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        검색결과 193

        62.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We demonstrated an effective way of preparing melt spinnable mesophase pitches via catalytic hydrogenation of petroleum residue (fluidized catalytic cracking-decant oil) and their subsequent thermal soaking. The mesophase pitches thus obtained were analyzed in terms of their viscosity, elemental composition, solubility, molecular weight, softening point and optical texture. We found that zeolite-induced catalytic hydrogenation under high hydrogen pressure contributed to a large variation in the properties of the pitches. As the hydrogen pressure increased, the C/H ratio decreased, and the solubility in n-hexane increased. The mesophase pitch with entirely anisotropic domains of flow texture exhibited good meltspinnability. The mesophase carbon fibers obtained from the catalytically hydrogenated petroleum residue showed moderate mechanical properties.
        4,000원
        63.
        2017.09 구독 인증기관 무료, 개인회원 유료
        Xenotransplantation is proposed as a solution to the problem of organ shortage. However, transplantation of xenogeneic organs induces an antigen-antibody reaction in α-1,3-gal structure that are not present in humans and primates, and thus complement is also activated and organs die within minutes or hours. In this study, we used FasL gene, which is involved in the immune response of NK cell, and US11, which suppresses MHC Class I cell membrane surface expression, to inhibit cell mediated rejection in the interspecific immunity rejection, and also hDAF(CD55) was introduced to confirm the response to C3 complement. These genes were tranfeced into Korean native pig fetal fibroblasts using pCAGGS vector. And cytotoxicity of NK cell and human complement was confirmed in each cell line. The US11 inhibited the cytotoxicity of NK cell and, in addition, the simultaneous expression of US11 and Fas ligand showed excellent suppress to T-lymphocyte cytotoxicity, hDAF showed weak resistance to cytotoxicity of natural killer cell but not in CD8+ CTLs. Cytotoxicity study with human complement showed that hDAF was effective for reducing complement reaction. In this studies have demonstrated that each gene is effective in reducing immune rejection.
        4,000원
        64.
        2017.04 구독 인증기관·개인회원 무료
        We performed a survey for flavivirus infection and distribution of Aedes albopictus that known as Zika and Dengue virus vector using black–light trap and BG-sentinel trap around urban area in Korea. Mosquitoes were collected in 27 cities during March to November (twice a month) year 2016. Total numbers of mosquitoes collected 102,102 including 19 species 8 genera during collecting period. Total 21,467 Ae. albopictus was collected that 20,961(24.3%) by BG-sentinel trap and 506 (3.2%) by Black-light trap in urban area. Trap index(trap/night) of Ae. albopictus was showed highest in Hamyang (TI:992.3) and lowest in Taebaek (TI:0.3) there was only collected by Black-light trap. A total of 894 pools from all collecting Ae. albopictus were performed a Flavivirus detection. Flavivirus was not detected during study period. This study may provide basic information for surveillance of imported diseases (include Zika virus) and vectors in Korea.
        65.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Earthworms, especially Eisenia andrei, are cultivated for a variety of purposes including waste disposal and compost production. In this study, bacteria from earthworm gut were cultured and the dominant species identified. Subsequently, we isolated bacteriophages able to lyse the isolated gut bacteria. Two dominant genera of gut bacteria, Aeromonas sp. and Citrobacter sp. were identified by using MALDI-TOF MS analysis and a library was constructed to find lytic phages. Phage EF1 showed lytic activity for C. freundii and two Citrobacter isolates, C. braakii and C. murliniae. These 3 species have similar sensitivities to EF1. Several aspects of the life cycle of EF1 were investigated by using C. freundii under optimal growth conditions. EF1 infects C. freundii with a moderate latent period, approximately 25 min, and a large burst size averaging 5 × 109 per infected cell. Moreover, the antimicrobial activity of EF1 was well maintained under diverse conditions including a broad temperature range of 40°C to 50°C and a wide pH range of 4 to 11. In conclusion, the results indicate that earthworm casting contain a wide range of bacteria species, for which there are various corresponding bacteriophages.
