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The conventional peptide substrates of SARS-CoV-2 main protease (Mpro) are frequently associated with high cost, unstable kinetics, and multistep synthesis. Hence, there is an urgent need to design affordable and stable Mpro substrates for pharmacological research. Herein, we designed a functional Mpro substrate based on a dimerization-dependent red fluorescent protein (ddRFP) for the evaluation of Mpro inhibitors in vitro . The codon-optimized DNA fragment encoding RFP-A 1 domain, a polypeptide linker containing Mpro cleavage sequence (AVLQS), and the RFP-B 1 domain was subcloned into the pET-28a vector. After transformation into Escherichia coli Rosetta(DE3) cells, the kanamycin resistant transformants were selected. Using a low temperature induction strategy, most of the target proteins (ddRFP-M) presented in the supernatant fractions were collected and purified by a HisTrap TM chelating column. Subsequently, the inhibition of Mpro by ensitrelvir and baicalein was assessed using ddRFP-M assay, and the biochemical properties of ddRFP-M substrate were analyzed. Our results showed that the fluorogenic substrate ddRFP-M was successfully prepared from E . coli cells, and this biosensor exhibited the expected specificity, sensitivity, and reliability. In conclusion, the production of the fluorogenic substrate ddRFP-M provides an expedient avenue for the assessment of Mpro inhibitors in vitro .

Objective To investigate the tumor microenvironment of immune tolerance induced by glioma stem cells (GSC). Methods Human GSC SU3 cells transfected with red fluorescent protein (SU3-RFP) gene were implanted into the brain, subcutis (armpit and foot), liver and abdominal cavity of transgenic green fluorescence protein (OFF) nude mice to establish RFP+/GFP+ dual fluorescence solid tumor model. The re-cultured cells derived from implanted tumor tissues, SU3-RFP cells eo-cultured with peritoneal fluid of transgenic OFF nude mice and malignant ascites of tumor-bearing mice were observed by fluorescence microscopy and real-time video image tracing to analyze the microenvironment of immune tolerance mediated by RFP+/GFP+ implanted tumor. Results Dual fluorescence labeled frozen section showed that all of cells in the tumor microenvironment were GFP+, while the pressed tissue-patch showed that the tumor blood vessels exhibited a RFP+/GFP+ double-positioning yellow. In the GFP single fluorescence labeled tumor tissue, all of cells in the microenvironment were green, including tumor edge, necrotic foci and blood vessel. Among them, CD68+, F4/80+, CD11c+, CD11b+ and CD80+ cells were observed. In the dual fluorescence labeled co-cultured cells, the phagocytosis and fusion between green host cells and red tumor cells were also observed, and these fusion cells might transfer to the malignant dendritic cells and macrophages. Conclusions The tumor microenvironment of immune tolerance induced by GSC is not affected by the tissue types of tumor-inoculated sites, and the immune tolerance mediated by inflammatory cells is associated with the inducible malignant transformation, which may be driven by cell fusion. [ABSTRACT FROM AUTHOR]

Objective: To establish a nude mouse model of subcutaneous lung cancer using dual fluorescence reporting genes of luciferase (Luc) and near-infrared fluorescent protein (iRFP). Methods: The Luc and iRFP expressed lentiviral vector was constructed by Gateway method. After verified by sequencing, the lentivirus particle was prepared and infected into lung cancer A549 cells. Successfully infected A549 (mA549) cells were selected by puromycin and amplified. The expression of Luc and iRFP were observed under fluorescence microscope, and the expression of c-Met protein on the cell surface was detected by immunofluorescence. Twelve female nude mice were randomly divided into 2 groups, 6 in each group. A549 and mA549 cells were inoculated subcutaneously into the right forelimb of nude mice. The growth and fluorescence expression of the tumor were observed by in vivo imaging. The tumor formation was evaluated by hematoxylin-eosin (HE) staining and immunohistochemistry. Results: The Luc and iRFP stably expressed mA549 cell line was successfully constructed. The expressions of iRFP and Luc in mA549 cells were observed under fluorescence microscope. The results of immunofluorescence showed that c-Met protein expressed in both A549 cells and mA549 cells. The growth period of mA549 xenograft in nude mice was moderate and the tumorigenesis rate was 100%. The growth trend of mA549 cells in vivo was not significantly different from that of A549 cells ( P >0.05). HE staining and immunohistochemistry results showed that the tumor issues displayed typical histopathological features of tumor. Immunohistochemistry results showed that both A549 and mA549 tumors expressed c-Met protein. Conclusion: A stable, real-time monitoring model of iRFP-Luc-A549 lung cancer cell xenograft in nude mice was successfully constructed.

In order to enrich the library of domestic research about new red fluorescent marker in lactic acid bacteria (LAB), we described a new fusion expression system in Lactobacillus plantarum WCFS1 based on the pSIP vector. This system contained red fluorescent protein mCherry as a marker and bile salt hydrolase gene (bsh) as a reporter gene. Moreover, in this study, four different promoters (PsppA, PldhL, P32 and PslpA) were used to regulate the expression of the fusion protein mCherry-BSH, completing the inducible and constitutive expression in lactic acid bacteria. The recombinant protein mCherry-BSH presented activity of red fluorescence and bile salt hydrolase (BSH). The successful construction of the fusion expression system in LAB using a red fluorescent protein mCherry provides favorable conditions for the distribution, intestinal colonization and survival rate of lactic acid bacteria, so as to reveal the function mechanism of its probiotic characteristics; and the system also could lay the foundation for researches on protein expression, cellular localization and properties identification of active protein in lactic acid bacteria.

Objective: To construct the expression vectors for red fluorescent protein fused with inhibiting peptides for nuclear import (Bimax),and explore the location of Bimax and its potential effects on cell proliferation and migration in HeLa cells., Methods: Two kinds of polynucleotide encoding inhibiting peptides for nuclear import were synthesis respectively and subsequently annealed for inserting into vector pDs-Red-C1. The recombinant plasmids were transfected into competent bacterial DH-5α. After transfection,the positive bacteria were picked up for DNA sequencing. The recombinant plasmids pDs-Red-Bimax2,pDs-Red-Bimax1 and negative plasmid pDs-Red-C1 were transfected into HeLa cells respectively according to Lipofectamine2000 protocol. After transfection,the expression and location of red fluorescent protein were observed with fluorescence microscope. Furthermore,MTT assay and cell-migration assay were used to detect the proliferation and migration of Bimax transducted cells., Results: DNA sequencing showed that the polynucleotides encoding Bimax1 or Bimax2 were inserted into pDs-Red-C1 vector successfully. After transfected into HeLa cells,the inhibiting peptide induced red fluorescent protein locating in nuclear. Furthermore,either the fusion protein RFP-Bimax1 or RFP-Bimax2 can suppress the proliferation and migration of HeLa cells., Conclusion: The expression vectors for red fluorescent protein fused with inhibiting peptides for nuclear import were successfully constructed. In addition,the fusion proteins were expressed and located in nuclear and suppressed the proliferation and migration of tumor cells.

