• Mass Spectrometry Letters
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• v.3 no.4
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• pp.93-100
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• 2012

Cellular processes such as proliferation, differentiation, and adaptation to environmental changes are regulated by protein phosphorylation. In order to enhance the understanding of molecular dynamics for biological process in detail, it is necessary to develop sensitive and comprehensive analytical methods for the determination of protein phosphorylation. Neural stem cells hold great promise for neural repair following an injury or disease. In this study, we made differentiated oligodendrocytes from human neural stem cells using over-expression of olig2 gene. We confirmed using quantitative phosphoproteome analysis approach that combines stable isotope labeling by amino acids in cell culture (SILAC) and $TiO_2$ micro-column for phosphopeptide enrichment with $MS^2$ and $MS^3$ mass spectrometry. We detected 275 phosphopeptides which were modulated at least 2-fold between human neural stem cells and oligodendrocytes. Among them, 23 phosphoproteins were up-regulated in oligodendrocytes and 79 phosphoproteins were up-regulated in F3 cells.

• Mass Spectrometry Letters
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• v.1 no.1
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• pp.25-28
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• 2010

The high-throughput identification and accurate quantification of proteins are essential strategies for exploring cellular functions and processes in quantitative proteomics. Stable isotope tagging is a key technique in quantitative proteomic research, accompanied by automated tandem mass spectrometry. For the differential proteome analysis of mouse neuronal cell lines, we used a multiplexed isobaric tagging method, in which a four-plex set of amine-reactive isobaric tags are available for peptide derivatization. Using the four-plex set of isobaric tag for relative and absolute quantitation (iTRAQ) reagents, we analyzed the differential proteome in several stroke time pathways (0, 4, and 8 h) after the mouse neuronal cells have been stressed using a glutamate oxidant. In order to obtain a list of the differentially expressed proteins, we selected those proteins which had apparently changed significantly during the stress test. With 95% of the peptides showing only a small variation in quantity before and after the test, we obtained a list of eight up-regulated and four down-regulated proteins for the stroke time pathways. To validate the iTRAQ approach, we studied the use of oxidant stresses for mouse neuronal cell samples that have shown differential proteome in several stroke time pathways (0, 4, and 8 h). Results suggest that histone H1 might be the key protein in the oxidative injury caused by glutamate-induced cytotoxicity in HT22 cells.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.279-288
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• 2016

Stable Isotope Analysis(SIA) of carbon and nitrogen is useful tool for the understanding functional roles of target organisms in biological interactions in the food web. Recently, mixing model based on SIA is frequently used to determine which of the potential food sources predominantly assimilated by consumers, however, application of model is often limited and difficult for non-expert users of software. In the present study, we suggest easy manual of R software and package SIAR with example data regarding selective feeding of crustaceans dominated freshwater zooplankton community. We collected SIA data from the experimental mesocosms set up at the littoral area of eutrophic Chodae Reservoir, and analyzed the dominant crustacean species main food sources among small sized particulate organic matters (POM, <$50{\mu}m$), large sized POM (>$50{\mu}m$), and attached POM using mixing model. From the results obtained by SIAR model, Daphnia galeata and Ostracoda mainly consumed small sized POM while Simocephalus vetulus consumed both small and large sized POM simultaneously. Copepods collected from the reservoir showed no preferences on various food items, but in the mesocosm tanks, main food sources for the copepods was attached POM rather than planktonic preys including rotifers. The results have suggested that their roles as grazers in food web of eutrophicated reservoirs are different, and S. vetulus is more efficient grazer on wide range of food items such as large colony of phytoplankton and cyanobacteria during water bloom period.

• Journal of the Korean Geographical Society
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• v.40 no.5 s.110
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• pp.571-583
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• 2005

This paper presents a paleoenvironmental study on Hoya San Nicolas, a maar lake in Valle de Santiago in Central Mexican Bajio. Maar lake sediments have been widely used for high-resolution reconstruction of paleoenvironment. Many different paleoenvironmental proxy data such as stable isotopes, pollen, and sediment chemistry were produced in this study. These data help to reveal paleoenviromental changes throughout the whole period covered by sediment materials from this study site. The evidence indicates that during ca. 11,000 - ca. 8,900 cal yr B.P. there was dry climate; during ca. 8,900 - ca. 7,000 cal yr B.P. it was wetter; during ca. 7,000 - ca. 4,000 cal yr B.P. drier; during ca. 4,000 cal yr B.P - the present wetter. Prominent dominance of Pinus pollen during ca. 11,000 - ca. 8,900 cal yr B.P. and during ca. 7,000 - ca. 4,000 cal yr B.P. may reflect very low lake levels resulting in poor preservation of pollen. Pinus pollen, the most resistant pollen type, may have been able to survive severe deterioration due to arid climate, but other pollen types may not. Due to likely droughts in these periods, a sedimentation gaps are probably present in the core.

• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.113-118
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• 2017

BACKGROUND: The carbon (C) isotope ratio (${\delta}^{13}C$) of dissolved organic C (DOC) is an indicator of water pollution source. In this study, the potential use of two pre-treatments for the ${\delta}^{13}C$ analysis, alkaline persulfate oxidation coupled with carbonate precipitation (precipitation) and freeze drying (drying), were compared to suggest a more feasible pre-treatment method. METHODS AND RESULTS: Two reference materials with different ${\delta}^{13}C$ values were used for the experiments; chemical grade glucose ($-12.0{\pm}0.02$‰) and pig manure compost extract ($-23.3{\pm}0.04$‰). In the precipitation method, the measured ${\delta}^{13}C$ values were consistently lower than the theoretically calculated values as dissolved $CO_2$ could not be removed due to the alkaline property of the reagents and the dissolution of air $CO_2$ into the alkaline solution. The drying method also resulted in more negative ${\delta}^{13}C$ than the calculated ${\delta}^{13}C$; however, the difference was systematic ($3.9{\pm}0.3$‰) and there was a strong correlation (${\delta}^{13}C_{calculated}=0.87{\times}{\delta}^{13}C_{measured}-0.624$, $r^2=0.98$) between the calculated and measured ${\delta}^{13}C$. Calibration of ${\delta}^{13}C$ using the relationship between the calculated and the measured ${\delta}^{13}C$ values produced reliable and accurate ${\delta}^{13}C$ values. CONCLUSION: Our results suggest that the drying method is more accurate pre-treatment method to minimize the influence of air $CO_2$ compared to the precipitation method for the determination of ${\delta}^{13}C$ of DOC.

• Korean Journal of Ecology and Environment
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• v.46 no.3
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• pp.332-342
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• 2013

We collected zooplankton from May to October, 2011, with the aim of understanding the zooplankton community distribution and food web interaction between the open water and littoral (aquatic plants) zones in two small reservoirs with different land covers (Sobudang, Myeongdong). Small-sized reservoirs are more abundant in South Korea, and a total of 51 and 65 species of zooplankton were identified at the two small reservoir (Sobudang and Myeongdong), where zooplankton densities were more abundant in the littoral zone than in the open water zone. Cladocerans and copepods densities were also higher in the littoral zone, in contrast, rotifers showed higher densities in the open water zone (t-test, P/0.05). Epiphytic zooplankton dominated at the littoral zone (Lecane, Monostyla, Alona and Chydorus) because aquatic plants provided refuge spaces for attachment. Some rotifers (e.g. Brachionus, Keratella and Polyarthra) were more abundant in the open water zone because of their small size, which might help them to go unnoticed by predators. In two-way ANOVA, rotifers related to two reservoirs or habitat space (littoral zone and open water zone), but cladocerans and copepods showed a statistically significant relationship on only two reservoirs. The results of stable isotope analysis showed that zooplankton in the littoral zone tended to depend on organic matter attached to aquatic plants as a food source, which indicates the avoidance of competition of zooplankton with other macro-invertebrates (e.g. Damselfly larva, Cybister brevis and Neocardina denticulate). As a result, zooplankton community distribution is determined by not only habitat space (aquatic plant zone and open water zone) but also by food source (phytoplankton).