        4,000원
        66.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Soil salinity is the most critical problem at reclaimed tidal saline soil in Korea. The objective of this study was carried out investigate the salt movement in upland soils at Gyehwa-do region in Saemangeum reclaimed land on the south Korea coasts. The experiment was conducted 5% sloped polt (3.0 m × 10.0 m) with 14 treatments and it were separated by low salinity division (LSD) and high salinity division (HSD) install. The cation content in ground water increased during time course, but in the case of land surface water the content was variable, and K+was lower than that of Na and Mg. At the LSD under rainproof condition, the salinity was directly proportional to soil water content, but at the HSD the tendency was no reversed. In condition of rainproof, the amount of soil salinity was higher at the HSD than at the LSD. Positive correlation was obtained between the soil water content and available phosphorous content at the rainfall division, but there was no significance at the surface soil of the rainproof division. Sodium adsorption ratio (SAR) and anion (Cl−, SO4 −) contents in soil were repressed in the order of vinyl-mulching > Rice straw-mulching > control plot. Our results indicate that soluble salt control is critical at reclaimed tidal saline soil and the results can provide some useful information for deciding management plans to reduce salt damage for stable crop production and diverse utilization or cultivation could be one of the management options to alleviate salt damages at reclaimed tidal saline soil in Korea.
        4,000원
        67.
        2016.04 구독 인증기관·개인회원 무료
        Oxalic acid has a nematicidal activity against the root-knot nematode Meloidogyne incognita. High producer of oxalic acid was isolated, and then named as Aspergillus niger F22. Oxalic acid production was investigated under various temperatures from 20 – 33oC and rotational speeds in 5 L jar fermenters. Yield of oxalic acid increased with decreasing temperature. The highest yield was obtained at 23oC, showing the yield of oxalic acid of 8.7 g/L, whereas oxalic acid production was least at 33oC. At 20oC, the yield was lower than that of 23oC. At a rotational speed of 300 rpm, serious oxygen depletion was present from 48 - 72 h, resulting in low productivity of 26.2 mg /L·h. When a rotational speed was set at 600 rpm, dissolved oxygen tension was over 40% and oxalic acid production increased up to approximately 55%. Viscosity during the culture differed with temperatures. Viscosity increased with the increment of temperatures. When A. niger F22 was cultured at 23oC, viscosity was 810 cP, which was favorable for oxalic acid production.
        68.
        2016.04 구독 인증기관·개인회원 무료
        Biological control has been tried for integrated pest management. It is often comparable, safe, and environment-friendly, making itself an alternative for chemical agents. Filamentous microorganisms, i.e., fungi and streptomystes, produce many kinds of useful metabolites, and some of them have been developed as a biocontrol agent. However, they still have a long way because of the concern of manufacturing cost. Therefore, process development was intensively studied to meet cost-effectiveness. Operating conditions of bioreactor, e.g., agitation and aeration, had an effect on biological and physiological responses such as mycelial morphology, oxygen and nutrient transfer. Understanding relationship between operating parameters and microbial responses in terms of growth, substrate and oxygen consumption, and production yield was critical for process development. This study dedicated to build strategies for mass production of biological control agent using aerobic filamentous microorganisms.
        69.
        2016.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Soil salinity at newly reclaimed land in west coast of Korea is highly variable and depending on soil characteristics and weather conditions. The objective of this study was to evaluate the spatiotemporal distribution characteristics changes on soil electrical conductivity and exchangeable sodium percentage in Saemangeum newly reclaimed land. Experimental sites was selected at Gyehwa (35o75'N, 126o60'E) in Saemangeum reclaimed land and their dominant soil series was Munpo (coarseloamy, mixed, non-acid, mesic, typic Fluvaquents). Soil samples were periodically collected at 0 ~ 20 cm and 20 ~ 40 cm layer from each site. Soil electrical conductivity had a wide range from 0.15 to 41.76 dS/m, which was variable according to the weather conditions. The average soil electrical conductivity from March 2014 to 2015 was 6.4 and 3.4 dS/m at Gyehwa in Seamangeum reclaimed land. Calcium concentration in soil solution was negatively correlated with soil electrical conductivity and soluble sodium. Soluble sodium concentration had great variations and it was the most influencing single factor for temporal variations of soil electrical conductivity regardless of soil textural properties. The characteristics of Saemangeum reclaimed land had different shares of saline and sodic properties during the experimental period. Our results indicate that persistent monitoring and modeling on soil salinity at coastal tide land is fundamental and the results can provide some useful information for deciding management plans for diverse utilization or to reduce salt damage for stable crop production at reclaimed tidal land.
