• BMB Reports
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• v.44 no.10
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• pp.635-646
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• 2011

Due to its high external and low internal concentration the $Ca^{2+}$ ion is used ubiquitously as an intracellular signaling molecule, and a great many $Ca^{2+}$-sensing proteins have evolved to receive and propagate $Ca^{2+}$ signals. Among them are ion channel proteins, whose $Ca^{2+}$ sensitivity allows internal $Ca^{2+}$ to influence the electrical activity of cell membranes and to feedback-inhibit further $Ca^{2+}$ entry into the cytoplasm. In this review I will describe what is understood about the $Ca^{2+}$ sensing mechanisms of the three best studied classes of $Ca^{2+}$-sensitive ion channels: Large-conductance $Ca^{2+}$-activated $K^+$ channels, small-conductance $Ca^{2+}$-activated $K^+$ channels, and voltage-gated $Ca^{2+}$ channels. Great strides in mechanistic understanding have be made for each of these channel types in just the past few years.

• Journal of Plant Biology
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• v.30 no.4
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• pp.249-255
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• 1987

The effect of polyamine and Ca2+ on D-glucose-6-phosphate cyclohydrolase activity was studied in Daucus carota root. The enzyme activity was reduced in response to increase in concentration of Ca2+, not the Ca2+-calmodulin complex. The inhibition effect due to Ca2+ was reversed by polyamine, especially remarkable at low concentration of Ca2+. The effect of the Ca2+ on the enzyme seemed to compete with polyamine according to the Lineweaver-Burk plot. The enzyme activity from carrot root protoplast cultured in the prescence of verapamil was higher than that of the control. Such cumulative results suggest that the inhibition by the Ca2+ and enhancement or reversal by polyamine could regulate the biosynthesis of pectin and hemicellulose to some extent.

• The Korean Journal of Physiology
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• v.19 no.1
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• pp.25-33
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• 1985

Renal arterial infusion of renotropic agents has been a very useful technique in the renal function studies. This type of experiments have usually been conducted in the large animals such as dogs and sheep. In these animals a catheter can be placed in the site without much disturbances of renal blood flow. Rabbits as an experimental model, however, caused a disturbances of renal blood flow by a catheterization of renal artery by its properties. Therefore we have developed a new technique that allows a simple and selective access to one side of renal arteries and the other as a control, without any disturbances of renal function. The distance between the both bifurcations of renal arteries on abdominal aorta is about 7 mm. To locate the tip of catheter on one side renal artery, ascending cannulation performed via femoral artery was done. We did an experiment with the technique to clarify the effect of calmodulin inhibitor on the renal function. One of the phenothiazine derivatives, trifluoperazine known as a powerful calmodulin inhibitor. Trifluoperazine, actual dose ranges of $2.76-5.20\;ug\;{\cdot}\;kg^{-1}\;{\cdot}\;min^{-1}$, increased urine volume and glomerular filtration rate significantly. Significant increases in urinary excretion of sodium, chloride and potassium were found. Fractional excretion of sodium and free water clearance increased significantly. These data suggest that this new technique is very useful in field of renal physiology and that striking effect of trifluoperazine on the renal function may be caused by increasing the renal hemodynamics, and by the inhibition of sodium, chloride and potassium reabsorption in the renal tubules.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.72.2-73
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• 2003

We found a soybean (Glycine max) cultivar 561 that was strongly resistant to a virulent bacterial strain of a Pseudomonas spp. Further identification revealed that the Pseudomonas spp. was a strain of Pseudomonas aeruginosa. Furthermore we identified specific genes involved in the resistance of soybean 561 and analyzed the pattern of gene expression against the Pseudomonas infection using differential-display reverse transcription PCR (DDRT-PCR). More than 126 cDNA fragments representing mRNAs were induced within 48 hours of bacteria inoculation. Among them, 28 cDNA fragments were cloned and sequenced. Twelve differentially displayed clones with open reading frames had unknown functions. Sixteen selected cDNA clones were homologous to known genes in the other organisms. Some of the identified cDNAs were pathogenesis-related genes (PR genes) and PR-like genes. These cDNAs included a putative calmodulin-binding protein, an endo-1,3-1,4-b-D-glucanase, a b-1,3-endoglucanase, a b-1,3-exoglucanase, a phytochelatin synthetase-like gene, a thiol pretense, a cycloartenol synthase, and a putative receptor-like sorineithreonine protein kinase. Among them, we found that four genes were putative pathogenesis-related genes (PR) induced significantly by the p. aeruginosa infection. These included a calmodulin-binding protein gene, a b-1,3-endoglucanase gene, a receptor-like sorine/threonine protein kinase gene, and pS321 (unknown function). These results suggest that the differentially expressed genes may mediate the strong resistance of soybean 561 to Pseudomonas aeruoginosa.

