ABSTRACT
Abstract Drought stress is the main limiting factor of soybean yield. Currently, genetic engineering has been one important tool in the development of drought-tolerant cultivars. A widely used strategy is the fusion of genes that confer tolerance under the control of the CaMV35S constitutive promoter; however, stress-responsive promoters would constitute the best alternative to the generation of drought-tolerant crops. We characterized the promoter of α-galactosidase soybean (GlymaGAL) gene that was previously identified as highly up-regulated by drought stress. The β-glucuronidase (GUS) activity of Arabidopsis transgenic plants bearing 1000- and 2000-bp fragments of the GlymaGAL promoter fused to the uidA gene was evaluated under air-dried, polyethylene glycol (PEG) and salt stress treatments. After 24 h of air-dried and PEG treatments, the pGAL-2kb led to an increase in GUS expression in leaf and root samples when compared to the control samples. These results were corroborated by qPCR expression analysis of the uidA gene. The pGAL-1kb showed no difference in GUS activity between control and treated samples. The pGAL-2kb promoter was evaluated in transgenic soybean roots, leading to an increase in EGFP expression under air-dried treatment. Our data indicates that pGAL-2kb could be a useful tool in developing drought-tolerant cultivars by driving gene expression.
ABSTRACT
Objective To construct the vector for ?-galactosidase (?-gal) gene expression regulation with tetracycline-regulated gene expression system,and to control ?-galactosidase gene expression in hepG2 cells with the vector.So that offer a experimental base for regulating gene expression for liver cancer gene therpy with this system.Methods The primers for explanding two tetracycline operator (TetO2) gene according to the gene nucleotide sequences of TetO2 gene and pcDNA3.1 vector were designed.TetO2 gene was amplified by PCR with pcDNA3.1 plasmid as template.The TetO2 PCR products were cloned into pcDNA3.1 and the vector was named as pcDNA3.1-TetO2.The pcDNA3.1-Teto2 with TetO2 PCR products sequence was analyzed by ABI3130 sequencing analysis.Then ?-gal gene was cloned into pcDNA3.1-TetO2,the vector was named as pcDNA3.1-TetO2-?-gal.The pcDNA6/TR plasmid vector with tetracycline repressor(TR) was transfected into HepG2 cells by Lipotap,and the stable transfection cells were screened by blasticidin.TR gene expression was detected by RT-PCR in HepG-2 cells with and without pcDNA6/TR plasmid transfection.The pcDNA3.1-TetO2-?-gal plasmid vector was transfected into HepG2 cells with and without pcDNA6/TR plasmid transfection,and 3 to 4 d later, these transfected gene cells were treated with doxycline(4 mg?L-1).After 48 h,?-gal gene expression was detected with ?-gal cell staining.Results The pcDNA3.1-TetO2 sequencing analysis results showed that a cassette was made for a cytomegalovirus-type 2 tetracycline operator (TetO2)-TetO2 promoter in pcDNA3.1-Teto2.The double digestion reslut of pcDNA3.1-TetO2-?-gal plasmid vector demonstrated that ?-gal gene was successfully cloned into pcDNA3.1-TetO2 vector .The RT-PCR result of TR gene showed TR gene could be expressed in HepG2 cells with pcDNA6/TR plasmid transfection and TR gene didn’t express in HepG2 cells without pcDNA6/TR plasmid transfection.?-gal gene expressed in HepG2 cells without pcDNA6/TR plasmid transfection,but didn’t express in HepG2 cells with pcDNA6/TR plasmid transfection.However,?-gal gene expression could be induced with doxycline in HepG2 cells with pcDNA6/TR plasmid transfection.Conclusion The tetracycline-regulated gene expression system vector for regulating ?-gal gene expression is successfully constructed and the vector system can control ?-gal gene expression in HepG2 cells.
ABSTRACT
Objective: Purpose to investigate the different in vitro function of targetable non-viral vector containing poly-L-lysine or protamine. Methods: Using GV1 and GV2 targetable non-viral vectors, the influences of the poly-L-lysine and protamine on in vitro gene transfer efficiency and the course of gene expression were observed. Results: ?-galactosidase was expressed at intermediate level (50% ) in A375 cells using a complex containing either protamine or poly-L-lysine. Howerver, in case of ABAE cells, ?－galactosidase expression level was low (20% ) transferred with a comPlex containing protamine. On the contrary, ?－ galactosidase expression was at high level (70% ) provided that protamine was replaced with poly-L-lysine. In addition, ?-galac- tosidase activity reached the peak at the 6th day after transfection with the complex containing protamine. The expression was not altered with subsequent subcultures, at least for 3 passages. Using poly-L-lysine, the expression peak in A375 reached the peak at the 7th day after transfection, but the level declined along with subsequent passages of cells. Conclusion: The apllication of protamine in VEGF receptor mediated gene delivery system was limited.