        4,000원
        70.
        2016.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        One hundred seventy two accessions of safflower, collected in four countries were investigated for their morphological and biochemical characters in 2014. The accessions were categorized into two groups; South-Central (S-C) Asia and South-West (S-W) Asia, and each group was represented the accessions of two countries. Variation in morphological and biochemical characters was observed between two groups of accessions. The average value of seed weight and range of variability were higher in S-C Asia accessions while S-W accessions exhibited the variation in plant height, leaf length and days to flowering. The average value of oleic and total oil content were higher in S-C Asia accessions, and the values were 19.8%, and 231.4 mg.g-1, respectively, while the range of variability for total oil content was higher in S-W accessions. Plant height exhibited a significant positive correlation with days to flowering (r = 0.625**). Palmitic acid had positively correlated with stearic acid (r = 0.282**) and linoleic acid (r = 0.444**). Oleic and linoleic acid showed a strong negative correlation (r = -0.977**). The first three principal components explained 57% of the total variation. Morphological and biochemical variation exist in different groups of accessions could be useful to breeder for developing new safflower cultivars with high oil quantity and quality.
        4,000원
        71.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This review presents current progress in the preparation methods of liquid crystalline nanocarbon materials and the liquid crystalline spinning method for producing nano-carbon fibers. In particular, we focus on the fabrication of liquid crystalline carbon nanotubes by spinning from superacids, and the continuous production of macroscopic fiber from liquid crystalline graphene oxide.
        4,000원
        72.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        사우디아라비아 북부지역에서 수집된 홍화 총 100자원에 대 한 총폴리페놀 함량 및 항산화 활성을 평가하여 항산화활성이 높은 홍화자원을 선발하고자 연구를 수행하였으며 그 결과는 다음과 같다. 1. 총 100자원의 홍화유전자원에 대한 총폴리페놀 함량은 14.2 ± 0.41 μg GAE mg−1dw에서 81.6 ± 1.56μg GAEmg−1dw 까지 분포하였다. DPPH 라디컬 소거능은 1.6 ± 0.07 μg ASC mg−1 dw에서 14.1 ± 0.23 μg ASCmg−1 dw까지 활성을 나 타냈다. ABTS 활성은 34.5 ± 0.70 μg Trolox mg−1 dw에서 156.5 ± 3.06 μg Trolox mg−1 dw까지 평가되었다. 항산화활성 을 측정한 DPPH와 ABTS 활성간에는 상당한 유의성(r = 0.954**)을 보였다. 2. 홍화자원 100자원의 총폴리페놀 함량 및 항산화활성 결 과값에 대한 상호관계를 분석하여 활성이 높은 그룹(Group1)을 얻었다. Group1에 포함된 8개의 홍화자원은 나머지 그룹에 속한 자원들에 비해 항산화활성이 높았으며, 이중 K185841, K185879, K185863은 Group1내의 다른 자원들보다도 항산화 활성이 상당히 높아 홍화육종이나 기능성물질연구에 좋은 소 재가 될 것으로 사료된다.
        4,300원
        73.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Oncholaimid nematode, Oncholaimus secundicollis Shimada, Kajihara and Mawatari, 2009, is firstly reported based on a comparative morphological study. The present specimens of O. secundicollis are collected from rocky intertidal seagrass on the eastern coast of Korea. Oncholaimus secundicollis is distinguished from all of its congeners by the following combination of morphological characteristics: buccal cavity large with thick cuticular wall and three teeth, left subventral tooth larger than right subventral or dorsal teeth, and the presence of two remarkable precloacal papillae with nine pairs of cloacal setae and single ventral tail papilla with two pairs of short setae. In this study, we provide taxonomic description and illustration of unrecorded species of the genus Oncholaimus.
