• Animal cells and systems
• /
• v.14 no.3
• /
• pp.147-154
• /
• 2010

It is well-established that phosphoinositide 3-kinase (PI3-kinase) regulates myogenesis by inducing transcription of myogenin, a key muscle regulatory factor, at the initiation of myoblast differentiation. In this study, we investigated the role of PI3-kinase in cells that have committed to differentiation. PI3-kinase activity increases during myogenesis, and this increase is sustained during the myogenic process; however, its function after the induction of differentiation has not been investigated. We show that LY294002, a PI3-kinase inhibitor, blocked myoblast fusion even after myogenin expression initially increased. In contrast to the inhibitory effects of LY294002 on myogenin mRNA levels during the initiation of differentiation, LY294002 blocked the accumulation of myogenin protein without affecting its mRNA level after differentiation was induced. Treatment with cycloheximide, a translation inhibitor, or actinomycin D, a transcription inhibitor, indicated that the stability of myogenin protein is lower than that of its mRNA. LY294002 inhibited the activities of several important translation factors, including eukaryotic elongation factor-2(eEF2), by altering their phosphorylation status. In addition, LY294002 blocked the incorporation of [$^{35}S$]methionine into newly synthesized proteins. Since myogenin has a relatively short half-life, LY294002-mediated inhibition of post-transcriptional processes resulted in a rapid depletion of myogenin protein. In summary, these results suggest that PI3-kinase plays an important role in regulating the expression of myogenin through post-transcriptional mechanisms after differentiation has been induced.

• Applied Biological Chemistry
• /
• v.43 no.4
• /
• pp.291-297
• /
• 2000

This study was conducted to find out the environmental factors affecting the differences in the half-life of the insecticide cyfluthrin in soil between field and laboratory tests carried out in 1998. Degradation and leaching of cyfluthrin in soil were examined under various environmental conditions that were considered to affect the residuality. Cyfluthrin was degraded 1.9 times faster in non-sterilized soil than in sterilized soil and 1.2 times at $25^{\circ}C$ than at $15^{\circ}C$. The half-lives of cyfluthrin were 61.4 days under the dark condition and 4.5 days under sunlight, and those were 11.8 days under the open condition and 23.8 days under the closed condition. The half-lives of the authentic compound and the commercial product of cyfluthrin were 15 and 1 day in the field test and 26 and 3 days in the laboratory test, respectively. Cyfluthrin was rapidly degraded with an increase in soil moisture content and decomposed faster in the alkaline solution of pH 12 than in the acidic solution of pH 3, but the half-life of cyfluthrin did not make any difference between pH 6.4 of the field test soil and pH 5.6 of the laboratory test soil. Cyfluthrin was immobile in soil from the results that $81{\sim}94%$ of the initial amount remained in the $0{\sim}2\;cm$ layer of the soil column regardless of the amount and time of rainfall after the chemical treatments. From viewing the abovementioned results, soil moisture content, sunlight and formulation type affected greatly soil microbes and volatilization affected slightly, and temperature, pH and rainfall did not affect the big difference in the half-life of cyfluthrin in soil between the field and laboratory tests in the year of 1998.

• Journal of Applied Biological Chemistry
• /
• v.63 no.4
• /
• pp.457-462
• /
• 2020

Pancreatic cancer is among the most difficult-to-treat tumors. More than half of patients with this cancer have very few symptoms at the early stages, allowing the development of distant metastases and resistance to cancer treatment. In this study, we found that Juniperus chinensis extract (JCX) decreased the cell viability and migration activity of PANC-1 and SNU-213 pancreatic cancer cells in a dose-dependent manner. JCX increased caspase-3 activation and generation of reactive oxygen species (ROS). N-acetylcysteine treatment blocked JCX-induced ROS generation and the negative effects on pancreatic cancer cell viability. In addition, JCX down-regulated the levels of phospho-focal adhesion kinase (p-FAK) and phospho-extracellular signal-regulated kinase (p-ERK). Together, these results indicate that JCX induces apoptosis in human pancreatic cancer cell lines through ROS production, downregulating FAK/ERK signaling and activating caspase-3. We propose that JCX-derived compounds represent candidates for the development of alternative medicines for the treatment of pancreatic cancer.

