• Ocean Science Journal
• /
• v.41 no.3
• /
• pp.125-137
• /
• 2006

Nutrients, chlorophyll-a, particulate organic carbon (POC), and environmental conditions were extensively investigated in the northern East China Sea (ECS) near Cheju Island during three seasonal cruises from 2003 to 2005. In spring and autumn, relatively high concentrations of nitrate ($2.6{\sim}12.4\;{\mu}mol\;kg^{-1}$) and phosphate ($0.17{\sim}0.61\;{\mu}mol\;kg^{-1}$) were observed in the surface waters in the western part of the study area because of the large supply of nutrients from deep waters by vertical mixing. The surface concentrations of nitrate and phosphate in summer were much lower than those in spring and autumn, which is ascribed to a reduced nutrient supply from the deep waters in summer because of surface layer stratification. While previous studies indicate that upwellings of the Kuroshio Current and the Changjiang (Yangtze River) are main sources of nutrients in the ECS, these two inputs seem not to have contributed significantly to the build-up of nutrients in the northern ECS during the time of this study. The lower nitrate:phosphate (N:P) ratio in the surface waters and the positive correlation between the surface N:P ratio and nitrate concentration indicate that nitrate acts as a main nutrient limiting phytoplankton growth in the northern ECS, contrary to previous reports of phosphate-limited phytoplankton growth in the ECS. This difference arises because most surface water nutrients are supplied by vertical mixing from deep waters with low N:P ratios and are not directly influenced by the Changjiang, which has a high N:P ratio. Surface chlorophyll-a levels showed large seasonal variation, with high concentrations ($0.38{\sim}4.14\;mg\;m^{-3}$) in spring and autumn and low concentrations ($0.22{\sim}1.05\;mg\;m^{-3}$) in summer. The surface distribution of chlorophyll-a coincided fairly well with that of nitrate in the northern ECS, implying that nitrate is an important nutrient controlling phytoplankton biomass. The POC:chlorophyll-a ratio was $4{\sim}6$ times higher in summer than in spring and autumn, presumably because of the high summer phytoplankton death rate caused by nutrient depletion in the surface waters.

• Journal of Korean Society of Forest Science
• /
• v.98 no.2
• /
• pp.170-177
• /
• 2009

There are remarkable differences in growth and morphological characters of roots between mountain and field cultivated Panax ginseng. Growth of root in mountain cultivated ginseng was much slower than that of field cultivated ginseng. However, the factor affecting the retarded growth in mountain ginseng was not known. Soil analysis revealed that phosphorus (P) content of mountain soil was exceptionally low at least ten-fold lower compared to that of field soil. Thus, we suggest that low availability of P in mountain soil may be one of the limiting factors for growth of ginseng in mountain soil environment. We had monitored the growth of ginseng plants after one and three years of phosphate fertilizer application. Three kinds of phosphate fertilizers: fused magnesium phosphate, fused superphosphate, and single superphosphate were applied to mountain soil. Application of phosphate fertilizers increased the fresh-, dry weight, and diameter of ginseng roots and resulted in increased P accumulation in roots. These results demonstrate that slow growth of ginseng in mountain soil environment might be attributed to the low P content in mountain soil. Thus, analysis of P amount in mountain soil will be a good indicator for the selection of suitable site the ginseng cultivation in forest.

