• Ocean and Polar Research
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• v.32 no.3
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• pp.187-201
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• 2010

The purpose of this study was to investigate the temporal and spatial variability of taxonomic groups and major species of the mesozooplankton community in Lake Shihwa, Korea. Monthly collections were carried out at five stations in Lake Shihwa for a period of one year. The mesozooplankton community showed distinct seasonal variability with water temperature and salinity. Major mesozooplankton species in each seasonal community were derived from non-metric MDS and SIMPER as follows: winter community (Acartia hongi and Eurytemora pacifica), spring community (Acartia hudsonica and Polychaeta larvae), summer community (Acartia sinjiensis, Pavocalanus crassirostris, Evadne tergestina and Cirripedia nauplii) and fall community (Paracalanus indicus and Podon leuckarti). The succession of the seasonal species, A. hudsonica and A. sinjiensis, was the most remarkable event during the seasonal changes of the mesozooplankton community. The species response curve of these species fitted with the logistic regression in relation to water temperature and salinity. The curve also correctly represented the characteristics of the occurrence of A. hudsonica and A. sinjiensis in Lake Shihwa.

• The Korean Journal of Applied Statistics
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• v.34 no.6
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• pp.945-956
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• 2021

In this study, we considered the algorithm of Legendre and Legendre (2012), which derives canonical correspondence analysis from weighted principal component analysis. And, it was proved that the canonical correspondence analysis based on the weighted principal component analysis is exactly the same as Ter Braak's (1986) canonical correspondence analysis based on the Gaussian response model. Ter Braak (1986)'s canonical correspondence analysis derived from a Gaussian response curve that can explain the abundance of species in ecology well uses the basic assumption of the species packing model and then conducts generalized linear model and canonical correlation analysis. It is derived by way of binding. However, the algorithm of Legendre and Legendre (2012) is calculated in a method quite similar to Benzecri's correspondence analysis without such assumptions. Therefore, if canonical correspondence analysis based on weighted principal component analysis is used, it is possible to have some flexibility in using the results. In conclusion, this study shows that the two methods starting from different models have the same site scores, species scores, and species-environment correlations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.4
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• pp.346-351
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• 2003

Single-cell gel electrophoresis (comet assay) was used to detect DNA single strand break in blood cells from several marine fish species. Three fish species were collected from Georgia coastal area. Mummichog, Fundulus heteroclitus showed higher DNA damage than sea bass, Lateolabrax japonicus and trout, Oncorhynchus masou masou under the same experimental conditions. Mummichogs had more alkaline-labile sites on their DNA than other fish species. The comet assay with mummichog blood cells at pH 12.5 showed a dose-response curve with the increasing concentrations of hydrogen peroxide. While the isolated leucocytes showed no increase of DNA damage after in vitro exposure to 2-methyl-1,4-naphthoquinone (MNQ), erythrocytes showed dose-dependent DNA damage. These results indicate that the comet assay can be applied successfully as a bioassay using erythrocyte for environmental monitoring.

• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.4
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• pp.141-148
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• 2008

This study was conducted to investigate the photosynthetic responses of four Oak species (Quercus mongolica, Q. serrata, Q. acutissima and Q. variabilis) by shading treatment. We investigated light response curve, photosynthesis (A)-intercellular $CO_2$ concentration (Ci) curve, leaf growth and chlorophyll content at the level of 35, 55 and 75% shading treatments and under the full sunlight. In our results, Q. variabilis and Q. acutissima showed increased leaf growth, chlorophyll content and net apparent quantum yield but reduced chlorophyll a/b and carboxylation efficiency under the low light intensity. Therefore, light absorption and light utilization efficiency were improved under the low light intensity. Q. mongolica showed the similar responses that Q. variabilis and Q. acutissima showed, but net apparent quantum yield was reduced. The effects of shading treatment on Q. serrata were lower than those of other three species.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.4
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• pp.219-233
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• 2013

