• Journal of Applied Biological Chemistry
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• v.51 no.6
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• pp.262-271
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• 2008

Natural abundances of stable isotopes of nitrogen and carbon (${\delta}^{15}N$ and ${\delta}^{13}C$) are being widely used to study N and C cycle processes in plant and soil systems. Variations in ${\delta}^{15}N$ of the soil and the plant reflect the potentially variable isotope signature of the external N sources and the isotope fractionation during the N cycle process. $N_2$ fixation and N fertilizer supply the nitrogen, whose ${\delta}^{15}N$ is close to 0%o, whereas the compost as. an organic input generally provides the nitrogen enriched in $^{15}N$ compared to the atmospheric $N_2$. The isotope fractionation during the N cycle process decreases the ${\delta}^{15}N$ of the substrate and increases the ${\delta}^{15}N$ of the product. N transformations such as N mineralization, nitrification, denitrification, assimilation, and the $NH_3$ volatilization have a specific isotope fractionation factor (${\alpha}$) for each N process. Variation in the ${\delta}^{13}C$ of plants reflects the photosynthetic type of plant, which affects the isotope fractionation during photosynthesis. The ${\delta}^{13}C$ of C3 plant is significantly lower than, whereas the ${\delta}^{13}C$ of C4 plant is similar to that of the atmospheric $CO_2$. Variation in the isotope fractionation of carbon and nitrogen can be observed under different environmental conditions. The effect of environmental factors on the stomatal conductance and the carboxylation rate affects the carbon isotope fractionation during photosynthesis. Changes in the environmental factors such as temperature and salt concentration affect the nitrogen isotope fractionation during the N cycle processes; however, the mechanism of variation in the nitrogen isotope fractionation has not been studied as much as that in the carbon isotope fractionation. Isotope fractionation factors of carbon and nitrogen could be the integrated factors for interpreting the effects of the environmental factors on plants and soils.

• ALGAE
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• v.32 no.4
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• pp.349-357
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• 2017

Korean mariculture Undaria pinnatifida was collected during the months of January, February, March, and December of 2010, as well as from January of 2011 to investigate the changes in the carbon and nitrogen stable isotope ratios (${\delta}^{13}C$ and ${\delta}^{15}N$) and heavy metal with respect to it growth and to identify the factors that influence such changes. The blades of U. pinnatifida showed ${\delta}^{13}C$ and ${\delta}^{15}N$ in the range (mean) of -13.11 to -19.42‰ (-16.93‰) and 2.99 to 7.57‰ (4.71‰), respectively. Among samples with the same grow-out period, those that weighed more tended to have higher ${\delta}^{13}C$ suggesting a close association between the carbon isotope ratio and growth rate of U. pinnatifida. Indeed, we found a very high positive linear correlation between the monthly average ${\delta}^{13}C$ and the absolute growth rate in weight ($r^2=0.89$). Nitrogen isotope ratio tended to be relatively lower when nitrogen content in the blade was higher, probably due to the strengthening of isotope fractionation stemming from plenty of nitrogen in the surrounding environment. In fact, a negative linear correlation was observed with the nitrate concentration in the nearby seawaters ($r^2=0.83$). Concentrations of Cu, Cd, Pb, Cr, Hg, and Fe in the blades showed a rapid decrease in their concentration per unit weight in the more mature U. pinnatifida. Specifically, compared to adult samples, Cu, Hg, and Pb were concentrated by 30, 55, and 73 folds, respectively, in the young blades. Therefore, U. pinnatifida tissue ${\delta}^{13}C$ is as an indirect indicator of its growth rate, while ${\delta}^{15}N$ values and heavy metal concentrations serve as tracers that reflect the environmental characteristics.

• Journal of the korean society of oceanography
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• v.32 no.1
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• pp.28-37
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• 1997

Two marine bivalve shells were collected from the eastern and western coastal regions of Korea, respectively. Stable oxygen and carbon isotope profiles are constructed using the incremental sampling along the axis of maximum growth to provide the continuous ${\delta}^{18}$O and ${\delta}^{13}$C records, which register the physical, biological and chemical properties of seawater where the organisms live. Cycles in the ${\delta}^{18}$O profiles are interpreted as annual along with the identification of annual growth bands; the maximum ${\delta}^{18}$O values correspond with the coldest temperature of seawater whereas the minimum ${\delta}^{18}$O values with the warmest temperature. The primary control on the amplitude of the ${\delta}^{18}$O profiles is seasonal variation of seawater temperature. The offset of the baseline between ${\delta}^{18}$O values of the two specimens is attributed to differences in both temperature and seawater ${\delta}^{18}$O values between two localities. The ${\delta}^{13}$C profiles show the similar seasonality of carbon cycling associated with phytoplankton productivity. The offset in the ${\delta}^{13}$C profiles between two specimens may be, as in the case of oxygen isotope profile, attributed to the different ${\delta}^{13}$C value of the seawater DIC (dissolved inorganic carbon) between the western coast and the eastern coast. Relationships between the shell isotopic composition and the coastal water properties of shell growth are readily interpreted from the ${\delta}^{18}$O-${\delta}^{13}$C pair diagram of the shell isotope data, similar to the use of salinity-${\delta}^{18}$O diagram for identifying water masses. The preliminary stable isotope results of this study suggest that mollusk shell isotope geochemistry may be useful to monitor the properties of water masses in the coastal and inner shelf setting around Korea and improve the interpretation of paleoceanography, provided the fossil mollusks are well preserved.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.4
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• pp.259-273
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• 2021

