Cell disruption focuses on obtaining a desired bioproduct within a cell, and it is the cell wall that must be disrupted to allow access to the contents of the cell. In animal cells, the plasma membrane is the only bar...Cell disruption focuses on obtaining a desired bioproduct within a cell, and it is the cell wall that must be disrupted to allow access to the contents of the cell. In animal cells, the plasma membrane is the only barrier separating cell contents from the environment. Sound waves from sonication, a mechanical technique for cell disintegration, have been used to disrupt as well as to aggregate cells as a step towards purification of a desired bioproduct. In the present study, an improved sonication process for the high yield of Newcastle disease virus （NDV） propagated in tissue culture was described. DF-I cell was cultured in 25cm^2 T flask. When cells were about 80% confluent, a lentogenic strain of NDV （F strain） was used to infect the cell monolayer. With evident cytopathic effect, cells were subjected to cycles of freeze-thaw before sonicating with varying combinations of amplitude, temperature and time. Cells were sonicated using a water bath Sonicator, Jac Ultrasonic 1505 JEIO TECH 4 KHz. From ANOVA analysis, a significant interaction between sonication time and amplitude was observed. This also corresponds to the highest F value observed.展开更多
The marine algal-derived endophytic fungus Aspergillus wentii EN-48 produces the potential anti-tumor agent asperolide A, a tetranorlabdane diterpenoid active against lung cancer. However, the fermentation yield of as...The marine algal-derived endophytic fungus Aspergillus wentii EN-48 produces the potential anti-tumor agent asperolide A, a tetranorlabdane diterpenoid active against lung cancer. However, the fermentation yield of asperolide A was very low and only produced in static cultures. Static fermentation conditions of A. wentii EN-48 were optimized employing response surface methodology to enhance the production of asperolide A. The optimized conditions resulted in a 13.9-fold yield enhancement, which matched the predicted value, and the optimized conditions were successfully used in scale-up fermentation for the production of asperolide A. Exogenous addition of plant hormones （especially 10 pmol/L methyl jasmonate） stimulated asperolide A production. To our knowledge, this is first optimized production of an asperolide by a marine-derived fungus. The optimization is effective and valuable to supply material for further anti-tumor mechanism studies and preclinical evaluation of asperolide A and other norditerpenoids.展开更多
This paper employs a stochastic endogenous growth model with productive government expenditure in a small open economy to analyze the optimal fiscal policy. First, a stochastic model of a small open economy is constru...This paper employs a stochastic endogenous growth model with productive government expenditure in a small open economy to analyze the optimal fiscal policy. First, a stochastic model of a small open economy is constructed. Second, the equilibrium solutions of the representative agent＇s stochastic optimization problem are derived. Third, we obtain the equilibrium solutions of the central planner＇s stochastic optimization problem and the optimal government expenditure policy. Finally, the optimal tax policy is characterized.展开更多
文摘Cell disruption focuses on obtaining a desired bioproduct within a cell, and it is the cell wall that must be disrupted to allow access to the contents of the cell. In animal cells, the plasma membrane is the only barrier separating cell contents from the environment. Sound waves from sonication, a mechanical technique for cell disintegration, have been used to disrupt as well as to aggregate cells as a step towards purification of a desired bioproduct. In the present study, an improved sonication process for the high yield of Newcastle disease virus （NDV） propagated in tissue culture was described. DF-I cell was cultured in 25cm^2 T flask. When cells were about 80% confluent, a lentogenic strain of NDV （F strain） was used to infect the cell monolayer. With evident cytopathic effect, cells were subjected to cycles of freeze-thaw before sonicating with varying combinations of amplitude, temperature and time. Cells were sonicated using a water bath Sonicator, Jac Ultrasonic 1505 JEIO TECH 4 KHz. From ANOVA analysis, a significant interaction between sonication time and amplitude was observed. This also corresponds to the highest F value observed.
基金Supported by the National Natural Science Foundation of China(NSFC,Nos.31200042,31570038)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406402)
文摘The marine algal-derived endophytic fungus Aspergillus wentii EN-48 produces the potential anti-tumor agent asperolide A, a tetranorlabdane diterpenoid active against lung cancer. However, the fermentation yield of asperolide A was very low and only produced in static cultures. Static fermentation conditions of A. wentii EN-48 were optimized employing response surface methodology to enhance the production of asperolide A. The optimized conditions resulted in a 13.9-fold yield enhancement, which matched the predicted value, and the optimized conditions were successfully used in scale-up fermentation for the production of asperolide A. Exogenous addition of plant hormones （especially 10 pmol/L methyl jasmonate） stimulated asperolide A production. To our knowledge, this is first optimized production of an asperolide by a marine-derived fungus. The optimization is effective and valuable to supply material for further anti-tumor mechanism studies and preclinical evaluation of asperolide A and other norditerpenoids.
基金This research is supported by the National Natural Science Foundation of China （No. 70271069）.
文摘This paper employs a stochastic endogenous growth model with productive government expenditure in a small open economy to analyze the optimal fiscal policy. First, a stochastic model of a small open economy is constructed. Second, the equilibrium solutions of the representative agent＇s stochastic optimization problem are derived. Third, we obtain the equilibrium solutions of the central planner＇s stochastic optimization problem and the optimal government expenditure policy. Finally, the optimal tax policy is characterized.
