Objective To construct yeast eukaryotic expression vector carrying human endostatin (ES) cDNA. Methods The functional fragment of endostatin gene in human hepatic tissue was amplified by using RT-PCR technology, and cloned into yeast pPIC9 expression vector. The positive clone was sequenced by using automatized sequencer. Results The endostatin cDNA was successfully cloned. The positive ES clone gene in pPIC9 expression vector was sieved, and its coding sequence was identified to be as same as the previously reported sequence. Conclusion The successful construction of ES gene in pPIC9 expression vector using molecular biological method maybe helpful for the high expression of ES protein, which may lay the foundation for the treatment of malignant tumor through anti-angiogenesis appoach.
Two vectors were used to construct the recombinant gene yeast cell that can be used to bioassay of the pollution of tetracycline antibiotics in the environment. In the expression vector, the GPD (glyceraldehyde-3-phosphate dehydrogenase) promoter was used to drive the gene expression of tetracycline repressor protein (TR) fused with V5 antigen epitope gene, while in the reporter vector, the tetracycline response element (TRE) was used to regulate Lac Z report gene expression. The specificity and the sensitivity of the recombinant gene yeast cell were evaluated respectively by different concentrations of tetracycline antibiotics and non-tetracycline antibiotics. The results showed that there were significant dose effect relationships between the tetracycline antibiotics and the yeast cells, while non-tetracycline antibiotics showed no dose effect relationships with this biosensor. It is illustrated that the recombinant yeast cells can be used to monitor the tetracycline antibiotic pollution on the environment.
ObjectiveTo construct a lentiviral vector carrying rat sirt1 gene and observe the expression of sirt1 in retinal ganglion cell (RGC) of rat. MethodsRat sirt1 cDNA was inserted into pLV5 vector. After identification by sequencing analysis and PCR, the recombinant sirt1expressinglentivirus vector was packaged by cotransfecting 293T cells with packaged plasmid.Then pLV5-sirt1 was used to infect the cultured Sprague-Dawley rat RGC cell in vitro.The expressions of sirt1 protein and mRNA in infected rat RGC were detected by quantitative real-time PCR and Western blot. ResultsThe sirt1 expression vector pLV5 was successful constructed and sequence was proved to be correct. The expression of sirt1 protein and mRNA in RGC was significantly increased than that in cells infected with control lentiviruses(P < 0.05). ConclusionWe have successful constructed a sirt1 expression lentivirus vector pLV5-sirt1 and it can increase the expression of sirt1 protein and mRNA in the rat retinal ganglion cells.
Human lymphocyte function-associated antigen 3 (hLFA3) has been identified as an important T cell accessory molecule. Rhesus monkeys (Macaca mulatta) have been widely used as animal models for human immune disorders. Due to the species-specificity of immune system, it is necessary to study M. mulatta LFA3 (mmLFA3). In this study, the gene encoding mmLFA3 CD2-binding domain (mmLFA3Sh) was amplified by polymerase chain reaction (PCR) and genetically fused to human IgG1 Fc fragment in pPIC9K to construct the expression plasmid pPIC9K-mmLFA3Sh-Ig. Approximately 3-4 mg mmLFA3Sh-Ig protein was recovered from 1 L of inductive media, and mmLFA3Sh-Ig produced by the P. pastoris can bind to the CD2 positive cells, and suppress the monkey and human lymphocytes proliferation induced by Con A and alloantigen in a dose-dependent manner. These results suggested that mmLFA3Sh-Ig might be used as a novel tool for pathogenesis and experimental immunotherapy of Rhesus monkey immune disorders.
ObjectiveTo study the efficient expression conditions, purification, and partial enzymatic properties of His-tagged recombinant Candida utilis uricase.MethodsThe effects of isopropyl β-D-1-thiogalactopyranoside (IPTG) and lactose as inducers which were added in the end logarithmic phase were compared by the method of shake flask culture. The induction culturing time was studied with 50 L fermentor. The protein of interest was purified by Ni-Sepharose and Sephacryl S-200 HR chromatographies, and the optimal pH value, temperature, and thermal stability were also studied.ResultsThe shake flask culturing experiment results showed that IPTG was better than lactose as an inducer. In the fermentor culturing and at the end of the logarithmic growth stage, the enzyme activity of 164 U per gram bacteria and biomass of 23 grams per litter fermented solution were maximal after adding lactose for 7 hours as an inducer, i.e. the enzyme activity could be collected at 3 772 U per liter. The specific activity of purified uricase was 4.5 U/mg and the optimal pH value and temperature were 7.5 and 40℃. Additionally, the enzyme was stable at pH 6.0–10.0 and the thermal stability was below 45℃.ConclusionsIt is better to use lactose as an inducer in the process of culture. The recombinant uricase with His label can be purified by Ni-column affinity chromatography and Sephacryl S-200HR molecular sieve chromatography, and the purification process is easier than ever before. The optimum temperature, pH value, acid-base stability and thermal stability of the purified enzyme have been established to provide some experimental basis for the relationship between structure and function and practical application in the future.
