• The Korean Journal of Physiology and Pharmacology
• /
• v.1 no.5
• /
• pp.495-504
• /
• 1997

Water transport is mediated by two distinct pathways, diffusional and channel-mediated water transport. The first molecular water channel was identified from human erythrocytes in 1992. Genetically-related proteins from other mammalian tissues have subsequently been identified to transport water, and the group is referred to as th "Aquaporins". Aquaporin-4 (AQP4) is most abundant in the brain, which may be involved in CSF reabsorption and osmoregulation. However, ontogeny and regulatory mechanisms of AQP4 channels have not been reported. Northern blot analysis showed that AQP4 mRNA began to be expressed in the brain just before birth and that its expression gradually increased by PN7 and then decreased at adult level. AQP4 was expressed predominantly in the ependymal cells of ventricles in newborn rats. And then its expression decreased in ependymal cells and increased gradually in other regions including supraoptic and paraventricular nuclei. AQP4 is also expressed in the subfornical organ, in which the expression level is not changed after birth. Cryogenic brain injury did not affect expression of AQP4 mRNA, while ischemic brain injury decreased it. Osmotic water permeability of AQP4 channel expressed in Xenopus oocytes was inhibited by the pretreatment of BAPTA/AM and calmidazolium, a $Ca^{2+}/Calmodulin$ kinase inhibitor, in a dose-dependent manner. These results indicate that the expression and the function of AQP4 channel are regulated by developmental processes and various pathophysiological conditions. These results will contribute to the understanding of fluid balance in the central nervous system and the osmoregulatory mechanisms of the body.

• Genomics & Informatics
• /
• v.2 no.2
• /
• pp.67-74
• /
• 2004

Cells consistently face stressful conditions, which cause them to modulate a variety of intracellular processes and adapt to these environmental changes via regulation of gene expression. Hyperosmotic and oxidative stresses are significant stressors that induce cellular damage, and finally cell death. In this study, oligonucleotide microarrays were employed to investigate mRNA level changes in cells exposed to hyperosmotic or oxidative conditions. In addition, since heat shock protein 70 (HSP70) is one of the most inducible stress proteins and plays pivotal role to protect cells against stressful condition, we performed microarray analysis in HSP70-overexpressing cells to identify the genes expressed in a HSP70-dependent manner. Under hyperosmotic or oxidative stress conditions, a variety of genes showed altered expression. Down­regulation of protein phosphatase1 beta (PP1 beta) and sphingosine-1-phosphate phosphatase 1 (SPPase1) was detected in both stress conditions. Microarray analysis of HSP70-overexpressing cells demonstrated that diverse mRNA species depend on the level of cellular HSP70. Genes encoding Iysyl oxidase, thrombospondin 1, and procollagen displayed altered expression in all tested conditions. The results of this study will be useful to construct networks of stress response genes.

• Journal of Microbiology and Biotechnology
• /
• v.12 no.3
• /
• pp.522-525
• /
• 2002

A very rapid and efficient separation technique for cellular rhizobial cyclosophoraoses was developed based on fractional precipitation and partition chromatography. Cyclosophoraoses are known to function in the osmotic regulation and root nodule formation of legumes during the nitrogen fixation process. Cyclosophoraoses are produced as unbranched cyclic (1longrightarrow12)-${\beta}$-D-glucans in Agrobacterium or Rhizobium species. Recent research has shown that cyclosophoraoses can form inclusion complexation with various unstable or insoluble guest chemicals, thereby implying great potential for industrial application. Typical separation of pure cellular cyclosophoraoses has been so far carried out by several time-consuming steps, including size exclusion, anion exchange, and desalting liquid chromatographies, with a relatively poor recovery. However, the proposed method demonstrated that the successive application of fractional ethanol precipitation and one step of silica gel-based flash column chromatography was enough to simultaneously purify neutral or anionic forms of cyclosophoraoses. This novel technique is very rapid and provides a high recovery.

