• 한국균학회소식:학술대회논문집
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• 한국균학회 2014년도 춘계학술대회 및 임시총회
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• pp.27-28
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• 2014

Beauveria bassiana (Cordycipitaceae, Hypocreales, Ascomycota) is an anamorphic fungus having a potential to be used as a biological control agent because it parasitizes a wide range of arthropod hosts including termites, aphids, beetles and many other insects. A number of bioactive secondary metabolites (SMs) have been isolated from B. bassiana and functionally verified. Among them, beauvericin and bassianolide are cyclic depsipeptides with antibiotic and insecticidal effects belonging to the enniatin family. Non-ribosomal peptide synthetases (NRPSs) play a crucial role in the synthesis of these secondary metabolites. NRPSs are modularly organized multienzyme complexes in which each module is responsible for the elongation of proteinogenic and non-protein amino acids, as well as carboxyl and hydroxyacids. A minimum of three domains are necessary for one NRPS elongation module: an adenylation (A) domain for substrate recognition and activation; a tholation (T) domain that tethers the growing peptide chain and the incoming aminoacyl unit; and a condensation (C) domain to catalyze peptide bond formation. Some of the optional domains include epimerization (E), heterocyclization (Cy) and oxidation (Ox) domains, which may modify the enzyme-bound precursors or intermediates. In the present study, we analyzed genomes of B. bassiana and its allied species in Hypocreales to verify the distribution of NRPS-encoding genes involving biosynthesis of beauvericin and bassianolide, and to unveil the evolutionary processes of the gene clusters. Initially, we retrieved completely or partially assembled genomic sequences of fungal species belonging to Hypocreales from public databases. SM biosynthesizing genes were predicted from the selected genomes using antiSMASH program. Adenylation (A) domains were extracted from the predicted NRPS, NRPS-like and NRPS-PKS hybrid genes, and used them to construct a phylogenetic tree. Based on the preliminary results of SM biosynthetic gene prediction in B. bassiana, we analyzed the conserved gene orders of beauvericin and bassianolide biosynthetic gene clusters among the hypocrealean fungi. Reciprocal best blast hit (RBH) approach was performed to identify the regions orthologous to the biosynthetic gene cluster in the selected fungal genomes. A clear recombination pattern was recognized in the inferred A-domain tree in which A-domains in the 1st and 2nd modules of beauvericin and bassianolide synthetases were grouped in CYCLO and EAS clades, respectively, suggesting that two modules of each synthetase have evolved independently. In addition, inferred topologies were congruent with the species phylogeny of Cordycipitaceae, indicating that the gene fusion event have occurred before the species divergence. Beauvericin and bassianolide synthetases turned out to possess identical domain organization as C-A-T-C-A-NM-T-T-C. We also predicted precursors of beauvericin and bassianolide synthetases based on the extracted signature residues in A-domain core motifs. The result showed that the A-domains in the 1st module of both synthetases select D-2-hydroxyisovalerate (D-Hiv), while A-domains in the 2nd modules specifically activate L-phenylalanine (Phe) in beauvericin synthetase and leucine (Leu) in bassianolide synthetase. antiSMASH ver. 2.0 predicted 15 genes in the beauvericin biosynthetic gene cluster of the B. bassiana genome dispersed across a total length of approximately 50kb. The beauvericin biosynthetic gene cluster contains beauvericin synthetase as well as kivr gene encoding NADPH-dependent ketoisovalerate reductase which is necessary to convert 2-ketoisovalarate to D-Hiv and a gene encoding a putative Gal4-like transcriptional regulator. Our syntenic comparison showed that species in Cordycipitaceae have almost conserved beauvericin biosynthetic gene cluster although the gene order and direction were sometimes variable. It is intriguing that there is no region orthologous to beauvericin synthetase gene in Cordyceps militaris genome. It is likely that beauvericin synthetase was present in common ancestor of Cordycipitaceae but selective gene loss has occurred in several species including C. militaris. Putative bassianolide biosynthetic gene cluster consisted of 16 genes including bassianolide synthetase, cytochrome P450 monooxygenase, and putative Gal4-like transcriptional regulator genes. Our synteny analysis found that only B. bassiana possessed a bassianolide synthetase gene among the studied fungi. This result is consistent with the groupings in A-domain tree in which bassianolide synthetase gene found in B. bassiana was not grouped with NRPS genes predicted in other species. We hypothesized that bassianolide biosynthesizing cluster genes in B. bassiana are possibly acquired by horizontal gene transfer (HGT) from distantly related fungi. The present study showed that B. bassiana is the only species capable of producing both beauvericin and bassianolide. This property led to B. bassiana infect multiple hosts and to be a potential biological control agent against agricultural pests.