        4,000원
        74.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Three unrecorded species of free-living marine nematodes, belonging to genus Enoplus Dujardin, 1845 collected from rocky intertidal seagrass on the eastern coast of Korea, are described and illustrated. Enoplus taipingensis Zhang and Zhou, 2012 is characterized by longer body size, a series of lateral setae throughout the tail in male, the presence of trumpet-shaped precloacal supplement with well-dilated proximal end, and the presence of spicules with five to eight semicircular plates. Enoplus meridionalis Steiner, 1921 is characterized by the presence of trumpetshaped precloacal supplement with slightly dilated proximal end, paired massive spicules, and tail with two pairs of stout terminal setae. Enoplus mammillatus Timm, 1959 is easily distinguished from the congeners by narrow tubular-shaped precloacal supplement. In this study, we provide detailed morphological features of three Enoplus species by differential interference contrast microscopy and scanning electron microscopy. This is the first report on the species of the genus Enoplus from the Korean waters.
        4,000원
        75.
        2014.07 구독 인증기관 무료, 개인회원 유료
        As advances in digital technologies (e.g., Apps, QR code, RFID tag) is rapidly changing market environment, marketing researches have extended technology acceptance models in different contexts. Since a supermarket chain, “Home Plus,” in Korea, had opened the first QR code virtual store at the subway platform in 2011, many firms attempt to use QR code technology convergence into their retail business. According to a survey report (Embrian, 2012), QR codes are highly familiar with consumers in Korea, and more than 70% mobile phone users have ever scanned QR codes. Due to ubiquitous nature of QR codes, it is obviously implied that marketers would capitalize the QR code technology on their retail business. Yet, it is skeptical for individuals to adopt QR code virtual store because it is in an infant stage in the retail store context. Therefore, marketers need to predict acceptance and use of QR code virtual store from a consumer perspective. Based on UTAUT (Unified Theory of Acceptance and Use of Technology) suggested by Venkatesh et al. (2003; 2012), this study formulated consumer acceptance model with four core determinants of intentions in the context of QR code virtual stores. Specific objectives are (a) identify perceived value in the context of QR code virtual store; (b) test the changes in consumer perceived value by experience over time; and (c) to predict UTAUT model for consumer acceptance to use QR code virtual store across different time points (i.e., from the time of their initial introduction to stages of experience). A longitudinal field study was conducted at the selected QR code virtual stores among individuals using smart phones. A self-administered questionnaire was developed based on literatures the context of consumer use of QR code virtual store. The multi-item scales of perceived value (i.e., performance expectancy, effort expectance, social influence, and facilitating condition) were adapted from Venkatesh et al.’s (2003) UTAUT constructs. Four items of behavioral intention to use QR code virtual store was developed. All items were measured on 5 points rating scale. Sample in this study was obtained from volunteers who participated in three different points in time: initial experience (T1), one month after first experience (T2) and three months after second experience (T3). Participants were required to visit to an assigned QR code store and do shopping task per each time. Then, they were asked to answer the questions on a survey, and there were 123 valid respondents to the first stage of the field experiment. As removed the respondents who did not participate in T2 or T3 point, a total of 309 pooled data across time (103 each time) were analyzed. The sample represents more females (n=66, 68%) than males (n=31, 32%), aging from 19 to 29 years (mean=21.58 years). Preliminarily, using the data pooled across times, factor analysis was conducted to identify underlying constructs for all research variables. As expected, a factor analysis of perceived value constructs revealed four factors: social influence (5 items), performance expectancy (5 items), effort expectancy (4 items), and facilitating condition (3 items). All factor loadings were ranged from .63 to .86, and all internal consistency reliabilities were greater than .80. Also, a unidimensional behavioral intention (4 items) confirmed to be valid (factor loadings=.88 to .93) and reliable (α=.94). Therefore, it is deemed that content validity and reliability were within acceptable ranges for further analysis. Of the four perceived value constructs, there were significant differences in the effort expectancy (F=7.10, p<.01) and facilitating condition (F=8.22, p<.001) across times of