• Journal of Life Science
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• v.10 no.5
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• pp.456-466
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• 2000

Aquaperin 4 (AQP4) is the mercurial water channel expressed abundantly in brain, especially the region related with cerebrospinal fluid reabsorption and osmoregulation. The primary structure of AQP4 water channel was elucidated but the molecular mechanism of AQP4 channel regulation is still unknown. To investigate the possible regulation of AQP4 water channel by phosphorylation via various protein kinases, osmotic water permeability of AQP4 expressed in Xenopus oocytes was measured by videomicroscopy technique. Forskolin (10 $\mu$M) did not affect osmotic water permeability of oocytes injected with AQP4 cRNA, excluding the regulation of AQP4 water cnannel by protein kinase A. Osmotic water permeability (P아래첨자) of AQP4-expressed oocytes was ingibited by the pretreatmeat of BAPTA/AM (up to 500$\mu$M), an intracellular Ca윗첨자 chelator, and calmidazolium (100$\mu$M), a specific Ca윗첨자/calmodulin antagonist, in a dose-dependent manner. The inhibition of osmotic water permeability (P아래첨자) by the calmidazolium treatment was completely reversed by the addition of calyculin A (0.1$\mu$M), a nonspecific phosphatase inhibitor. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C activator, had biphasic effects on osmotic water permeability in AQP4 cRNA injected oocytes depending on its concentration; 21% increase by 100 nM PMA, 35% decrease by 1$\mu$M PMA. These effects were reversed with 2$\mu$M staurosporine, a nonspecific PKC inhibitor. These results suggest that phosphorylation of AQP4 water channel by Ca윗첨자/calmodulin kinase and protein kinase C might regulate the osmotic water permeability.

• Journal of Plant Biotechnology
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• v.34 no.3
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• pp.213-221
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• 2007

The treatment of radish cotyledons with a nitric oxide (NO)-releasing substance, sodium nitroprusside (SNP) resulted in an increased adventitious root development in a dose-dependent manner. However, this NO-mediated enhancement effect was reversed when either 0.5 mM EGTA (an extracellular $Ca^{2+}$ chelator) or 0.1 mM $LaCl_3$ (a calcium channel blocker) was applied with $50\;{\mu}M$ SNP. Our results also showed that guaiacol peroxidase (GPX) and syringaldazine peroxidase (SPX) activities, which are known to play a key role in rooting, were more largely increased during adventitious root induction in the cotyledons treated with SNP. However, the treatment of cotyledons with SNP plus $LaCl_3$ inhibited the SNP-induced increases in the activities of both GPX and SPX. Trifluoperazine (TFP), an antagonist of calmodulin (a specific calcium-binding protein), also delayed adventitious root formation and significantly reduced the root length and number of the SNP-treated cotyledons as well as the deactivation of GPX and SPX enzymes. In conclusion, our results suggest that calcium is involved in the NO response leading to induction of adventitious root through a regulation of GPX and SPX.

• Journal of Plant Biology
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• v.32 no.4
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• pp.215-226
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• 1989

The effects of Ca2+ on polyamines on callose contents of carrot suspension cultured cells were studied. The regeneration process of the cell wall of carrot protoplast observed through the electron microscope. Treatment of the carrot suspension cultured cells with Ca2+ and polyamines resulted in considerable increase on callose contents at 0.1 mM of Ca2+ and polyamines, particulary spermidine. Poly-L-lysine and poly-L-ornithine increased about 30% and 100% of callose contents than that of the control respectively, whereas verapamil and flunarizine markedly decreased the callose contents. These effects of Ca2+ of free ion rather than as Ca2+-calmodulin complex. During the cultivation of the protoplast, the regeneration of the cell wall was somewhat observed on the 4th day, however, it was inhibited by verapamil. These results suggested that the promotive action of Ca2+ and polyamines were manifested in the callose contents and the regeneraton of the cell wall.