• 대한소아치과학회지
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• 제31권1호
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• pp.98-107
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• 2004

적절한 마무리와 연마는 치아 수복물의 심미성과 내구성 향상을 위해 필수적인 과정이다. 본 연구에서는 복합레진의 마무리/연마 과정 시행에 있어서 시기적 차이를 두어 마무리/연마 시기가 복합레진의 표면 거칠기와 경도에 미치는 영향을 비교하고자 하였다. 네 종류의 복합레진(Filtek A110, Silux Plus, Revolution formular2, Palfique Estelite)을 이용하여 시편을 제작하고 마무리/연마 과정을 거치지 않은 대조군과 중합 직후 마무리/연마를 시행한 경우와 1주 후 마무리/연마를 시행한 두 가지 실험군으로 구분하였다. 이 시편들의 표면 거칠기$(R_a\;value,\;{\mu}m)$와 경도(VHN)를 측정하고, 주사전자현미경으로 관찰하여 다음과 같은 결과를 얻었다. 1 네 가지 재료 모두 대조군에서 가장 활택한 표면을 얻었고 마무리/연마 과정을 거친 후 표면 거칠기가 증가하였으나, 마무리/연마시기에 따른 유의한 차이는 보이지 않았다. 2. 표면 거칠기는 중합 직후 마무리/연마를 시행한 경우 Silux Plus와 Revolution formular 2가 차이를 보였고, 1 주 후 시행한 경우 Silux Plus와 Palfique Estelite가 차이를 나타내었다(p<0.05). 3. 경도는 재료에 따라 Palfique Estelite > Filtek A110 > Silux Plus > Revolution formular 2 순으로 감소하였으나, 마무리/연마시기에 따른 차이는 보이지 않았다. 4. 마무리 연마시기가 표면 거칠기와 경도에 미치는 영향은 재료에 따라 차이를 보였다.

• 설비공학논문집
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• 제26권12호
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• pp.605-619
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• 2014

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

• Clinical and Experimental Reproductive Medicine
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• 제26권1호
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• pp.9-20
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• 1999

The genetic defects in human gametes and embryos can cause adverse effects on overall reproductive events. Biopsy of embryos for preimplantation genetic diagnosis (PGD) offers a new possibility of having children free of the genetic disease. In addition, advanced embryo culture method may enhance the effectiveness of embryo biopsy for the practical application of PGD. This experimental study was undertaken to evaluate the effects of coculture on the development in vitro of biopsied mouse embryos as a preclinical model for PGD of human embryos. Embryos were obtained after in vitro fertilization (IVF) from F1 hybrid mice (C57BLfemale/CBAmale). Using micromanipulation, 1, 2, 3 or 4 blastomeres of 8-cell stage embryos were aspirated through a hole made in the zona pellucida by zona drilling (ZD) with acidic Tyrode's solution (ATS). After biopsy of blastomeres, embryos were cultured in vitro for 110 hours in Ham's F-10 supplemented with 0.4% BSA or cocultured on the monolayer of Vero cells in the same medium. The frequence of blastocyst formation were recorded, and the embryos beyond blastocyst stage were stained with 10% Giemsa to count the total number of nuclei in each embryo. There was no significant difference in the blastocyst formation between the zona intact control group and the zona drilling (ZD) only, or biopsied groups. The hatching rate of all the treatment groups except 4/8 group was significantly higher than that of control group. In all the treatment groups, there was a significant reduction in the mean cell number of embryos beyond blastocyst stage ($50.2{\pm}14.0$ in control group vs. $41.2{\pm}7.9$ in ZD, $39.3{\pm}8.8$ in 7/8, $29.7{\pm}6.4$ in 6/8, $25.1{\pm}5.7$ in 5/8, and $22.1{\pm}4.3$ in 4/8 groups, p<0.05). When the same treatments were followed by coculture with Vero cells, a similar pattern was seen in the blastocyst formation and the hatching rate. However, in all the treatment groups, there was a significant increase in the mean cell number of embryos beyond blastocyst stage with coculture, compared with the parallel groups without coculture. In the cleavage rate of biopsied blastomeres cultured for 110 hours after IVF, there was no significant difference between coculture and non-coculture groups (87.2% vs. 78.7%). However, the mean cell number of embryos developed from the biopsied blastomeres was significantly higher in coculture group ($11.5{\pm}4.7\;vs.\;5.9{\pm}1.9$, p<0.05). In conclusion, biopsy of mouse embryos after ZD with ATS is a safe and highly efficient method for PGD, and coculture with Vero cells showed a positive effect on the development in vitro of biopsied mouse embryos and blastomeres as a preclinical model for PGD of human embryos.