• Journal of Nutrition and Health
• /
• v.19 no.4
• /
• pp.246-254
• /
• 1986

Weanling female Sprague Dawley rats were fed d diets containing 22mg pyridoxine. BCI/kg diet (control diet) and l.2mg pyridoxine. BCI/kg diet (deficient diet). One control group and one defi­c dent group were fed their diet throughout growth, g gestation and lactation. After the pups were born and weaned, the deficient group was divided into two groups. One switched to control diet(supple­I mented group) and the other continued the same d deficient diet( deficient group) until 10 week -old. The liver mitochondrial and cytosolic asparate a aminotransferase activity and pyridoxal phosphate content were determined in offspring rats. The aspartate aminotransferase activities in both liver mito$\phi$ondrial and cytosolic fractions of den­d cient group were significantly lower than those of controls, but there were no significant differences between two groups after addition of 1O^{-4}M pyri­d do뼈I phosphate to the medium. By pyridoxine s supplementation after weaning, the reduced aspar­a tate aminotnmsferase activities were only partialy I restored to control levels. The pyridoxal phospha­t te content of deficient group in Iiver mitochondr­ial and cytosoIic fractions were alo significantly different from those of controls, but readily restored by dietary supplementation. These results suggest that there is a quantitative and a qualitative changes of aspartate amino trans­f ferase and pyridoxal phosphate in liver mitochon­d drial and cytosolic fraction by long-term pyrido­x xine deficiency and these reductions can partially recovered by dietary pyridoxine supplementation after weaning.

• Ocean and Polar Research
• /
• v.26 no.2
• /
• pp.377-384
• /
• 2004

Annual variations of inorganic nutrients such as nitrate(+nitrite), phosphate and silicate in association with thermocline were investigated in the upper 200 m of the water column at KODES Long-term Monitoring (KOMO) station in the northeast equatorial Pacific from 1995 to 2002. Global climatic disturbances such as El Nino and La Nina, should have affected KODES area during the study period. In 1995-97 and 2000-2002, a thermocline where temperatures rapidly decrease with depth, was formed at 50-70 m water depth. Nutrient depletion, specially for nitrate and phosphate, was extended down to approximately 50 m depth, which coincided with the surface mixed layer depth. In 1998 and 1999, however a very fluctuating thermocline was observed at 20-100 m water depth. In the photic zone (up to 100 m depth), depth integration of nitrate, phosphate and silicate ranged from 2.02 to $23.14\;gN/m^2$, from 0.87 to $4.05\;gP/m^2$ and from 35.67 to $176.21\;gSi/m^2$, respectively. As a result of changes in the water column structures, nutrient concentrations also showed fluctuation parallel to the changes of thermocline in the study area.

• Korean Journal of Clinical Laboratory Science
• /
• v.41 no.2
• /
• pp.83-92
• /
• 2009

This study was undertaken to examine the effect of oxidants on membrane transport function in renal epithelial cells. Hydrogen peroxide ($H_2O_2$) was used as a model oxidant and the membrane transport function was evaluated by measuring $Na^+$-dependent phosphate ($Na^+$-Pi) uptake in opossum kidney (OK) cells. $H_2O_2$ inhibited $Na^+$-Pi uptake in a dose-dependent manner. The oxidant also caused loss of cell viability in a dose-dependent fashion. However, the extent of inhibition of the uptake was larger than that in cell viability. $H_2O_2$ inhibited $Na^+$-dependent uptake without any effect on $Na^+$-independent uptake. $H_2O_2$-induced inhibition of $Na^+$-Pi uptake was prevented completely by catalase, dimethylthiourea, and deferoxamine, suggesting involvement of hydroxyl radical generated by an iron-dependent mechanism. In contrast, antioxidants Trolox, N,N'-diphenyl-p-phenylenediamine, and butylated hydroxyanisole did not affect the $H_2O_2$ inhibition. Kinetic analysis indicated that $H_2O_2$ decreased Vmax of $Na^+$-Pi uptake with no change in the Km value. Phosphonoformic acid binding assay did not show any difference between control and $H_2O_2$-treated cells. $H_2O_2$ also did not cause degradation of $Na^+$-Pi transporter protein. Reduction in $Na^+$-Pi uptake by $H_2O_2$ was associated with ATP depletion and direct inhibition of $Na^+$-$K^+$-ATPase activity. These results indicate that the effect of $H_2O_2$ on membrane transport function in OK cells is associated with reduction in functional $Na^+$-pump activity. In addition, the inhibitory effect of $H_2O_2$ was not associated with lipid peroxidation.

