• Molecules and Cells
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• 제40권10호
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• pp.787-795
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• 2017

Avoiding ingestion of excessively salty food is essential for cation homeostasis that underlies various physiological processes in organisms. The molecular and cellular basis of the aversive salt taste, however, remains elusive. Through a behavioral reverse genetic screening, we discover that feeding suppression by $Na^+$-rich food requires Ionotropic Receptor 76b (Ir76b) in Drosophila labellar gustatory receptor neurons (GRNs). Concentrated sodium solutions with various anions caused feeding suppression dependent on Ir76b. Feeding aversion to caffeine and high concentrations of divalent cations and sorbitol was unimpaired in Ir76b-deficient animals, indicating sensory specificity of Ir76b-dependent $Na^+$ detection and the irrelevance of hyperosmolarity-driven mechanosensation to Ir76b-mediated feeding aversion. Ir76b-dependent $Na^+$-sensing GRNs in both L- and s-bristles are required for repulsion as opposed to the previous report where the L-bristle GRNs direct only low-$Na^+$ attraction. Our work extends the physiological implications of Ir76b from low-$Na^+$ attraction to high-$Na^+$ aversion, prompting further investigation of the physiological mechanisms that modulate two competing components of $Na^+$-evoked gustation coded in heterogeneous Ir76b-positive GRNs.

• The Korean Journal of Physiology and Pharmacology
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• 제5권3호
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• pp.231-241
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• 2001

The mammalian cortical collecting duct (CCD) plays a major role in regulating renal NaCl reabsorption, which is important in $Na^+$ and $Cl^-$ homeostasis. The M-1 cell line, derived from the mouse cortical collecting duct, has been used as a mammalian model of the study on the electrolytes transport in CCD. M-1 cells were grown on collagen-coated permeable support and short circuit current $(I_{sc})$ was measured. M-1 cells developed amiloride-sensitive current $5{\sim}7$ days after seeding. Apical and basolateral addition of ATP induced increase in $I_{sc}$ in M-1 cells, which was partly retained in $Na^+-free$ or $Cl^--free$ solution, indicating that ATP increased $Na^+$ absorption and $Cl^-$ secretion in M-1 cells. $Cl^-$ secretion was mediated by the activation of apical cystic fibrosis transmembrane regulator (CFTR) chloride channels and $Ca^{2+}-activated$ chloride channels, but $Na^+$ absorption was not mediated by activation of epithelal sodium channel (ENaC). ATP increased cAMP content in M-1 cells. The RT-PCR analysis demonstrated that M-1 cells express $P2Y_2,\;P2X_3\;and\;P2Y_4$ receptors. These results showed that ATP regulates $Na^+$ and $Cl^-$ transports via multiple P2 purinoceptors on the apical and basolateral membranes in M-1 cells.

• Fisheries and Aquatic Sciences
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• 제18권2호
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• pp.173-181
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• 2015

We identified the $Na^+-K^+-2Cl^-$ cotransporter 2 (NKCC2) cDNA isoform from starry flounder, Platichthys stellate. The NKCC2 cDNA encoded a polypeptide of 1,043 amino acids representing 12 putative transmembrane domains based on the bioinformatic topology prediction. In addition, starry flounder NKCC2 possessed highly conserved residues within transmembrane domain 4, known as an essential site for its function. End-point reverse transcription-polymerase chain reaction analysis revealed that the NKCC2 transcript was moderately expressed only in the anterior and posterior intestines and the rectum. The NKCC2 mRNA level in the rectum, but not in other segments, was significantly induced 3 days post Streptococcus parauberis challenge, indicating that excess salt may be transported into the rectum. Taken together, our data indicate that an S. parauberis infection could tip the intestinal fluid balance in favor of fluid accumulation, indicating that bacterial pathogens can interfere with intestinal osmotic balance and normal mucosal immune homeostasis.