We employed the ecological niche modeling framework using GARP (Genetic Algorithm for Ruleset Production) to model the current and future geographic distribution of Pinus densiflora based on environmental predictor variable datasets such as climate data including the RCP 8.5 emission climate change scenario, geographic and topographic characteristics, soil and geological properties, and MODIS enhanced vegetation index (EVI) at 4 $km^2$ resolution. National Forest Inventory (NFI) derived occurrence and abundance records from about 4,000 survey sites across the whole country were used for response variables. The current and future potential geographic distribution of Pinus densiflora, one of the tree species dominating the present Korean forest was modeled and mapped. Future models under RCP 8.5 scenarios for Pinus densiflora suggest large areas predicted under current climate conditions may be contracted by 2090 showing range shifts northward and to higher altitudes. Area Under Curve (AUC) values of the modeled result was 0.67. Overall, the results of this study were successful in showing the current distribution of major tree species and projecting their future changes. However, there are still many possible limitations and uncertainties arising from the select of the presence-absence data and the environmental predictor variables for model input. Nevertheless, ecological niche modeling can be a useful tool for exploring and mapping the potential response of the tree species to climate change. The final models in this study may be used to identify potential distribution of the tree species based on the future climate scenarios, which can help forest managers to decide where to allocate effort in the management of forest ecosystem under climate change in Korea.

• ALGAE
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• v.32 no.2
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• pp.131-137
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• 2017

Although green algae of the genus Closterium are considered ideal models for testing toxicity in aquatic ecosystems, little data about the effects of toxicity on these algal species is currently available. Here, Closterium ehrenbergii was used to assess the acute toxicity of copper (Cu). The median effective concentration ($EC_{50}$) of copper sulfate based on a dose response curve was $0.202mg\;L^{-1}$, and reductions in photosynthetic efficiency ($F_v/F_m$ ratio) of cells were observed in cultures exposed to Cu for 6 h, with efficiency significantly reduced after 48 h (p < 0.01). In addition, production of reactive oxygen species significantly increased over time (p < 0.01), leading to damage to intracellular organelles. Our results indicate that Cu induces oxidative stress in cellular metabolic processes and causes severe physiological damage within C. ehrenbergii cells, and even cell death; moreover, they clearly suggest that C. ehrenbergii represents a potentially powerful test model for use in aquatic toxicity assessments.

• Korean Journal of Plant Resources
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• v.21 no.5
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• pp.357-361
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• 2008

The photosynthetic characteristics of three Ligularia species, L. fischeri, L. fischeri var. spiciformis and L. stenocephala under-tree cultivated in Dunnae-myeon, Hoengsung-gun were measured and compared. Total mean photosynthetic rate increased with increasing the light intensity up to 2,000 PPFD. Mean photosynthetic rate of L. fischeri increased to maximum value of $21.1{\mu}mol\;CO_{2}m^{-2}s^{-1}$ with increasing the light intensity up to 1,600 PPFD, but it was decreased at 2,000 PPFD. The highest photosynthetic rate was shown in L. fischeri var. spiciformis, followed by L. fischeri, and L. stenocephala. was the highest $27.39{\mu}mol\;CO_{2}m^{-2}s^{-1}$ among three species, followed by that of The differences in photosynthetic rates were significantly different among the species each measuring date. L. fischeri var. spiciformis was more adaptive species at the low elevated under-tree cultivated sites, such as, Sanchemaeul Dunnae-myeon Hoeyngseung-gun than L. fischeri and L. stenocephala.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.1
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• pp.21-28
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• 2006

