• Journal of Life Science
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• v.20 no.12
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• pp.1777-1783
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• 2010

Plants generate reactive oxygen species (ROS) as a by-product of normal aerobic metabolism or when exposed to a variety of stress conditions, which can cause widespread damage to biological macromolecules. To protect themselves from oxidative stress, plant cells are equipped with a wide range of antioxidant proteins. However, the detailed reaction mechanisms of these are still unknown. Peroxiredoxins (Prxs) are ubiquitous thiol-containing antioxidants that reduce hydrogen peroxide with an N-terminal cysteine. The active-site cysteine of peroxiredoxins is selectively oxidized to cysteine sulfinic acid during catalysis, which leads to inactivation of peroxidase activity. This oxidation was thought to be irreversible. Recently identified small protein sulphiredoxin (Srx1), which is conserved in higher eukaryotes, reduces cysteine.sulphinic acid in yeast peroxiredoxin. Srx1 is highly induced by $H_2O_2$-treatment and the deletion of its gene causes decreased yeast tolerance to $H_2O_2$, which suggest its involvement in the metabolism of oxidants. Moreover, Srx1 is required for heat shock and oxidative stress induced functional, as well as conformational switch of yeast cytosolic peroxiredoxins. This change enhances protein stability and peroxidase activity, indicating that Srx1 plays a crucial role in peroxiredoxin stability and its regulation mechanism. Thus, the understanding of the molecular basis of Srx1 and its regulation is critical for revealing the mechanism of peroxiredoxin action. We postulate here that Srx1 is involved in dealing with oxidative stress via controlling peroxiredoxin recycling in Arabidopsis. This review article thus will be describing the functions of Prxs and Srx in Arabidopsis thaliana. There will be a special focus on the possible role of Srx1 in interacting with and reducing hyperoxidized Cys-sulphenic acid of Prxs.

• The Korean Journal of Ecology
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• v.27 no.3
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• pp.147-153
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• 2004

The objective of this study was to understand differences among three half-sib families of Betula schmidtii seedlings in the effect of three Cd levels on growth and photosynthesis. One-year-old seedlings of B. schmidtii were treated with 0, 0.4 and 0.8 mM CdSO$_4$ㆍ8/3$H_2O$ for two months. Growth and physiological responses to Cd treatment levels of three families determined using dry weight, relative height growth rate(RHGR), apparent quantum yield and carboxylation efficiency. The B. schmidtii seedlings exposed to 0.4 and 0.8 mM Cd showed statisticall significant decrease in dry weight and RHGR relative to controls. In addition, the growth inhibition of B. schmidtii seedlings was accompanied by a significant decrease in net photosynthesis measured as $CO_2$ assimilation. Apparent quantum yield and carboxylation efficiency were also affected by Cd treatment, undergoing a significant and progressive reduction with increasing Cd concentrations in all families. We also found significant difference among three families of B. schmidtii in growth, biomass and photosynthesis when exposed to Cd stress. Therefore the present study showed that the difference in Cd tolerance among families might be attributed to genetic factor in response to Cd stress.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.311-318
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• 2022

Salicylic acid (SA), a phenolic compound, plays a pivotal role in regulating a wide range of physiological and metabolic processes in plants such as antioxidant cellular defense, photosynthesis, and biotic and abiotic stress responses during the growth and development. We examined the effect of exogenous SA application (100 mg·L^-1) on the growth, yield, photosynthetic characteristics, lipid peroxidation, and antioxidant enzyme activity of chili pepper plants under high temperature and drought stress conditions. SA treatment induced increases of net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) under the stress condition with the highest level after the third treatment. The contents of malondialdehyde and H₂O₂ were significantly lower in the third treatment of SA compared to the control. The activity of ascorbate peroxidase, catalase, peroxidase and superoxide dismutase, increased in treated plants by up to 247, 318, 55 and 54%, respectively compared to the nontreated control. There was no significant difference in the growth characteristics between SA-treated and nontreated plants, while the SA treatment increased marketable yield (kg/10a) by about 15% compared to the nontreated control. Taken together, these results suggest that foliar application of SA alleviates physiological damages caused by the combination of drought and heat stress, and enhances the photosynthetic capacity and antioxidant enzyme activities, thereby improving tolerance to a combination of water deficit and heat stress in chili pepper plants.

