• Journal of Life Science
• /
• v.18 no.4
• /
• pp.522-529
• /
• 2008

High-temperature requirement A2(HtrA2) has been known as a human homologue of bacterial HtrA that has a molecular chaperone function. HtrA2 is mitochondrial serine protease that plays a significant role in regulating the apoptosis; however, the physiological function of HtrA2 still remains elusive. To establish experimental system for the investigation of new insights into the function of HtrA2 in mammalian cells, we first obtained $HtrA2^{+/+}$ and $HtrA2^{-/-}$ MEF cells lines and identified those cells based on the expression pattern and subcellular localization of HtrA2, using immunoblot and biochemical assays. Additionally, we observed that the morphological characteristics of $HtrA2^{-/-}$ MEF cells are different form those of $HtrA2^{+/+}$ MEF cells, showing a rounded shape instead of a typical fibroblast-like shape. Growth rate of $HtrA2^{-/-}$ MEF cells was also 1.4-fold higher than that of $HtrA2^{+/+}$ MEF cells at 36 hours. Furthermore, we verified both MEF cell lines induced caspsase-dependent cell death in response to apoptotic stimuli such as heat shock, staurosporine, and rotenone. The relationship between HtrA2 and heat shock-induced cell death is the first demonstration of the research field of HtrA2. Our study suggests that those MEF cell lines are suitable reagents to further investigate the molecular mechanism by which HtrA2 regulates the balance between cell death and survival.

• Journal of Life Science
• /
• v.23 no.2
• /
• pp.167-174
• /
• 2013

Peroxiredoxin 6 (Prx 6) is a member of the thiol-specific antioxidant protein family, which may play a role in protection against oxidative stress and in regulating phospholipid turnover. The aim of this study was to determine whether a human Prx 6/Luc vector was stably expressed and responded to antioxidants in a lung cell line (NCI-H460). To achieve this, the luciferase signal, hPrx 6 mRNA expression, and superoxide dismutase (SOD) activity were measured in transfectants with a hPrx 6/Luc plasmid after treatment with four antioxidant extracts, including Korea white ginseng (KWG), Korea red ginseng (KRG), Liriope platyphylla (LP), and red Liriope platyphylla (RLP). First, the hPrx 6/Luc plasmid was successfully constructed with DNA fragments of human Prx 6 promoter, amplified by PCR using genomic DNA isolated from NCI-H460 cells, and cloned into the pTransLucent reporter vector. The orientation and sequencing of the hPrx 6/Luc plasmid were identified with restriction enzyme and automatic sequencing. A luciferase assay revealed significant enhancement of luciferase activity in the four treatment groups compared with a vehicle-treated group, although the ratio of the increase was different within each group. The KRG- and LP-treated groups showed higher activity than the KWG- and RLP-treated groups. Furthermore, the luciferase activity against RLP occurred roughly in a dose-dependent manner. However, the level of endogenous hPrx 6 mRNA did not change in any group treated with the four extracts. The SOD activity was in agreement with the luciferase activity. Therefore, these results indicate that the hPrx 6/Luc vector system may successfully express and respond to antioxidant compounds in NCI-H460 cells. The data also suggest that the Prx 6/Luc vector system may be effectively applied in screening the response of hPrx 6 to antioxidant compounds in transgenic mice.

• Molecules and Cells
• /
• v.21 no.1
• /
• pp.52-62
• /
• 2006

In previous reports we demonstrated that ginsenosides, active ingredients of Panax ginseng, affect some subsets of voltage-dependent $Ca^{2+}$ channels in neuronal cells expressed in Xenopus laevis oocytes. However, the major component(s) of ginseng that affect cloned $Ca^{2+}$ channel subtypes such as ${\alpha}_{1C}$(L)-, ${\alpha}_{1B}$(N)-, ${\alpha}_{1A}$(P/Q)-, ${\alpha}_{1E}$(R)- and ${\alpha}_{1G}$(T) have not been identified. Here, we used the two-microelectrode voltage clamp technique to characterize the effects of ginsenosides and ginsenoside metabolites on $Ba^{2+}$ currents ($I_{Ba}$) in Xenopus oocytes expressing five different $Ca^{2+}$ channel subtypes. Exposure to ginseng total saponins (GTS) induced voltage-dependent, dose-dependent and reversible inhibition of the five channel subtypes, with particularly strong inhibition of the ${\alpha}_{1G}$-type. Of the various ginsenosides, $Rb_1$, Rc, Re, Rf, $Rg_1$, $Rg_3$, and $Rh_2$, ginsenoside $Rg_3$ also inhibited all five channel subtypes and ginsenoside $Rh_2$ had most effect on the ${\alpha}_{1C}$- and ${\alpha}_{1E}$-type $Ca^{2+}$ channels. Compound K (CK), a protopanaxadiol ginsenoside metabolite, strongly inhibited only the ${\alpha}_{1G}$-type of $Ca^{2+}$ channel, whereas M4, a protopanaxatriol ginsenoside metabolite, had almost no effect on any of the channels. $Rg_3$, $Rh_2$, and CK shifted the steady-state activation curves but not the inactivation curves in the depolarizing direction in the ${\alpha}_{1B}$- and ${\alpha}_{1A}$-types. These results reveal that $Rg_3$, $Rh_2$ and CK are the major inhibitors of $Ca^{2+}$ channels in Panax ginseng, and that they show some $Ca^{2+}$ channel selectivity.

