• Molecules and Cells
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• 제25권3호
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• pp.438-445
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• 2008

Leaf senescence is a highly regulated genetic process that constitutes the last stage of plant development and provides adaptive fitness by relocating metabolites from senescing leaves to reproducing seeds. Characterization of various senescence mutants, mostly in Arabidopsis, and genome-wide analyses of gene expression, have identified a wide array of regulatory components, including transcription factors and enzymes as well as signaling molecules mediating growth hormones and environmental stress responses. In this work we demonstrate that a membrane-associated NAC transcription factor, NTL9, mediates osmotic stress signaling in leaf senescence. The NTL9 gene is induced by osmotic stress. Furthermore, activation of the dormant, membrane-associated NTL9 is elevated under the same conditions. A series of senescence-associated genes (SAGs) were upregulated in transgenic plants overexpressing an activated form of NTL9, and some of them were slightly but reproducibly downregulated in a T-DNA insertional NTL9 knockout mutant. These observations indicate that NTL9 mediates osmotic stress responses that affect leaf senescence, providing a genetic link between intrinsic genetic programs and external signals in the control of leaf senescence.

• 한국식품영양과학회지
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• 제28권2호
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• pp.371-377
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• 1999

In order to evaluate the antimicrobial function of natural herb extracts as antimicrobial agent or packaging material for the preservation of foods and greenhouse produce, the water extract of chopi (Zanthoxylum piperitum DC.) was prepared and its antimicobial activity was determined. In the paper disk test its antimicrobial activity was increased in proportion to its concentraion. The growth of microorganisms was completely inhibited above 500ppm of its concentration. It showed wide spectrum of thermal(40 to 180oC) and pH(4 to 10) stabilities. In the electronic microscopic observation(TEM and SEM) of microbial morphological change it showed to decrease the activation of physiological enzymes and to lose the function of cell membranes. Even in the activation test of galactosidase, it seemed to weaken the osmotic function of cell membranes remarkably in comparison with chloroform and its activation corresponded to 40~50% of toluene. Zanthoxylum piperitum DC. extract seemed to be an excellent antimicrobial for the inhibition of food borne microorganisms as well as the pre servation of greenhouse produces.

• 한국식품과학회지
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• 제27권3호
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• pp.387-393
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• 1995

삼투건조시 물질이동 특성을 알아보기 위하여 수분과 용질의 이동을 확산식으로 평가하여 침지온도와 농도에 따른 영향을 조사하였으며 또한 품질변화 정도는 carotene 함량을 지표로 하여 반응속도식으로 구명하고자 하였으며 삼투공정시 수분의 이동을 기존의 건조모델로 표현하고자 적합도를 알아보았다. 수분손실이나 용질의 증가는 온도와 농도가 증가함에 따라 높은값을 보였으며 농도보다는 온도의 영향을 많이 받는 것으로 나타났다. 확산계수 또한 고온과 고농도에서 높은 값을 가져 확산이 빠르게 일어남을 알 수 있었다. 고온에서는 수분 손실이 용질의 증가보다 높아 용질의 확산계수가 수분의 확산계수보다 높았으며, 품질변화를 나타내는 반응속도상수는 온도의 증가보다 농도의 증가에 따라 더 큰 값을 가져 고농도에서 파괴가 많이 일어남을 알 수 있었다. 확산계수와 품질변화 속도상수에 대한 온도의 영향을 알아보고자 Arrhenius 식에 적합시켜 본 결과 낮은 농도인 $20^{\circ}Brix$에서 확산에 많은 활성화에너지가 필요하고 고농도인 $60^{\circ}Brix$에서는 상대적으로 낮은 활성에너지로도 용질의 확산이 일어난다는 것을 알 수 있었고 활성화 에너지의 크기로 보아 수분의 이동은 $40^{\circ}Brix$에서, 용질의 이동은 $60^{\circ}Brix$에서 이동이 효과적으로 일어남을 알 수 있었다. 침지온도와 농도를 독립변수로 하여 확산계수와 반응속도상수를 예측하고자 각 독립 변수의 최적함수를 구하여 수립한 최적 함수 모델식과 polynomial 형태로 모델화 하였을 경우 수분이나 용질의 확산계수는 높은 적합도를 결정계수를 가지나 품질변화를 나타내는 반응속도강수는 다소 낮아 온도와 농도의 함수로 예측하기에는 미흡한 것으로 나타났다. 삼투건조 공정 중 수분의 이동을 시간의 함수로 표현하기 위한 가장 적합한 모델은 quadratic 모델의 $R^{2}$값이 침지온도와 농도에 관계없이 전반적으로 0.99 이상으로 나타나 다른 모델보다 더 높은 적용 가능성을 보였다. 따라서 quadratic 모델을 이용하여 삼투건조공정에서의 시간에 따른 수분함량을 예측할 수 있으며 확산계수와 아울러 물질이동 특성을 나타낼 수 있을 것으로 생각된다.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2001년도 학술 발표회 진행표 및 논문초록
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• pp.65-65
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• 2001

