• Microbiology and Biotechnology Letters
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• v.31 no.1
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• pp.63-68
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• 2003

Saccharomyces cerevisiae KNU5377 is a constitutively thermotolerant, fermentative strain at high temperatures over 4$0^{\circ}C$. The exposure to 0.5 M NaCl caused S. cerevisiae KNU5377 to be lost its constitutive thermotolerance. Furthermore, the NaCl adaptation beyond 0.3 M during the overnight culture forced the strain-specific fermentation ability of S. cerevisiae KNU5377 to be disappeared. However, these phenomena did not occur in the reference, Saccharomyces cerevisiae ATCC24858. As a result, this adaptation led both strains to show the closely similar thermotolerance level and alcohol fermentation ability, implying the NaCl adaptation eliminated its strain-specific characteristics of S. cerevisiae KNU5377 Therefore it indicated that the superior intrinsic characteristics of S. cerevisiae KNU5377 must be related to the NaCl adaptation. On the other hand, the heat adaptation elevated alcohol productivity for both strains, but surprisingly did it for KNU5377 at the rate of two times higher than the reference's one; this suggests that KNU5377 possesses more efficient system enough to cause the difference. Consequently, these characteristics of S. cerevisiae KNU5377 must be interesting targets for further study to understand on how KNU5377 could acquire the constitutive thermotolerance and the outstanding fermentative capacity at high temperatures.

• Food Science of Animal Resources
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• v.36 no.4
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• pp.469-475
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• 2016

This study examined the relationship between NaCl sensitivity and stress response of Listeria monocytogenes. Nine strains of L. monocytogenes (NCCP10805, NCCP10806, NCCP10807, NCCP10808, NCCP10809, NCCP10810, NCCP10811, NCCP10920 and NCCP 10943) were exposed to 0%, 1%, 2% and 4% NaCl, and then incubated at 60℃ for 60 min to select strains that were heat-sensitized (HS) and non-sensitized (NS) by NaCl exposure. After heat challenge, L. monocytogenes strains were categorized as HS (NCCP 10805, NCCP10806, NCCP10807, NCCP10810, NCCP10811 and NCCP10920) or NS (NCCP10808, NCCP10809 and NCCP10943). Total mRNA was extracted from a HS strain (NCCP10811) and two NS strains (NCCP10808 and NCCP10809), and then cDNA was prepared to analyze the expression of genes (inlA, inlB, opuC, betL, gbuB, osmC and ctc) that may be altered in response to NaCl stress, by qRT-PCR. The expression levels of two invasion-related genes (inlA and inlB) and two stress response genes (opuC and ctc) were increased (p<0.05) in NS strains after NaCl exposure in an NaCl concentration-dependent manner. However, only betL expression was increased (p<0.05) in the HS strains. These results indicate that the effect of NaCl on heat sensitization of L. monocytogenes is strain dependent and that opuC and ctc may prevent NS L. monocytogenes strains from being heat sensitized by NaCl. Moreover, NaCl also increases the expression of invasion-related genes (inlA and inlB).

• KSBB Journal
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• v.16 no.6
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• pp.626-631
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• 2001

Lactobacilli have been considered to play important roles in the health of human vagina. They secrete inhibitory substances to prevent vaginal infection by pathogenic organisms. In a previous study, we have isolated several lactobacilli from Korean woman and one of them (KLB46) was selected and indentified as Lactobacillu crispatus which showed high antimicrobial activity. In this study. cold adaptation prior to subsequent stresses exposure was examined whether L. crispatus KLB46 maintain the viability better than the non-adapted calls under stresses. For pharmaceutical formulation, the lyophilization process is required where stresses such as freezing/thawing and dehydration are routinely applied. Formulated L. crispatus KLB46 can be used for ecological treatment of bacterial vaginosis. The response of cold-adapted cells to other environmental stresses such as acid, heat, ethanol, NaCl, and H$_2$O$_2$ was also examined. The results showed that cold-adapted cells maintained higher survival rate compared with the non-adapted cells (freezing-thawing. 3-folds; dehydration: 3-folds; acid, 3-folds; heat, 10-folds). However, we did net observe any positive effect of cold adaptation on other stresses such as ethanol, NaCl and H$_2$O$_2$. When chloramphenicol was added during cold adaptation, adaptation effect was abolished. This confirms that de novo protein synthesis is necessary during the adaptation process. Moreover, we have identified cold shock protein homolog that codes for a major cold shock protein by PCR amplification using degenerate primers.

