Expression of the Capsid Precursor Protein gene of Foot-and-mouth Disease Virus and Green Fluorescent Protein Gene in BHK-21 Cells Mediated by Retroviral Vector

We have constructed a retroviral vector mediated mammalian cell expression system of the capsid precursor protein of foot-and-mouth disease virus(FMDV).The recombinant retroviral vector pBABEpuro-P1-2A-EGFP was constructed by sequentially inserting capsid precursor protein gene(P1) of FMDV and enhanced green fluorescent protein gene(EGFP) into pBABEpuro.The recombinant retroviral vector and the pVSV-G plasmid were co-transfected into packaging cells(GP2-293) by liposomemediated transduction to produce the pseudovirus.The pseudovirus was used to infect BHK-21 cells and resistant cells were screened with puromycin.Green fluorescent proteins were observed by fluorescence microscopy and expression of the capsid precursor protein gene of FMDV was detected by indirect immunofluorescence.The recombinant retroviral vector pBABEpuro-P1-2A-EGFP was constructed successfully.The capsid precursor protein of FMDV and green fluorescent protein were expressed in BHK-21 cells.The mammalian cell expression system for the capsid precursor protein of FMDV has been constructed successfully,which lays the foundation of development of a FMDV subunit vaccine.

Construction of the Eukaryotic Expression Vector with EGFP and hVE GF121 Gene and its Expression in Rat Mesenchymal Stem Cells

Objectives To construct a recombinant plasmid carrying enhanced green fluore- scent protein (EGFP) and human vascular endothelial growth factor (VEGF) 121 gene and detect its expre- ssion in rat mesenchymal stem cells (MSCs). Methods Human VEGF121 cDNA was amplified with polymerase chain reaction (PCR) from pCD/hVEGF121 and was inserted into the eukaryotic expression vector pEGFP- C1. After being identified with PCR, double enzyme digestion and DNA sequencing. The recombinant plasmid pEGFP/hVEGF121 was transferred into rat MSCs with lipofectamine. The expression of EGFP/VEGF121 fusion protein were detected with fluorescence microscope and immunocytochemical staining respectively. Results The recombinant plasmid was confirmed with PCR, double enzyme digestion and DNA sequencing. The fluoresce- nce microscope and immunocytochemical staining results showed that the EGFP and VEGF121 protein were expressed in MSCs 48 h after transfection. Conclusions The recombinant plasmid carrying EGFP and human VEGF was successfully constructed and expressed positively in rat MSCs. It offers a promise tool for further research on differentiation of MSCs and VEGF gene therapy for ischemial cardiovascular disease.

Construction of OsWRKY17 Specific Expression Vector in Rice

[Objective] To study the physiological biochemical characteristic of Os- WRKY17 in rice and identify the subcellular location of OsWRKY17. [Method] The primer of the OsWRKY17 gene was designed according to the full-length sequence of OsWRKY17 in Genbank and was cloned by RT-PCR. The cloned fragment was then recombined with the green fluorescent protein gene of plasmid vector pBinGFP. The recombinant plasmid pBinGFP-OsWRKY17 was transformed into Arabidopsis through Agrobacterium tumefaciens strain GV3101. [Result] Colony PCR and diges- tion identification proved that the plant expression vector pBinGFP-OsWRKY17 was successfully constructed by the fusion of OsWRKY17 and GFP, and the expression vector was successfully transformed into the genome of Arabidopsis, there by ob- taining a resistant plant. [Conclusion] The construction of OsWRKY17 expression vector established the foundation for study on the physiological the biochemical char- acteristics of QsWRKY17.

Efficient generation of transgenic chickens using the spermatogonial stem cells in vivo and ex vivo transfection

The highly efficient novel methods to produce transgenic chickens were established by directly in-jecting the recombinant plasmid containing green fluorescent protein (GFP) gene into the cock's testis termed as testis-medianted gene transfer (TMGT), and transplanting transfected spermatogonial stem cells (TTSSCs). For the TMGT approach,four dosages of pEGFP-N1 DNA/cationic polymer complex were injected intratesticularly. The results showed: (1) 48 h after the injection,the percentages of testis cells expressing GFP were 4.0%, 8.7%, 10.2% and 13.6% in the 50, 100, 150 and 200 μg/mL group, re-spectively. The difference from the four dosage groups was significant (P<0.05). On day 25 after the injection, a dosage-dependent and time-dependent increase in the number of transgenic sperm was observed. The percentages of gene expression reached the summit and became stable from day 70 to 160, being 12.7%, 12.8%, 15.9% and 19.1%, respectively. The difference from the four dosage groups was also significant (P<0.05). (2) 70 d after the injection, strong green fluorescent could be observed in the seminiferous tubules by whole-mount in-situ hybridization. (3) 70 d after the injection, the semen was collected and used to artificially inseminate wild-type females. The blastoderms of F1 and F2 transgenic chicken expressed GFP were 56.2% (254/452) and 53.2% (275/517), respectively. The detec-tion of polymerase chain reaction (PCR) of F1 and F2 transgenic chicken blood genomic DNA showed that 56.5% (3/23) of F1 and 52.9% (9/17) of F2 were positive. Southern blot showed GFP DNA was in-serted in their genomic DNAs. (4) Frozen whole mount tissue sections of F1 and F2 transgenic chicken liver, heart, kidney and muscle showed that the rates of green fluorescent positive were between 50.0% and 66.7%. (5) With the TTSSCs method, SSCs ex vivo transfected with GFP were transplanted into recipient roosters whose endogenic SSCs had been resoluted. The donor SSCs settled and GFP ex-pression became readily detectable in the frozen whole mount tissue sections of recepient testes. Moreover, sperms carrying GFP could be produced normally. The results of artificially inseminating wild-type females with these sperms showed 12.5% (8/64) of offspring embryo expressed GFP and 11.1% (2/18) hatched chicks were tested transgenic. Our data therefore suggest TMGT and TTSSCs are the feasible methods for the generation of transgenic chickens.

Mesenchymal stem cells transduced by PLEGFP-N1 retroviral vector maintain their biological features and differentiation

Background Enhanced green fluorescent protein （EGFP） has been an important reporter gene for gene therapy. Human mesenchymal stem cells （hMSCs） are ideal target cells in cell transplantation and tissue engineering. We investigated their biological characteristics and differentiation mediated by PLEGFP-N1 retroviral transduction.Methods hMSCs were isolated from human bone marrow by density gradient fractionation and adherence to plastic flasks. Individual colonies were selected and cultured in tissue dishes. Packaging cells PT67 were transfected by PLEGFP-N1 retroviral vector , and hMSCs were transduced by viral supernatant infection. Meanwhile, hMSCs-EGFP were identified by immune phenotypes and whether it could differentiate into osteoblasts or adipocytes under conditioned media was investigated.Results The rate of stably transduced hMSCs-EGFP was up to 96% after being screened by G418. hMSCs-EGFP exhibited fibroblast-like morphological features. Flow cytometric analyses showed that hMSCs-EGFP were positive for CD73, CD105, CD166, CD90 and CD44, but negative for CD34 and CD45. In addition, it could functionally be induced into osteocytes or adipocytes under conditioned media. These biological features of hMSCs-EGFP were consistent with those of hMSCs.Conclusions hMSCs transduced by PLEGFP-N1 retroviral vector can be used in vivo securely because they can maintain their biological characteristics and differentiation. It is a simple and reliable way to trace the changes of hMSCs in vivo by EGFP during cell transplantation and gene therapy.