Proinsulin (Pins) is the precursor of insulin. The expression of proinsulin in Escherichia coli forms inclusion body, so that the recombinant protein should be processed with multiple steps to form active insulin. With the development in biotechnology, cell-free protein synthesis (CFPS) system is becoming a valuable tool in protein expression by decoupling the cell growth with protein production, which allows it to express proteins that would interfere with cell physiology. In this study, we synthesized soluble proinsulin in CFPS system in order to establish a new approach for both insulin expression and delivery. The soluble proinsulin was successfully expressed in CFPS system by fusing proinsulin with two types of fluorescent protein. The expression of Pins-mCherry was confirmed by Western blotting analysis, and the Pins-eGFP titer was (12.28±3.45) μg/mL in CFPS system. These results implicated that the proinsulin was expressed partially in soluble form. Here, for the first time, we successfully expressed soluble proinsulin in CFPS system by fluorescent protein fusion. These results provide useful information in developing new insulin expression and delivery method.

Objective: To observe mutual interactions between macrophages(Mφ) and glioma stem cells (GSCs)in dual-color tracing model in vitro, to identify the biological characteristics of fusion cells in multiple levels, and to analysis the relevant molecular mechanisms. Methods: Red fluorescent protein(RFP) gene was stably transfected into human GSCs cell line SU4. Mφ cells were obtained from Balb/c nude mice with enhanced green fluorescent protein (EGFP) expression. Then two cells were co-cultured in dual-color tracing platform. RFP/EGFP double positive cells with high proliferation ability were mono-cloned. The fusion cells were verified by Western blot, fluorescence in situ hybridization, immunocytochemistry and chromosome karyotype analysis.The biological characteristics of fusion cells were further analyzed, together with relevant molecular changes. Results: RFP / EGFP double positive cells were obtained through in vitro co-culture. RFP and EGFP coexpression were proved at transcriptional and translational levels in the fusion cells. They also co-expressed GSCs marker Nestin and Mφ marker CD68, and karyotype analysis showed two types of characteristic chromosomes, which confirmed that the fusion cells originated from spontaneous fusion between SU4-RFP and Mφ.Fusion cell proliferation rate and invasion ability were higher than SU4-RFP, which were relevant with down-regulation of miR-146b-5p and activation of STAT3. Fusion cells transfected with miR-146b-5p showed a higher apoptosis rate(18.83%) and lower tumor formation(4/5). Conclusion: Mφ could fuse with GSCs spontaneously in local tumor micro-environment. The proliferation and invasion abilities of fusion cells were higher than their parent cells, which were relevant with down-regulation of miR-146b-5p and activation of STAT3. It revealed the possible mechanisms of malignant progression of gliomas.

Objective: To establish the transgenic RAW264.7 monoclone cell line labelled by green fluorescent protein(GFP) and modified red fluorescent protein(mRFP), for investigating the mechanism of cell membrane fusion and cell biological behavior during osteoclastogenesis., Methods: A dual-labeling technique involving GFP and mRFP was applied to RAW264.7 cell line by pVSVG for in situ monitoring of membrane fusion during osteoclastogenesis. The live-cell imaging technology was adopted to consecutively observe the process of osteoclast formation induced by receptor activator of NF-κB ligand(RANKL). Furthermore, tartrate-resistant acid phosphatase staining(TRAP) and 4',6-diamidino-2-phenylindole(DAPI) staining were also used to identify the function and characteristics of RAW264.7 monoclonecell line transfected with phosphatidylserine(PS) and + 8 membrane charge., Results: The normal morphology of RAW264.7 monoclonecell line transfected with + 8-GFP and PS-mRFP was preserved. The PS and (8+) biosensors co-expressed on the membrane of monocytes. No significant difference of fluorescence density was found. In osteoclasts, (8 + )probes disappeared, while PS expressed in both internal organelles and membrane of osteoclasts. Live-cell imaging observation showed that the multinuclear osteoclasts were generated among monocytes and apocytes. All fusion processes occurred under the condition of cell adherence., Conclusions: Successful construction of transgenic RAW264.7 monoclone cell line by GFP and mRFP tags provided a wide field of vision for further investigating the cytoskeleton and organelles of subcellular spatial dimension in osteoclastogenesis.

Objective: To establish murine macrophage RAW264.7 cell strain with stable expression of red fluorescent protein-green fluorescent protein-microtubule associated protein light chain 3 (RFP-GFP-LC3)., Methods: A lentiviral vector containing RFP-GFP-LC3 gene was constructed and then packaged in HEK293T cells with the packaging plasmids. The viral supernatant was collected to infect RAW264.7 cells. The RAW264.7 cell strain with stable expression of RFP-GFP-LC3 was screened with puromycin and analyzed with flow cytometry and fluorescent microscopy for infection efficiency. The number of RFP-GFP-LC3 puncta was observed using florescence microscopy following starvation treatment., Results: The recombinant lentivirus pLV-CMV-RFP-GFP-LC3 was successfully constructed. The RAW264.7 cells with stable expression of RFP-GFP-LC3 were obtained by viral infection and puromycin screening. Fluorescent microscopy and flow cytometry demonstrated the expression rates of RFP and GFP reached to 100%. The number of autophagic puncta significantly increased after starvation treatment., Conclusion: The RAW264.7 cell strain with stable expression of RFP-GFP-LC3 has been successfully constructed, which provides a reliable cellular platform for autophagy research.

Objective: To observe the co-localization of human immunodeficiency virus (HIV) capsid protein p24 and tripartite motif containing 22 (TRIM22) in HEK293T cells., Methods: The retroviral packaging vector pLP1 was used as the template of p24. After the amplification by PCR, the sequence of p24 was cloned into the eukaryotic expression vector pDsRed-Monomer-N1. The recombinant vector was confirmed by colony PCR, double restriction enzyme digestion and DNA sequencing. HEK293T cells were co-transfected with the vector pDsRed-Monomer-N1-p24 together with pEGFP-N3-TRIM22. After 24 hours, the co-localization of p24-DsRed-Monomer and TRIM22-EGFP was detected under a fluorescence microscope., Results: Colony PCR, double restriction enzyme digestion and DNA sequencing confirmed that the eukaryotic expression vector pDsRed-Monomer-N1-p24 was constructed successfully. Fluorescence microscope showed that p24-DsRed-Monomer was co-localized with TRIM22-EGFP in HEK293T cells., Conclusion: HIV capsid protein p24 is co-localized with TRIM22 in HEK293T cells.