We have recently demonstrated that high glucose (50 mM D-glucose) upregulates fibronectin mRNA expression and protein synthesis by human peritoneal mesothelial cells (HPMC) through activation of protein kinase C (PKC) and suggested that this may lead to progressive peritoneal fibrosis during a long-term peritoneal dialysis (PD) using glucose as an osmotic agent.(omitted)

• Molecules and Cells
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• 제26권2호
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• pp.200-205
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• 2008

The mitogen-activated protein kinase (MAPK) signaling pathway is activated in response to extracellular stimuli and regulates various activities in eukaryotic cells. Following exposure to stimuli, MAPK is known to be activated via dual phosphorylation at a conserved TxY motif in the activation loop; both threonine and tyrosine residues are phosphorylated by an upstream kinase. However, the mechanism underlying dual phosphorylation is not clearly understood. In the budding yeast Saccharomyces cerevisiae, the Hog1 MAPK mediates the high-osmolarity glycerol (HOG) signaling pathway. Tandem mass spectrometry and phosphospecific immunoblotting were performed to quantitatively monitor the dynamic changes occurring in the phosphorylation status of the TxY motif of Hog1 on exposure to osmotic stress. The results of our study suggest that the tyrosine residue is preferentially and dynamically phosphorylated following stimulation, and this in turn leads to the dual phosphorylation. The tyrosine residue was hyperphosphorylated in the absence of a threonine residue; this result suggests that the threonine residue is critical for the control of signaling noise and adaptation to osmotic stress.

• BMB Reports
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• 제39권4호
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• pp.394-399
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• 2006

The transport of putrescine into a moderately salt tolerant cyanobacterium Synechocystis sp. PCC 6803 was characterized by measuring the uptake of radioactively-labeled putrescine. Putrescine transport showed saturation kinetics with an apparent $K_m$ of $92{\pm}10\;{\mu}M$ and $V_{max}$ of $0.33{\pm}0.05\;nmol/min/mg$ protein. The transport of putrescine was pH-dependent with highest activity at pH 7.0. Strong inhibition of putrescine transport was caused by spermine and spermidine whereas only slight inhibition was observed by the addition of various amino acids. These results suggest that the transport system in Synechocystis sp. PCC 6803 is highly specific for polyamines. Putrescine transport is energy-dependent as evidenced by the inhibition by various metabolic inhibitors and ionophores. Slow growth was observed in cells grown under salt stress. Addition of low concentration of putrescine could restore growth almost to the level observed in the absence of salt stress. Upshift of the external osmolality generated by either NaCl or sorbitol caused an increased putrescine transport with an optimum 2-fold increase at 20 mosmol/kg. The stimulation of putrescine transport mediated by osmotic upshift was abolished in chloramphenicol-treated cells, suggesting possible involvement of an inducible transport system.

• 한국식품영양과학회지
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• 제25권5호
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• pp.824-830
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• 1996

삼투건조의 여러 가지 가공변수 중 설탕용액의 농도를 달리하고 침지시간, 침지온도를 달리하여 삼투건조를 행하여 물질이동을 나타내는 Solid Gain(SG), Weight Reduction(WR), Moisture Loss(ML) 등을 조사하여 물질이동특성을 알아 보고자 하였다. 온도와 농도 시간에 따른 수분의 이동과 용질의 이동을 확산식으로 평가하였다. 색차의 변화((equation omitted)E)는 $60^{\circ}C에서만$ 높은 값을 보여 갈변이 심해짐을 확인할 수 있었으며, 높은 온도에서는 낮은 농도에서 처리가 더 큰 (equation omitted)E값을 나타내었고, 낮은 온도에서는 농도에 따라서 큰차이를 나타내지 않았다. SG은 농도가 증가할수록 설탕의 흡수가 많아져 증가하였으며, WR 또한 고농도에서 무게감소가 많이 이루어지고 저농도에서는 낮은 값을 보여 설탕농도가 높아질수록 많은 양의 무게감소가 이루어짐을 알 수 있었다. ML는 저농도 보다는 고농도에서 빠른 증가가 일어나 건조가 빠르게 진행됨을 알 수 있었으며 수분 함량은 삼투농도가 높을수록 수분 함량이 점차 낮아져 삼투처리로 건조가 이루어짐을 화인할 수 있었다. 수분의 이동에 따른 확산계수는 같은 온도, 같은 농도에서 각각 농도나 온도의 증가시 높은 값을 가져 확산이 빠르게 일어남을 알 수 있었다. 용질의 이동에 따른 확산계수는 온도의 증가에 따라 증가하는 경향을 보였으며, 농도의 영향에 있어서는 $20^{\circ}C에서는$ 농도의 증가에 따라 증가함을 보였으나 $40^{\circ}C와$ $60^{\circ}C에서는$ 감소하는 경향을 보였다. 확산계수에 대한 온도의 영향을 Arrhenius 식에 적합시켜 본 결과, 5% 유의 수준에서 수분의 이동은 60 。Brix, 용질의 경우는 40。Brix의 농도에서만 적합하다고 할 수 있었다. 수분과 용질의 확산에 있어서 낮은 농도인 20。Brix에서는 높은 활성화 에너지를 보였으며 상대적으로 고농도인 40 Brix와 60 。Brix에서는 낮은 활성화 에너지를 보여 확산이 쉽게 일어남을 알 수 있었다.