We conducted a study to investigate the characteristics of the carbon cycle of two streams (located in Shig a Prefecture, Japan), having similar size, namely, the Adokawa stream (length: 52 km, area: 305 km², watershed population: 8,000) and the Yasukawa stream (length: 62 km, area: 380 km², watershed population: 120,000), but with different degree of human activity. Samples were collected from these two streams at 14 (Adokawa stream) and 23 (Yasukawa stream) stations in the flowing direction. The dissolved inorganic carbon (DIC) concentration and the stable carbon isotope ratio of DIC (δ¹³C-DIC) were measured in addition to the watershed features and the chemical variables of the stream water. The δ¹³C-DIC (-9.50 ± 2.54‰), DIC concentration (249 ± 76 µM), and electric conductivity (52 ± 13 µS/cm) in Adokawa stream showed small variations from upstream to downstream. However, the δ¹³C-DIC (-8.68 ± 2.3‰) upstream of Yasukawa stream was similar to that of Adokawa stream and decreased downstream (-12.13 ± 0.43‰). DIC concentration (upstream: 272 ± 89 µM, downstream: 690 ± 37 µM) and electric conductivity (upstream: 69 ± 17 µS/cm, downstream: 193 ± 37 µS/cm) were higher downstream than upstream of Yasukawa stream. The DIC concentration of Yasukawa stream was significantly correlated with watershed environmental variables, such as, watershed population density (r = 0.8581, p<0.0001, n = 23), and forest area percentage of the watershed (r = -0.9188, p<0.0001, n = 23). δ¹³C-DIC showed significant negative correlation with the DIC concentration (r = -0.7734, p<0.0001, n = 23), electric conductivity (r = -0.5396, p = 0.0079, n = 23), and watershed population density (r = -0.6836, p = 0.0003, n = 23). Our approach using a stable carbon isotope ratio suggests that DIC concentration and δ¹³C-DIC could be used as indicators for monitoring the health of stream ecosystems with different watershed characteristics.

• Mass Spectrometry Letters
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• v.13 no.4
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• pp.139-145
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• 2022

Protein glycosylation is a common post-translational modification by non-template-based biosynthesis. In fungal biotechnology, which has great applications in pharmaceuticals and industries, the importance of research on fungal glycoproteins and glycans is accelerating. In particular, the importance of quantitative analysis of fungal glycans is emerging in research on the production of filamentous fungal proteins by genetic modification. Reliable mass spectrometry-based techniques for quantitative glycomics have evolved into chemical, enzymatic, and metabolic stable isotope labeling methods. In this study, we intend to expand quantitative glycomics by metabolic isotope labeling of glycans in Aspergillus niger, a filamentous fungus model, by the MILPIG method. We demonstrate that incubation of filamentous fungi in a culture medium with carbon-13 labeled glucose (1-¹³C₁) efficiently incorporates carbon-13 into N-linked glycans. In addition, for quantitative validation of this method, light and heavy glycans are mixed 1:1 to show the performance of quantitative analysis of various N-linked glycans simultaneously. We have successfully quantified fungal glycans by MILPIG and expect it to be widely applicable to glycan expression levels under various biological conditions in fungi.

• Journal of Environmental Analysis, Health and Toxicology
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• v.21 no.4
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• pp.229-236
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• 2018

In this study, inter-laboratory comparison was done using elemental analyzer-isotope ratio mass spectrometers (EA-IRMSs) to determine carbon and nitrogen contents as well as stable carbon and nitrogen isotopic compositions (${\delta}^{13}C$ and ${\delta}^{15}N$) of five environmental samples containing lake and marine sediments, higher plant leaves, and fish muscle, and one organic analytical standard (Protein (Casein) Standard OAS). Five national laboratories participated in this comparison study, and each laboratory analyzed all five samples and the analytical standard. Results showed that variations in total organic carbon (TOC) and total nitrogen (TN) contents as well as ${\delta}^{13}C_{TOC}$ and ${\delta}^{15}N_{TN}$ values among the laboratories were large compared to the analytical uncertainties. The results highlighted the inhomogeneity of the test samples and thus, the need to select suitable standard reference materials for future inter-laboratory studies. Further inter-laboratory comparison exercises could promote good measurement practices in the acquisition of stable carbon and nitrogen isotopic composition data.