Objective: The aim of this study was to clarify whether the fusion of bone marrow mesenchymal stem cells (MSCs) with tumor cells can promote tumor angiogensis., Methods: Human glioma stem/progenitor cells (GSPCs) (SU3 cells) were transfected with red fluorescent protein (RFP) gene. Bone marrow mesenchymal stem cells (MSCs) were harvested from nude mice with whole-body green fluorescent protein (GFP) gene expression. Then the two kinds of cells were co-cultured in vitro. At the same time SU3-RFP was transplanted into the brain of GFP-expressing nude mice to establish xenograft tumors. The co-cultured cells, GFP/RFP double positive (yellow) cells and blood vessels obtained from the xenograft tumors were observed under fluorescent microscope and laser scanning confocal microscope., Results: After five passages in vitro, MSCs maintained the proliferative activity and highly expressed CD105. CD105 was also expressed in the femurs of GFP-expressing nude mice, tumor cells, blood vessels of SU3 xenograft tumors, and clinical malignant gliomas. When MSCs were co-cultured with SU3-RFP, the ratio of yellow cells co-expressing RFP and GFP was significantly increased after extended time and continuous passages. According to the flow cytometry, yellow cells co-expressing RFP and GFP were 83.7% of the cultured cells. In tissue slices of the xenograft tumors, bundles of yellow vessel-like structure and cross-sectioned yellow vascular wall structures including vascular wall stroma cells were observed with RFP and GFP expression, and were identified as de novo formed vessels derived from fusion of MSCs with SU3-RFP cells., Conclusion: Cell fusion occurs between tumor cells and host MSCs and it promotes tumor angiogenesis.

Objective: To evaluate the survival of bone marrow mesenchymal stem cells (BMMSC) and periodontal ligament stem cells (PDLSC) in BMMSC/PDLSC cell sheets which transplanted ectopically into subcutaneous dorsum of nude mice., Methods: The canine BMMSC and PDLSC from primary culture were tranfected with lentiviral vectors carrying green fluorescent protein (GFP) gene (Lentivirus-GFP) or red fluorescent protein (RFP) gene (Lentivirus-RFP) respectively. The immunophenotypes of GFP-labeled BMMSC and RFP-labeled PDLSC were identified by flow cytometry. Adipogenic and osteogenic differentiation of them were detected by alizarin red or oil red O respectively. Then, both GFP-labeled BMMSC cell sheets and RFP-labeled PDLSC cell sheets were fabricated respectively using normal culture dish (6 cm) after stimulation of extracellular matrix formation. Each was enveloped by collagen membrane (Bio-Gide) and then transplanted into the subcutaneous dorsum of nude mice. In vivo non-invasive biofluorescence imaging(BFI) was performed at 1, 2, 4 and 8 w post-tranplantation to trace and quantify the survival and growth of RFP-labeled PDLSC and GFP-labeled BMMSC via the BFI system of the NightOWL. The fluorescence intensity change of GFP/RFP signal was monitored and compared. The mice were sacrificed 8 weeks after cell sheets transplantation and the survival of stem cells was verified by fluorescence immunohistochemistry., Results: The flow cytometry showed that GFP-labeled BMMSC positively expressed CD29, CD44, CD34, STRO-1 were 93.07%, 92.84%, 3.23%, 67.67%, and RFP-labeled PDLSCs were 89.91%, 88.47%, 6.04%, 74.11%, respectively. Both of them had the potency of differentiating into osteoblasts and adipocytes. The stemness of both of them was almost same. After being transplanted into nude mice, the signal strength of GFP(BMMSC) was weaker and weaker in 1, 2, 4 and 8 w [(83.1±3.1)×10(6), (65.1±2.3)×10(6), (51.5 ± 2.3)×10(6), (33.8 ± 2.0)×10(6) ph/s, respectively.]. The signal strength of RFP(PDLSC) was weakenedin 1, 2 and 4 w [(53.8±3.0)×10(6), (42.2±2.6)×10(6), (34.5±2.1)×10(6) ph/s], then recovered in 8 w ([ 45.1±2.9)×10(6) ph/s]. The signal strength of RFP(PDLSC) was signifcantly stronger in 8 w than in 4 w(P < 0.01). The survival of RFP-labeled PDLSC was significant higher than that of GFP-labeled BMMSC. After 8 weeks, lots of RFP-labeled PDLSC were observed by microscope, but less GFP-labeled BMMSC were observed., Conclusions: Histometric analysis revealed that the survival of stem cells in the RFP-labeled PDLSC cell sheets was significantly higher than that of in the GFP-labeled BMMSCs cell sheets.

Objective: Tumor stromal cells have the potential of undergoing malignant transformation induced by glioma stem cells (GSCs) in orthotopic glioma model. The purpose of this study was to explore whether malignant transformation of tumor stromal cells induced by GSCs is dependent on specific local microenvironment., Methods: Human glioma stem/progenitor cell line SU3 transfected with red fluorescent protein (SU3-RFP) gene were implanted into the liver of nude mice with whole-body expressing green fluorescence protein (GFP). Then hepatic tumors were harvested to prepare single cell suspension and analyzed with routine pathological examinations. GFP cells with high proliferative abilities were obtained from the cultivation of single cell suspension. Immortalized glioma stromal cells only expressing GFP and double expressing GFP/RFP were further monocloned with micro-pipetting techniques and under continuous passages. Cell phenotypic analysis and tumorigenicity tests were also performed., Results: SU3-RFP was transplanted into liver with a tumor formation rate of 83%. Immortalized glioma stromal cells were obtained from re-cultured xenograft tumor tissue. Three monoclonal cell lines B4, B9, B10 were established and proved to be host-derived cells. B4 was found to be a fusion cell co-expressing GFP/RFP and dendritic cell markers CD1 a, CD83 and CD86. Both B9 and B10 were GFP⁺ cells. B9 expressed macrophage markers CD68 and F4/80 while B10 produced fibroblast marker proteins FAP-α, α-SMA and S100. Three cells were all aneuploid with a tumorigenicity rate of 100% in nude mice., Conclusion: Tumor stromal cells have the potential of malignant transformation in a heterotopic xenograft glioma model. Malignant transformation may also occur outside the central nervous system and contribute to tumor heterogeneity. Further studies are warranted for elucidating the relationship between tumorigenesis, evolution and tumor microenvironment.

Objective: To construct a eukaryotic expression vector to express the hepatitis E virus protein open reading frame 3 (ORF3) and investigate the intracellular location of the expressed protein using the baby hamster kidney (BHK-21) fibroblast cell line., Methods: The ORF3 gene was amplified by RT-PCR, cloned into the HindIII and EcoRI sites in the multicloning site of the pDsRed-Monomer-N1mammalian expression vector that encodes a red fluorescent protein (DsRed), and confirmed by restriction enzyme digestion and sequencing. The recombinant plasmid was then transfected into BHK-21 cells via the Lipofectamine 2000 reagent; the subsequent ORF3 gene overexpression was confirmed by RT-PCR and the protein expression and location was detected by Western blotting and immunofluorescence assay.Results TThe pDsRed-Monomer-N1-ORF3 recombinant plasmid was successfully constructed. After transfection into BHK-21 ceils, the ORF3 gene was transcribed and expressed, and the ORF3 protein was mainly located in the cytoplasm, where it could react with a specific antibody., Conclusion: The ORF3-DsRed fusion protein was mainly located in the cytoplasm of BHK-21 fibroblasts, and may represent a useful tool for research on the role of this protein in HEV infection.

