Cationic polymers are being developed quickly as gene delivery vectors. For in vivo gene delivery, the cationic polymers are usually further modified by hydrophilic polymer grafting or ligand conjugation, which have been shown to increase the vector stability, gene delivery efficiency and specificity greatly. Some previous research had shown that modified hydrophilic polymer may partly shield the targeting ligand and result in poor delivery specificity. Developing a method to evaluate the influence of PEG modification on targeting delivery is particularly critical to cationic polymer design and gene therapy development. One of most commonly used cationic polymer polylysine (PLL) was chosen as a model. Targeting ligand epidermal growth factor(EGF)was conjugated with PLL to form PLL-EGF. Then hydrophilic polymer polyethylene glycol (PEG) with molecular mass 7 000 and 20 000 were used to modify PLL-EGF respectively to generate PEG7000-g-PLL-EGF and PEG20000-g-PLL-EGF. In BIAcore experiments, epidermal growth factor receptor (EGFR) was conjugated onto BIAcore chip and various PEG modified PLL-EGF solutions were flowed over the chip. By observing the change of RU value, the specific interaction of EGF to EGFR was compared. Compared with PLL-EGF, PEG modified PLL-EGF showed lower association rate and higher disassociation rate to EGFR. Furthermore, compared to PEG7000 modified PLL-EGF, PEG20000 modified PLL-EGF got lower association rate and higher disassociation rate to EGFR. The Scatchard analysis results showed that the interactions between EGFR and PLL-EGF or PEG-PLL-EGF are non-linear. It can be concluded that PEG modification indeed reduced the association rate and enhanced the dissociation rate of EGF to EGFR. The length of PEG chain was also a key factor to influence interaction between ligand and receptor. The results showed that it was critical important to evaluate the influence of PEG modification on delivery specificities. The BIAcore method developed in this paper can successfully evaluate the influence, which would be important for cationic polymer design and its application as potential non-viral gene delivery vectors.

The mice B lymphocyte hybridoma cells were irradiated by 60Co?-rays with doses of 1, 2, 4, 6. 8Gy. A markedly dose-relation depression in cell survival rate, cell concentration and clone-forming rate was observed. D37 value of clone-forming rate was 8.26 Gy. Dose-relation depression was also observed in total production of monoclonal antibody of clones. But production of monoclonal antibody per clone was raised with radiation doses. These results indicate that ionization radiation depresses the survival activity of hybridoma cells, but stimulates the secretion of monoclonal antibody of survival cells.

Industrial microorganisms are subject to various stress conditions, including products and substrates inhibitions. Therefore, improvement of stress tolerance is of great importance for industrial microbial production. Acetic acid is one of the major inhibitors in the cellulosic hydrolysates, which affects seriously on cell growth and metabolism of Saccharomyces cerevisiae. Studies on the molecular mechanisms underlying adaptive response and tolerance of acetic acid of S. cerevisiae benefit breeding of robust strains of industrial yeast for more efficient production. In recent years, more insights into the molecular mechanisms underlying acetic acid tolerance have been revealed through analysis of global gene expression and metabolomics analysis, as well as phenomics analysis by single gene deletion libraries. Novel genes related to response to acetic acid and improvement of acetic acid tolerance have been identified, and novel strains with improved acetic acid tolerance were constructed by modifying key genes. Metal ions including potassium and zinc play important roles in acetic acid tolerance in S. cerevisiae, and the effect of zinc was first discovered in our previous studies on flocculating yeast. Genes involved in cell wall remodeling, membrane transport, energy metabolism, amino acid biosynthesis and transport, as well as global transcription regulation were discussed. Exploration and modification of the molecular mechanisms of yeast acetic acid tolerance will be done further on levels such as post-translational modifications and synthetic biology and engineering; and the knowledge obtained will pave the way for breeding robust strains for more efficient bioconversion of cellulosic materials to produce biofuels and bio-based chemicals.
Acetic Acid ; pharmacology ; Genomics ; Industrial Microbiology ; Saccharomyces cerevisiae ; drug effects ; genetics

Objective To investigate gene transfer efficiency of a novel target non-viral vector GE7 and effects of herpes simplex virus thymidine kinase (HSV 1-tk)/ganciclovir(GCV) mediated by it in vitro. Methods The epidermal growth factor receptor (EGF-R) target gene delivery system GE7 was constructed.Human ovarian cancer cell line CAOV3 was transfected in vitro with ?-galactosidase(?-gal) as reporter gene and HSV 1-tk gene as therapeutic gene using this gene delivery system.By means of the assay of X-gal staining, Northern blotting, cell growth-inhibiting curve and so on,the transferring efficiency of exogenous genes and killing effects are observed. Results It showed that gene transfer efficiency is over 80%.When 10 mg/L GCV was put into ovarian cells transfected with HSV 1-tk gene, 95% of cells were killed, and the apoptosis ratio reached up to 30. Conclusions The GE7 gene delivery system is an effective and safe delivery system.GE7/ HSV 1-tk /GCV therapeutic gene system is appraising for ovarian cancer.