• Asian-Australasian Journal of Animal Sciences
• /
• v.5 no.1
• /
• pp.81-90
• /
• 1992

Five buffaloes kept in normal ambient temperature ($30^{\circ}C$) showed no significant changes in the heart rate, respiratory rate, packed cell volume, plasma constituents and renal hemodymics during intravenous infusion of urea for 4 h. The rate of urine flow, fractional urea excretion, urinary potassium excretion and osmolar clearance significantly decreased while the renal urea reabsorption markedly increased during urea infusion. The decrease of fractional potassium excretion was concomitant with the reduction of the rate of urine flow and urine pH. In animals exposed to heat ($40^{\circ}C$) the rectal temperature heart rate and respiratory rate significantly increased while no significant changes in GFR and ERPF were observed. An intravenous infusion of urea in heat exposed animals caused the reduction of the rate of urine flow with no changes in renal urea reabsorption, urine pH and fractional electrolyte excretions. During heat exposure, there were marked increases in concentrations of total plasma protein and plasma creatinine whereas plasma inorganic phosphorus concentration significantly decreased. It is concluded that an increase in renal urea reabsorption during urea infusion in buffaloes kept in normal ambient temperature depends on the rate of urine flow which affect by an osmotic diuretic effect of electrolytes. The limitation of renal urea reabsorption in heat stressed animals would be attributed to an increases in either plasma pool size of nitrogenous substance or body metabolism.

• Molecules and Cells
• /
• v.22 no.2
• /
• pp.203-209
• /
• 2006

TBP (TATA-binding protein)-related factor 2 (TRF2) regulates transcription during a nuber of cellular processes. We previously demonstrated that it is localized in the cytoplasm and is translocated to the nucleus by DNA-damaging agents. However, the cytoplasmic localization of TRF2 is controversial. In this study, we reconfirmed its cytoplasmic localization in various ways and examined its nuclear migration. Stresses such as heat shock, redox agents, heavy metals, and osmotic shock did not affect localization whereas genotoxins such as methyl methanesulfonate (MMS), cisplatin, etoposide, and hydroxyurea caused it to migrate to the nucleus. Adriamycin, mitomycin C and ${\gamma}$-rays had no obvious effect. We determined optimal conditions for the nuclear migration. The proportions of cells with nuclei enriched for TRF2 were 25-60% and 5-10% for stressed cells and control cells, respectively. Nuclear translocation was observed after 1 h, 4 h and 12 h for cisplatin, etoposide and MMS and hydroxyurea, respectively. The association of TRF2 with the chromatin and promoter region of the proliferating cell nuclear antigen (PCNA) gene, a putative target of TRF2, was increased by MMS treatment. Thus TRF2 may be involved in genotoxin-induced transcriptional regulation.

• Journal of Life Science
• /
• v.18 no.11
• /
• pp.1606-1611
• /
• 2008

Outer membrane proteins (OMPs) expressed in the Gram negative bacteria such as Salmonella play multiple functions including material transports, adhesive factors and reception of external signals. This study has been focused on an OmpW protein known as a protein required to form a hydrophobic porin in outer membrane. We have constructed a S. typhimurium CK10 mutant deleting an ompW gene on chromosome. The CK10 strain was more tolerant to SDS than the wild-type strain did. As increase of salt concentration in the culture media, significantly decreased amount of OmpW protein in cells were detected. The maximum OmpW protein was expressed in the absence of salt supplement. However, the growth of CK10 strain was indistinguishable compared to that of the wild-type strain at the variable osmotic conditions. The biological role of differential OmpW expression in response to osmotic conditions remains to be investigated.

• The Korean Journal of Food And Nutrition
• /
• v.28 no.3
• /
• pp.404-414
• /
• 2015