Objective: To establish red-green dual-color fluorescence glioma model in nude mice and to explore its practical values., Methods: CM-DiI-stained rat glioma C6 cells (C6-CM- DiI cells) expressing red fluorescence were inoculated into the brain of athymic nude mice expressing green fluorescence protein (NC-C57BL/6J-EGFP). Then the whole-body dual-color fluorescence imaging was detected dynamically. Finally whole brains of the tumor-bearing mice were removed and 5 µm thick serial frozen slices were made. Light microscopy, fluorescence microscopy and confocal laser scanning microscopy were performed to observe the transplanted tumor tissue structure and fluorescent cells., Results: Tumor mass with red fluorescence increased gradually under continuous in-vivo fluorescence imaging monitoring. Under the fluorescence microscope, cells with red, green and yellow fluorescence were observed in the frozen sections of transplanted tumor tissue and the mutual structural relationship among them could be defined. The tumor cells migration, implantation and cell fusion between transplanted tumor cells and host cells could be observed. It could be distinguished according to the fluorescence, that blood vessels of tumor-origin displayed red fluorescence, blood vessels of host-origin displayed green fluorescence and mosaic blood vessels appeared yellow fluorescence. It was depicted that host innate astrocytes and oligodendrocytes in the microenvironment at the tumor periphery could be activated and dedifferentiated into nestin-positive cells., Conclusions: In contrast to traditional animal model, the dual-color fluorescence imaging of nude mouse models of glioma possesses enormous advantages in investigating tumor mass in-vivo fluorescence imaging, tumor cells migration and metastasis, tumor angiogenesis and reactive activation of host innate cells in the microenvironment at tumor periphery, thus, has highly practical application value.

Synthetic biology of natural products is the design and construction of new biological systems by transferring a metabolic pathway of interest products into a chassis. Large-scale production of natural products is achieved by coordinate expression of multiple genes involved in genetic pathway of desired products. Promoters are cis-elements and play important roles in the balance of the metabolic pathways controlled by multiple genes by regulating gene expression. A detection plasmid of Saccharomyces cerevisiae was constructed based on DsRed-Monomer gene encoding for a red fluorescent protein. This plasmid was used for screening the efficient promoters applying for multiple gene-controlled pathways. First of all, eight pairs of primers specific to DsRed-Monomer gene were synthesized. The rapid cloning of DsRed-Monomer gene was performed based on step-by-step extension of a short region of the gene through a series of PCR reactions. All cloned sequences were confirmed by DNA sequencing. A vector named pEASYDs-M containing full-length DsRed-Monomer gene was constructed and was used as the template for the construction of S. cerevisiae expression vector named for pYeDP60-Ds-M. pYeDP60-Ds-M was then transformed into S. cerevisiae for heterologous expression of DsRed-Monomer gene. SDS-PAGE, Western blot and fluorescence microscopy results showed that the recombinant DsRed-Monomer protein was expressed successfully in S. cerevisiae. The well-characterized DsRed-Monomer gene was then cloned into a yeast expression vector pGBT9 to obtain a promoter detection plasmid pGBT9Red. For determination efficacy of pGBT9Red, six promoters (including four inducible promoters and two constitutive promoters) were cloned by PCR from the S. cerevisiae genome, and cloned into pGBT9Red by placing upstream of DsRed-Monomer gene, separately. The fluorescence microscopy results indicated that the six promoters (GAL1, GAL2, GAL7, GAL10, TEF2 and PGK1) can regulate the expression of DsRed-Monomer gene. The successful construction of pGBT9Red lays the foundation for further analysis of promoter activity and screening of promoter element libraries.

Objective: During the process of tissue remodeling in human tumor transplantation models, the roles of the inoculated tumor cells and host tissue in tumor progression is still largely unknown. The aim of this study was to investigate the relationships and interactions between these two sides using GFP-RFP double fluorescence tracing technique., Methods: Red fluorescence protein (RFP) gene was stably transfected into glioma stem cell line SU3, then SU3-RFP cells were transplanted into the brain of athymic nude mice with green fluorescence protein (GFP) expression. After the intracerebral tumors were formed, the relationship and interaction between GFP cells and RFP cells were analyzed. Highly proliferative GFP cells were screened out, and monocloned with micro-pipetting. DNA content assay, chromosome banding and carcinogenicity test of the GFP cells were performed to observe the GFP cells' cancerous phenotype in nude mice., Results: In the transplantable tumor tissue, besides a great quantity of RFP cells, there were still a proportion of GFP cells and GFP/RFP fusion cells. The proportion of RFP cells, GFP cells and GFP/RFP cells were (88.99 ± 1.46)%, (5.59 ± 1.00)%, and (4.11 ± 1.020)%, respectively. Two monoclonal host GFP cells (H1 and H9) were cloned, which demonstrated the properties of immortality, loss of contact inhibition, and ultra-tetraploid when cultured in vitro. Both H1 and H9 cells expressed CNP, a specific marker of oligodendrocytes. The GFP cells also demonstrated 100% tumorigenic rate and high invasive properties in vivo., Conclusions: In this glioma transplantation model, the transplanted tumor tissues contained not only transplanted glioma stem cells but also cancerous host GFP cells. Our findings offer important clues to further research on the relationships among different members in the tumor microenvironment.

Objective: To establish an animal model of prostate cancer (PCa) metastasis to the lung using PCa PR7 (PCa PC-3 cells stably expressing red fluorescent protein AsRed2) cell lines that can be monitored by in vivo fluorescence imaging technology., Methods: MTT and Transwell assay were used to compare the abilities of proliferation, migration and invasion of PC-3 and PR7 cells. Twenty BALB/c nude mice were equally randomized to 4 groups to receive tail vein injection of PR7 cell suspension at the concentration of 1 x 107/ml (group A), 2.5 x 107/ml (group B), 5 x 107/ml (group C) and 2.5 x 107/ml followed by the same dose 1 week later (group D). PCa metastasis to the lung was then monitored by in vivo fluorescence imaging technology at the end of 2, 4, 6 and 8 weeks., Results: There were no statistically significant differences between PC-3 and PR7 cells in their abilities of proliferation, migration and invasion (P > 0.05). At the end of 4 weeks, lung metastasis was observed in 40% of the mice in group D, and at the end of 8 weeks, it was detected in 20% in group A, 60% in group B, 100% in group C, and 100% in group D, all confirmed by pathological examination., Conclusion: The animal model of PCa metastasis to the lung that can be monitored by in vivo fluorescence imaging technology was established successfully by tail vein injection of PR7 cells carrying red fluorescent protein.

Objective: To construct a red fluorescent shuttle vector controlled by recA operon promoter to transform Streptococcus mutans., Methods: The promoter of recA was amplified from Streptococcus mutans UA159, and connected to plasmid pDsRed2-N1 to construct pRred with a red fluorescent coding gene, which was then inserted into the shuttle vector pDL276 to construct pLRred., Results: pLRred was successfully constructed, and Escherichia coli transformed with the pLRred plasmid could express reporter gene DsRed., Conclusions: The recombination plasmid pLRred can be used in the further research of the expression of cariogenic virulence factor gene by Streptococcus mutans in biofilm.