experience. Specifically, the perceive effort expectancy tended to be increased over time, indicating a difference of means between T1 and T2 at the significant level of .01 as a result of Duncan’s post-hoc test. With respect to facilitating condition, the mean tended to be increased over time, but post hoc test indicated a significant difference between T1 and T2. The perceived effort expectancy and facilitating condition tended to be changed in positive from T2 to T3 point, which were not significantly different. Therefore, the finding implies that the second stage of experience (i.e., one month after first experience) is a critical point for consumers to increase perceived value of QR code virtual store as a new retail technology. Otherwise, the other factors, such as social influence, performance expectancy and behavioral intention were not significantly increased during the three times of experience. To predict UTAUT model for consumer acceptance to use QR code virtual store, behavioral intention was served as dependent variable and the four factors of perceived value were served as independent variables in regression analysis. In the initial experience (T1), behavioral intention was significantly predicted by social influence (β=.39, t=4.42, p<.001) and performance expectancy (β=.46, t=4.44, p<.001), which explained for 57% of total variance (F=32.08, p<.001, adjusted R²=.57). In the second experience (T2), behavioral intention was significantly predicted by three factors, such as social influence (β=.43, t=5.91, p<.001), performance expectancy (β=.35, t=4.10, p<.001) and facilitating condition (β=.15, t=2.32, p<.05), accounted for 68 % of total variance (F=52.35, p<.001, adjusted R²=.68). In the three month after second experience (T3), behavioral intention was significantly predicted by social experience (β=.36, t=3.33, p<.01) and performance expectancy (β=.33, t=3.33, p<.001), accounted for 52 % of total variance (F=27.65, p<.001, adjusted R²=.52). This study supports the UTAUT model for consumer acceptance of QR code virtual store over time from a theoretical perspective. It should be noted that social influence and performance expectancy appears to be a determinant of behavioral intention to use in most situations. The effect of facilitating condition on behavioral intention was only significant when experienced in second stage. In addition, future study needs to expend technology acceptance model of virtual store in conjunction with digital technological attributes across different product categories.
        3,000원
        76.
        2014.07 구독 인증기관 무료, 개인회원 유료
        Introduction E-retailers take advantage of apparel products which are viewed as a constantly changing experiential product rich that lead to various kinds of hedonic consumption, like impulse buying (Park and Kim, 2008). Apparel purchases are often affected by irrational and emotional attraction making them one of the most frequent impulsively purchased items online (Rhee, 2007). The e-shoppers are more spontaneous due to marketing stimuli which makes it easier to purchase impulsively and reduces risk aversion (Madhavaram and Laverie, 2004). In fact, shoppers are more likely to overspend when e-shopping because it does not feel like spending money (Dittmar, Long, and Meek, 2004). Apparel retailers need to pay special attention to converting web browsers to impulse purchasers—a capability that plays an important role in the growth of e-business. Despite the vast amount of data available online, few efforts have been made to identify the relationship among services attributes, browsing, urges to buy, and e-impulse buying of apparel products. This study explores a model of e-impulse buying for strategic e-business management in apparel products by understanding critical factors of e-store service attributes over the shopping websites and its impact on browsing and urges to buy for apparel in Korea. Specifically, the objectives of this study were to (a) identify underlying factors of online service attributes related to apparel products; (b) estimate structural equation model for causative relationship among service attributes, browsing, urges to buy, and e-impulse buying; and (c) examine mediating effect of browsing and urges to buy on e-impulse buying for apparel. By focusing on apparel products, this study will shed light on complex issues surrounding online service and provide opportunities for strategic development and promotion in fashion merchandising online. Also, this study could help mangers to identify successful global applications of e-marketing for apparel products. Methods A self-administered questionnaire was developed based on previous literatures. The instrument consisted of the main variables; e-service attributes of apparel stores, browsing, urge to buy, and e-impulse buying of apparel products. Participants responded to questions on a 5-point rating scale (1=very unlikely to 5=very