• Nuclear Engineering and Technology
• /
• v.51 no.3
• /
• pp.755-760
• /
• 2019

Compound samples based on the mineral-like magnesium potassium phosphate matrix $MgKPO_4{\times}6H_2O$ were synthesized by solidification of high level waste surrogate. Phase composition and structure of synthesized samples were studied by XRD and SEM methods. Compressive strength of the compounds is $12{\pm}3MPa$. Coefficient of thermal expansion of the samples in the range $250-550^{\circ}C$ is $(11.6{\pm}0.3){\times}10^{-6}1/^{\circ}C$, and coefficient of thermal conductivity in the range $20-500^{\circ}C$ is $0.5W/(m{\times}K)$. Differential leaching rate of elements from the compound, $g/(cm^2{\times}day)$: $Mg-6.7{\times}10^{-6}$, $K-3.0{\times}10^{-4}$, $P-1.2{\times}10^{-4}$, $^{137}Cs-4.6{\times}10^{-7}$; $^{90}Sr-9.6{\times}10^{-7}$; $^{239}Pu-3.7{\times}10^{-9}$, $^{241}Am-9.6{\times}10^{-10}$. Leaching mechanism of radionuclides from the samples at the first 1-2 weeks of the leaching test is determined by dissolution ($^{137}Cs$), wash off ($^{90}Sr$) or diffusion ($^{239}Pu$ and $^{241}Am$) from the compound surface, and when the tests continue to 90-91 days - by surface layer depletion of compound. Since the composition and physico-chemical properties of the compound after irradiation with an electron beam (absorbed dose of 1 MGy) are constant the radiation resistance of compound was established.

• Molecules and Cells
• /
• v.39 no.4
• /
• pp.322-329
• /
• 2016

Voltage-gated $Ca^{2+}$ ($Ca_V$) channels are dynamically modulated by Gprotein-coupled receptors (GPCR). The $M_1$ muscarinic receptor stimulation is known to enhance $Ca_V2.3$ channel gating through the activation of protein kinase C (PKC). Here, we found that $M_1$ receptors also inhibit $Ca_V2.3$ currents when the channels are fully activated by PKC. In whole-cell configuration, the application of phorbol 12-myristate 13-acetate (PMA), a PKC activator, potentiated $Ca_V2.3$ currents by ~two-fold. After the PMA-induced potentiation, stimulation of $M_1$ receptors decreased the $Ca_V2.3$ currents by $52{\pm}8%$. We examined whether the depletion of phosphatidylinositol 4,5-bisphosphate ($PI(4,5)P_2$) is responsible for the muscarinic suppression of $Ca_V2.3$ currents by using two methods: the Danio rerio voltage-sensing phosphatase (Dr-VSP) system and the rapamycin-induced translocatable pseudojanin (PJ) system. First, dephosphorylation of $PI(4,5)P_2$ to phosphatidylinositol 4-phosphate (PI(4)P) by Dr-VSP significantly suppressed $Ca_V2.3$ currents, by $53{\pm}3%$. Next, dephosphorylation of both PI(4)P and $PI(4,5)P_2$ to PI by PJ translocation further decreased the current by up to $66{\pm}3%$. The results suggest that $Ca_V2.3$ currents are modulated by the $M_1$ receptor in a dual mode-that is, potentiation through the activation of PKC and suppression by the depletion of membrane $PI(4,5)P_2$. Our results also suggest that there is rapid turnover between PI(4)P and $PI(4,5)P_2$ in the plasma membrane.

