• Journal of Aquaculture
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• v.21 no.4
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• pp.218-225
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• 2008

Changes in 13 free amino acids (FAA) of Haliotis discus discus exposed to various salinities were investigated using a high performance liquid chromatography (HPLC). Taurine, glycine and alanine are three major contributors to the total FAA in the gill tissues of H. discus discus. Concentration of taurine was 114 imol/g dry tissue weights accounting for 76.64% of total FAA in H. discus discus. Levels of most FAAs in H. discus discus exposed to low and high salinities for 24 h decreased dramatically. Taurine concentration was slightly increased in the samples exposed to 20 psu and 25 psu for 48 h, and greatly increased after 120 h exposure. After 48 hrs exposure to 20 psu, 25 psu, 30 psu and 40 psu, methionine in H. discus discus was not detected; no methionine was detected in the sample exposed to 20 psu, 25 psu, 30 psu and 40 psu after 120 h of exposure. Taurine:glycine ratio increased depending upon hyper-hypoosmotic condition as well as period of osmotic stress. These data indicate that taurine, glycine and methionine play important role in regulating osmotic stress in H. discus discus. This study suggesting that FAA analysis is a useful tool to diagnose osmotic stress to H. discus discus.

• Journal of The Korean Society of Grassland and Forage Science
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• v.10 no.2
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• pp.77-83
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• 1990

A three year's field experiment was carried out on newly reclaimed tidal saline soils to evaluate the salt tolerance and growht characteristics, and their relationship to dry matter production and nutrient quality of main selected pasture species. Nine temperate grasses (14 varieties) and two forage crops (sorghum and pearl millet) were grown under different mulching treatments with medium sand and red-yellow soils (fine loamy materials of Typic Hapludults) from 1986 to 1988. Tall wheatgrass, tall fescue, reed canarygrass and alfalfa showed a good tolerance to soil salinity, especially tall wheatgrass (cv. Alkar) produced 19.6 ton/ha dry matter yield annualy under mulching treatment with medium sand depth in lcm. Pearl millet (cv. Gahi-3) was also evaluated as a salt tolerable forage species. Under salt stress in newly reclaimed tidal lands, plant showed a decrease in the assimirable leaf area (LA) as well as specific leaf area (SP. LA) and a low leaf weight ratio(LWR), and it resulted in a low concentration of crude protein and low digestible dry matter contents. Absorption of macro and micro elements in the plant on tidal lands was increased markedly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6852-6859
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• 2015

The purpose of this study was to determine the growth characteristics and distribution pattern of a brackish water clam Corbicula japonica in Seomjin River. Field samples were taken from 14 stations with salinity gradients during spring. Salinity at the bottom layer ranged from 1.0 psu to 32.9 psu, with low salinities in the upper area of the river. In particular, salinity at St.11 was decreased drastically to be ca. 15.0 psu, indicating an intermediate salinity zone. The distribution pattern of C. japonica was related to the salinity gradient, with the highest densities of $2,102ind.m^{-2}$ at Station 13, followed by $1,507ind.m^{-2}$ at Station 11. Here, we focused on the growth characteristics of collected C. japonica collected at two stations with different salinity values. The relationship between shell length and total weight was highly correlated ($R^2=0.91$, P<0.001) at Station 13 compared to that at Station 11 ($R^2=0.72$, P<0.001). On the other hands, the degree of correlation between shell length and shell height (SH) or shell width (SW) at Station 11 (SH: $R^2=0.91$, P<0.001; SW: $R^2=0.69$, P<0.001) was higher than that at Station 13 (SH: $R^2=0.64$, P<0.001; SW: $R^2=0.48$, P<0.001). In addition, fatness index of C. japonica at Station 13 was significantly (P < 0.001) higher than that at St. 11 (t-test value=-22.8, p<0.001). This implies that C. japonica at Station 13 might have enhanced their somatic growth, whereas C. japonica at Station 11 might have this kind of defense mechanism their internal organization against the salinity stress. Ecologically, this kind of defense mechanism of C. japonica against salinity flucuation may play an important role in their survival strategy.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.4
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• pp.271-278
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• 2004

This study was conducted to obtain basic information of growth, chlorophyll, and $Na^+\;and\;K^+$ content of rice (Oryza sativa L.) seedlings after transplanting in different NaCl conditions. Plants grown in pots for 8 days after germination were grown for 10 days after transplanting in 50 and 100 mM NaCl concentrations. At higher NaCl concentration, plant height, root length, dry weight and chlorophyll content were reduced with NaCl stress. Among rice cultivars, the shoot dry weight of Gancheokbyeo, Janganbyeo and Hwasungbyeo, and the root dry weight of Janganbyeo, Gancheokbyeo and Juanbyeo showed relatively low reduction compared to the other rice cultivars at 100 mM NaCl stress. The $Na^+$ content in seedling rapidly increased with the increase of NaCl concentration but $K^+$ contents decreased. There was a significant relationship between $Na^+$ content and shoot and root dry weight after transplanting rice seedlings to saline conditions. The shoot and root dry weight showed highly negative relationship with the $Na^+/K^+$ ratio in saline conditions.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.5
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• pp.588-597
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• 2010