• Journal of Genetic Medicine
• /
• v.4 no.1
• /
• pp.72-79
• /
• 2007

Purpose : Glycogen storage disease type III (GSD-III) is a rare autosomal recessive disorder of glycogen metabolism. The affected enzyme, amylo-1,6-glucosidase, 4-alpha-glucanotransferase (AGL, glycogen debranching enzyme), is responsible for the debranching of the glycogen molecule during catabolism. The disease shows clinical and biochemical heterogeneity, reflecting genotype-phenotype heterogeneity among different patients. In this study, we aim at analyzing mutations of the AGL gene in three unrelated Korean GSD-III patients, and characterizing their clinical and laboratory findings. Methods : We characterized the clinical features of three unrelated Korean GSD-III patients by biochemical, histological and imaging studies. The 35 exons and part of exon-intron boundaries of AGL were analyzed by direct sequencing using genomic DNA extracted from the peripheral leukocytes of patients. Results : Diverse clinical features were observed in these patients including hepatomegaly (all patients), seizures (patient 2), grow th failure (patients 1 and 2), hyperlipidemia (patients 1 and 3), raised transaminase and creatine kinase concentrations (all patients), and mild cardiomyopathy (patient 2). Liver transplantation w as performed in patient 2 due to progressive hepatic fibrosis. A dministration of uncooked corn starch maintained normoglycemia and improved biochemical and growth profiles. DNA sequence analysis revealed mutations in 5 out of 6 alleles. Patient 1 was a compound heterozygote of c.1282 G>A (p.R428K) and c.1306delA (p.S603PfsX6), patient 2 had c.1510_1511insT (p.Y 504L fsX 10), and patient 3 had c.3416 T >C (p.L 1139P) and c.1735+1 G>T (p.Y 538_R578delfsX 4) mutations. A part from the p.R428K mutation, the 4 other substitutions identified w ere nov el. Conclusion : GSD-III patients display variable phenotypic characteristics resembling those of GSD-Ia. Molecular defects in the AGL gene of Korean GSD-III patients are genetically heterogeneous.

• Asia pacific journal of information systems
• /
• v.19 no.4
• /
• pp.77-100
• /
• 2009