This study was aimed to construct, package and purify the recombinant lentivirus vector carrying the firefly luciferase gene (FLUC) and red fluorescent protein gene (RFP) and to transfect the recombinant lentivirus into HeLa cells, so as to observe the expression levels of these two genes. The FLUC and RFP genes were amplified by RT-PCR and inserted in the lentiviral expression vector (pLenti-Bi-cistronic) to construct the lentiviral vector pLenti-FLUC-RFP. The viral particles were generated by cotransfection of 293T cells with pLenti-FLUC-RFP and three packaging vectors, and the virus titer was determined by calculating the percentage of RFP positive cells. After transfection of pLenti-FLUC-RFP into HeLa cells, the expression of RFP was observed by fluorescent microscopy, and the activity of FLUC was determined by luciferase reporter gene assay kit. The results showed that the inserting orientation of the RFP and FLUC genes in the lentiviral vector pLenti-FLUC-RFP were verified by restriction analysis. Targeted RFP and FLUC sequences were confirmed by DNA sequencing. The final titer obtained was 1×10(7)TU/ml. The expressions of RFP and FLUC were observed in the transfected HeLa cells. It is concluded that the pLenti-III-FLUC-RFP recombinant lentivirus vector carrying RFP gene and FLUC gene with high viral titer is constructed and packaged successfully, and provides experimental basis for studying dynamic distribution of mesenchymal stem cells in vivo.

Aim: Used RFP gene to construct a RNA interference vector for convenience to obtain the good effective hairpins sequence., Methods: NUDC and RFP genes were cloned into pDs vector separately, resulting in pDs-NUDC- RFP. as above, human U6 promoter and 9 hairpins sequence of NUDC were cloned into the pDs- NUDC-RFP vector separately.The RNA interfererence vectors target to 9 points of NUDC were constructed. Construct- ed recombinant vectors and then were identified by restrictive digestion and DNA sequencing.293T cells were transfected with the recombinant DNA samples by the liposome complex method, and then fluorescence photographs were taken., Results: Enzyme digestion and DNA sequencing showed that the target gene and shRNA fragments were correctly inserted in pDs vector. fluorescence photographs showed that shNUDC-A is the best effective fragment., Conclusion: The NUDC gene targeted shRNA and its vector are successfully constructed.

Objective: To create far-red fluorescence protein reporter gene mKate2 lentivirus, label human liver cancer cell line HepG2 with lentivirus and explore the feasibility of in vitro fluorescence imaging of labeled tumor cells so as to provide experimental rationales for in vivo fluorescence tumor imaging., Methods: mKate2 gene was amplified from pmKate2-N plasmid. Then the fragment was inserted into the lentivirus expression vector pLenti6.3/V5-DEST. The expression plasmids pLenti6.3-mKate2 and the packaging plasmids were cotransfected into 293T cells. The biological titer of lentivirus was determined. HepG2 cells were infected with mKate2 lentivirus at a MOI (virus multiplicity of infection) of 6 for 96 hours. The infection efficiency was assayed through fluorescence microscope and fluorescent-activated cell scanning (FACS). And 2 × 10(6) mKate2-HepG2 cells were collected for fluorescence imaging through an optical imaging system. And the optimal imaging parameters were determined., Results: DNA sequencing analysis confirmed that mKate2 gene sequence was correct and there was no mutation or deletion. The biological titer of produced mKate2 lentivirus was 1.6 × 10(6) TU/ml. At 96 hours after mKate2 lentivirus infection, fluorescence microscope showed that mKate2 was expressed in a large percentage of cells. FACS assay showed that the mKate2 positive rate was 93.8% ± 0.4%. Excitation light 530 ± 15 nm and emission light 710 ± 28 nm were the optimal imaging parameters for mKate2-HepG2 cells., Conclusion: Lentivirus can mediate efficiently the mKate2 reporter gene labeling of human liver cancer cell line HepG2. The mKate2-labeled HepG2 cells can be detected through in vitro fluorescence imaging. Further tracing studies of in vivo tumor fluorescence imaging are technically feasible.

Aim: To construct the recombinant eukaryotic expression vector pDsRed1-C3/XAPC7 and to investigate the cellular localization of XAPC7 protein in 786-O and 293T and Chang liver cell lines., Methods: The cDNA of XAPC7 was amplified from HBE135-E6E7 cell line by RT-PCR method. The aim gene fragment XAPC7 from pMD18-T/XAPC7 was subcloned into eukaryotic expression vector pDsRed1-C3. The recombinant plasmid pDsRed1-C3/XAPC7 was identificated by BamH I/Xho I double digestion and sequence analysis, and then transfected into786-O and 293T and Chang liver cell lines by lipofectamine 2000. The expression and cellular localization of XAPC7 protein were detected by fluorescence microscope., Results: The construction of the recombinant plasmid pDsRed1-C3/XAPC7 was proved successfully by restriction enzyme digestion analysis and DNA sequencing. Red fluorescent protein pDsRed1-C3/XAPC7 was distributed granularly in transfected cell lines. Our researches showed that XAPC7 protein was mainly expressed in the cytoplasm of 786-O cell line, rare in its nucleus, evenly distributed in the cytoplasm and nucleus of 293T cell line, and mainly located in the cytoplasm of Chang liver cell line, few in its nucleus., Conclusion: The eukaryotic expression plasmid pDsRed1-C3/XAPC7 has been successfully constructed and expressed in the 786-O and 293T and Chang liver cell lines, but there was obvious difference in different cell lines. Our researches will help further studies on the function of human gene XAPC7.

Glutamate-1-semiadhyde aminotransferase (GSAT) is an enzyme in the upstream biosynthetic pathway of uroporphyrinogen III that is the substrate of uroporphyrinogen III methyltransferase (UPMT), a novel red fluorescent protein. In order to detect the effect of overexpression of GSAT with UPMT on the fluorescent intensity in Escherichia coli, we amplified maize upmt gene by PCR and inserted into the first cistron of pET Duet-1 plasmid to create the vector pETU. The expressed UPMT was fused histidine tag at N terminus. We also amplified E. coli hemL gene encoding GSAT by PCR reaction, eliminated Nco I site within the hemL gene by site-directed mutagenesis and subcloned into pET-51b plasmid. The resultant hemL gene was inserted the second cistron of pETU plasmid to produce the vector pETeGU. The expressed GSAT has the extra Strep-TagII at N terminus. Compared to overexpression upmt gene alone, coexpression both genes did not resulted in the remarkable change in either the amount of the UPMT, as estimated by western blot analysis, or the constitution of red fluorescent materials, as shown by UV/visible light scanning analysis, but increased cellular level of the fluorescent material trimethylpyrrocorphin with the specific absorption at 354 nm. The red fluorescence emitted by the colonies cooverexpressing both enzymes completely disappeared after treated by 2 mmol/L gabaculine, the GSAT inhibitor, suggested that the recombinant GSAT may increase the cellular level of uroporphyrinogen III, and thus enhanced the red fluorescence of the E. coli cells conferred by the recombinant UPMT.