We investigated the effect of quercetin on growth and plasma cholesterol level and the effects of quercetin pretreatment (Diet 1, 0%; Diet 2, 0.25%; and Diet 3, 0.5% quercetin) for 30 and 60 days on oxidative stress induced by hypo-osmotic conditions (17.5, 8.75, and 4 psu) in olive flounder. The weights of flounder were higher with Diet 3 than with Diet 1 and 2, which indicated that a high concentration (Diet 3) of quercetin was very effective in growth. Total cholesterol levels were lower with Diets 2 and 3 than with Diet 1, leading us to hypothesize that quercetin removed low-density lipoproteins from circulation and thereby reduced total cholesterol. To understand the antioxidant role of quercetin, we measured the mRNA expression and activities of superoxide dismutase (SOD) and catalase (CAT) and the $H_2O_2$ concentration in quercetin-treated flounder exposed to osmotic stress. The $H_2O_2$ concentration and the SOD and CAT expression and activity levels were lower in flounder fed with Diets 2 and 3 than with Diet 1, suggesting that quercetin directly scavenges reactive oxygen species to reduce oxidative stress. Furthermore, the plasma lysozyme activity and osmolality were higher with Diets 2 and 3 than with Diet 1, indicating that quercetin increases immune function and helps to maintain physiological homeostasis. Plasma cortisol was lower with Diets 2 and 3 than with Diet 1, suggesting the quercetin protects against stress. These results indicate that quercetin has hypocholesterolemic and antioxidant effects, increases immune function, and acts to maintain physiological homeostasis.

• Horticultural Science & Technology
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• v.28 no.3
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• pp.343-352
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• 2010

In order to understand the plant responses to salt stress (0, 50, and 100 mM NaCl), Chinese cabbage seedlings grown up to two leaf stages by hydroponic culture were used. Fresh and dry weight, chlorophyll (Chl), antioxidant materials, polyamine content, antioxidant enzyme activities, and inorganic ion level were evaluated. Fresh and dry weights of Chinese cabbage increased with the increase in salinity while the optimal growth occurred at 50 mM NaCl. The Chl a, total Chl, carotenoid content, and Chl a/b ratio increased by the 6 days after treatment with 100 mM NaCI; however, the Chl b content decreased. Glutathione increased in the root of Chinese cabbage for 6 days. Dehydroascorbate increased remarkably by day 6 caused by the salt stress in both leaf and the root. While ascorbate peroxidase increased, the activity of catalase and glutathione reductase decreased gradually in the first leaf for 6 days. The $Na^+$ content increased by 12.5-fold in the 3 days after treatment with 100 mM NaCI in the shoot, whereas the $Ca^{2+}$, $K^+$, and $Mg^{2+}$ content measured in the same treatment decreased by 43 to 57%. Spermidine content decreased as salinity increased, but spermine content increased. The growth promotion, glutathione and ascorbic acid content in Chinese cabbage were increased by low salt stress, and shortening of the cultivation period for growth increase of Chinese cabbage is expected.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.203-203
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• 2017

The Earth's climate is rapidly changing because of increasing carbon dioxide content in atmosphere so, climate prediction models anticipate that earth surface temperature will rise by 3 to $5^{\circ}C$ in next 50 to 100 years. Therefore, frequency of un-expected weather events such as drought, salinity, low or high temperature and flooding etc. will be increasing worldwide. Furthermore, increased atmosphere temperature can influence pests and pathogens spread as well. Therefore, to protect enormous grain loss from unexpected weather conditions, studies related with combine stress conditions like abiotic plus biotic stress condition are really required. Thus, our research focused on physiological responses under combined abiotic and biotic stress condition in rice plant. To induce uniform stress condition, we used NaCl (100 mM) and salicylic acid (0.5 and 1.0 mM SA) as each stress a stimulator. Each artificial abiotic and biotic stress inducer was applied to hydroponically grown rice seedlings alone or together for four day. The data were collected in a time-dependent manner [1, 2, 3 and 4 day(s) after treatment (DAT)] and were matched with our anticipation that shoot length and shoot fresh weight was decreased in solo and combined abiotic and biotic stress condition. The lipid peroxidation content was significantly increased ($1.5{\pm}0.2$ to $2.7{\pm}0.1mg$ mg of $MDA\;g^{-1}FW$) in the first two days in both stress exposed plants, and showed the opposite trend ($0.5{\pm}0.01$ to $0.1{\pm}0.001mg$ of $MDA\;g^{-1}FW$) in last two days under multi stress condition. Superoxide dismutase (SOD) activity did not showed difference in only biotic stress condition (alone 0.5 and 1.0 mM SA) as compared to control however, it was significantly increased in multi stress condition or solo abiotic stress condition whereas, catalase (CAT), and ascorbate peroxidase (APX) activities were significantly decreased in solo biotic and combined abiotic and biotic condition. In particular, both enzymes activities were more decreased in multi stress condition as compared to solo biotic stress condition. The results for relative mRNA expression level of CAT and APX enzymes were in agreement with results of spectrophotometric values. Correlation value between each stress condition and phenotypic data showed that biotic stress condition showed high correlation with activity of CAT and APX whilst, abiotic stress condition revealed significant correlation with SOD activity.

