Construction and Expression of Recombinant Plasmid pCD-rbFGF in Osteoblasts

Summary: To construct basic fibroblast growth factor (bFGF) eukaryotic expression vector and to evaluate the possibility of bFGF gene therapy in orthopedic disease, the pCD-rbFGF recombinant plasmid was constructed by cloning rat basic fibroblast growth factor (bFGF) cDNA into an eukaryotic expression vector, pcDNA 3. Rat osteoblasts were transfected with pCD-rbFGF plasmid by lopofectin mediated gene transfer, the transient expression was detected by streptavidin-biotin-enzyme complex (SABC) method. It was observed that the expression of rat bFGF gene was detected 72 h after transfected distinctly. Basic fibroblast growth factor gene therapy is a method of potential for a wide array of orthopedic diseases.

Construction and Expression of Recombinant Ghrelin Plasmid and Effects on Growth Performance and Gastric Acid Secretion of Rats

The paper was to study construction and expression of rGhrelin （pcDNA3 -Ghrelin） and its effect on growth performance and gastric acid secretion of rats. Ghrelin amplified from gastric mucosa of weaned piglets was cloned into the expression vector pcDNA3 to get recombinant plasmid pcDNA3 - Ghrelin. Twelve weaning rats were randomly divided into two groups, six rats each group. The rats in each treatment group were individually injected with 100pg of naked plasmid pcDNA3 -Ghrelin, and the rats in control group were injected with empty plasmid. The weights and feed consumption of rats were measured after injection for 7, 14 and 29 d, respectively. The rats were sacrificed at the end of the experiment, and their stomach was separated and weighed, the pH value of gastric juice was measured as well. The results showed that the average daily gain of rats at 7 and 29 d were significantly higher than that in control group, respectively （P〈0.05）, and feed consumption did not have significant chan- ges; the feed meat ratio of rats in the treatment groups was significantly lower than that in control group （ P 〈0.05） ; the gastric relative weight and gastric weight did not change significantly, while the pH value of gastric juice of rats in treatment groups was significantly lower than that in control group （P 〈 0.05）. This indicated that after transfected expression of muscle tissue, ghrelin played an important regulatory role in growth and gastric acid secretion of rats.

Detection of the copy number of plasmid encoding HBsAg in recombinant yeast by PCR relative quantitative assay

The purpose of this study is to detect the plasmid copies encoding HBsAg in recombinant yeast Saccharomyces cerevisiae by real-time PCR, and provide the data for setting up an optimal process of manufacturing hepatitis B vaccine in future. A single copy URA3 gene in the yeast genome was employed as internal control to test the plasmid copies by real-time PCR. The yeast cells carrying plasmids encoding HBsAg were cultured in regular non-feeding process and fed-batch process in shaking flasks at laboratory level and industrial fermentor. The cells at different stages of cultivation were collected and broken. Then the total DNAs of the cells were extracted and the plasmid copies were detected by real-time PCR with the method of relative quantification. The method of the real-time relative quantitative PCR used in this study was reliable with good accuracy and quickness. The plasmid copies in non-feeding and fed-batch flasks were 39.22±12.00 and 43.06±5.70, while the copies in fermentor were 96.16±21.00 and 82.50±7.78, respectively. The data show that the variation of the result is very small and the data precision is quite good. To prolong the fermentation time may increase the cell density without influence on the stability of the plasmid, and the method of relative quantification can also be applied to test the copy number of interest target gene in any host cell with certain known copy gene.

A novel recombinant DNA vaccine encodingMycobacterium tuberculosis ESAT-6 and FL protects againstMycobacterium tuberculosis challenge in mice

Mycobacterium tuberculosis 6-kDa early secretory antigenic target （ESAT-6） is a dominant target antigen for cell-mediated immunity in the early phase of tuberculosis. The fms-like tyrosine kinase 3 ligand （FL） that induces potent immune response has been used as an adjuvant in vaccine development. In this study, a new recombinant plasmid （plRES-epitope-peptides-FL） encoding three T cell epitopes of ESAT-6 and FL was constructed, and the immunogenicity of the DNA vaccine was assessed in C57BL/6 mice immunized with the plasmid DNA vaccine. Additionally, a strategy of intramuscular injection with the DNA vaccine （prime） and intranasal administration of the epitope peptides （boost） was employed to induce higher immune reaction of the mice. The results showed that mice vaccinated with the recombinant plasmid DNA vaccine and boosted with the peptides not only increased the levels of Thl cytokines （IFN-γ and IL-12）, the number of IFN-γ＋ T cells and activities of cytotoxic T lymphocytes as well as IgG, but also enhanced protection against Mycobacterium tuberculosis challenge. In conclusion, these data indicate that the novel recombinant plRES-epitope-peptides-FL plasmid is a useful DNA vaccine for pre- venting Mycobacterium tuberculosis infection.