Objective: CD133(+) tumor cells are regarded as cancer stem cells (CSCs), responsible for tumor initiation, development, and relevant with chemo- and radio-resistance of tumors. However, how the destiny of CD133(+) cells is regulated by their niche remains largely unknown. In this study the interpretation of the relationship between CD133(+) cells and their niche were performed through investigating the distribution characteristics of CD133(+) cells in transplanted human glioma xenograft., Methods: CD133(+) tumor cell spheres or tumor cells transfected with red fluorescent protein (RFP) gene were implanted in situ, subcutaneously or intraperitonealy in nude mice, then the xenografts were dissected and embedded in paraffin, stained with hematoxylin-eosin (HE), tumor tissues were further stained against CD133 with immunohistochemical and immunofluorescent techniques. The pathological structures of tumors and distribution characteristics of CD133(+) tumor cells were observed under microscope and confocal fluorescence microscope., Results: Under microscope, distribution of CD133(+) glioma cells showed certain regularity and can be classified morphologically into three types: cell clusters, in pairs and single cells. Distribution of CD133(+) cells can also be classified according to their distribution location: accumulating around tumor vasculature areas, among the vascular endothelial cells, or in the normal brain tissue and ventricles. Under fluorescence microscope and laser confocal microscope, some of vascular endothelial cells inside the tumor region and some cells around tumor vessels co-express CD133 and RFP., Conclusion: CD133(+) tumor cell clusters in nude mice are actually similar to those in CSCs spheres cultured in vitro. The single CD133(+) cells and CD133(+) cells in pairs represent asymmetric and symmetric division of CSCs within the CSCs niche, respectively. CD133(+) cells residing along tumor vessels are CSCs depending on CSC niche, and those locating far away from tumor blood vessels or tumor tissues, residing in normal brain tissues are the disseminated CSCs or neural stem cells which are not controlled or regulated by CSCs niche.

Objective: To investigate the expression of exogenous gene transferred by piggyBac (PB) transposon in various gynecological malignant cell lines and reveal its potential application of gene therapy in gynecological cancer., Methods: Amplified herpes simplex virus thymidine kinase (HSV-tk) gene coding region by PCR and integrated it into PB expression vector, PB[Act-RFP]DS, for reconstructing PB[Act-RFP, HSV-tk]DS (pPB/TK). By using different transfection reagents: FuGENE HD, jetPEI, lipofectamine 2000, pPB/TK together with helper plasmid Act-PBase were cotransfected into four mostly common gynecological malignant tumor cell lines HeLa, JEG-3, SKOV3 and HEC-1B. The mRFP1 report gene expressions was observed and detected by fluorescence microscope and flow cytometry to analyze transfection efficiency. The expressions of HSV-tk and mRFP1 gene were detected by reverse transcription PCR (RT-PCR). The cytotoxic effect of various concentration of pro-drug ganciclovir (GCV) for transfected cells was detected by methyl thiazole tetrazolium assay. The transfected cells were positive sorted by flow cytometry and limiting diluted to obtain the stable transfected cell line. The insertion sites of foreign gene transferred by PB transposon in genome were analyzed by inverse PCR., Results: (1) Double digests analysis and sequences test demonstrated that pPB/TK vector was reconstructed successfully. (2) Using three different transfective reagents, PB transposon transferred HSV-tk gene and mRFP1 gene into HeLa, HEC-1B, SKOV3 and JEG-3 cell efficiently, and the transfection efficiency of pPB/TK for the same cell was different by using different transfective reagents; in Hela cell, the transfection efficiency of FuGENE HD [(78.7+/-9.2)%] was higher than that of lipofectamine 2000 [(54.1+/-11.4)%] and jetPEI [(46.5+/-7.4)%, all P<0.05]; using the same transfective reagent, the transfection efficiency of pPB/TK was also different on various cell lines, using FuGENE HD, the transfection efficiency of pPB/TK on HeLa, JEG-3 and SKOV3 cell was (78.7+/-9.2)%, (74.4+/-8.9)% and (83.2+/-9.7)% respectively, which all were higher than that on HEC-1B [(39.5+/-8.7)%, P<0.05]. (3) RT-PCR showed that there were the mRNA expression of HSV-tk and mRFP1 in all cell lines. (4) 50% inhibitory concentration of GCV for transfected cells, HeLa, JEG-3, SKOV3 and HEC-1B, was 1.29, 3.35, 0.09 and 13.28 microg/ml respectively. Inhibitory effect of GCV (10 microg/ml) on SKOV3 transfected with pPB/TK was (86+/-9)%, which was superior to that transfected with pORF-HSVtk alone [(52+/-12)%, P<0.05]. (5) The insertion sites of PB transposon in the target cells genome were located at TTAA sites. mRFP1 expression still could be detected in three months after transfected., Conclusions: PB transposon could transfer exogenous gene into various gynecological malignant cells, which could integrated into genome and obtain a long-term and stable expression. It is expected that PB transposon may supply a more efficient and safer transgene technology platform for gene therapy in gynecological cancer.

Objective: To construct red fluorescent protein (DsRed) and mouse vascular endothelial growth factor (mVEGF) lentiviral expression vector in order to obtain the DsRed and VEGF expression in 293T cells., Methods: The mVEGF was amplified from the lungs of fetal mouse by RT-PCR. The IRES-DsRed was obtained from plasmid pLV-tTRKRAB-red which contains IRES-DsRed sequence by PCR. Then they were cloned into lentiviral expression vector pTK-208. Human embryonic kidney 293T cells were co-transfected with the three plasmids by lipofectamine, and the expression of DsRed was examined under fluorescent microscope 24 h and 48 h after transfection. 48 h and 72 h later the viral supernatant was used to infect 293T cells, the expression of DsRed was examined under fluorescent microscope and Western blot assays was used to examine the expression of mVEGF in cells and the culture medium., Results: The recombinant lentiviral vector pTK208-mVEGF-IRES-DsRed was constructed, the virus titres were above 10(6) PFU/mL in the supernatant. After infection, DsRed and mVEGF proteins were successfully expressed in 293T cells., Conclusion: The lentiviral vector pTK208-mVEGF-IRES-DsRed contains DsRed and mVEGF were successfully constructed and expressed in 293T cells, it could provide a basis for further researches on the pathophysiological mechanism of VEGF and lay the foundation of gene therapy.

This study was purposed to construct a lentiviral vector encoding red fluorescent protein (DsRed) and transfect DsRed into EL4 cells for establishing mouse leukemia/lymphoma model expressing DsRed. The bicistronic SIN lentiviral transfer plasmid containing the genes encoding neo and internal ribosomal entry site-red fluorescent protein (IRES-DsRed) was constructed. Human embryonic kidney 293FT cells were co-transfected with the three plasmids by liposome method. The viral particles were collected and used to transfect EL4 cells, then the cells were selected by G418. The results showed that the plasmid pXZ208-neo-IRES-DsRed was constructed successfully, and the viral titer reached to 10(6) U/ml. EL4 cells were transfected by the viral solution efficiently. The transfected EL4 cells expressing DsRed survived in the final concentration 600 microg/ml of G418. The expression of DsRed in the transfected EL4 cells was demonstrated by fluorescence microscopy and flow cytometry. In conclusion, the EL4/DsRed cell line was established successfully.