• Korean Journal of Soil Science and Fertilizer
• /
• v.51 no.2
• /
• pp.111-118
• /
• 2018

A field experiment was conducted to investigate the effect of long-term (21-year) fertilizer and compost treatments on the yield of red pepper and chemical properties in top-dong, Suwon. Six treatments were chosen for this work: No fertilization (No fert.), NPK fertilizers (NPK), NPK and compost (NPK+Compost), NP and compost (NP+Compost), NK and compost (NK+Compost), PK and compost (PK+Compost). The yield of red pepper for 21 years indicated the significant differences among the No fertilization, the PK+Compost, and other treatments. The relative yield index was 13% and 59% respectively, for the No fertilization and the PK+Compost if the average yield of red pepper for the NPK regards $20,048kg\;ha^{-1}$ as the yield index with 100%. Soil organic matter at the compost applied treatments significantly increased compared with the No fert. and the NPK. The average increase rates of soil organic matter by applying the compost ranged from 0.69 to $0.73g\;kg^{-1}\;yr^{-1}$. Available phosphate content in soil appeared the significant increase all treatments excluding the No fert. It is estimated that the available phosphate in soil was increased by $7.0mg\;kg^{-1}\;yr^{-1}$ by applying compost and $14.2mg\;kg^{-1}\;yr^{-1}$ by applying P fertilizer. Application of K fertilizer or the compost alone, the NPK, the NP+Compost, continuously caused soil K depletion whereas K fertilization plus the compost maintained at a constant level of exchangeable K. The results indicated that the addition of compost to NPK fertilizer is recommended for the maximum stable yield for red pepper and enhancement of organic matter though it is also needed for adjusting of P and K fertilization.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.2
• /
• pp.305-312
• /
• 2007

This study focused on the involvement of the unusual nucleotide (p)ppGpp, a stringent factor, during the morphological and physiological differentiation of Streptomyces coelicolor. Two genes, relA and rshA, were disrupted to demonstrate the roles of the stringent factor in the differentiation. The intracellular concentration of (p)ppGpp in the wild-type (M600) and disrupted mutants was measured in relation to the intentional starvation of a specific nutrient, such as carbon, nitrogen, and phosphate or the in situ depletion of nutrients in a batch culture. As a result, it was found that the morphological characteristic of the ${\Delta}relA$ mutant was a bld phenotype forming condensed mycelia, whereas the ${\Delta}rshA$ mutant grew fast-forming spores and straightforward mycelia. In both mutants, the production of actinorhodin (Act) was completely abolished, yet the undecylprodigiosin (Red) production was increased. Intracellular (p)ppGpp was detected in the ${\Delta}relA$ mutant in the case of limited phosphate, yet not with limited carbon or nitrogen sources. In contrast, (p)ppGpp was produced in the ${\Delta}rshA$ mutant under limited carbon and nitrogen conditions. Therefore, (p)ppGpp in S. coelicolor was found to be selectively regulated by either the RelA or RshA protein, which was differentially expressed in response to the specific nutrient limitation. These results were also supported by the in situ ppGpp production during a batch culture. Furthermore, it is suggested that RelA and RshA are bifunctional proteins that possess the ability to both synthesize and hydrolyze (p)ppGpp.

• BioChip Journal
• /
• v.12 no.4
• /
• pp.317-325
• /
• 2018

This paper investigated the effects of ionic strength in the medium on a preconcentrator for a protein sample with low concentration. The preconcentration chip was designed and fabricated using a polydimethylsiloxane replica through standard lithophotography. A glass substrate is silanized prior to functionalizing the nanoparticles for self-assembly at a designed region. Due to the overlap of electrical double layers in a nanofluidic channel, a concentration polarization effect can be achieved using an electric field. A nonlinear electrokinetic flow is induced, resulting in the fast accumulation of proteins in front of the induced ionic depletion zone, so called exclusion-enrichment effect. Thus, the protein sample can be driven by electroosmotic flow and accumulated at a specific location. The chip is used to collect fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA) diluted in phosphate-buffered saline (PBS) buffer solution. Different concentrations of the buffer media were studied herein. Fluorescence intensity images show that the buffer concentration of 4 mM is more appropriate than all the other ones. The sample of FITC-BSA with an initial concentration of $10{\mu}M$ in the 4 mM PBS solution increases its concentration at the desired region by up to 50 times within 30 min, demonstrating the results in this investigation.