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.478-485
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• 2013

Fish field survey, especially fish distribution and their ecological characteristics, was performed in the downstream region of Gyeongan stream during the period of before (June) and after (October) the summer monsoon in 2010. Depending on the characteristics of each site, fyke net or casting net was used for fish sampling. Feeding classification was determined by the analysis of stomach contents. Total number of family and species sampled were 5 and 17, respectively. The dominant family was Cyprinidae (12 species), and relative abundance (RA) of the most dominant species, Lepomis macrochirus and Zacco platypus, was 38% and 24%, respectively. Exotic species and Korean endemic species observed were 3 (423 individuals, RA 44%) and 4 (98 individuals, RA 10%), respectively. Tolerance guild analysis as characteristics of ecological indicators revealed an undoubtedly high percentage (97%), compared to others as reflected by the identification of just one sensitive species. Analysis of trophic guilds showed that L. macrochirus dominated among insectivores (44% RA). The food of L. macrochirus composed of, aquatic insects, benthic invertebrates, zooplankton, Chironomidae, and waterweed. Thus, we determined that L. macrochirus could be classified as insectivores (partially carnivores) in this study. Conversely, Z. platypus consumed Cladocera exclusively, greater than 90% of their feed. We presume that stable isotope analysis would identify the exact position of these species in the food web.

• Korean Journal of Heritage: History & Science
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• v.41 no.1
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• pp.99-108
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• 2008

The paleogenetic analysis has become an increasingly important subject of archaeological, anthropological, biological as well as public interest. Recently, scientific research for human skeletal remains was more activated because of increasing awareness of the valuable archaeological information by the ancient DNA analysis. State of preservation of organic remains vary in different soil and burying environmental condition. Almost all available tissue disappear to analysis ancient DNA of bone in acidic soil caused by climate and geological features in Korea. Many preserved human remains excavated in the 'Heogwakmyo'(limelayered tomb of Chosun Dynasty Period) is able to explain through the relationship between burial conditions and bone survival form the burial method and ceremony. Ancient DNA analysis of excavated human bone form ancient tomb requires to remove contaminants such as microorganism's DNA and soil components that affect authentic results. Particularly, contamination control of contemporary human DNA is major serious problem and should verified by criteria of authenticity. In order to understand migration and culture of ancient population, when possible, ancient DNA studies needs to go abreast both radiocarbon and stable isotope studies because the dietary inferences will suggest ancient subsistence and settlement patterns. Also when the paleogenetic research supported with the arts and humanities research such as physical anthropology and archaeology, more valuable ancient genetic information is providing a unique results about evolutionary and population genetics studies to reconstruct the past.

• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.707-716
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• 2005

Organic geochemical analyses including Rock-Eval pyrolysis, elemental analysis and stable carbon isotope analysis were performed to evaluate the characteristics of organic matter in the ODP Leg 127 Site 794A sediments and to understand paleoceanographic changes. Based on the TOC contents, C/N ratio, HI vs. OI, $\delta^{13}C_{org}$ and C/S ratio, results imply that dark layers containing a large amount of terrigenous organic matter were deposited under the suboxic/anoxic conditions, whereas the light layers containing largely marine organic matter were deposited under the oxic conditions. These results indicate that increasing surface-productivity by the input of a large amount of terrigenous organic matter from adjacent continent led to the deposition of dark layers during the interglacial highstands, whereas marine primary production and dilution caused by Kosa from the China desert area led to the deposition of light layers with the decreased to terrigenous organic matter during the glacial lowstands.

• Journal of Korean Society of Forest Science
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• v.102 no.1
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• pp.129-135
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• 2013

Japanese larch (Larix leptolepis) has been extensively planted in Korea as a reforestation species but their supply has been a major bottleneck due to sporadic natural seed production. In this study, stem girdling was applied to 32-year-old grafted Japanese larches, resulting in significantly enhanced seed production compared to the controls. Stem girdling induced about 4 times higher cone production than that of controls in the Japanese larch seed orchard. Time-dependent metabolic alterations after girdling were investigated by stable isotope ratio mass spectrometer, HPLC, and GC-MS analysis. In girdled trees, the contents of total nitrogen, sucrose, and total free amino acids were significantly higher than the non-girdled trees at the flowering differentiation season (from July to August). Moreover, the numbers of female strobilus per tree were positively correlated with the contents of both total nitrogen (r=0.765, p<0.01) and total amino acids (r=0.802, p<0.01) in the bark being collected at the flowering differentiation time (August 20). Interestingly, the levels of various individual amino acids at the flowering differentiation times, such as aspartic acid, glutamic acid, glycine, serine, and cysteine, were also significantly correlated (p<0.05) with the numbers of strobilus, suggesting that those amino acids might be involved in the induction of female strobilus formation of Japanese larches.