In order to trace the expression of exogenous hepatocyte growth factor (HGF) in eukaryotic cells exactly, a recombinant plasmid that expresses the fusion protein of HGF and red fluorescent protein (RFP) was constructed. The gene encoding HGF without stop code was amplified from pMD19-T-HGF by PCR technique and then cloned in pDsRed-express-N1. The recombinant plasmid (pDsRed-HGF) was identified by restriction endonuclease enzyme analysis and DNA sequence analysis. pDsRed-HGF was transfected into 293T cells. The expression of HGF mRNA, HGF and red fluorescent protein was detected. The results showed that the target gene sequence in pDsRed-HGF was completely in conformity with HGF cDNA in GenBank, and it was expressed highly in 293T cells. In this study, pDsRed-HGF was successfully constructed and expressed in eukaryotic cells.

Objective: To construct a red fluorescent protein reporter gene driven by human catalase gene promoter., Methods: The red fluorescent protein reporter gene plasmid pDsRed-CATp containing human catalase gene promoter was constructed by gene recombination technique. The plasmid was transiently transfected into NIH/3T3 cells to observe their response to H(2)O(2) stimulation., Results: The plasmid was constructed correctly as verified by double enzyme digestion and sequence analysis. The plasmid was lowly expressed in resting NIH/3T3 cells, but the expression level increased obviously after stimulation by H(2)O(2). CONCLSIONS: A red fluorescent protein reporter gene plasmid driven by human catalase gene promoter has been constructed successfully with a sensitive response to H(2)O(2) stimulation. This system provides a convenient tool for the study of the regulatory mechanism of catalase gene expression.

Objective: To establish a stable high red fluorescent protein (RFP)-expressing orthotopic transplantation nude mice spontaneous metastasis model of pancreatic cancer., Methods: Stable high RFP-expressing cells SW1990-RFP were injected subcutaneously into mice to establish subcutaneous implantation model. Fluorescent tumor piece from subcutaneous was transplanted into the body of the pancreas to establish surgical orthotopic implantation model. The growth of primary tumor, metastasis and micrometastasis were assessed by whole-body fluorescence imaging system., Results: Twelve RFP orthotopic transplantation nude mice metastasis models of pancreatic cancer were established successfully, the percentage of success rate was 100%. RFP-labeled pancreatic cancer growth could be monitored in real time way. The micrometastasis of primary lesions were detected in early stage with whole-body fluorescence imaging system., Conclusions: The RFP orthotopic transplantation nude mice metastasis model of pancreatic cancer is stable and reliable, and can be observed dynamically in vitro in a noninvasive way, with much higher sensitivity and specificity.

The plasmodium of Physarum polycephalum is a suitable eukaryotic cell for cell cycle investigation, but there is no compatible transient expression system for the plasmodium. Using the promoter and terminator of ardC actin of Physarum polycephalum substituted the CMV IE and SV40 polyA of plasmid pDsRedl-N1, using cassette PardC-MCS-DsRed1-TardC substituted the cassette PardC-hph-TardC of plasmid pTB38, we constructed plasmids pXM1 and pXM2 for transient expression of red fluorescent protein (RFP) in Physarum polycephalum respectively. After reconstituting the transcription elongation factor homologous gene (pelf1) of Physarum polycephalum into the pXM2, we generated a plasmid pXM2-pelf1. After the plasmid pXM1, pXM2 and pXM2-pelf1 were electroporated into the plasmodium of Physarum polycephalum, we observed optimum RFP and PELF1-RFP expression under fluoroscope and confocal microscope between 24-48 h after electroporation, and found that ELF1-RFP expression was accumulated in nucleus of microplasmodium, the optimum electroporation parameters were 40 V/cm electric field, 1 ampere current, and 70 micros electric shock time. The results suggest that this expression system is qualified for transient expression of specific protein in plasmodium of Physarum polycephalum.

Aim: To construct the recombinant eukaryotic expression vector pDsRed1-C3/LOC51255 and investigate the subcellular localization of LOC51255 protein in HePG2 cell line., Methods: The cDNA of LOC51255 was amplified from the recombinant plasmid pET28b/LOC51255 by PCR. The aim gene fragment LOC51255 from pMD18-T/LOC51255 was subcloned into eukaryotic expression vector pDsRed1-C3. The recombinant plasmid pDsRed1-C3/LOC51255 was identificated by BamH I/Xho I double digestion and sequence analysis, and then transfected into HePG2 cell line by lipofectamine 2000. The expression of LOC51255 protein and its subcellular localization were detected by fluorescence microscope., Results: The construction of the recombinant plasmid pDsRed1-C3/LOC51255 was proved by restriction enzyme digestion analysis and DNA sequencing. Its red fluorescent protein was mainly detected in the cytoplasm of HePG2 cell line., Conclusion: The eukaryotic expression plasmid pDsRed1-C3/LOC51255 has been successfully constructed and expressed in the HepG2 cell line. LOC51255 protein has been proved to be located in the cytoplasm of HePG2 cell line. Our research will help further studies on the function of human gene LOC51255.

Objective: To construct an inducible eukaryotic vector carrying red fluorescent protein (DsRed) and evaluate the regulation of DsRed gene expression in vitro., Methods: The vector pRS17-RUDsRed containing DsRed gene, promoter and RU486-inducible system was constructed using molecular biological methods. To minimize potential interference, the two transcriptional elements were spaced with a 1.6 kb insulator. Fluorescence microscopy and flow cytometry were used to observe the activation of this regulatable vector after transfection in MFC cells., Results: The vector was identified by digestion with different restriction enzymes, sequencing and PCR. In the absence of RU486, the cells transfected with the vector exhibited very low DsRed protein expression, and the addition of RU486 induced efficient DsRed expression in the cells., Conclusion: The RU486-inducible eukaryotic vector carrying DsRed protein allows effective regulation of the target gene expression in vitro, which provides a useful tool for gene regulation and gene therapy studies.

Most studies related to determining the expression profile of genes and specific promoters used histochemical localization of the reporter gene, gusA. While the histochemical method for visualizing gusA expression suffers from several limitations in the determination of gene expression and location, especially in the tissues with high background acitivty. To solve this problem, a transient expession vector pBI221-RFP/GFP, was constructed using GFP and RFP as double fluorescent marker genes. This vector used CaMV 35S promoter to drive GFP and determine the transforming efficiency. It analyzed expression profile of the target gene and promoter through the RFP activities of the tranformed tissues. Through the specific promoter AGPL1 from watermelon and E8 promoter from tomato, it is resistible to use this vector to study the expression patterns of promoters. Results indicated that the pBI221-RFP/GFP is a very efficient transient expression vector that can be verify the functions of the genes and promoters.