• 대기
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• 제28권2호
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• pp.211-222
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• 2018

Cloud droplet activation process is well described by $K{\ddot{o}}hler$ theory and several parameterizations based on $K{\ddot{o}}hler$ theory are used in a wide range of models to represent this process. Here, we test the two different method of calculating the solute effect in the $K{\ddot{o}}hler$ equation, i.e., osmotic coefficient method (OSM) and ${\kappa}-K{\ddot{o}}hler$ method (KK). To do that, each method is implemented in the cloud droplet activation parameterization module of WRF-CHEM (Weather Research and Forecasting model coupled with Chemistry) model. It is assumed that aerosols are composed of five major components (i.e., sulfate, organic matter, black carbon, mineral dust, and sea salt). Both methods calculate similar representative hygroscopicity parameter values of 0.2~0.3 over the land, and 0.6~0.7 over the ocean, which are close to estimated values in previous studies. Simulated precipitation, and meteorological variables (i.e., specific heat and temperature) show good agreement with reanalysis. Spatial patterns of precipitation and liquid water path from model results and satellite data show similarity in general, but on regional scale spatial patterns and intensity show some discrepancy. However, meteorological variables, precipitation, and liquid water path do not show significant differences between OSM and KK simulations. So we suggest that the relatively simple KK method can be a good alternative to the OSM method that requires various information of density, molecular weight and dissociation number of each individual species in calculating the solute effect.

• Korean Chemical Engineering Research
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• 제57권3호
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• pp.338-343
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• 2019

고분자전해질 연료전지에서 전해질막의 물이동과 함수율은 고분자막의 성능에 많은 영향을 미친다. 본 연구에서는 간단한 방법에 의해 물이동에 관한 고분자막의 물성(전기삼투계수, 물 확산계수)을 측정하고 이들을 이용해 막을 통한 물의 이동량과 이온전도도를 모델식에 의해 모사한 후 실험값과 비교하였다. 물이동의 구동력은 전기삼투와 확산만이 라고 본 1차원 정상상태 지배방정식을 매트랩으로 수치해석하였다. $144{\mu}m$ 두께의 고분자막의 전기삼투계수를 수소펌핑셀에서 구한 결과 1.11을 얻었다. 물확산계수를 상대습도의 함수로 나타냈고 물확산에 대한 활성화에너지는 $2,889kJ/mol{\cdot}K$였다. 이들 계수를 적용해 모사한 물이동량과 이온전도도 결과는 실험값과 잘 일치함을 보였다.

• The Korean Journal of Physiology and Pharmacology
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• 제1권4호
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• pp.435-443
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• 1997

We employed the whole-cell patch clamp technique to investigate the effects of arachidonic acid (AA) on barium inward current through the L-type calcium channels ($I_{Ba}$) and on osmotic stretch-induced increase of $I_{Ba}$ in guinea-pig antral gastric myocytes. Under isosmotic condition, AA inhibited $I_{Ba}$ in a dose-dependent manner to $91.1{\pm}1.4,\;72.0{\pm}3.2,\;46.0{\pm}1.8,\;and\;20.3{\pm}2.3%$ at 1, 5, 10, 30 mM, respectively. The inhibitory effect of AA was not affected by 10 ${\mu}M$ indomethacin, a cyclooxygenase inhibitor. Other unsaturated fatty acids, linoleic acid (LA) and oleic acid (OA) were also found to suppress $I_{Ba}$ but stearic acid (SA), a saturated fatty acid, had no inhibitory effect on $I_{Ba}$. The potency sequence of these inhibitory effects was AA ($79.7{\pm}2.3%$) ＞ LA ($43.1{\pm}2.7%$) ＞ OA ($14.2{\pm}1.1%$) at 30 ${\mu}M$. On superfusing the myocyte with hyposmotic solution (214 mOsm) the amplitude of $I_{Ba}$ at 0 mV increased ($38.0{\pm}5.5%$); this increase was completely blocked by pretreatment with 30 mM AA, but not significantly inhibited by lower concentrations of AA (1, 5 and 10 ${\mu}M$) (P＞0.05). Unsaturated fatty acids shifted the steady-state inactivation curves of $I_{Ba}$ to the left; the extent of shift caused by AA was greater than that caused by LA. The activation curve was not affected by AA or LA. The results suggest that AA and other unsaturated fatty acids directly modulate L-type calcium channels and AA might modulate the hyposmotic stretch- induced increase of L-type calcium channel current in guinea-pig gastric smooth muscle.