Information Systems (IS) is an essential tool for any organizations. The last decade has seen an increasing body of knowledge on IS usage. Yet, IS often fails because of its misuse or non-use. In general, decisions regarding the selection of a system, which involve the evaluation of many IS vendors and an enormous initial investment, are made not through the consensus of employees but through the top-down decision making by top managers. In situations where the selected system does not satisfy the needs of the employees, the forced use of the selected IS will only result in their resistance to it. Many organizations have been either integrating dispersed legacy systems such as archipelago or adopting a new ERP (Enterprise Resource Planning) system to enhance employee efficiency. This study examines user resistance prior to the adoption of the selected IS or ERP system. As such, this study identifies the importance of managing organizational resistance that may appear in the pre-adoption context of an integrated IS or ERP system, explores key factors influencing user resistance, and investigates how prior experience with other integrated IS or ERP systems may change the relationship between the affecting factors and user resistance. This study focuses on organizational members' resistance and the affecting factors in the pre-adoption context of an integrated IS or ERP system rather than in the context of an ERP adoption itself or ERP post-adoption. Based on prior literature, this study proposes a research model that considers six key variables, including perceived benefit, system complexity, fitness with existing tasks, attitude toward change, the psychological reactance trait, and perceived IT competence. They are considered as independent variables affecting user resistance toward an integrated IS or ERP system. This study also introduces the concept of prior experience (i.e., whether a user has prior experience with an integrated IS or ERP system) as a moderating variable to examine the impact of perceived benefit and attitude toward change in user resistance. As such, we propose eight hypotheses with respect to the model. For the empirical validation of the hypotheses, we developed relevant instruments for each research variable based on prior literature and surveyed 95 professional researchers and the administrative staff of the Korea Photonics Technology Institute (KOPTI). We examined the organizational characteristics of KOPTI, the reasons behind their adoption of an ERP system, process changes caused by the introduction of the system, and employees' resistance/attitude toward the system at the time of the introduction. The results of the multiple regression analysis suggest that, among the six variables, perceived benefit, complexity, attitude toward change, and the psychological reactance trait significantly influence user resistance. These results further suggest that top management should manage the psychological states of their employees in order to minimize their resistance to the forced IS, even in the new system pre-adoption context. In addition, the moderating variable-prior experience was found to change the strength of the relationship between attitude toward change and system resistance. That is, the effect of attitude toward change in user resistance was significantly stronger in those with prior experience than those with no prior experience. This result implies that those with prior experience should be identified and provided with some type of attitude training or change management programs to minimize their resistance to the adoption of a system. This study contributes to the IS field by providing practical implications for IS practitioners. This study identifies system resistance stimuli of users, focusing on the pre-adoption context in a forced ERP system environment. We have empirically validated the proposed research model by examining several significant factors affecting user resistance against the adoption of an ERP system. In particular, we find a clear and significant role of the moderating variable, prior ERP usage experience, in the relationship between the affecting factors and user resistance. The results of the study suggest the importance of appropriately managing the factors that affect user resistance in organizations that plan to introduce a new ERP system or integrate legacy systems. Moreover, this study offers to practitioners several specific strategies (in particular, the categorization of users by their prior usage experience) for alleviating the resistant behaviors of users in the process of the ERP adoption before a system becomes available to them. Despite the valuable contributions of this study, there are also some limitations which will be discussed in this paper to make the study more complete and consistent.

• Asia pacific journal of information systems
• /
• v.24 no.4
• /
• pp.559-575
• /
• 2014

Individual investors are increasingly flocking to message boards to seek, clarify, and exchange information. Businesses like Seekingalpha.com and business magazines like Fortune are evaluating, synthesizing, and reporting the comments made on message boards or blogs. In March of 2012, Yahoo! Finance Message Boards recorded 45 million unique visitors per month followed by AOL Money and Finance (19.8 million), and Google Finance (1.6 million) [McIntyre, 2012]. Previous studies in the finance literature suggest that online communities often provide more accurate information than analyst forecasts [Bagnoli et al., 1999; Clarkson et al., 2006]. Some studies empirically show that the volume of posts in online communities have a positive relationship with market activities (e.g., trading volumes) [Antweiler and Frank, 2004; Bagnoli et al., 1999; Das and Chen, 2007; Tumarkin and Whitelaw, 2001]. The findings indicate that information in online communities does impact investors' investment decisions and trading behaviors. However, research explicating the correlation between information on online communities and stock market activities (e.g., trading volume) is still evolving. Thus, it is important to ask whether a volume of posts on online communities influences trading volumes and whether trading volumes also influence these communities. Online stock message boards offer two different types of information, which can be explained using an economic and a psychological perspective. From a purely economic perspective, one would expect that stock message boards would have a beneficial effect, since they provide timely information at a much lower cost [Bagnoli et al., 1999; Clarkson et al., 2006; Birchler and Butler, 2007]. This indicates that information in stock message boards may provide valuable information investors can use to predict stock market activities and thus may use to make better investment decisions. On the other hand, psychological studies have shown that stock message boards may not necessarily make investors more informed. The related literature argues that confirmation bias causes investors to seek other investors with the same opinions on these stock message boards [Chen and Gu, 2009; Park et al., 2013]. For example, investors may want to share their painful investment experiences with others on stock message boards and are relieved to find they are not alone. In this case, the information on these stock message boards mainly reflects past experience or past information and not valuable and predictable information for market activities. This study thus investigates the two roles of stock message boards-providing valuable information to make future investment decisions or sharing past experiences that reflect mainly investors' painful or boastful stories. If stock message boards do provide valuable information for stock investment decisions, then investors will use this information and thereby influence stock market activities (e.g., trading volume). On the contrary, if investors made investment decisions and visit stock message boards later, they will mainly share their past experiences with others. In this case, past activities in the stock market will influence the stock message boards. These arguments indicate that there is a correlation between information posted on stock message boards and stock market activities. The previous literature has examined the impact of stock sentiments or the number of posts on stock market activities (e.g., trading volume, volatility, stock prices). However, the studies related to stock sentiments found it difficult to obtain significant results. It is not easy to identify useful information among the millions of posts, many of which can be just noise. As a result, the overall sentiments of stock message boards often carry little information for future stock movements [Das and Chen, 2001; Antweiler and Frank, 2004]. This study notes that as a dependent variable, trading volume is more reliable for capturing the effect of stock message board activities. The finance literature argues that trading volume is an indicator of stock price movements [Das et al., 2005; Das and Chen, 2007]. In this regard, this study investigates the correlation between a number of posts (information on stock message boards) and trading volume (stock market activity). We collected about 100,000 messages of 40 companies at KOSPI (Korea Composite Stock Price Index) from Paxnet, the most popular Korean online stock message board. The messages we collected were divided into in-trading and after-trading hours to examine the correlation between the numbers of posts and trading volumes in detail. Also we collected the volume of the stock of the 40 companies. The vector regression analysis and the granger causality test, 3SLS analysis were performed on our panel data sets. We found that the number of posts on online stock message boards is positively related to prior stock trade volume. Also, we found that the impact of the number of posts on stock trading volumes is not statistically significant. Also, we empirically showed the correlation between stock trading volumes and the number of posts on stock message boards. The results of this study contribute to the IS and finance literature in that we identified online stock message board's two roles. Also, this study suggests that stock trading managers should carefully monitor information on stock message boards to understand stock market activities in advance.

