• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.191-204
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• 1994

Due to its topographic complexities and various climatical condition, Korea exhibits diverse forest types. Dominant tree species in this zone are Quercus spp., Betula spp., Zelkova spp., Fraxinus spp., Pinus densiflora, Pinus koraiensis, and Pinus thunbergii ete. Genetic conservation in forest species in Korea there are three ways ; one is in situ, other is ex situ and third is in-facility conservation. In situ conservation include that are the present status of conservation of rare and endangered flora and ecosystem, the reserved forest, the national and provincial park, and the gene pool of natural forests. Ex situ conservation means to be established the new forest from in situ forest stands, progeny and provenance test populations, seed orchard and clone banks, and gene conservation in-facility. As a tool for low temperature storage, several aspects on in vitro system were studied ; (1) establishment of in vitro cultures from juvenile and/or rejuvenated tissues, (2) induction of multiple shoots from the individual micropropagules, (3) elongation of the proliferated shoots. Studies on cold storage for short-and long-term maintenance of in vitro cultures under $4^{\circ}C$ in the refrigerator were conducted. For the cryopreservation at $-196^{\circ}C$, various factors affecting survivability of the plant materials are being examined. The necessity of gene conservation of forest trees is enlarged not only to increase the adaptability for various environments but also to gain the breeding materials in the future. For effective gene conservation of forest trees, I would like to suggest followings ; 1. Forest stands reserved for other than the gene conservation purposes such as national parks should be investigated by botanical and gene-ecological studies for selecting bio-diversity and gene conservation stands. 2. Reserved forest for gene pool should be extented both economically important tree spp. and non-economical species. 3. Reserved forest for progeny test and clone bank should be systematically investigated for the use of Ex situ forest gene conservation. 4. We have to find out a new methodology of genetic analysis determining the proper and effective size of subpopulation for in situ gene conservation. 5. We should develop a new tree breeding systems for successful gene conservation and utilization of the genetic resources. 6. New method of in-facility gene conservation using advanced genetic engineering should be developed to save time and economic resources. 7. For the conservation of species with short-life span of seed or shortage of knowledge of seed physiology, tissue culture techniques will be played a great role for gene conservation of those species. 8. It is are very useful conservation not only of genes but of genotypes which were selected already by breeding program. 9. Institutional and administrative arrangements including legistlation must be necessarily taken for gene conservation of forest trees. 10. It is national problems for conservation of forest resources which have been rapidly destroyed because of degenerating environmental condition and of inexperienced management system of bio-diversity and gene conservation. 11. In order to international cooperation for exchanging data of bio-diversity and gene conservation, we should connect to international net works as soon as possible.

• Reproductive and Developmental Biology
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• v.32 no.1
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• pp.51-58
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• 2008

This study was performed to investigate the relation between birth weight and survivability on the production of cloned Hanwoo calves. The 580 cloned embryos were transferred into the 293 recipients. The pregnancy rate of the cloned embryos was 72.3% at 50 days after embryo transfer, and then the rate was dramatically decreased. The mean gestation lengths were 287 days in both clone (range of$279{\sim}295$ days) and artificial insemination (AI, range of $255{\sim}293$ days) calves, respectively. The mean birth weight of cloned calves (30.3kg) was significantly higher compared to that of AI calves (23.7kg) (p<0.05). Among the cloned calves, the birth weight was not different in both normal delivery (n=17, 29.9kg) and caesarean section (n=14, 32.3kg). The weight, however, was significantly higher in the clones (n=18, 32.8kg) dead within 175 days than that of the clones (n=11, 28.3kg) alive more than 175 days after birth (p<0.05). Interestingly, all cloned calves weighed <15kg (n=5) or >35kg (n=9) at birth have been dead within 175 days from the date of birth. The causes of death in the cloned calves were premature birth (n=2, 10.0%), abnormal function of lung and liver (n=2, 10.0%), abnormal function of lung (n=4, 20.0%), malformation (n=4, 20.0%), unknown (n=4, 20.0%), and sudden death syndrome (n=4, 20.0%), respectively. Our findings suggest that normal birth weight is one of the most important factors to survive more than 6 months in cloned calves.

• Journal of Embryo Transfer
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• v.23 no.1
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• pp.43-49
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• 2008