Study on DNA Immunization by Recombinants Encoding Japanese Encephalitis Virus prME and E Proteins

To study the expression characteristic of Japanese encephalitis virus (JEV) prME and E proteins and the efficacy of DNA immunization by different recombinant plasmids containing JEV prME (2001 bp) and E (1500 bp) genes, two recombinants (pJME and pJE) containing JEV prME and E genes fused with FLAG were constructed and then transfected into HepG2 and COS-1 cells by liposome fusion. The expression feature of FLAG-prME (about 72 kDa) and FLAG-E (about 54 kDa) proteins in transfected cells were analyzed by Western blot and two antibody systems (anti-FLAG and anti-E). BALB/c mice were immunized with 100 μg of two kinds of recombinants by intramuscular injection, and JEV JaGAr-01 strains (10 5 PFU/100 μl)were given to BALB/c mice by intraperioneal injection 3 wk after twice DNA immunization by a lethal virus challenge. BALB/c mice were observed for 21 days after challenge. 80% plaque reduction neutralization test was performed to titrate neutralization antibody before and after viral challenge. It was found that the expression of proteins associated with pJME and pJE was determined in transfected cells with anti-FLAG and a new protein of 11 kDa was detected in HepG2 and COS-1 cells transfected with pJME. Only E (53 kDa) protein was identified as transfected with pJME using anti-E. Higher level of neutralization antibodies and the efficacy of protective immunity were induced with pJME immunization, and were similar to those induced by inactivated Japanese encephalitis vaccine, but were better than those induced with pJE. It concludes that the expression level from prM to E proteins of JEV is different in vitro, and the in vitro expression efficiency of pJME was better than that of pJE. FLAG-prME protein expressed by pJME could be cleaved by peptidase from host. The efficacy of DNA immunization is correlated to the expression characterization of related proteins expressed in vitro.

Construction of Prokaryotic Expression Plasmid of Fusion Protein Including Porin A and Porin B of Neisseria Gonorrhoeae and Its Expression in E.coli

In order to provide a rational research basis for clinical detection and genetic engineering vaccine, plasmid pET-28a (+) encoding both Porin gene PIA and PIB of Neisseria gonorrhoeae was constructed and a fusion protein in E.coli DE3 expressed. The fragments of PIA and PIB gene of Neisseria gonorrhoeae were amplified and cloned into prokaryotic expression plasmid pET-28a(+) with double restriction endonuclease cut to construct recombinant pET-PIB-PIA. The recombinant was verified with restriction endonuclease and sequenced and transformed into E.coli DE3 to express the fusion protein PIB-PIA after induced with IPTG. The results showed PIA-PIB fusion DNA fragment was proved correct through sequencing. A 67 kD (1 kD=0 992 1 ku) fusion protein had been detected by SDS-PAGE. It was concluded that the fusion protein was successively expressed.

Construction of a recombinant plasmid harbouring the rhoptry protein 1 gene of Toxoplasma gondii and preliminary observations on DNA immunity

Objective To observe the immune responses elicited in BALB/c mice by a DNA vaccine. A gene encoding rhoptry protein 1 (ROP1) from Toxoplasma gondii (T. gondii) was cloned into vector pcDNA3. Methods Amplifyied gene fragments coding for ROP1 from the genomic DNA of T.gondii ZS2 were inserted into cloning vector, pUC18, and sub-cloned into pcDNA3. Mice were injected at a dosage of 100?μg recombinant plasmid DNA by intramuscular injection and boosted after 2 weeks. pcDNA3 and normal saline were used as control. 30, 50 and 70 days after the second immunization, NK cell activity, T lymphocyte proliferation and sub-clusters and serum IgG antibody were assayed.Results The specific gene fragment coding for ROP1 was amplified and a pcROP1 recombinant was constructed. At 30 days after immunization, the spleens of the mice were obviously enlarged evidently. NKC activity and the proliferation of spleen T lymphocytes seen on MTT assay were higher in pcROP1 group than in the controls. The number of CD4+ T cells exhibited no obvious increase compared with that of the control, but CD8+ T cells were obviously increased (P<0.05). At 90 days after vaccination, the titer of IgG antibody in the serum of vaccinated mice was positive (1∶100). Conclusion pcROP1 was constructed and it could elicit both cellular and humoral immune responses in immunized mice.