• Journal of the Korean Magnetic Resonance Society
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• v.21 no.3
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• pp.102-108
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• 2017

Escherichia coli responds to ever-changing external and internal stresses by rapidly adjusting its physiology for better survival. This adjustment occurs at all levels including metabolites as well as mRNAs and proteins. Although there has been many reports describing E. coli's adaptation to various stresses regarding transcriptomics or proteomics, only a few investigations have been reported regarding this adaptation viewed from metabolites' perspective. We applied four different types of stresses at four different doses as imposed by NaCl, sorbitol, ethanol, and pH to investigate the similarities or differences among the stresses, and which stress causes the largest perturbation of the metabolite composition. We profiled the metabolites under such external stresses by using two-dimensional NMR spectroscopy and identified 39 metabolites including amino acids, sugars, organic acids, and nucleic acids. According to our statistical analysis, the osmotic stress caused by sorbitol differentiated itself from others, while NaCl showed the largest dose dependent metabolic perturbations. We hope this work will form a foundation on which an approach to a successful protein production is systematically provided by a favorable metabolic environment by imposing proper external stresses.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.152-152
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• 2017

Plants exposed to environmental stress for long durations often can adapt to stress conditions with improved tolerance. Moreover this acquired tolerance to stress can be retained even after reverting to destressed growth conditions, which is known to stress memory. In these adaptation and stress memory processes, epigenetic regulation, such as DNA methylation and histone modifications play a key role. Here, we showed that regenerated rice plants from embryogenic callus exposed to gradually increasing NaCl concentrations (up to 120 mM NaCl) acquired salt tolerance and their enhanced tolerance are inherited to subsequent generations. The rice plants (R0) regenerated from rice callus under saline conditions were transplanted into normal paddy field and R1 seeds were harvested. These R1 seeds displayed higher germination rate on MS medium containing 100mM NaCl than wild-type. The callus derived from R1 seeds showed better growth than control callus on high salinity medium. And the salt-adapted R1 plants exhibited higher chlorophyll contents and also higher $K^+/Na^+$ ratio than wild-type rice under saline conditions. The results indicated that rice plants successfully adapted to saline growth conditions during regeneration on high salt medium and moreover this acquired tolerance to salt stress was inherited subsequent generation.

• The Korean Journal of Ecology
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• v.25 no.2
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• pp.101-107
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• 2002

Three species of Chenopodiaceae, i.e. Suaeda japonica, Salicomia herbacea, Beta vulgaris var. cicla, were investigated to compare the physiological characteristics through inoic balances and osmoregulations under different environmental salt gradients. Plats were harvested in two weeks from treatments with salt gradients (0, 50, 100, 200 and 400 mM NaCl) and mineral nutrition gradients(1/1, 1/5, 1/10 dilutions of Hoagland solution). Plants were analyzed for growth responses, ionic balances, osmolalities, conductivities, glycinebetaine and proline contents quantitatively. Three plants of Chenopodiaceae accumulated slats into tissues unlike some salt sensitive species, and showed unique adaptation patterns to overcome saline environments, i.e. strong growth stimulation for Salicomia herbacea, growth negative tolerance for Suaeda japonica, and growth positive tolerance for Beta vulgaris var. cicla. The absorption of inorganic Ca/sup 2+/ ions was inhibited remarkably due to the excess uptake of Na+ with increasing salinity. The K+ content in plants was significantly reduced with increasing salinity. Total nitrogen content was reduced as mineral nutritions and salinity increased. Conductivity and osmolality increased with increasing salinity regardless of mineral nutritions. The ranges of glycinebetaine and proline contents were 0.2∼2.5 μM/g plant water and 0.1∼0.6μM/g plant water, respectively.

• Ocean and Polar Research
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• v.26 no.3
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• pp.433-438
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• 2004

Stress response to the seawater acclimation in coho salmon (Oncorhynchus kisutch) smolt was investigated. Salt concentration of rearing water was gradually increased for 3 days from freshwater to seawater (30 ppt salt level). The changes of serum concentrations of cortisol as a primary stress indicator, and as secondary indicators, glucose (GLC), lactate (LAC), triglyce.ide (TG), cholesterol (CHOL), sodium ion $(Na^+)$, chloride ion $(Cl^-)$ and enzyme activities (alanine aminotransferase, ALT: aspartate aminotrasferase, AST; lactate dehydrogenase, LDH) were quantified during the acclimation experiment. Among them, cortisol, LAC, TG, CHOL, ALT, AST concentrations showed rapid increase at the first exposure to the 10ppt salt level (day 1), and began to decrease to the constant values after day 2 of adaptation at 20ppt salt level. However, LDH concentration tended to decrease during the whole experimental period. $Na^+\;and\;Cl^-$ showed slight decrease at day 1, and increased to a little bit higher values after day 2 rather than those in freshwater. All the fishes started on taking a food after day 4 of seawater adaptation. From these results, to reduce osmotic shock inducible stress to fish in seawater acclimation, gradual increase of salt levels is recommended.