• Journal of Plant Biotechnology
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• 제5권3호
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• pp.143-148
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• 2003

Bax, a mammalian pro-apoptotic member of the Bcl-2 family induces cell death when expressed in yeast. To investigate whether Bax expression can induce cell death in plant, we produced transgenic Arabidopsis plants that contained murine Bax cDNA under control of a glucocorticoid-inducible promoter. Transgenic plants treated with dexamethasone, a strong synthetic glucocorticoid, induced Bax accumulation and cell death, suggesting that some elements of cell death mechanism by Bax may be conserved among various organisms. Therefore, we developed novel yeast genetic system, and cloned several Plant Bax Inhibitors (PBIs). Here, we report the function of two PBIs in detail. PBI1 is ascorbate peroxidase (sAPX). Fluorescence method of dihydrorhodamine123 oxidation revealed that expression of Bax in yeast cells generated reactive oxygen species (ROS), and which was greatly reduced by co-expression with sAPX. These results suggest that sAPX inhibits the generation of ROS by Bax, which in turn suppresses Baxinduced cell death in yeast. PBI2 encodes nucleoside diphosphate kinase (NDPK). ROS stress strongly induces the expression of the NDPK2 gene in Arabidopsis thaliana (AtNDPK2). Transgenic plants overexpressing AtNDPK2 have lower levels of ROS than wildtype plants. Mutants lacking AtNDPK2 had higher levels of ROS than wildtype. $H_2O_2$ treatment induced the phosphorylation of two endogenous proteins whose molecular weights suggested they are AtMPK3 and AtMPK6. In the absence of $H_2O_2$ treatment, phosphorylation of these proteins was slightly elevated in plants overexpressing AtNDPK2 but markedly decreased in the AtNDPK2 deletion mutant. Yeast two-hybrid and in vitro protein pull-down assays revealed that AtNDPK2 specifically interacts with AtMPK3 and AtMPK6. Furthermore, AtNDPK2 also enhances the MSP phosphorylation activity of AtMPK3 in vitro. Finally, constitutive overexpression of AtNDPK2 in Arabidopsis plants conferred an enhanced tolerance to multiple environmental stresses that elicit ROS accumulation in situ. Thus, AtNDPK2 appears to playa novel regulatory role in $H_2O_2$-mediated MAPK signaling in plants.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.184-184
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• 2012

Recently, InGaN/GaN multi-quantum well grown on GaN pyramid structures have attracted much attention due to their hybrid characteristics of quantum well, quantum wire, and quantum dot. This gives us broad band emission which will be useful for phosphor-free white light emitting diode. On the other hand, by using quantum dot emission on top of the pyramid, site selective single photon source could be realized. However, these structures still have several limitations for the single photon source. For instance, the quantum efficiency of quantum dot emission should be improved further. As detection systems have limited numerical aperture, collection efficiency is also important issue. It has been known that micro-cavities can be utilized to modify the radiative decay rate and to control the radiation pattern of quantum dot. Researchers have also been interested in nano-cavities using localized surface plasmon. Although the plasmonic cavities have small quality factor due to high loss of metal, it could have small mode volume because plasmonic wavelength is much smaller than the wavelength in the dielectric cavities. In this work, we used localized surface plasmon to improve efficiency of InGaN qunatum dot as a single photon emitter. We could easily get the localized surface plasmon mode after deposit the metal thin film because lnGaN/GaN multi quantum well has the pyramidal geometry. With numerical simulation (i.e., Finite Difference Time Domain method), we observed highly enhanced decay rate and modified radiation pattern. To confirm these localized surface plasmon effect experimentally, we deposited metal thin films on InGaN/GaN pyramid structures using e-beam deposition. Then, photoluminescence and time-resolved photoluminescence were carried out to measure the improvement of radiative decay rate (Purcell factor). By carrying out cathodoluminescence (CL) experiments, spatial-resolved CL images could also be obtained. As we mentioned before, collection efficiency is also important issue to make an efficient single photon emitter. To confirm the radiation pattern of quantum dot, Fourier optics system was used to capture the angular property of emission. We believe that highly focused localized surface plasmon around site-selective InGaN quantum dot could be a feasible single photon emitter.