likely). The questionnaire was administered during a regularly scheduled class in universities. Usable data were obtained from 319 students aged between 18 and 25 residing at the metropolitan areas in Korea. More than half of the respondents (65.5%) were 18 to 21 years old. Nearly 65.5 percent of the subjects were women, and more than half of the respondents (63.8%) were below the sophomore. For data analysis, exploratory factor analysis with varimax rotation was conducted to determine dimensions of perceived service attributes of the apparel online store. Cronbach's alpha established inter-item reliability between items. The structural equation model analysis was conducted by AMOS 18.0 using a correlation matrix with maximum likelihood approach. The overall fit of the model was assessed by various statistic indexes: chi-square (χ2), goodness of fit index (GFI), adjusted goodness of fit index (AGFI), and root mean squared residual (RMR). Results An exploratory factor analysis revealed three types of e-store service attributes: Ease of Use, Accuracy, and Reliability. The structural equation model, which was estimated to examine causal relationships among variables (i.e. three types of service attributes, browsing, urges to buy, and e-impulse buying), was relatively acceptable (chi-square value = 168.23, df = 157, p = .026; GFI = .95, AGFI = .93, RMR = .05). The model demonstrated that the two factors of service attributes (i.e. ease of use, accuracy of service) were significant variables to influence the browsing, which influence the urges to buy and e-impulse buying for apparel stores. E-impulse buying of apparel products was influenced by browsing and urges to buy. In addition, the urges to buy and browsing mediated the casual relationship between service attributes and e-impulse buying for apparel products. This result suggests that browsing and urges to buy perceived by shoppers were important predicting e-impulse buying of apparel products. Especially, urges to buy apparel products was the most important mediator to trigger e-impulse buying of apparels. Conclusions & Implication This study explores a structural equation model for understanding e-impulse buying in conjunction with browsing, urges to buy and service attributes of apparel store perceived by shoppers in Korea. The findings suggest that the browsing and urges to buy perceived by shoppers play important roles as mediators of the e-impulse buying for apparel stores. Especially, service attributes of apparel e-store perceived by shoppers had indirect effects on e-impulse buying through the browsing and urges to buy, implying that the consumers perceived the ease to use of e-store was the more browsing at e-store and then the more perceiving the urges to buy apparel products. However, the more browsing at apparel e-store was the less the e-impulse buying of apparel products and the more perceiving urges to buy at e-store is the more e-impulse buying of apparel products. This study provides retail managerial implications for stimulating e-shoppers' impulse buying of apparel products. They could increase shoppers' unplanned purchases by developing the service program for convenience (e.g. easy to use the structure of contents, wide ranges of products/service packages, various menu options of website) to stimulate the browsing at e-store.
        3,000원
        77.
        2013.04 구독 인증기관·개인회원 무료
        Mealworms, Tenebrio molitor (L.) is used as an important animal feed additive for growth promotion and health management, but potentially exposes to fungal infection. In this work, virulence of two species of entomopathogenic fungi against the insect, and the relationship between abiotic features and virulence were investigated. Secondly our consideration was also given to the effect of chemical fungicides on conidial germination for risk control. Between Beauveria bassiana (Bb) and Metarhizium roberstii (Mr) (previously M. anisopliae), Bb isolates had much higher virulence (~100% mortality in 3~4 days after the treatment), rather than Mr isolates in laboratory assays. Next, fungus-treated mealworms were kept at wheat bran at 20, 25, 30 and 35℃ with 3, 6, 9 times of water spray to the feeds for set-up of different humidity conditions. Inoculation of fungi to mealworms was conducted by fungal spray and feeding methods, which resulted in higher virulence in feeding method. In the feeding method, all temperature treatments except 35℃ showed high virulence against mealworms, but any significant relationship between virulence and humidity was not observed. In the chemical fungicide screening, fluazinam (CAS No. 79622-59-6) and mancozeb (8018-01-7) significantly inhibited the germination of Bb and Mr conidia. This work suggest that contamination of wheat bran with fungal pathogens, particularly B. bassiana may induce mycosis of mealworms, but introduction of effective fungicides possibly reduce fungal infection.