Overexpression of cytoglobin gene inhibits hypoxic injury to SH-SY5Y neuroblastoma cells

A plasmid for cytoglobin expression, pAcGFP1-Cl-cytoglobin, was transfected into SH-SY5Y cells. Cobalt chloride was used to establish a model of hypoxia. Western blotting indicated that cytoglobin was overexpressed and there was low expression of hypoxia-inducible factor-la in SH-SY5Y cells after transfection. Following cobalt chloride-induced hypoxia, cytoglobin and hypoxia-inducible fac- tor-la expression gradually increased in SH-SY5Y cells. Flow cytometry showed that with increas- ing duration of hypoxia, the proportion of normal cells significantly diminished in the transfected and non-transfected groups. The proportion of cells in the early stages of apoptosis increased. However, the proportion of apoptotic cells was significantly lower in the transfected group compared with the non-transfected group. These results demonstrate that cytoglobin and hypoxia-inducible factor-la are strongly up-regulated by hypoxia, and that there is a strong relationship between hy- poxia-inducible factor-la and cytoglobin during hypoxic injury.

Overexpression of the neuroglobin gene delivered by ultrasound-targeted microbubble destruction protects SH-SY5Y cells against cobalt chloride induced hypoxia

In this study, we examined the effects of neuroglobin gene （Ngb） transfection into SH-SY5Y cells, using ultrasound-targeted microbubble destruction （UTMD）, on cobalt chloride-induced hypoxia. With an ultrasound intensity of 0.8 W/cm2, a 60-second exposure duration, 50% duty cycle, and 20% microbubble concentration, pAcGFP1-C1-Ngb-transfected cells exhibited the highest cell viability and transfection efficiency. The efficiency of plasmid delivery was significantly higher with UTMD than transfection with plasmid alone, transfection with plasmid using microbubbles, or transfection of plasmid by ultrasound. In addition, during cobalt chloride-induced hypoxia, caspase-3 activity in pAcGFP1-C1-Ngb-transfected cells was significantly lower than in untransfected cells. Ngb protein and mRNA expression were significantly higher in cells transfected by UTMD than in cells transfected with the other methods. These results demonstrate that UTMD can very efficiently mediate exogenous gene delivery, and that Ngb overexpression protects cells against cobalt chloride-induced hypoxia.

Hepatocyte growth factor gene transfer effects on the femoral and intramuscular nerve in a canine model of lower limb ischemia

BACKGROUND： Recent advancements in gene therapy have provided new methodology for treating ischemia in lower extremities. Gene transfer of angiogenic factors to ischemic tissues may promote local proliferation of new vessels and form collateral circulation. OBJECTIVE： To observe histopathological changes in the femoral and intramuscular nerve three months after intramuscular injection of hepatocyte growth factor （HGF） into the peripheral skeletal muscle in a canine model of lower limb ischemia. DESIGN： Randomized occlusion modelled and verification animal study. SETTING： Experimental Center, Lanzhou General Hospital of Lanzhou Military Area Command of Chinese PLA. MATERIALS： This study was performed at Animal Experimental Center, Lanzhou General Hospital of Lanzhou Military Area Command of Chinese PLA from September to November 2006. A total of eight male mongrel dogs, weighing 12–15 kg and 1.5–3 years of age, were selected for this study. This experimental study was in accordance with local ethics standards. Recombinant plasmid carrying HGF （pUDKH） and occlusion model plasmid （pUDK） were provided by the Third Laboratory of Radiation Medical Institute, Academy of Military Medical Sciences of PLA. METHODS： Grouping and model establishment： under anesthesia, complete vascular occlusion models were established on the left lower extremities. The experimental dogs were randomly divided into a model group and a pUDKH treatment group, with four dogs in each group. Dogs in the pUDKH group were injected with 0.15 mg/kg pUDKH. Ten minutes later, intramuscular injections were performed at three spots into the peripheral skeletal muscle of the left hind limb, as well as lateral injections at two spots. The injection volume at each spot was 0.2 mL. Dogs in the model group were injected with pUDK, and dosage and injection method were identical to the treatment group. MAIN OUTCOME MEASURES： Histopathological changes in the femoral nerve, as well as internal and external intramuscular nerve tissues in the hind limb of dogs three months after plasmid injection under optic microscope. RESULTS： （1） Histopathological changes in the femoral nerve： tiny nerves from the femoral nerve to the intramuscular nerve exhibited marked degeneration in the model group. The degenerating features included neurites, myelin sheaths, and Schwann cell nuclei. Neuropathy in the pUDKH treatment group was not detected. （2） Histopathological changes of the intramuscular nerve： large and irregular vacuoles were present on several longitudinal sections of intramuscular nerve fibers in the model group, as well as annular-shaped blank regions on transverse sections of peripheral neurites. In the pUDKH treatment group, large, blank regions were present in several segments of partial nerve fibers of the longitudinal intramuscular nerve region, but only a few nerve fibers exhibited annular-shaped blank regions on the transverse section of peripheral neurites. CONCLUSION： Local pUDKH injection may relieve or block femoral and intramuscular nerve tissue injury in a canine mocel of lower limb ischemia.