Aim: To construct the fusion gene of transmembrane programmed death ligand (PD-L1) and red fluorescent protein (DsRed2), and to study the expression and effect of the fused PD-L1/pDsRed2-N1., Methods: The cloning technology was employed to construct the PD-L1/pDsRed2-N1 fusion gene. The fusion gene was transfected into NIT cells by lipofectamine. The expression of the fusion gene was determined by flow cytometry (FCM) and inverted phase contrast microscope. The effects on allo-spleen cells proliferation were detected by single mixed lymphocyte reaction. FCM was used to detect the proliferation of spleen cells., Results: The expression of the fusion gene was observed in transiently transfected NIT cells. The fusion protein was expressed on cell membrane. These data suggested that the red fluorescent protein tag did not interfere with the natural assembly and the biological activity of PD-L1 molecule., Conclusion: The PD-L1-RFP fusion gene is constructed successfully and the fusion protein has biological activity.

To analyze the localization of attenuated Salmonella typhimurium after oral immunization. Prokaryotic expression plasmid pYA33-DsRed, carrying the RFP gene, was constructed and electro-transformed into an attenuated strain X4550 of Salmonella typhimurium, the recombinant bacteria were named as X4550 (33-DsRed). The macrophage cell line RAW264.7 and bone marrow dendritic cell (BMDC) were invaded by X4550 (33-DsRed) in vitro. Furthermore, BALB/c mice were immunized with recombinant bacteria orally. RFP positive cells (RFP+ cells) were detected by Flow Cytometry (FCM) from spleen, liver, Mesenteric lymp node (MLN), Peyer's patch (PP), Inguinal lymph node (ILN). The invasion rate increased when the multiplicity of infection(MOI) were improved in this two kinds of cells respectively. After oral immunization with X4550 (33-DsRed), RFP+ cells were detected by FCM on 1d, 2d, 3d, 5d, 7d in spleen, liver, MLN, PP, ILN cells. The first day, RFP+ cells were detected in MLN and PP, and in PP at a higher rate of 1.4% than that of MLN. 0.4% RFP+ cells were detected the next day in ILN. On 3th day, the rates of RFP+ cells were increased in all of above tissues or organs and decreased on the 5th day. At the 7th day, RFP+ cells couldn't be detected in all tissues or organs tested. It is suggested that the invasion ability and the transfer through mucosal pathway and targeting to recognize immune tissue or organs are favor of the research in mucosal vaccine and the vaccine efficiency.

Comprehensive analysis of the mechanism of metabolite synthesis in filamentous fungi is important for optimization of the filamentous fungus related industrial fermentation processes. In this work, the mechanism of cellulase synthesis in Trichoderma reesei was analyzed with red fluorescent protein (DsRed) as the reporting protein. The expression cassette for heterologous protein expression in T. reesei was constructed, through which the DsRed gene was inserted into the chromosomal DNA of T. reesei. The recombinant T. reesei strain, in which expression of DsRed was controlled by the promoter of cellobiohydrolase gene, was designated as T. reesei TR2. Expression of DsRed in T. reesei TR2 under different culture conditions was analyzed by using a fluorescent microscopy, and thereby the mechanism of cellulase gene expression in T. reesei could be interpreted. With induction of lactose, the pattern of change of red fluorescence in T. reesei TR2 was similar to that of the cellulase activity in the cultivation supernatant. As the culture aged, the red fluorescence in the mycelial increased. This was followed by a reduction in the end of the culture period because of death and autolysis of the mycelial. In the spatial aspect, the red fluorescence was distributed uniformly in the whole hypha after induction, indicating that all the three morphology including apical compartment, subapical compartment and hyphal compartment played a same role in cellulase synthesis. When T. reesei TR2 was cultivated without induction, faint red fluorescence appeared after a relative long period of cultivation, indicating that a small amount of cellulase was still synthesized without induction. This result was useful in explaining the mechanism of cellulase induction by insoluble cellulose.

Objective: To find the valid siRNA (small interference RNA) sequence to knock down rat Mecp2 expression for the analysis of Mecp2 function by RNA interference (RNAi)., Methods: A plasmid (pMecp2-RFP) expressing rat Mecp2 and marker gene red fluorescent protein (RFP) as a fusion gene was constracted. We first selected a candidate valid sequence by cotransfecting the pMecp2-RFP with 4 candidate siRNAs targeting rat Mecp2 to HEK293T cells respectively, and then identified the RNAi efficiency of the candidate valid siRNA by detecting its effect on suppressing the expression of endogenous rat Mecp2 in PC12 cells., Results: siRNA sequence (5'-GCUGUGAAGGAAUCUUCUA-3') targeting rat Mecp2 mRNA 918-936nt was the valid sequence to knock down rat Mecp2 expression by RNA interference. As the target sequence was located in exon 4 of rat Mecp2 mRNA, we assumed that it could suppress the expression of Mecp2alpha and Mecp2beta at the same time. And as the target sequence was located in the coding region of rat Mecp2, we assumed that it could suppress the expression of both 1.9 kb and 10 kb of rat Mecp2 transcript., Conclusion: This study has laid the foundation for constructing rat Mecp2 knocked-down neuronal cell model to study the gene function of Mecp2 in brain development.

Objective: To construct the red fluorescent protein reporter gene vector containing human eNOS promoter sequence to study the mechanism of regulating the expression of eNOS gene by vessel wall shear stress., Methods: The genomic DNA of endothelial cells from fetal umbilical vein was drawn. The gene sequence of eNOS promoter gene therein was cloned by PCR technique and constructed into the red fluorescent protein vector, pDsRed-1. The recombinant vector, pDseNOSRed was then transfected into 293 cells, human fetal renal epithelial cells. Blank vector, pDsRed-1, was transfected into 293 cells as controls. The expression and distribution of the reporter gene were observed by fluorescent microscopy., Results: PCR and double restriction enzyme digestion showed that the recombinant vector, pDseNOSRed, was constructed correctly. This vector was highly expressed in the 293 cells. Expression of red fluorescence, evenly distributed in whole cells, occurred since 12 hours after transfection, reached the peak concentration 3648 h after transfection, and dissappeared almost completely 120 h after. No red fluorescence was observed in the control cells., Conclusion: A red fluorescent protein reporter gene vector containing human eNOS promoter sequence and expressed highly in mammalian cells has been constructed successfully, thus providing an important and convenient tool to study the mechanism mechanism of regulating the expression of eNOS gene by vessel wall shear stress.

Objective: To construct the vector that expresses the fusion protein of p38 mitogen-activated protein kinase (MAPK) and red fluorescent protein (RFP) in mammalian cells., Methods: FLAG-tagged p38 MAPK in pcDNA3 vector was subcloned into RFP vector pDsRed1-N1, the construct of which was then transfected into HeLa cells and observed with fluorescence microscope., Results: The recombinant plasmid was verified by enzyme digestion, PCR and sequence analysis, and p38 MAPK-RFP fusion protein was highly expressed in HeLa cells. Fluorescence microscope found the red fluorescence distributed all over the cytoplasm and in the nuclei as well., Conclusion: The expression vector for p38 MAPK-RFP fusion protein is successfully constructed and effective expression of this fusion protein is achieved, which might be instrumental in the study of intracellular localization of p38 MAPK.