• Korean journal of applied entomology
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• v.5_6
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• pp.39-46
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• 1968

This experiment was conducted to study the effects of nitrogen, phosphorus, potassium, and sugar contents in the loaves of five different host plants on tile larval period, pupal period, pupal period, number of eggs in the ovary, and the tolerance of fall webworm larvae (Hyphantria cunea DRURY) to gamma-BHC. The results obtained in this study were as follows; 1. The contents of nitrogen, phosphorus, potassium, and sugar in tile leaves tested were varied with the species of the host plants and sampling time. 2. The larval and pupal periods were also varied with the host plants and generation of the fall webworm. The shortest larval and pupal periods were found in the mulberry and the longest ones in the apple tree, and their periods were shortened much more in the second generation. Except the relation between the larval period and tile nitrogen content in the first generation, significant correlation could not be found between their periods and nitrogen, phosphorus, potassium and surgar contents. The nitrogen contents among the other chemical factors, however, might be much more influenced on their developing period. 3. The pupal weight and number of eggs in the ovary were also varied with the host plants. sex, and generation. In both generations, the greatest pupal weight and number of eggs per female were found in the mulberry and the least ones in the apple tree. No significant correlation could be found between the pupal weight and number of eggs per female and the chemical factors analyzed. However, only the nitrogen content seemed to be highly related to the pupal weight and number of eggs. 4. The tolerance of the fall webworm larval to gamma-BHC was highly varied with the host plants. The host order o( the larval tolerance level to gamma-BHC was box-elder, popla, platanus, apple tree, and mulberry. There was no significant correlation between the larval tolerance to the BHC and the chemical factors analyzed. However, the larvae fed on the host plant with higher pottassium content were shown a tendency to be higher tolerant.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.5
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• pp.345-350
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• 2018

Nanomaterials have considerable potential to solve several key challenges in various electrochemical devices, such as fuel cells. However, the use of nanoparticles in high-temperature devices like solid-oxide fuel cells (SOFCs) is considered problematic because the nanostructured surface typically prepared by deposition techniques may easily coarsen and thus deactivate, especially when used in high-temperature redox conditions. Herein we report the synthesis of a self-regenerated Pd metal nanoparticle on the perovskite oxide anode surface for SOFCs that exhibit self-recovery from their degradation in redox cycle and $CH_4$ fuel running. Using Pd-doped perovskite, $La(Sr)Fe(Mn,Pd)O_3$, as an anode, fairly high maximum power densities of 0.5 and $0.2cm^{-2}$ were achieved at 1,073 K in $H_2$ and $CH_4$ respectively, despite using thick electrolyte support-type cell. Long-term stability was also examined in $CH_4$ and the redox cycle, when the anode is exposed to air. The cell with Pd-doped perovskite anode had high tolerance against re-oxidation and recovered the behavior of anodic performance from catalytic degradation. This recovery of power density can be explained by the surface segregation of Pd nanoparticles, which are self-recovered via re-oxidation and reduction. In addition, self-recovery of the anode by oxidation treatment was confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

• Journal of the Korean Institute of Landscape Architecture
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• v.19 no.2
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• pp.65-74
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• 1991

The purpose of this study was to find the basic application of Disporum genus in landscape-arc-hitectual space. Environment of native site (Daeducksan, Piseulsan) and growth characteristics of experiment plot were investigated and analyzed in this study. The results of this study were as follows; 1. In the case of environment of native site, the relative light intensity was about 10% and distribution of species were primarily north slope. Gradient of Daeducksan and Piseulsan were 10$^{\circ}$, 18$^{\circ}$ Soil textures was Lic both and field capacity of Daeducksan and Piseulsan were 69%, 73.5%. The soil pH of Daeducksan and Piseulsan were 6.1 and 5.8. The both content of organic matter and C.E.C. were high markedly. The P2O5 content of Daeducksan showed high but total nitrogen showed nearly the same level when comparing with the common dry field condition. 2. In tree layer, Daeducksan composed of broadleaved forest of 80% involving Quercus variabilis, and Piseulsan composed of coniferous forest of 80% involving Pinus densiflora on the other hand. Daeducksan, therefore, was more appearance species than Piseulsan in herbaceous layer. 3. Result in ANOVA Test, significance followed with light intensity was recognized in plant height, leaf width, leaf length, leaf thick and No. of leaf, while in the case of soil was not. Plant height was longest in 1% and leaf width, leaf length was largest in 25%. Therefore ornamental value of leaf was the very best in 25%. 4. Result in correlation coefficient analysis, plant height was correlated leaf width, leaf length. The longer plant height, the smaller leaf width, leaf length. In relative light intensity of 1%, flower was hardly expected because of the more shade, the less flower. Disporum smilacinum is expected great use as ground covers in the shades of tall-building or hdavy woods.

• Korean journal of applied entomology
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• v.49 no.4
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• pp.363-369
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• 2010

A postharvest treatment called CATTS (controlled atmosphere and temperature treatment system) has been used as an alternative nonchemical measure for methyl bromide fumigant treatment. This study applied CATTS to control the red flour beetle, Tribolium castaneum, infesting stored grains. Adults of T. castaneum were susceptible to $46^{\circ}C$ heat treatment. The susceptibility was further enhanced by addition of CA conditions (15% $CO_2$ and 1% $O_2$). When CATTS ($46^{\circ}C$, 15% $CO_2$, $16^{\circ}C/h$ treating rate) was applied to different developmental stages of T. castaneum, it showed 100% control efficacy by 120 min exposure. There was a variation in CATTS susceptibility among developmental stages, in which late instar larvae were most tolerant. Heat shock proteins of T. castaneum appeared to be implicated in the tolerance of CATTS.