This study was carried out to examine the efficiency of biopsy methods, and the pregnancy rate, calving and abortion rates, gestation length and birth weight of Hanwoo calves following transfer of fresh, frozen and sexed Hanwoo embryos produced in vitro. The survivability of biopsied embryos was 80.0 and 90.0% using aspiration and punching methods at 24 h after culturing, respectively. The ratios of male and female embryos were 42.1 and 52.6%, respectively, and the percentage of sex unidentified was 5.3%. Pregnancy rates was not significantly different between hCG and control group (46.4 vs. 38.5%), fresh and frozen embryos (41.3 vs. 35.0%), and sexed and IVP embryos (27.5 vs. 41.2%) (p>0.05). Calving and abortion rates of IVP and sexed embryos were not significantly different in calving (85.0 vs. 87.0%) and in abortion (15.2 vs. 13.3%) (p<0.05). Gestation length of IVP and sexed calves were 281.3 and 288.2 days in female and 283.0 and 282.3 days in male, and the birth weight of IVP and sexed calves were 23.6 and 25.0 kg in female and 24.6 and 23.8 kg in male, respectively. There were no difference in gestation length and birth weight between IVP embryos and sexed embryos (p>0.05). Administration of hCG to recipients did not improve the pregnancy rate following transfer of Hanwoo embryos produced in vitro and sexed embryos. Although the production of calves derived from sexed Hanweoo embryos cultured in vitro can be obtained, the efficiency of sexed calves production need to be improved in biopsy methods and pregnancy rate. Further study should be focused on the improvement of pregnancy rates for commercial application of embryo transfer.

• Korean Journal of Animal Reproduction
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• v.24 no.1
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• pp.97-108
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• 2000

The objectives of this study were performed to increase the efficiency of the culture conditions of embryos produced in vitro, and to assess the developmental potential after transfer of those embryos into recipients. The mean number of folliclular oocytes recovered from an ovary was 10.7. The rates of maturation and fertilization in Grade I oocytes were significantly (P＜0.05) higher than Graden and III. Developmental rate into blastocyst in the culture group of TCM-199 with BOEC were significantly higher (P＜0.05) than the groups of TCM-199 and conditioned medium (24.7% vs. 12.4% and 18.2%). The survivability of post-thawed blastocysts equilibrated for 3 min in EFS solution was significantly (P＜0.05) lower than l0 for 1 and 2 min (32.1% vs. 82.9% and 73.3%). Significantly higher (P＜0.05) survival rate in blastocysts was seen after freezing than in morulae stage embryos. Out of all 105 recipients, 49 (46.7%) were confirmed in pregnant. On pregnancy of cattle, 48 calves were born from 40 recipients. The ratio of twin and single calves was 30.5% (32/40 and 7.6% (8/40), respectively. However, the others composed of abnormal, as judging as 6 (12.2%) for abortion and 3 (6.1%) for stillbirth during the pregnant period.

• Korean journal of applied entomology
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• v.24 no.3 s.64
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• pp.117-121
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• 1985

Through the laboratory and vinyl house experiments, the effects of inoculum density, plant age and temperature on the incidence of Phytophthora crown rot of pepper (Capsicum annum L.) were investigated. The propagule survival was greater in the natural soil than in autoclaved soil within first 2 weeks when the sporangial suspension of the pathogenic fungus was incorporated into soil, thereafter the survivability reduced rapidly. The propagule was not detectable in 35 days by means of Papavizas selective medium neither in natural nor in autoclaved soil. At least 5 sporangia per gram soil were required to induce crown rot for 30 days old pepper seedlings. Further increase in inoculum concentration above this threshold level resulted in higher disease incidence and shorter incubation period. When the same amount of inoculum was infested, higher disease incidence was observed for younger plants until 3 weeks after inoculation. On the other hand after 4 weeks this tendency was not extended any more. Younger plants were recognized as having shorter incubation period upon infection, however, the days from first symptom appearance to complete death were not significantly different among differently aged seedlings. Exposure of inoculated pepper seedlings to $25^{\circ}C$ resulted in highest infection rates and followed by those to $30^{\circ}C\;and\;20^{\circ}C$ but no disease was found at $15^{\circ}C\;and\;35^{\circ}C$ for 10 days. When the plants previously incubated at different temperature for 10 days were moved to $25^{\circ}C$ room temperature, prior exposure to $20^{\circ}C\;and\;30^{\circ}C$ brought continuous disease development. Even those plants preincubated at $15^{\circ}C$ were diseased up to 50%. But the prior exposure to $35^{\circ}C$ induced no symptom developed, indicating no seedlings infected at all.

• Journal of Life Science
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• v.16 no.1
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• pp.131-135
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• 2006

Oligopeptide is known to be an essential nitrogen nutrient for bacterial growth. Oligopeptide can be transported into cytoplasm by a specific transport system, Opp system. Opp system is composed of five proteins, which are transcribed by an operon. These are responsible for oligopeptide binding protein (OppA), permease (OppB and OppC) and energy generation system (OppD and OppF), respectively. Previously, we isolated the opp operon from Vibrio fluvialis and constructed the oppA mutant by allelic exchange method. In this study, we investigated the growth pattern and biofilm production under the different growth condition. When the cells were cultivated using brain heart infusion(BHI) medium, the wild type was faster than the mutant in growth during the exponential phase. However, it showed that the growth pattern of two strains in M9 medium is very similar. The growth of wild type showed better than that of the mutant grown at pH 8. At pH 7, there was no an obvious difference in growth. After 5 mM $H_2O_2$ was treated to the cells $(OD_{600}=1.2)$, the cell survival was examined. The oppA mutation did not affect in survivability. In the presence of $10{\mu}g/ml$ polymyxin B, the biofilm production of the oppA mutant was higher than that of the wild type.