2 no.4
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• pp.435-438
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• 1998

In the present study, we have examined the crossability of four species in the A. jaluense complex to provide additional information on their delimitation and levels of differentiation. Crosses between diploid A. chiisanense and the tetraploid species including A. jaluense s. str., A. triphyllum, and A. pseudoproliferum yielded no fruit- or seed-set, indicating that the former species is reproductively completely isolated from the latter three species. In interspecific crosses between the tetraploid species, combinations involving A. jaluense s. str. resulted in much reduced fruit- and seed-set, indicating that A. jaluense s. str. is more or less reproductively isolated from the other tetraploid species. However, crossing data revealed the absence of reproductive isolation between A. triphyllum and A. pseudoproliferum These results strongly support the relationships that have been previously suggested for the A. jaluense complex on the basis of morphology, chromosome number, and flavonoid chemistry.

• Journal of Ecology and Environment
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• v.30 no.3
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• pp.225-229
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• 2007

The mating systems of natural populations of Potentilla freyniana in Korea were determined using allozyme analysis. The result suggests that P. freyniana is outcrossing as well as employing vegetative reproduction by stolon (self-fertilization rate, s < 0.5). The values of the inbreeding coefficient of eight populations in Korea varied from 0.244 to 0.331, with an average value of 0.274. For eight natural populations, multi-locus estimates of outcrossing (tm) was 0.603 across 13 polymorphic loci, with individual population values ranging from 0.530 to 0.652. The relatively low outcrossing rates of some populations could be attributed to extensive vegetative reproduction by stolon and the isolation of flowering mature plants. Although P. freyniana usually propagated by asexually-produced ramets, I could not rule out the possibility that sexual reproduction occurred at a low rate because each ramet may produce terminal flowers. Although heterozygote excess was observed in some natural populations, most populations exhibited varying degrees of inbreeding and a heterozygote deficit.

• 대한생식의학회:학술대회논문집
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• 1999.11a
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• pp.111-112
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• 1999