• 한국어류학회지
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• 제5권1호
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• pp.113-121
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• 1993

지리적으로 분리 분포하고 있는 한국산 송사리 두 집단간의 분류학적 위치를 검토하기 위하여 두 집단간의 형태 및 교잡실험을 하여 비교하고 그 자손에 대하여 핵형과 발생율을 비교 조사하였다. 이 들 두 종의 대부분의 계수 계측형질은 대체로 유사하지만 가슴지느러미 기조수, 뒷지느러미의 기조수 및 척추골 수에 있어서 차이를 보였다. 가슴지느러미 기조수의 경우 Oryzias latipes는 9~10의 범위를 갖는데 비해 O. sinensis는 8~9개이었고 뒷지느러미 기조수에 있어서는 O. latipes는 19~21의 범위를 보인 반면 O. sinensis는 17~19개이었다. 또한 척추골 수에 있어서도 O. latipes가 31~33개인 반면 O. sinensis는 30~31개이었다. 2n 염색체수가 48인 O. latipes와 46인 O. sinensis 두 종간의 교잡에 의한 제 1세대의 염색체 수는 2n이 47로 하나의 large metacentric chromosome을 가지고 있었다. 그리고 이들 제 1세대를 자가교배하여 얻은 제 2세대의 염색체 수는 2n=46, 47, 48개이었는데 이들의 비율은 13 : 3 : 1로 나타났다. 또한 두 종의 교잡에 의한 제 1세대의 수정율 및 부화율은 동일 종간의 교잡의 결과와 큰 차이가 없는데 비해 제 1세대를 자가교배하여 얻은 제 2세대의 경우에는 수정율, 부화율에서 감소를 보였고 개체가 대조군에 비해 증가했다. 이러한 결과들로 보아 이들 두 종은 지리적 분리요인에 의하여 염색체가 분화되었다고 보아 이 두 집단은 분류학적으로 아종이라기 보다는 종으로 간주하는 것이 타당하다고 생각한다.

• Journal of Plant Biotechnology
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• 제44권1호
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• pp.35-41
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• 2017

본 연구에서는 유지형 배추인 LP08과 청경채형 LP21을 교배한 교잡종 $F_1$을 소포자 배양하여 유전적으로 고정된 계통을 획득하였다. 엽의 결각 유무 및 결각수에서 다양한 형태적 특징을 보이는 66개 고정계통을 대상으로 항암 및 항산화 물질로 알려진 플라보노이드의 함량을 분석하였다. 66개 고정 계통의 엽의 결각 유무와 플라보노이드 함량 간 상관관계는 관찰되지 않았다. 양친으로 사용된 LP08, LP21 그리고 결구 배추형 품종인 Chiifu를 대상으로 플라보노이드 분석을 실시한 결과, quercetin, naringenin, 및 kaempferol 함량의 다양한 분포가 관찰되었다. 또한 모계인 LP08에서 가장 높은 총 플라보노이드 함량을 나타내었고 결구 배추형인 Chiifu에서 가장 낮은 함량을 보였다. 66개 고정 계통을 대상으로 플라보노이드 함량을 분석한 결과, quercetin은 LP08 보다 높은 함량을 보이는 18 계통이 확인되었으나 naringenin과 kaempferol에서는 교배친 보다 높은 함량을 보이는 계통을 발견할 수 없었다. 총 플라보노이드 함량에서 kampferol은 79.7 %, quercetin은 17.4 %의 비율을 보였고 naringenin의 경우 2.8 %로 거의 대부분의 계통에서 가장 낮은 함량을 보이고 22개 계통에서는 전혀 발견되지 않았다. 또한 성분간 상관관계를 분석한 결과 quercetin과 kaempferol의 함량간에 유의한 상관관계가 있음을 확인할 수 있었다. 본 실험의 결과는 향후 플라보노이드 생합성 기작 관련 유전자 탐색을 위한 자료로 활용할 예정이다. 또한 고정 계통을 대상으로 다양하고 광범위한 형질 조사를 실시하여 배추의 품종 개발이 가능할 것으로 기대된다.