• YAKHAK HOEJI
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• v.39 no.5
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• pp.516-520
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• 1995

The anti-dansyl antibodies were specifically labeled with stable isotope by growing hybridoma cells in serum-free medium. Assignments of the observed carbonyl carbon resonances have been determined by using $^{13}C-{15}N$ double labeling method in order to assign the Leu resonances. However, when the identical dipeptide appears more than twice in the polypeptide sequences, we applied the proteolytic fragments in the fragment-specific method. Carboxypep-tidase B-treated antibody has also been used to assign the Lys-447 in C terminal amino acid. These unambiguously assigned carbonyl carbon resonances in antibodies are thought to be useful in elucidating not only the structure of antibodies but also the structure-function relationship in the antibody by $^{13}C$ neuclear magnetic resonance spectroscopy.

• Journal of the korean society of oceanography
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• v.32 no.2
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• pp.63-68
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• 1997

Stable isotope profiles with fine-scale resolution were constructed from the fossil mollusk shells, Mercernaria mercernaria, obtained from the late Pleistocene transgressive deposits of Gomez Pit, Virginia, USA. Incremental sampling were made along the axis of maximum growth to provide high-resolution ${\delta}^{18}$O and ${\delta}^{13}$C records. The ${\delta}^{18}$O shell profiles exhibit a series of pronounced cycles in the overall amplitude, corresponding to strong seasonal variations in temperature, which is apparently positive environmental variable. Contrasts between the patterns of ${\delta}^{18}$O and ${\delta}^{13}$C profiles reflect the relationship influencing the seasonal carbon cycling in the shallow marine environment. Positive anomalies of the ${\delta}^{13}$C values during the summer were observed to be out of phase with the ${\delta}^{18}$O profile. Such relatively heavier carbon source may be alternated due to seasonal methanogenesis during the summer. A hypothesized methane-based system may be operated in the shallow and marginal marine environment, resulting in a ${\delta}^{13}$C enriched bicarbonate pool, in which the heavier isotope seems to be incorporated to the shell carbonate.

• Journal of the korean society of oceanography
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• v.35 no.2
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• pp.124-127
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• 2000

The analysis of stable carbon isotope ratios for benthic fauna was applied to identify the source of carbon in benthic food webs in Youngil Bay, Korea. The ${\delta}^{13}$C values of 9 invertebrate species collected in this area showed a narrow range between -20.5 and -16.3%$_o$ with a mean of-18.1 (${\pm}$1.1)"%$_o$. The results suggest that the major source of organic carbon for the benthic fauna of the lower estuarine reaches and the oceanic sites is autochthonous marine particulate organic matter. The contribution of organic matter from terrestrial and riverine sources to the diet of the benthic fauna in this area appears to be minor, despite the considerable inflow of riverine waters.

• Ocean Science Journal
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• v.42 no.4
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• pp.223-230
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• 2007

To understand the origin and biogeochemistry of the organic matter in surface sediments of Lake Shihwa and Lake Hwaong, organic nitrogen, inorganic nitrogen, labile organic carbon, and residual organic carbon contents as well as stable isotope ratios for carbon and nitrogen were determined by KOBr-KOH treatment. Ratios of organic carbon to organic nitrogen $(C_{org}/N_{org})$ (mean = 24) were much higher than ratios of organic carbon to total nitrogen $(C_{org}/N_{tot})$ (mean= 12), indicating the presence of significant amounts of inorganic nitrogen in the surface sediments of both lakes. Stable isotope ratios for organic nitrogen were, on average, $5.2\%_{\circ}$ heavier than ratios of inorganic nitrogen in Lake Shihwa, but those same ratios were comparable in Lake Hwaong. This might be due to differences in the origin or the degree of degradation of sedimentary organic matter between the two lakes. In addition, stable isotope ratios for labile organic carbon were, on average, $1.4\%_{\circ}$ heavier than those for residual organic carbon, reflecting the preferential oxidation of $^{13}C$-enriched organic matter. The present study demonstrates that KOBr-KOH treatment of sedimentary organic matter can provide valuable information for understanding the origin and degradation state of organic matter in marine and brackish sediments. This also suggests that the ratio of $(C_{org}/N_{org})$ and stable isotope ratios for organic nitrogen can be used as indexes of the degree of degradation of organic matter.