• Mycobiology
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• v.49 no.2
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• pp.105-121
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• 2021

Six interesting fungal strains were isolated during a survey of fungal diversity associated with freshwater; these strains were designated as CNUFC YJW2-22, CNUFC MSW11-6-2, CNUFC HRS5-3, CNUFC MSW242-6, CNUFC DMW2-2, and CNUFC CPWS-1. Based on a polyphasic approach including phylogenetic analyses of internal transcribed space (ITS), large subunit (LSU), beta-tubulin (BenA), and calmodulin (CaM) gene sequences, morphological analyses, the six strains were found to be identical to Acremonium guillematii, Cadophora novi-eboraci, Lectera nordwiniana, Mycoarthris corallina, Talaromyces siamensis, and Tetracladium globosum, respectively. To our knowledge, these are the first records of the rare Lectera, Mycoarthris, and Tetracladium genera in Korea, and the first reports of A. guillematii, C. novi-eboraci, L. nordwiniana, M. corallina, T. siamensis, and Te. globosum in a freshwater environment.

• Mycobiology
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• v.48 no.1
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• pp.75-79
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• 2020

Anthracnose is one of the major problems for cultivating many crops, including vegetables, fruits, and trees. It is a continual threat for fruits grower worldwide. Colletotrichum fructicola was isolated from Shine Muscat berries showing typical anthracnose symptom in Korea. It was identified as C. fructicola based on morphology, pathological signs and concatenated sequences of internal transcribed spacer region of rDNA, glyceraldehyde-3-phosphate dehydrogenase, β-tubulin-2, chitin synthase-1, calmodulin, and the Apn2-Mat1-2 intergenic spacer and partial mating type (Mat1-2) gene. To the best of our knowledge, this is the first report first report of anthracnose of Shine Muscat caused by C. fructicola in Korea.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.6
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• pp.717-730
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• 1997

$Mg^{2+}$ is the fourth most abundant cation in cellular organisms. Although the biological chemistry and the physiological roles of the magnesium ion were well known, the regulation of intracellular $Mg^{2+}$ in mammalian cells is not fully understood. More recently, however, the mechanism of $Mg^{2+}$ mobilization by hormonal stimulation has been investigated in hearts and in myocytes. In this work we have investigated the regulation mechanism responsible for the $Mg^{2+}$ mobilization induced by ${\alpha}1-adrenoceptor$ stimulation in perfused guinea pig hearts or isolated myocytes. The $Mg^{2+}$ content of the perfusate or the supernatant was measured by atomic absorbance spectrophotometry. The elimination of $Mg^{2+}$ in the medium increased the force of contraction of right ventricular papillary muscles. Phenylephrine also enhanced the force of contraction in the presence of $Mg^{2+}$-free medium. ${\alpha}1-Agonists$ such as phenylephrine were found to induce $Mg^{2+}$ efflux in both perfused hearts or myocytes. This was blocked by prazosin, a ${\alpha}1-adrenoceptor$ antagonist. $Mg^{2+}$ efflux by phenylephrine was amplified by $Na^+$ channel blockers, an increase in extracellular $Ca^{2+}$ or a decrease in extracellular $Na^+$. By contrast, the $Mg^{2+}$ influx was induced by verapamil, nifedipine, ryanodine, lidocaine or tetrodotoxin in perfused hearts, but not in myocytes. $W_7$, a $Ca^{2+}/calmodulin$ antagonist, completely blocked the pheylephrine-, A23187-, veratridine-, $Ca^{2+}-induced$ $Mg^{2+}$ efflux in perfused hearts or isolated myocytes. In addition, $Mg^{2+}$ efflux was induced by $W_7$ in myocytes but not in perfused heart. In conclusion, An increase in $Mg^{2+}$ efflux by ${\alpha}1-adrenoceptor$ stimulation in hearts can be through $IP_3$ and $Ca^{2+}-calmodulin$ dependent mechanism.