• Korean Journal of Organic Agriculture
• /
• v.22 no.4
• /
• pp.743-760
• /
• 2014

This study aimed to isolate and identify freshwater algae from the organic agricultural ecosystems and investigate its biological characteristics to study the possibility of utilizing a biomass freshwater algae in organic farming. In the survey area, average water temperature was $12.4{\sim}28.2^{\circ}C$ and the pH ranges were from 6.1 to 8.5. The solid culture method is more suitable than liquid culture method for isolation of freshwater algae with lower contamination level and higher isolation frequency. A total of 115 strains were isolated from six freshwater algae habitats in nine regions in Korea. BGMM (BG11 Modified Medium) amended with NaNO3 and $KNO_3$ as a nitrogen, and $Na_2CO_3$ as carbon source was designed to isolate and culture freshwater algae. Absorbance of freshwater algae culture has increased dramatically to four days and decreased after eight days after inoculation. CHK008 of the seven isolates showed the highest absorbance in seven days after culturing in BGMM. The optimal pH of BGMM for culturing freshwater algae was pH 6-7. As light intensity increased, growth of freshwater algae increased. Among the five kinds of carbon sources, glucose and galactose promoted good growth of freshwater algae in BGMM. The colony color of purified 16 green algae isolates showed a separation of green, dark and light green, and of them, eleven algae strains showed a strong fluorescent light under fluorescence microscopy. Cell size of the green algae showed a wide range of variation depending on the species. General morphology of the green algae strains was spherical. Chlamydomonas sp. was elliptical, and Chlorella sorokiniana was ellipsoidal and cylindrical. All strains of the green algae except for Chlamydomonas sp. did not have flagella. One isolate of Chlamydomonas sp. and five isolates of C. sorokiniana secreted mucus. Sixteen isolates of 16 green algae were identified as two family and six species, Chlorella vulgalis, C. sorokiniana, C. pyrenoidosa, C. kessleri, C. emersonii, and Chlamydomonas sp. based on their morphological characteristics.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.8 no.2
• /
• pp.111-120
• /
• 2003

To describe dinoflagellate cysts from Gwangyang Bay, surface sediment samples were collected at 20 sites by the TFO core sampler on 24 August 2001, in coupled with a phytoplankton investigation by surface seawater sampling. More than 17 genera, 36 species of dinoflagellate cysts were Identified from the sediment samples of Gwangyang Bay, consisting of 14 species of gonyaulacoid, 14 species of protoperidinioid, 3 species of diplopsalid, 2 species of gymnodinioid, 1 species of tuberculodinioid and calciodinellid, respectively. Cyst concentrations in Gwangyang Bay varied from 115 to 2,188 cysts/g, and generally increased toward a western part of the study area. The highest cyst concentration was observed at St. 11 located in the northwestern region with 11 genera and 19 species(2,188 cysts/g), while the lowest value with 6 genera and 9 species(115 cysts/g) was observed at St. 3 located in the center of the study area. The predominant dinoflagellate cyst was Spiniferites bulloideus, followed by Alexandrium sp., Brigantedinium simplex and S. delicatus. The motile forms of eight dinoflagellate cysts recorded in the sediment samples were also observed in the seawater: Polykrikos swartzii/kofoidii complex, Scripssiella trochoidea, Protoperidinium claudicans(cyst name: Votadinium spinosum), P. pentagonum(: Trinovantedinium capitatum capitatum), P. conicum(: Selenopemphix quanta), P. leonis(: Quinquecuspis concretum), P. conicoides(: Brigantedinium simplex), Gonyaulax spp.(: Spiniferites spp.). In this study, heterotrophic dinoflagellate cysts show the highest concentration at St. 6 where the highest density of diatoms simultaneously observed from surface water sample. This result suggests that the grazing of heterotrophic dinoflagellates on the diatoms in high concentration caused the higher concentration of heterotrophic dinoflagellate cysts.