• 한국초지조사료학회지
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• 제41권3호
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• pp.210-216
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• 2021

Pollution of agricultural soil by alkaline salts, such as Na₂CO₃, is a critical and long-lasting problem in cultivable land. The aim of the study was to examine the putative role of citric acid (CA) in alleviating Na₂CO₃-stress in alfalfa. In this study, Na₂CO₃ significantly induced leaf chlorosis, inhibited plant growth and photosynthesis related parameters, increased hydrogen peroxide (H₂O₂) and reduced major antioxidant enzymes (SOD, CAD, APX) in alfalfa. However, the presence of CA these negative effects of Na₂CO₃-stress largely recovered. Interestingly, expression of antioxidant and ion transporter genes (Fe-SOD, CAT, APX, DHAR and NHX1) involved in Reactive oxygen species (ROS) homeostasis and oxidative stress tolerance in alfalfa. These findings suggest that CA-mediated Na₂CO₃ stress alleviation is an ecofriendly approach that would be useful to local farmer for alfalfa and other forage crop cultivation in alkaline soils.

• Asian-Australasian Journal of Animal Sciences
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• 제27권4호
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• pp.479-487
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• 2014

Leptin plays an important role in energy homeostasis and reproductive function in fish, especially in reproduction. Migrating fish, such as salmonoids, are affected by external environmental factors, and salinity changes are a particularly important influence on spawning migrations. The aim of this study was to test whether changes in salinity affect the expression of leptin, estrogen receptors (ERs), and vitellogenin (VTG) in chum salmon (Oncorhynchus keta). The expression and activity of leptin, the expression of ERs and VTG, and the levels of estradiol-$17{\beta}$ and cortisol increased after the fish were transferred to FW, demonstrating that changes in salinity stimulate the HPG axis in migrating female chum salmon. These findings reveal details about the role of elevated leptin levels and sex steroid hormones in stimulating sexual maturation and reproduction in response to salinity changes in chum salmon.

• Journal of Chest Surgery
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• 제19권2호
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• pp.197-208
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• 1986

Propranolol is one of clinically useful antiarrhythmic agents and electrophysiologically classified as group II. And the negative inotropic effect which is not related to adrenolytic effect has been demonstrated with high concentration of propranolol. On the other hand, it has been well known that the calcium plays a central role in excitation-contraction coupling process of myocardium and also in electrophysiological changes of cell membrane. Author studies the effect of propranolol on calcium uptake and release in sarcoplasmic reticulum and mitochondria prepared from porcine myocardium to investigate the mechanism of action of propranolol on myocardium. The results are summarized as follow: 1] The maximum Ca++-uptake of sarcoplasmic reticulum is inhibited by propranolol in a dose dependent manner. 2] The release of calcium from sarcoplasmic reticulum is not affected by propranolol but with higher than 1x10-3 M of propranolol, rate of calcium release from sarcoplasmic reticulum is decreased. 3] Propranolol inhibits the maximum uptake and uptake rate of calcium in mitochondria non-competitively. [Ki = 6.21 x 10-4 M] 4] The rate of Na+ induced calcium release from mitochondrion shows a function of [Na+]2 and is inhibited by propranolol with the concentration significantly lower than that affect the calcium uptake in sarcoplasmic reticulum and in mitochondria [Ki = 2.91 x 10-5 M]. These results suggest that propranolol affects the intracellular calcium homeostasis which may considered to be one of the mechanism of action of propranolol on myocardium.

• Journal of Plant Biotechnology
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• 제7권1호
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• pp.1-15
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• 2005

Salinity is one of the major limiting factors for agricultural productivity. In plants, accumulation of osmolytes plays a pivotal role in abiotic stress tolerance. Likewise, exclusion or compartmentation of $Na^+$ ions into vacuoles provides an efficient mechanism to avert deleterious effects of $Na^+$ in the cytosol. Both vacuolar and plasma membrane sodium transporters and $H^+-ATPases$ can provide the necessary ion homeostasis. A variety of crop plants were engineered with respect to the synthesis of osmoprotectants and ion-compartmentation, but there are other cellular pathways involved in the salinity responses that are still not completely explored. Genomics approaches are increasingly used to identify genes and pathway changes involved in salt-tolerance. The new knowledge may be used via guided genetic engineering of multiple genes to create crop plants with significantly increased productivity in saline soils. This review surveys how plants deal with high salt conditions and how salt tolerance can be improved by transgenic approaches.