• Applied Biological Chemistry
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• v.38 no.3
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• pp.202-206
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• 1995

In order to obtain the basic data for clarifing the mechanism of cold tolerance in crops, we analyzed various biochemical changes according to the Uniconazole treatment in Brassica seedling. Peroxidase activity in the root fraction of Brassica seedling was about 3 to 4 times higher than that in hypocotyl fraction, while catalase activity in those fractions showed opposite trend to the peroxidase activity. The content of hydrogen peroxide in root fraction was higher than that of hypocotyl fraction as being a reciprocal proportion with catalase activity. Especially in all fractions, peroxidase· activity of 'Sandongchae' (B. campestris) seedling, known as cold tolerant, was two-fold higher than that of cold sensitive rape(B. napus). The elongation rate of hypocotyl after germination was faster in B. napus than in B. campestris. The application of Uniconazole at 0.3 to 1.0 ppm to B. napus suppressed 43 to 46% of hypocotyl elongation and increased 65 to 73% of peroxidase activity in hypocotyl fraction. The shortening rate of hypocotyl length due to Uniconazole treatment was positively correlated with the increasing rate of peroxidase activity in hypocotyl fraction. Superoxide dismutase was not induced upon Uniconazole treatment and has only 3 isozymes in any fractions. Its activity was observed in the order of cotyledon>root>hypocotyl fraction.

• Korean Journal of Weed Science
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• v.8 no.2
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• pp.199-207
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• 1988

The study was intended to know any relations between the rice tolerance to oxyfluorfen and varietal speciation in seed protein composition or any enzymatical allelies with or without chemical treatment. Rice varieties used were Chokoto, Aichiasahi, Agabyeo, IR 3941 and Tablei as the tolerant group, and Mushakdanti, Weld Pally, HP 1033, HP 857, and HP 907 as the susceptible, respectively. Electrophoretic methods used were SDS-PAGE for seed protein, 7% PAGE for isozymes (acid phosphatase and peroxidase from rice seedling) and changes in isoenzyme activity (malate dehydrogenase, peroxidase and esterase) as affected by oxyfluorfen treatment ($10^{-4}M$) was also studied. The results are summarized as follows. -Among 19 bands separated in seed proteins, two different rice groups selected in terms of tolerance were clustered in dissimilarity. This was based on 2 facts in that G band was not present in susceptible varieties and that less activity of H, N, O, P, Q, Rand S band was shown. -Among 4 bands separated in acid phosphatase, the presence of (band and lower activity of B band was specific for tolerant varieties. For 4 minor bands separated in peroxidase, the tolerant varieties had no activity in B band and higher activity in A, C, D bands. -Time-course study of isozymes as affected by $10^{-4}M$ oxyfluorfen showed that Chokoto, the tolerant varieties, had little activity in A band and consistently higher activities in Band C bands for malate dehydrogenase. For 5 bands separated in peroxidase, B band was not found in Chokoto while A, C, D, and E bands were consistently present. Esterase was separated into about 4 bands in which Chokoto had maintained higher activities in A, C and D bands.

• Food Science and Biotechnology
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• v.14 no.4
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• pp.503-508
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• 2005

Screening for antilisterial activity was performed in about three thousand isolates of lactic acid bacteria (LAB) from Chinese cabbage kimchi, and finally based on the relatively stronger antilisterial activities eight bacterial strains were selected. The bacteria were further characterized in terms of their tolerance to artificial gastric juice, pH 2.5, bile salts (0.3% oxgall), and to the different NaCl concentrations. Of the isolates, YK005 was especially investigated for its physiological characteristics due to its inhibitory activity against gram-positive Listeria monocytogenes as well as gram-negative Escherichia coli O157:H7, as they have been constantly reported to be resistant against bacteriocins produced by a number of LAB strains. YK005 was found to be rod-shaped, $3.8\;{\mu}m$ long ${\times}\;0.5\;{\mu}m$ wide, non-sporeforming, non-motile, catalase-negative, and produced gas from glucose (heterolactic). Based on the biochemical data obtained by API 50 CHL medium, the isolate was tentatively identified as Lactobacillus brevis. To validate the result obtained by the biochemical identification, rRNA-based PCR experiments using a pair of species-specific primers for L. brevis were conducted and a single band of 1400 bp was observed, which strongly indicated that YK005 belongs to L. brevis. The LAB isolates are potentially exploited as human probiotic organisms and are employed to control some food-borne pathogens like L. monocytogenes.