• 한국산학기술학회논문지
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• 제17권6호
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• pp.1-8
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• 2016

오늘날 전류센서는 전류량 제어, 감시, 계측 등 매우 다양한 분야에서 사용되고 있다. 또한 전력망의 스마트 그리드사업, 신재생에너지 발전, 전기자동차와 하이브리드 자동차 등의 수요가 커지면서 그 사용영역이 점차 확대되고 있는 추세이다. 여러 종류의 전류센서 중에서 홀 소자를 사용하는 개방형 전류센서는 다른 형식의 전류센서에 비해 가격이 싸고, 크기와 무게가 작은 장점이 있지만 정밀도가 낮고 주위의 온도 변화에 따라 특성이 변하는 것이 단점이다. 이러한 단점을 보완하기 위하여 본 연구에서는 정밀도와 온도성능이 뛰어난 300A급 개방형 전류센서를 설계 및 제작하였다. 300A급 개방형 전류센서를 제작하기 위해서 수치해석을 통해 철심을 설계하고 회로해석 프로그램을 이용하여 신호처리에 필요한 회로들을 설계하였다. 이러한 과정을 통해서 SMD(Surface Mount Device) 형태로 제작된 300A급 개방형 전류센서는 30 ~ 300A의 직류 및 교류전류를 통전한 실험에서 정밀도 오차가 0.75% 이내, 선형도 오차가 0.19% 이내였다. 또한 온도보상회로를 포함한 전류센서를 $-25{\sim}85^{\circ}C$의 온도범위에서 동작시켰을 때 온도계수는 $0.012%/^{\circ}C$ 이내였다.

• 한국가축번식학회지
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• 제20권4호
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• pp.371-378
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• 1997

본 연구는 인체 락토페린(hLF)을 우유 중으로 생산하는 형질전환 젖소의 개발에 관한 것이다. 이를 위한 모델 시스템으로서 락토페린 cDNAdhk 소의 베타-카제인 프로모터를 이용하여 형질전환 생쥐를 개발하였다. 발현 벡터의 락토페린에 대한 발현효율을 증가시키기 위하여 2개의 재조합 인트론을 삽입하였다. 20계통의 형질전환 생지를 개발하였는데 유즙에서의 락토페린 발현량은 1~200$\mu\textrm{g}$/ml이었다. hLF RNA의 발현 양상을 유선조직을 포함하여 뇌, 신장, 간 조직 등에서 조사하였을 때, 오직 유선에서만 발현되었을 뿐 아니라 엑손/인트론 경계 부위에서 정확하게 splicing되었다. hLF를 생산하는 형질전환 젖소를 개발하기 위하여 위에서 기술한 DNA를 소의 수정란에 미세주입한 후, 외과적 또는 비외과적 방법으로 대리모에 이식하였다. 한편, DNA가 주입된 수정란의 상태가 임신율에 미치는 영향을 조사하였다. 수정란을 최우수, 우수, 보통 등 3등급으로 나누었을 때, 각각의 임신율은 38.9, 15.4, 14.3%로 나타났다. 현재까지 유전자가 주입된 수정란을 대리모에 이식하여 태어난 35마리의 송아지 중, 30마리는 형절전환되지 않았으며 나머지는 현재 분석 중에 있다. 이상의 결과로 본 연구자들은 DNA가 미세주입된 젖소 수정란의 배양과 이식에 필요한 제반 기술을 확립하였으며, 아울러 임신율에 영향을 주는 여러 인자들에 대한 연구도 함께 조사하였다.