• 한국양식학회지
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• 제20권4호
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• pp.205-211
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• 2007

Stress-inducible proteins may function in part as molecular chaperones, protecting cells from damage due to various stresses and helping to maintain homeostasis. We examined the mRNA expression patterns of a 68-kDa heat shock protein (HSP68) and 78-kDa glucose-regulated protein (GRP78) in relation to physiological changes in Pacific oyster Crassostrea gigas under osmotic stress. Expression of HSP68 and GRP78 mRNA in the gill significantly increased until 48 h in a hypersaline environment (HRE) and 72 h in a hyposaline environment (HOE), and then decreased. Osmolality and the concentrations of $Na^+$, $Cl^-$, and $Ca^{2+}$ in the hemolymph of HRE oysters significantly increased until 72 h (the highest value) and then gradually decreased; in HOE oysters, these values significantly decreased until 72 h (the lowest value), and then increased. These results suggest that osmolality and $Na^+$, $Cl^-$, and $Ca^{2+}$ concentrations were stabilized by HSP68 and GRP78, and indicate that these two stress-induced proteins play an important role in regulating the metabolism and protecting the cells of the Pacific oysters exposed to salinity changes.

• BMB Reports
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• 제44권5호
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• pp.306-311
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• 2011

Although NCX-3 is highly expressed in the brain, the distribution of NCX-3 in the epileptic hippocampus is still controversial. Therefore, to assess the distribution and pattern of NCX-3 expression in epileptic hippocampus, we performed a comparative analysis of NCX-3 immunoreactivities in the hippocampus of seizure-resistant (SR) and seizure-sensitive (SS) gerbils. In SR gerbils, NCX-3 immunoreactivity was higher than pre-seizure SS gerbils, particularly in the pavalbumin (PV)-positive interneurons. Three h post-ictal, NCX-3 immunoreactivity in the SS gerbil hippocampus was markedly elevated to the level of SR gerbils. Six h post-ictal, the expression of NCX-3 was reduced to the level of pre-seizure SS gerbils. Therefore, the results of the present study suggest that down-regulation of NCX-3 expression in the SS gerbil hippo-campus may be involved in the hyperexcitability of SS gerbils due to an imbalance of intracellular $Na^+/Ca^{2+}$ homeostasis and $Ca^{2+}$ concentration.

• Journal of Microbiology and Biotechnology
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• 제27권9호
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• pp.1681-1691
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• 2017

This study investigated the effect of proline addition on the salt tolerance of Tetragenococcus halophilus. Salt stress led to the accumulation of intracellular proline in T. halophilus. When 0.5 g/l proline was added to hyperhaline medium, the biomass increased 34.6% (12% NaCl) and 27.7% (18% NaCl) compared with the control (without proline addition), respectively. A metabolomic approach was employed to reveal the cellular metabolic responses and protective mechanisms of proline upon salt stress. The results showed that both the cellular membrane fatty acid composition and metabolite profiling responded by increasing unsaturated and cyclopropane fatty acid proportions, as well as accumulating some specific intracellular metabolites (environmental stress protector). Higher contents of intermediates involved in glycolysis, the tricarboxylic acid cycle, and the pentose phosphate pathway were observed in the cells supplemented with proline. In addition, addition of proline resulted in increased concentrations of many organic osmolytes, including glutamate, alanine, citrulline, N-acetyl-tryptophan, and mannitol, which may be beneficial for osmotic homeostasis. Taken together, results in this study suggested that proline plays a protective role in improving the salt tolerance of T. halophilus by regulating the related metabolic pathways.