• Development and Reproduction
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• v.24 no.3
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• pp.215-224
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• 2020

Seawater adaptability of steelhead trout increases along with the increase in the size of the fish, independent of parr-smolt transformation. Three 96 h seawater challenge tests were conducted to determine the size at which seawater adaptability of steelhead trout develops. Plasma Na⁺ and Cl^- levels, moisture content, gill Na⁺/K⁺ ATPase activity, and mortality during the 96 h after direct transfer to seawater (32 ppt) were determined. Plasma Na⁺ and Cl^- levels in 50 g fish continuously increased during the 96 h after the transfer to seawater (p<0.05), but the levels in 100 and 150 g fish leveled off after 24 h (p<0.05). Both 100 and 150 g size steelhead trout maintained muscle moisture content (%) better than 50 g size fish (p<0.05). Gill Na⁺/K⁺ ATPase activity in the 100 g size group increased in a time-dependent manner after transfer to seawater (p<0.05), whereas activity in the 50 and 150 g sizes did not increase (p>0.05), for which a possible explanation was discussed. A mere 2.6% mortality in both the 50 and 150 g size groups was observed. In conclusion, the current results indicate that 50 g size steelhead trout did not show development of a high level of hypoosmoregulatory capacity, whereas fish in the 100 and 150 g size groups showed a high level in our experimental conditions. Therefore, the steelhead trout larger than a 100 g size is recommended for transfer to seawater culture.

• Journal of Aquaculture
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• v.18 no.2
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• pp.69-75
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• 2005

One 30-day feeding trial was conducted to examine the effects of dietary salt on seawater adaptability of rainbow trout (Onchorhynchus mykiss) fed three experimental diets containing 0% (control), 4% and 8% salt. The experimetal period included 30 days of feeding trial in freshwater, 3 days of the step by step seawater acclimation with-out feeding diets, and 21 more days of seawater adaptation period (not with all experimental fish) with feeding the basal diet. Growth rates from triplicate groups were determined fur 30 days of feeding trial. Blood samples were taken at the begining and at the end of feeding trial, and 3 times (on 1st, 4th and 8th day) of the seawater adaptation period. Daily survival rates of duplicate groups from three experimetal treatments were recorded for 21 days of the seawater adaptation period. Total average initial and final fish weight were $149.5{\pm}7.6\;and\;187.1{\pm}7.6g$. Feed efficiency of fish fed diets containing 4% and 8% salt were significantly better than those of fish fed the control diet. Average cumulative survival rates were 72, 80 and 88% from the control, 4% and 8% salt diets, respectively. Pulse rate per minutes decreased with dietary salt level. Serum $Na^+\;and\;Cl^-$ concentrations of fish fed 4% and 8% salt diets were significantly higher than those of fish fed the control diet (P<0.05), however, the concentrations were stabilized after 8 days of seawater adaptation. Serum cortisol, glucose, cholesterol and tryglyceride concentrations, and the osmorality of fish decreased with dietary salt level, these values were significantly lower than those of fish fed the control diet. These results indicated that the dietary supplementation of salt could have advantages for seawater adaptability of rainbow trout.

• The Korean Journal of Ecology
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• v.25 no.3 s.107
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• pp.171-177
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• 2002

Three species of Chenopodiaceae, i.e. Suaeda japonica, Salicomia herbacea, Beta vulgaris var. cicla, were investigated to compare the physiological characteristics through ionic balances and osmoregulations under different environmental salt gradients. Plants were harvested in two weeks from treatments with salt gradients(0, 50, 100, 200 and 400 mM NaCl) and mineral nutrition gradients(1/1, l/5, 1/10 dilutions of Hoagland solution). Plants were analyzed for growth responses, ionic balances, osmolalities, conductivities, glycinebetaine and proline contents quantitatively. Three plants of Chenopodiaceae accumulated salts into tissues unlike some salt sensitive species, and showed unique adaptation patterns to overcome saline environments, i.e. strong growth stimulation for Salicomia herbacea, growth negative tolerance for Suaeda japonica, and growth positive tolerance for Beta vulgaris var cicla. The absorption of inorganic $Ca^{2+}$ ions was inhibited remarkably due to the excess uptake of $Na^+$ with increasing salinity. The $K^+$ content in plants was significantly reduced with increasing salinity. Total nitrogen content was reduced as mineral nutritions and salinity increases. Conductivity and osmolality increased with increasing salinity regardless of mineral nutritions. The ranges of glycinebetaine and proline contents were $0.2{\sim}2.5{\mu}M/g$ plant water and $0.1{\sim}0.6{\mu}M/g$ plant water, respectively.