We investigated the mobilization of Cd, Pb, and Cr in two different soils in response to sorption capacities and competition for available sorption site while they moved under saturated water conditions. Two soil samples that were clay and sandy clay loam were collected within 20 cm from the upland surface. To do this, we used three different systems of heavy metal combinations such as single, binary, and ternary as solution phase. And then we observed the breakthrough curve (BTC) and elution as a function of pore volume by applying heavy metal solution and displacing K solution until these curves reached to maximum and minimum. The results showed that BTC and elution curves were not symmetric and it required more pore volumes with increasing species of heavy metals in solution phase, as well as longer tailings. Compared the areas over and under BTC and elution curve, relatively small amount of heavy metal was displaced by K even though there were differences in electronegativity among heavy metals. Conclusively, we assumed that heavy metals transport in soil could be influenced by soil physical nonequilibrium and chemical equilibrium in solution as far as there were more than two species of heavy metals existed.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.11
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• pp.1527-1534
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• 2010

Trace minerals such as zinc, copper, and manganese are essential cofactors for hundreds of cellular enzymes and transcription factors in all animal species, and thus participate in a wide variety of biochemical processes. Immune development and response, tissue and bone development and integrity, protection against oxidative stress, and cellular growth and division are just a few examples. Deficiencies in trace minerals can lead to deficits in any of these processes, as well as reductions in growth performance. As such, most animal diets are supplemented with inorganic and/or organic forms of trace minerals. Inorganic trace minerals (ITM) such as sulfates and oxides form the bulk of trace mineral supplementation, but these forms of minerals are well known to be prone to dietary antagonisms. Feeding high-quality chelated trace minerals or other classes of organic trace minerals (OTM) can provide the animal with more bioavailable forms of the minerals. Interestingly, many, if not most, published experiments show little or no difference in the bioavailability of OTMs versus ITMs. In some cases, it appears that there truly is no difference. However, real differences in bioavailability can be masked if source comparisons are not made on the linear portion of the dose-response curve. When highly bioavailable chelated minerals are fed, they will better supply the biochemical systems of the cells of the animal, leading to a wide variety of benefits in both poultry and swine. Indeed, the use of certain chelated trace minerals has been shown to enhance mineral uptake, and improve the immune response, oxidative stress management, and tissue and bone development and strength. Furthermore, the higher bioavailability of these trace minerals allows the producer to achieve similar or improved performance, at reduced levels of trace mineral inclusion.

• Journal of Nutrition and Health
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• v.55 no.4
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• pp.450-461
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• 2022

Purpose: DNA damage and repair responses are induced by metabolic diseases and environmental stress. The balance of DNA repair response and the antioxidant system play a role in modulating the entire body's health. This study uses a high-fat and high-calorie (HFC) drink to examine the new roles of a plant-based multivitamin/mineral supplement with phytonutrients (PMP) for regulating the antioxidant system and cellular DNA repair signaling in the body resulting from metabolic stress. Methods: In a double-blind, randomized, parallel-arm, and placebo-controlled trial, healthy adults received a capsule containing either a PMP supplement (n = 12) or a placebo control (n = 12) for 8 weeks. Fasting blood samples were collected at 0, 1, and 3 hours after consuming a HFC drink (900 kcal). The blood samples were analyzed for the following oxidative stress makers: areas under the curve reactive oxygen species (ROS) levels, plasma malondialdehyde (MDA), erythrocytes MDA, urinary MDA, oxidized low-density lipoprotein, and the glutathione:oxidized glutathione ratio at the time points. We further examined the related protein levels of DNA repair signaling (pCHK1 (Serine 345), p-P53 (Serine 15), and 𝛄H2AX expression) in the plasma of subjects to evaluate the time-dependent effects of a HFC drink. Results: In a previous study, we showed that PMP supplementation for eight weeks reduces the ROS and endogenous DNA damage in human blood plasma. Results of the current study further show that PMP supplementation is significantly correlated with antioxidant defense. Compared to the placebo samples, the blood plasma obtained after PMP supplementation showed enhanced DNA damage response genes such as pCHK1(Serine 345) (a transducer of DNA response) and 𝛄H2AX (a hallmark of DNA damage) during the 8 weeks trial on metabolic challenges. Conclusion: Our results indicate that PMP supplementation for 8 weeks enhances the antioxidant system against oxidative stress and prevents DNA damage signaling in humans.