Objective To construct human secreted apoptosis-related protein 1 (SARP1) gene yeast two-hybrid bait vector so as to study the biological functions of the SARP1 gene in the scar tissue. Methods The target gene from SARP1 gene full-length DNA segment was amplified by PCR, the upstream and downstream primers of the SARP1 gene with restriction enzymes Nde I and Sal I were designed. pGBKT7-SARP1 recombination plasmid was constructed by ligating the vector and the PCR production and identified by PCR and sequencing. Further more, pGBKT7-SARP1 was transformed into competent AH109 which contained kanamycin for selecting positive clones and screened the positive clony on the plate of SD/-Trp. The toxicity and transcriptional activation were tested by the phenotype assay. Results SARP1 was amplified and cloned into pGBKT7 successfully, SARP1 gene sequence in recombinant plasmid pGBKT7-SARP1 was verified by gel electrophoresis and DNA sequencing analysis. The sequence of inserted SARP1 gene was the same as the corresponding sequence found in GenBank database. The recombinant pGBKT7-SARP1 plasmids and empty pGBKT7 vector could form white colonies on SD/-Trp plates and none could survive on SD/-Leu plates. Conclusion The recombinant pGBKT7-SARP1 gene yeast two-hybrid bait vector is successfully constructed.
ObjectiveTo study the effect of intercellular adhesion (ica) operon of Staphylococcus epidermidis on the inflammation associated with mixed biofilm of Staphylococcus epidermidis and Candida albicans on endotracheal tube material in rabbits. MethodsThe standard strains of Staphylococcus epidermidis RP62A (ica operon positive, positive group) and ATCC12228 (ica operon negative, negative group) were taken to prepare a bacterial solution with a concentration of 1×106 CFU/mL, respectively. Then, the two bacterial solutions were mixed with the standard strain of Candida albicans ATCC10231 of the same concentration to prepare a mixed culture solution at a ratio of 1∶1, respectively. The mixed culture solution was incubated with endotracheal tube material for 24 hours. The formation of mixed biofilm on the surface of the material was observed by scanning electron microscope. Thirty New Zealand rabbits, aged 4-6 months, were divided into two groups (n=15), and the endotracheal tube materials of the positive group and the negative group that were incubated for 24 hours were implanted beside the trachea. The body mass of rabbits in the two groups was measured before operation and at 1, 3, and 7 days after operation. At 1, 3, and 7 days after operation, the levels of interleukin 1β (IL-1β), IL-6, tumor necrosis factor α (TNF-α), and monocytechemotactic protein 1 (MCP-1) were detected by using an ELISA test kit. At 7 days after operation, the formation of mixed biofilm on the surface of the endotracheal tube materials was observed by scanning electron microscope, the inflammation and infiltration of tissues around the materials were observed by HE staining, and the bacterial infections in heart, lung, liver, and kidney were observed by plate colony counting method.ResultsScanning electron microscope observation showed that the mixed biofilm structure was obvious in the positive group after 24 hours in vitro incubation, but no mixed biofilm formation was observed in the negative group. In vivo studies showed that there was no significant difference in body mass between the two groups before operation and at 1, 3, and 7 days after operation (P>0.05). Compared with the negative group, the levels of MCP-1 and IL-1β at 1 day, and the levels of IL-1β, MCP-1, IL-6, and TNF-α at 3 and 7 days in the positive group all increased, with significant differences (P<0.05). Scanning electron microscope observation showed that a large amount of Staphylococcus epidermis and mixed biofilm structure were observed in the positive group, and a very small amount of bacteria was observed in the negative group with no mixed biofilm structure. HE staining of surrounding tissue showed inflammatory cell infiltration in both groups, and neutrophils and lymphocytes were more in the positive group than in the negative group. There was no significant difference in the number of bacterial infections in heart and liver between the two groups (P>0.05). The number of bacterial infections in lung and kidney in the positive group was higher than that in negative group (P<0.05).ConclusionIn the mixed infection of Staphylococcus epidermidis and Candida albicans, the ica operon may strengthen the structure of the biofilm and the spread of the biofilm in vivo, leading to increased inflammatory factors, and the bacteria are difficult to remove and persist.
Objective To observe the effect of shRNA interference lentivirus vector targeting rat Sirt1 gene on the expression of Sirt1 in retinal ganglion cell (RGC). Methods Four short hairpin (sh) RNA interference sequences targeting rat Sirt1 gene were designed. The target sequences of Oligo DNA were synthesized and annealed to double strand DNA, which was subsequently connected with pGLV3 lentivirus vector to build the lentiviral vector. The positive clones were identified by polymerase chain reaction (PCR) and DNA sequencing. The lentiviral vector construct and lentiviral packaging plasmids were co-transfected into 293T cells, then the titer of lentivirus were determined. The RGC were divided into 6 groups including blank group, negative control group and si-Sirt1-1, si-Sirt1-2, si-Sirt1-3, si-Sirt1-4 groups. Real-time PCR and Western blotting were used to detect the expression of Sirt1 mRNA and protein in the RGC cells. Results PCR and DNA sequencing analysis confirmed that the shRNA sequence was successfully inserted into the lentivirus vector. The concentrated titer of virus suspension was 8×108 TU/ml after the recombinant lentiviral vector successfully transfected and harvested in 293T cells. Comparing with NC group, the expression of Sirt1 mRNA and protein were significantly decreased in the si-Sirt1-1, si-Sirt1-2, si-Sirt1-3 and si-Sirt1-4 groups (F=27.682, 1 185.206; P=0.000, 0.000). The si-Sirt1-2 group had the strongest effect in reducing the expression of Sirt1 mRNA and protein. Conclusion The 4 lentiviral vectors harboring RNAi targeting rat Sirt1 gene can effectively down regulate the expression of Sirt1 mRNA and protein in RGC cells.