• 한국해양학회지
• /
• v.30 no.2
• /
• pp.77-90
• /
• 1995

The sedimentary environments and biostratigrapy of the tidal sediments off the Mankyung-Dongjin River estuary were studied based on sedimentary facies and diatom assemblage analysis. Sediment facies from the five vibracores are mainly clay, silt, and sand facies. The clay and silty sediment facies are more dominant than the sandy facies, and contain diatom frustules. The frequency of the diatom frustules are rate to common, but not found in sandy sediment facies. Bigeneric structures such as burrow and non-bigeneric primary sedimentary structures such as laminated sand and mud or silt and mud couplets, flaser bedding, ripple-cross lamination are found in several stratigraphic levels of the sedimentary sequences. A total of 219 species and varieties, belonging to 61 genera has been identified in the present study. Among them, paralia sulcata is the most abundant species about 30 to 50% of the total diatom frustules. Another predominant species are Cyclotella striata. Thalassionema nitzschioides. Actinoptychus undulatus. Delphineis surirella, Raphoneis amphiceros. Most of the diatoms occurred in this study area are marine, marine-brackish water, and brackish water species, and are benthic and tychopelagic or meroplanktonic species. Also, most of the species are coastal to littoral and littoral to inner neritic species. The occurrences of freshwater species, about 1 to 5% is higher than that of the Namyang Bay tidal sediments. The ecological properties of the diatoms occurred in the study area and primary sedimentary structure such as flaser bedding ripple cross bedding indicate that the deposits are formed under coastal or littoral to subeditorial environments such as tidal zone which was subjected to the influenced of stream water and was more strongly influenced by temperate to warm water than cold water. The sedimentary environments have not been changed distinctively during the time of deposition. The vertical distribution pattern of diatoms in the study area is studied by Q-mode cluster Analysis using spss/pc+ (ver.4.0). The results show that the three cores (GE-3, GE-11, GE-12) are divided into two diatom assemblages, respectively. Biostratigraphic correlation using the data of Q-mode Cluster Analysis are attempt in this study.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.18 no.4
• /
• pp.214-226
• /
• 2013

To understand the changing patterns in phytoplankton communities, we conducted 12 surveys along the Nakdong River, its estuary, and adjacent coastal areas between January 2011 and October 2012 (during the period of barrage construction and sediment dredging). Monthly precipitation ranged from 0 to 502 mm during the survey period, and salinity ranged between 0.1 psu and 0.3 psu in the Nakdong River, regardless of the depth, indicating no seawater influence, while salinity showed large seasonal fluctuations in the estuarine and coastal station, ranging from 0.1 psu to 34.8 psu. A total of 402 phytoplankton species were identified, 178 species from the river and 331 species from the estuary and coastal areas. Phytoplankton standing crop increased in 2012 compared to that in 2011, and was found to be highest in the river, followed by the estuary and coastal areas. Among the top 20 species in frequency of occurrence and dominance, Stephanodiscus spp., Aulacoseira granulata, and Aulacoseira granulata var. angustissima and Pseudo-nitzschia spp. were important species along the river-estuary-coastal areas. Diatoms were the major taxonomic group inhabiting the Nakdong river-estuary-coastal areas. A comparison of seasonal dominant phytoplankton species revealed a slight decrease over the years, from 13 species in 2011 to 10 species in 2012. However, no significant difference was found in the diversity of phytoplankton species between the two survey years, although lightly greater diversity was observed in the coastal areas than in the river and estuary. Cluster analysis with community composition data revealed that the community structure varied significantly in 2011 depending on the time of survey, while in 2012, it hardly showed any variation and was simpler. An increase in the phytoplankton standing crop, fewer dominant species, and simpler community structure in 2012 compared to those in 2011 are probably due to the rapid environmental changes along the Nakdong River. To investigate these ecological relationships, it is necessary to conduct further studies focusing on integrated analyses of biocenosis, including phytoplankton with respect to the changes in nutrient distribution, variation of freshwater discharge, and effect area of freshwater in the Nakdong estuary and adjacent coastal areas.