• The Korean Journal of Pesticide Science
• /
• v.21 no.1
• /
• pp.84-89
• /
• 2017

This study was carried out to investigate residue dissipation of fluquinconazole and flusilazole in field-sprayed tomatoes during greenhouse cultivation and processing. The test pesticide, fluquinconazole+flusilazole 8.5 (7+1.5)% SC, was sprayed onto the tomatoes growing in a greenhouse according to Korea preharvest intervals and then samples were collected on 0 (3 hours after spraying), 1, 3, 5 and 7 days after last application for decline test. For processing test, tomatoes collected at harvest on 5 day after last application were processed to puree and juice. Limits of quantitation of fluquinconazole and flusilazole were 0.005 mg/kg in both tomatoes and their processed products. Recoveries for validation of the analytical methods for fluquinconazole and flusilazole in tomatoes and their processed products ranged from 74.8 to 97.5%. Biological half-lives of fluquinconazole and flusilazole in tomatoes under greenhouse conditions found to be 5.2 and 6.4 days, respectively. Average persistent residue levels of fluquinconazole and flusilazole were 37.34 and 79.53% after washing, 8.95 and 28.75% in filtrates after boiling, 3.58 and 14.66% in puree, and 3.34 and 13.52% in juice, respectively. These results indicated that the test pesticide residues on tomatoes could be largely removed through washing and boiling.

• Korean Journal of Environmental Agriculture
• /
• v.22 no.3
• /
• pp.220-226
• /
• 2003

The residue patterns of procymidone, chlorpyrifos and cypermethrin in peaches were examined. The pesticides were sprayed at 15 days before harvest and then were determined the residue at 0, 1, 2, 3, 5, 7, 10 and 15 days after pesticide application and calculated their $DT_{50}$. Also, the degradation patterns at $4^{\circ}C$ and $20^{\circ}C$ during storage period were compared. Biological half-lives of procymidone, chlorpyrifos and cypermethrin in peaches during the cultivation period were 3.1, 7.2 and 10.4 days, respectively. The biological half -life of procymidone was shorter than the others. During the storage period, half-lives of procymidone, chlorpyrifos and cypermethrin were 16.0, 14.3 and 13.1 days at $4^{\circ}C$ and 4.6, 10.2 and 12.9 days at $20^{\circ}C$, respectively. The degradation rates of these three pesticides in storage period were slower than them in cultivation period. Removal rates were $22.2{\sim}82.9%$ by tap water, and $12.5{\sim}88.8%$ by detergent solution.

• Mycobiology
• /
• v.44 no.4
• /
• pp.217-236
• /
• 2016

Polyporoid and corticioid fungi are among the most important wood-decay fungi. Not only do they contribute to nutrient cycling by decomposing wood debris, but they are also valuable sources for natural products. Polyporoid and corticioid wood-inhabiting fungi were investigated in Odaesan National Park. Fruit bodies were collected and identified based on morphological and molecular analyses using 28S and internal transcribed spacer regions of DNA sequences. As a result, a total of 149 species, 69 genera, 22 families, and 11 orders were recognized. Half (74 species) of the species were polypores, and the other half (75 species) were corticioid fungi. Most of the species belonged to Polyporales (92 species) followed by Hymenochaetales (33 species) and Russulales (11 species). At the genus level, a high number of species was observed from Steccherinum, Hyphodontia, Phanerochaete, Postia, and Trametes. Concerning distribution, almost all the species could be found below 1,000 m, and only 20% of the species were observed from above 1,000 m. Stereum subtomentosum, Trametes versicolor, T. hirsuta, T. pubescens, Bjerkandera adusta, and Ganoderma applanatum had wide distribution areas. Deciduous wood was the preferred substrate for the collected species. Sixty-three species were new to this region, and 21 species were new to Korea, of which 17 species were described and illustrated.

