Construction of an Escherichia coli strain for sensitive detection of arsenite ion in water / 生物工程学报

In order to construct an Escherichia coli strain with high sensitivity and specificity to detect arsenic ion using fluorescence as reporter, a sensitive strain to arsenic ion was obtained by knocking out the gene arsB that acts as an arsenic efflux pump. The pET28b vector containing arsenite detecting cassette Pars-arsR-egfp was constructed and then transformed into arsB deleted mutant. Measuring conditions of this constructed whole-cell biosensor were optimized and its linear concentration range, limit of detection and specificity were determined. This modified biosensor was much more sensitive than that using wild-type strain as host. The optimal detection range of As³⁺ concentration was 0.013 to 42.71 μmol/L, and the limit concentration of detection was as low as 5.13 nmol/L. Thus we successfully improved the sensitivity of arsenite detecting biosensor by modification of E. coli genome, which may provide useful strategies for development and optimization of microbial sensors to detect heavy metals.

Detection of cadmium by a double-promoters based Escherichia coli biosensor / 生物工程学报

To detect cadmium ions, we constructed a specific microbial sensor and screened detecting cassettes and different fluorescence proteins. Blue fluorescence protein mTagBFP2 was selected as a reporter and a double-promoters model was used in the construction of the fusion reporter vector Pmer::merR-m-Pmer::mTagBFP2-pMD19-T. The reporter vector was then transformed into Escherichia coli MC4100 wild type strain. The medium, incubation time, initial density for induction, and the optimal detection range were determined. The specificity of the biosensor was also checked. The biosensor responded specifically to cadmium irons with low background, and the linear concentration range detection ranged from 0.1 to 75 μmol/L at the initial OD600 = 0.1 with 2 h incubation in IHMM medium. Thus we successfully constructed a specific biosensor to detect cadmium irons and provided useful strategies for development and optimization of microbial sensors to detect heavy metals.

Effect of recombinant adenovirus-p53 on growth and chemosensitivity of human lung adenocarcinoma cell lines / 中国肺癌杂志

<p><b>BACKGROUND</b>p53 gene is the most commonly mutated gene in lung cancer. p53 mutation results in insensitivity of cells when exposed to chemotherapy. It has been reported that adenovirus-mediated wild-type p53 gene transfection into lung cancer cells can enhance the cytotoxic effect of anti-cancer drugs. The aim of this study is to evaluate the effects of domestic recombinant adenovirus-p53 (Ad-p53, Gendicine) on growth and chemosensitivity of human lung adenocarcinoma cell lines.</p><p><b>METHODS</b>Human lung adenocarcinoma cell lines GLC-82 (including mutant p53) and A549 (including wild-type p53) were treated with Ad-p53, cisplatin (DDP) or Ad-p53+DDP respectively. p53 expression was detected by Western blot. The cell growth inhibition was assessed by MTT, and cell cycle and apoptosis were detected by flow cytometry.</p><p><b>RESULTS</b>High-level p53 expression was detected in Ad-p53 infected GLC-82 and A549 cells by Western blot. There was a dose-dependent and time-dependent inhibition of cell proliferation by Ad-p53. After combined treatment with Ad-p53 (100MOI) and DDP (0.5mg/L) for 72h, the growth inhibition rate of A549 cells was 43.13%±0.72%, which was significantly higher than that in Ad-p53 group ( 23.44%±0.54%, P < 0.001) and DDP group (14.17%±1.39%, P < 0.001); and the growth inhibition rate of GLC-82 cells was 63.73%±0.92%, which was significantly higher than that in Ad-p53 group ( 41.51%±0.59%, P < 0.001) and DDP group (56.11%±1.12%, P < 0.001). Combined administration of Ad-p53 and DDP remarkably arrested A549 and GLC-82 cells in G0-G1, and cells in S phase significantly decreased. Meanwhile the apoptotic rate of A549 cells was 28.99%±1.07% in Ad-p53+DDP group, which was significantly higher than that in Ad-p53 group (15.35%±1.31%, P < 0.001) and DDP group (1.74%±0.77%, P < 0.001). The apoptotic rate of GLC-82 cells was 62.98%±2.43% in Ad-p53+DDP group, which was significantly higher than that in Ad-p53 group (20.88%±0.71%, P < 0.001) and DDP group (6.91%±1.52%, P < 0.001).</p><p><b>CONCLUSIONS</b>Ad-p53 (Gendicine) can inhibit the growth of human lung adenocarcinoma cell lines irrespective of the status of endogenous p53 gene. Its combination with DDP may significantly enhance the chemosensitivity of human lung adenocarcinoma cells to DDP.</p>