Advances in abscisic acid biosynthesis / 生物工程学报

Abscisic acid, a plant hormone that inhibits growth, is a key factor in balancing plant endogenous hormones and regulating growth and metabolism. Abscisic acid can improve the drought resistance and salt tolerance of crops, reduce fruit browning, reduce the incidence rate of malaria and stimulate insulin secretion, so it has a broad application potential in agriculture and medicine. Compared with traditional plant extraction and chemical synthesis, abscisic acid synthesis by microorganisms is an economic and sustainable route. At present, a lot of progress has been made in the synthesis of abscisic acid by natural microorganisms such as Botrytis cinerea and Cercospora rosea, while the research on the synthesis of abscisic acid by engineered microorganisms is rarely reported. Saccharomyces cerevisiae, Yarrowia lipolytica and Escherichia coli are common hosts for heterologous synthesis of natural products due to their advantages of clear genetic background, easy operation and friendliness for industrial production. Therefore, the heterologous synthesis of abscisic acid by microorganisms is a more promising production method. The author reviews the research on the heterologous synthesis of abscisic acid by microorganisms from five aspects: selection of chassis cells, screening and expression enhancement of key enzymes, regulation of cofactors, enhancement of precursor supply and promotion of abscisic acid efflux. Finally, the future development direction of this field is prospected.

Preparation and application of aminophyllin electrochemical sensor based on molecularly imprinting technique / 军事医学

Objective To establish a method for detection of aminophylline in blood samples of preterm infants . Methods A molecularly imprinted electrochemical sensing film on the glassy carbon electrode surface was prepared by electropolymerization using aminophylline as the template molecule and pyrrole as the functional monomer in 0.2 mol/L HAc-NaAc buffer solution ( pH 4.0).The surface morphology and properties of molecularly imprinted sensing films were characterized by three dimensional laser scanning microscopy , differential pulse voltammetry ( DPV) and electrochemical impedance spectroscopy ( EIS) while the effects of scanning cycle number and incubation time were investigated by square wave voltammetry(SWV) method in 5 mmol/L K3[Fe(CN)6] -0.1 mol/L KCl solution.Results Under optimized experimental conditions ,the SWV peak current difference was linear to the negative logarithm of aminophylline concentration in the range from 1.0 ×10 -7 to 1.0 ×10 -3mol/L with a detection limit (S/N=3) of 0.5 ×10 -8mol/L.The recovery rate was 92.2% -101.4%.Also, the molecularly imprinted electrochemical sensor for aminophylline had good selectivity , stability and reproducibility .Conclusion The molecularly imprinted electrochemical sensor for aminophylline can be used for rapid and accurate detection of clinical blood concentrations of aminophylline molecules in preterm infants in the future .

A simple microfluidic chip technology for assaying electrotaxis of cancer cells / 军事医学

Objective To develop a simple microfluidic chip technology for analyzing the electrotaxis of cancer cells . Methods The basic structure of the proposed microfluidic electrotaxis chip included a straight microchannel and liquid storage pools located on both sides of the microchannel .Two platinum electrodes were inserted into the liquid pools to create a controllable direct current ( DC ) field in the microchannel .The distribution and strength of the DC field in the microchannel was analyzed by the finite element analysis software COMSOL multiphysics and experiment tests .Finally, the electrotactic behavior of the rhabdomyosarcoma RD cells in the DC field of different strength was characterized using the accumulated distance, average velocity, x forward migration index ( xFMI) and y forward migration index ( yFMI) as quantitative parameters.Results The results of element analysis and experiments showed that the structure of the designed microfluidic electrotaxis chip was able to guarantee a uniform and strength-controllable DC field in the microchannel .The experiment of cell electrotaxis showed that the RD cells migrated toward the anode of the DC field .Meanwhile , the values of xFMI and accumulated distance for RD cells increased with the enlargement of the DC field , with the strength ranging from 188 to 1320 V/m.Conclusion The microfluidic chip technology developed in this paper for assaying the electrotaxis of cancer cells is simple and easily implementable , and it can be used for studies of the electrotactic behavior and underlying mechanisms of various cancer cells and normal cells in the future .