• Journal of Life Science
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• v.26 no.2
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• pp.164-173
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• 2016

Isotocin (IT), a nonapeptide homolog of oxytocin in mammals, has been suggested to be involved in physiological processes including social behaviors, stress responses, and osmoregulation in teleost fish. To study its structure and function, the gene encoding the IT precursor was cloned from the genomic DNA and brain cDNA of the cinnamon clownfish, Amphiprion melanopus. The IT precursor gene consists of three exons separated by two introns, and encodes an open reading frame of 156 amino acid (aa) residues, comprising a putative signal peptide of 19 aa, a mature IT protein of 9 aa, a proteolytic processing site of 3 aa, and 125 aa of neurophysin. Tissue-specific analysis of the IT precursor transcript indicated its expression in the brain and gonads of A. melanopus. To examine its osmoregulatory effects, the salinity of the seawater (34 ppt) used for rearing A. melanopus was lowered to 15 ppt. Histological analysis of the gills indicated the apparent disappearance of an apical crypt on the surface of the gill lamella of A. melanopus, as pavement cells covered the surface upon acclimation to the lower salinity. The level of Na⁺/K^+-ATPase activity in the gills was increased during the initial stage of acclimation, followed by a decrease to its normal level, suggesting its involvement in osmoregulation and homeostasis. The only slight increase in the level of IT precursor transcript in the A. melanopus brain upon low-salinity acclimation suggested that IT played a minor role, if any, in the process of osmoregulation.

• Korean Journal of Ecology and Environment
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• v.47 no.2
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• pp.71-81
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• 2014

A survey was carried out to understand the influence of hydrology on the composition, abundance and adaptive strategies of phytoplankton in artificial Lake Hwaseong, an estuarine reservoir with seawater exchange through a sluice. Samples were collected seven times from May to October 2012. Hydrological events (seawater exchange, rainfall) resulted in a wide variation in salinity along with nutrients and turbidity. Shifts in the dominant phytoplankton composition occurred on every survey. Chlorophyll-a ranged from 9.7 to $104.1{\mu}g\;L^{-1}$. Multivariate analysis allowed us to identify the four phases on phytoplankton community change. Phase I (May~June) was characterized by small-sized Gymnodinium sp. and Heterosigma akashiwo dominated in warm temperature and high salinity derived from seawater exchange, and followed by Cylindrotheca closterium blooms due to rainfall and winds during phase II (July and September). During phase III (August), the dominance of Oscillatoria spp. was correlated with high temperature and low salinity. Abundant cryptomonads were associated with lower temperature during phase IV (October). Adaptive strategies were identified in the phytoplankton as morphological and physiological characteristics. These strategies identified small-sized flagellates as CR-strategists, fast-growing opportunistic species, which might favor the weak stratification of lake due to the seawater exchange during phase I and IV. Dominant species during phase II and III were characterized with R-strategists, medium-sized stress-tolerant species, which might favor turbulence by river flow. The results indicate that stronger stratification following the termination of seawater exchange for the freshening might intensify the predominance of smaller flagellates. In conclusion, this study suggests that hydrology may drive phytoplankton community change and blooms through the controls of salinity, turbulence and nutrients.

• Journal of Life Science
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• v.19 no.10
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• pp.1456-1462
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• 2009

D-chiro-Inositol, which is the isomer of myo-inositol, is a well known drug for the treatment of type II diabetes. The methylated form of D-chiro-inositol, D-pinitol and D-chiro-inositol are synthesized when the plants are exposed to the abiotic stresses such as drought, salinity and low temperature as osmoprotectants. In soybean, myo-inositol is converted to ononitol by O-methyltransferase, and ononitol is converted to D-pinitol by ononitol epimerase and finally converted to D-chiro-inositol by demethylase. However there have been some reports that in buckwheat, myo-inositol can be converted to D-chiro-inositol directly. This study was conducted to determine the changes of soluble cyclitols in buckwheat seedlings after exposure to salt and drought stresses by GC-FID. The results indicated that myo-inositol may be the precursor of D-chiro-inositol biosynthesis.