Taurine is one of the most abundant free ${\beta}$-amino acids in the human body that accounts for 0.1% of the human body weight. It has a sulfonic acid group in place of the more common carboxylic acid group. Mollusks and meat are the major dietary source of taurine, and mother's milks also include high levels of this amino acid. The leukocytes, heart, muscle, retina, kidney, bone, and brain contain more taurine than other organs. Furthermore, taurine can be synthesized in the brain and liver from cysteine. There are no side effects of excessive taurine intake in humans; however, in case of taurine deficiency, retinal abnormalities, reduced plasma taurine concentration, and other abnormalities may occur. Taurine enters the cell via a cell membrane receptor. It is excreted in the urine (approximately 95%) and feces (approximately 5%). Taurine has a number of features and functions, including conjugation with bile acid, reduction of blood cholesterol and triglyceride levels, promotion of neuron cell differentiation and growth, antioxidant effects, maintenance of cell membrane stability, retinal development, energy generation, depressant effects, regulation of calcium level, muscle contraction and relaxation, bone formation, anti-inflammatory effects, anti-cancer and anti-atherogenic effects, and osmotic pressure control. However, the properties, functions, and effects of taurine require further studies in future.

• The Plant Pathology Journal
• /
• v.28 no.3
• /
• pp.227-238
• /
• 2012

Mitogen-activated protein kinase (MAPK) cascades are conserved signaling modules in the eukaryotic cells. They are involved in many major cell processes in fungi such as stress responses, vegetative growth, pathogenicity, secondary metabolism and cell wall integrity. In this review, we summarized the advances of research on the MAPK signaling pathways in Alternaria species. As major phytopathogenic fungi, Alternaria species reduce crop production. In contrast to the five MAPK pathways known in yeast, only three MAPK pathways as Fus3/Kss1-type, Hog1-type, and Slt2-type have been characterized in Alternaria. The Fus3/Kss1-type MAPK pathway participates in regulation of vegetative growth, conidiation, production of some cell-wall-degrading enzymes and pathogenicity. The Hog1-type pathway is involved in osmotic and oxidative stress, fungicides susceptibility and pathogenicity. The Slt2-type MAP kinases play an important role on maintaining cell wall integrity, pathogenicity and conidiation. Although recent advances on the MAPK pathways in Alternaria spp. reveal many important features on the pathogenicity, there are many unsolved problems regarding to the unknown MAP kinase cascade components and network among other major signal transduction. Considering the economic loss induced by Alternaria spp., more researches on the MAPK pathways will need to control the Alternaria diseases.

• Korean Journal of Weed Science
• /
• v.14 no.1
• /
• pp.1-7
• /
• 1994

The effects of S-23142{N-(4-chloro-2-fluoro-5-propargyloxyphenyl)-3, 4, 5, 6-tetrahydrophtalimide}, on protoporphyrin IX(PPIX) biosynthesis in Spinacia oleracea L, leaf in vivo and in vitro condition were investigated by reversed-phase HPLC with fluorescence detector. The stroma and the membrane fraction of spinach chloroplast were isolated by osmotic regulation. The conversion of ${\delta}$-aminolevulinic acid(ALA) to PPIX occured more in the stroma than in the membrane fraction. It suggested that the enzymes that catalyse PPIX biosynthesis from ALA were localized in the stroma. Also, the synthesized PPIX content from ALA was completely inhibited by $10^{-8}M$ of S-23412 or $10^{-7}M$ of acifluorfen in the stroma but not in the membrane fractions. Therefore, these results suggested that the target site of S-23142 and acifluorfen may exist in the stroma fraction of spinach chloroplast.

• Journal of Environmental Impact Assessment
• /
• v.23 no.4
• /
• pp.237-250
• /
• 2014

A wide range of projects for ocean renewable energy are currently in development around the world and ocean energy industries continue to receive significant support from their governments. Surrounded by sea on three sides, Korea has potentially abundant renewable ocean energy resources, which include tidal current, tidal range, offshore wind power, osmotic pressure and ocean thermal energy. Numerous ocean renewable energy projects has been developed in Korea. Nevertheless, there are some concerns that those developments often select an environmentally unsuitable location and/or there are very few existing information on those environmental effects. The purpose of this study is to improve supporting policies and regulation systems of ocean renewable energy development in Korea by reviewing and compiling government policies and environmental assessment systems related to ocean renewable energy development around the world. The study suggests several policy implications for its environmental-friendly development in Korea, including requirements of strategic environmental assessment for proactive and environmentally suitable site selection of ocean renewable energy development and continuous post-development environmental monitoring, and so on.