        78.
        2012.06 구독 인증기관·개인회원 무료
        Pluripotent stem cells can be derived from both pre- and post-implantation embryos. Embryonic stem cells (ES cells), derived from inner cell mass (ICM) of blastocyst are naïve pluripotent and epiblast stem cells (EpiSCs) derived from post-implantation epiblast are primed pluripotent. The phenotypes and gene expression patterns of the two pluripotent stem cells are different each other and EpiSCs thought to be in a more advanced pluripotent (primed pluripotent state) than mouse ES cells (naïve pluripotent state). Therefore, we questioned whether EpiSCs are less potential to be differentiated into specialized cell types in vitro. EpiSCs were isolated from 5.5~6.5 day post coitum mouse embryos of the post-implantation epiblast. The EpiSCs could differentiate into all tree germ layers in vivo, and expressed pluripotency markers (Oct4, Nanog). Interestingly, EpiSCs also were able to efficiently differentiate into neural stem cells (NSCs). The NSCs differentiated from EpiSCs (EpiSC-NSCs) expressed NSC markers (Nestin, Sox2, and Musasi), self-renewed over passage 20, and could differentiate into two neural subtypes, neurons, astrocytes and oligodendrocytes. Next, we compared global gene expression patterns of EpiSC-NSCs with that of NSCs differentiated from ES cells and brain tissue. Gene expression pattern of brain tissue derived NSCs were closer to ES cell-derived NSCs than EpiSC-NSCs, indicating that the pluripotent stem cell-derived somatic cells could have different characteristics depending on the origin of pluripotent stem cell types. * This work was supported by the Next Generation Bio-Green 21 Program funded by the Rural Development Administration (Grant PJ 008009).
        79.
        2012.06 구독 인증기관·개인회원 무료
        Neural stem cells (NSCs) are self-renewing tripotent cell populations and have capacity of neuronal (neurons) and glial (astrocytes and oligodendrocytes) differentiation. Many researchers have reported that NSCs have therapeutic effects in neurological disease by transplantation. However, it is not easy to obtain NSCs in vitro. Recently, Yamanaka and colleagues showed that somatic cells could be reprogrammed into pluripotent state by enforcing reprogramming factors. Induced pluripotent stem (iPS) cells undergo unlimited self-renewal and have differentiation potential into various types of cells like embryonic stem cells. Direct differentiation into a specialized cell types from iPS cells hold considerable promise for regenerative medicine as well as basic research. Here, we induced differentiation of iPS cells into NSCs in vitro and in vivo, which were compared with embryonic stem (ES) cell-derived NSCs and brain derived NSCs. NSCs from ES and iPS cells were morphologically indistinguishable from brain derived NSCs and stained positive for NSCs markers Nestin and Sox2. ES cells derived NSCs were transcriptionally distinguishable from brain derived NSCs. However, global gene expression pattern were similar but distinct between iPS derived NSCs and brain derived NSCs. Moreover, iPS derived NSCs were spontaneously aggregated upon passaging, formed ES cell like colonies, and finally reactivated Oct4-GFP. The spontaneously reverted GFP-positive cells (iPS-NSC-iPS) expressed similar levels of pluripotency markers (Oct4,Nanog) to ES and iPS cells, and could form germ line chimera. One possible explanation for this phenomenon is that spontaneously re-reprogramming was associated with transgene re-activation when iPS cells were differentiated into NSCs. However, NSCs from dox-inducible iPScells could not be reprogrammed into pluripotent state without doxycycline. Taken together, iPS derived NSCs were morphologically and similar to brain derived NSCs, but differ in gene expression pattern and maintenance. * This work was supported by the Next Generation Bio-Green21 Program funded by the Rural Development Administration (Grant PJ008009).
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