• The Korean Journal of Pesticide Science
• /
• v.15 no.3
• /
• pp.317-322
• /
• 2011

A comparative experiment was conducted to investigate the persistence of chlorfenapyr residue and its biological activity to two spotted spider mite, Tetranychus urticae, after treatment of chlorfenapyr suspension concentrate (10% SC) on paprika plants at recommended (2000 times dilution) and double dosage. Biological half-lives of chlorpfenapyr were estimated as 8 and 5 days in leaves and fruits of paprika plants, respectively. While initial deposits of chlorfenapyr residues in leaves at recommended and double dosages were 22.22 and 37.75 ${\mu}g\;g^{-1}$ at the time of application, its residue decreased to 1.56 ${\mu}g\;g^{-1}$ and 3.62 ${\mu}g\;g^{-1}$ at 29 days after treatment, respectively. Residual biological activity of chlorfenapyr SC to T. urticae at recommended dosage lasted for 7 or 15 days on the basis of 24 or 48-hrs mortality test assayed with feeding on excised leaf chlorfenapyr-treated. The control efficacy to the mite showed a good agreement with the persistence of chlorfenapyr residues in leaves.

• Journal of Microbiology and Biotechnology
• /
• v.10 no.6
• /
• pp.836-839
• /
• 2000

Beef tallow, which is an industrial lipid substrate, was hydrolyzed by lipase immobilized on a high-density polyethylene (HDPE) powder. Ethanol pre-washing process affected the immobilization efficiency. Half-life of storage of the HDPE at $4^{\circ}C$ was 150 days. And after 10 times of repeated use, more than 50% of initial activity remained. An apparent Michaelis constant ($K_m$) and maximum velocity ($V_{max}$) were 2.7M, and 1.4 mmol/min/l for immobilized lipase, and 0.5 M, and 1.9 mmol/min/l for soluble lipase, respectively.

• Journal of Applied Biological Chemistry
• /
• v.48 no.1
• /
• pp.11-15
• /
• 2005

Salinity of soils in greenhouse has been increased by massive application of fertilizers. Nitrogen fertilizer was most popular, and thus nitrate became the majority of soil salinity. Accumulation of nitrate led to deleterious effects on the growth and development of crops and vegetables. Microbial strains able to utilize nitrate and thus remove excess nitrate from farm land soils were isolated from 15 different soils of greenhouses and plastic film houses. Four strains able to grow in medium containing 50 mM $KNO_3$ were isolated, among which only E0461 showed high capacity of nitrate uptake. Nitrate uptake by E0461 was dependent on culture medium and was increased by addition of tryptone and peptone. Although E0461 was able to grow without tryptone and peptone, growth was slow, and no nitrate uptake was observed. Nitrate appeared to facilitate E0461 growth in the presence of tryptone and peptone. Through kinetic analysis, nitrate uptake was measured at various concentrations of nitrate, and half-life was calculated. Nitrate concentration decreased with increasing incubation period, and plot between half-lives and initial concentrations of nitrate fitted to single exponential function. These results suggest one major factor plays an important role in microbial nitrate uptake.

• Journal of Pharmaceutical Investigation
• /
• v.17 no.2
• /
• pp.95-98
• /
• 1987

The drug interaction between probenecid and lithium carbonate was studied pharmacokinetically in rabbits. The blood level and the area under the concentration curve (AUC) of lithium carbonate administered orally were elevated by coadministration of probenecid. Probenecid inhibited the urinary excretion of lithium carbonate in rabbits. Biological half-life and $t_{max}$ of lithium carbonate were prolonged by coadministration of probenecid. From these results, dosage regimen of lithium carbonate is considered to be adjusted for effective and safe therapy in the coadministration of probenecid.