Development of a Real-Time PCR Method (Taqman) for Rapid Identification and Quantification of Prorocentrum donghaiense

Prorocentrum donghaiense is a dinoflagellate that is widely distributed in the East China Sea and has become increasingly involved in Harmful Algal Blooms (HABs). Therefore, it is necessary to study this dinoflagellate to monitor HABs. In this study, 13 pairs of primers specific to P. donghaiense (within its internal transcribed spacer (ITS) regions) were designed for SYBR Green I real-time PCR. As the SYBR Green I real-time PCR could not identify P. donghaiense in a specific manner, a Taqman real-time PCR method was developed by designing a set of specific primers and a Taqman probe. A 10-fold serial dilution of recombinant plasmid containing ITS regions of P. donghaiense was prepared as standard samples and the standard curve was established. Additionally, we quantified the genomic DNA in P. donghaiense cells and utilized this DNA to prepare another 10-fold serial dilution of standard sample and accordingly set up the standard curve. The mathematic correlation between the cell number and its corresponding plasmid copy number was also established. In order to test the efficiency of the real-time PCR method, laboratory samples and P. donghaiense HAB field samples were employed for identification and quantitative analysis. As to laboratory samples, as few as 102 cells of P. donghaiense could be quantified precisely utilizing both centrifugation and filtration techniques. The quantification results from field samples by real-time PCR were highly similar to those by light microscopy. In conclusion, the real-time PCR could be applied to identify and quantify P. donghaiense in HABs.

Cloning and Expression of the Tpp17 Gene of Treponema pallidum And Clinical Application

Objective: To obtain recombinant Treponema pallidumsubsp pallidum (TP 17KD) lipoprotein in large quantities byamplification and to further purify antigens for laboratorydiagnosis of syphilis and development of a syphilis vaccine. Method: The Tpp17 lipoprotein gene was amplified fromthe TP(strain Nichols), and then it was recombinated into aplasmid pMAL-2c and cloned within E coli l2-TB1. The hostbacteria containing recombinant plasmids were induced withIPTG. The Tpp 17KD lipoprotein gene was amplified by us-ing PCR and positive clones were screened with double diges-tion and PCR. Recombinant plasmids were transformed intoE. coli and the E coli carrying recombinant plasmids wereinduced. The expression of TP 17KD was detected by sodiumdedecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) and immunoblot. Results:Gel staining with Coomassie blue G-250 showedthat the induced E coli carrying recombinant plasmid couldproduce 60KD fusion protein at high levels. Gel scanningshowed that 17KD protein expression in E coli accounted for10% of total cellular protein. The recombinant protein antigenreacted with the sera of syphilis patients. Conclusion: Our study lays a cornerstone for developingnew techniques of laboratory diagnosis for syphilis and newvaccines. Preliminary clinical application showed that thefusion protein could be used for the diagnosis of syphilis.

Assembly of long DNA sequences using a new synthetic Escherichia coli-yeast shuttle vector

Synthetic biology is a newly developed field of research focused on designing and rebuilding novel biomolecular components, circuits, and networks. Synthetic biology can also help understand biological principles and engineer complex artificial metabolic systems. DNA manipulation on a large genome-wide scale is an inevitable challenge, but a necessary tool for synthetic biology. To improve the methods used for the synthesis of long DNA fragments, here we constructed a novel shuttle vector named p GF(plasmid Genome Fast) for DNA assembly in vivo. The BAC plasmid p CC1 BAC, which can accommodate large DNA molecules, was chosen as the backbone. The sequence of the yeast artificial chromosome(YAC) regulatory element CEN6-ARS4 was synthesized and inserted into the plasmid to enable it to replicate in yeast. The selection sequence HIS3, obtained by polymerase chain reaction(PCR) from the plasmid p BS313, was inserted for screening. This new synthetic shuttle vector can mediate the transformation-associated recombination(TAR) assembly of large DNA fragments in yeast, and the assembled products can be transformed into Escherichia coli for further amplification. We also conducted in vivo DNA assembly using p GF and yeast homologous recombination and constructed a 31-kb long DNA sequence from the cyanophage PP genome. Our findings show that this novel shuttle vector would be a useful tool for efficient genome-scale DNA reconstruction.