Overexpression of multidrug resistance gene, (MDR1) is responsible for the resistance of anticancer agents in cancer cells. In this study, we designed three pairs of DNA primers to clone MDR, cDNA from human normal liver by polymerase chain reaction. The sites of these primers in MDR cDNA are (I)-64-46 (5') and 1680-1698 (3'); (II) 1471-1489 (5') and 2905-2923 (3'); (III)2729-2747 (5') and 3845-3863 (3). The three reactions were underwent after the human normal liver mRNA was reverse transcripted into single strand DNA. The lengths of PCR products are 1762bp, 1452 bp and 1134bp, respectively. The former two products were subcloned in pBluscript SK, respectively and the latter product was subcloned in pGEM7Z (named as pMDR1.7, pMDR1.4 and pMDRl.l, respectively). Cloned genes were certificated as MDR1 cDNA by sequence analysis. Full-length MDR, cDNA was obtained after further subcloning. Full-length MDR1 cDNA we obtained will be a very important tool in molecular diagnosis and gene therapy of anticancer drug resistance.

Objective To investigate the efficiency of antitumor immune responses induced by a controlled live dendritic cell(DC)vaccine Methods DC precursors were isolated from Fischer 344 rat bone marrow and cultured with granulocyte macrophage colony stimulating factor and interleukin 4 The rat ovarian tumor cell line NuTu 19 was genetically modified by retroviral mediated suicide gene(HSV 1 TK), and the positive clones were selected using G418 Live DC vaccine was then fused with DC and NuTu 19/TK cell by polyethylene glycol The characteristics of live DC vaccine were assayed with flow cytometry and confocal laser scanning microscopy The specific expression of HSV 1 TK gene in live DC vaccine was evaluated by RT PCR and western blot The sensitivity of live DC vaccine to ganciclovir (GCV) was evaluated by methylthiazoletetrazolium assay In vivo, rats vaccinated twice with live DC vaccine were compared to those vaccinated with killed DC vaccine, unfused DC and NuTu 19/TK cell or phosphate buffered saline Seven days following the last immunization, the rats were sacrificed to test the specific cytotoxic T lymphocyte (CTL) activity by lactate dehydrogenase release assay, or challenged with NuTu 19 and tumor incidence was observed Results The fusion efficiency was approximately (23?14) Live DC vaccine displayed an up regulated expression of major histocompatibility complex (MHC) IIOX6 (87 6?3 4)%, costimulatory molecule B 1 2 (71 1?9 3)%, integrin OX 62 (68 0?7 4)%, and adhesion ICAM 1 (77 1?2 0)%, and specifically expressed HSV 1 TK gene. Our data showed that spleen T lymphocytes from rats vaccinated with live vaccine displayed enhanced CTL aetivity (61 8?8 3)% contrast to that of rats vaccinated with killed vaccines (26 0?3 8)% ( P

BACKGROUNDTo study the structure and function of 2.2 kb spliced variant of HBV genome from liver tissues of hepatocellular carcinoma patients.

METHODSHBV genomes were amplified by using PCR from paired hepatocellular carcinoma tissues and peritumor tissues. The 3.2 kb full-length HBV genome and 2.2 kb spliced variant were separately cloned and sequenced. Hep G2 cells were co-transfected with full-length HBV DNA and 2.2 kb spliced variant, and after transfection, HBV DNAs from intracellular core particles were harvested and specific primers were used in PCR to evaluate the interactions between spliced variant and full-length counterpart in replication.

RESULTSSemi-quantification by scanning density showed that 2.2 kb spliced variant was present in all tumor and peri-tumor samples studied. Sequence analyes revealed that the 5 terminus packaging signal for pregenomic and X and PreC/C genes were retained. When full-length HBV DNA was co-transfected with 2.2 kb, the replication signal of 3.2 kb HBV genome was increased 3-7 times.

CONCLUSIONSThe 2.2 kb HBV spliced variant was present in liver tissues, and relative content was higher in tumor tissues than that in the peri-tumor tissues. This spliced variant could enhance the replication of full-length HBV genome, which suggested the possible role of the variant in the pathogenesis of development of hepatocellular carcinoma.

Adult ; Aged ; Carcinoma, Hepatocellular ; virology ; DNA, Viral ; analysis ; Female ; Genetic Variation ; Genome, Viral ; Hepatitis B virus ; genetics ; Humans ; Liver ; virology ; Liver Neoplasms ; virology ; Male ; Middle Aged ; RNA, Viral ; analysis ; Sequence Analysis, DNA

We have cloned full-length MDR1 cDNA from human normal liver tissue in previous study. Using this MDR1 cDNA as probe, we observed the MDR1 gene expression in human hepatocellular carcinoma treated with and without chemotherapy by Northern blot. The results showed that expression of MDR1 gene in hepatocellular carcinoma tissues was higher than that in their adjacent normal liver tissues; and enhanced MDR1 gene expression was also observed in hepatocellular carcinoma treated with chemotherapic agents. We also explored a method for quantitative analysis of MDR1 gene expression in hepatocellular carcinoma by polymerase chain reaction. This study suggests that overexpression of MDR1 gene may be responsible for the intrinsic and acquired drug resistance of human hepatocellular carcinoma, and PCR is a preferable method for quantitative analysis of MDR1 gene expression in hepatocellular carcinoma.

Objective To investigate the antimicrobial susceptibility of Pseudomonas aeruginosa (P. aeruginosa) isolated from Zhenjiang area to 13 routinely used antibiotics and identify the structure and dissemination of class Ⅰ integron. Methods K-B test was used to determine the resistant rate of 71 strains of P. aeruginosa. DNA template was extracted by boiling method, PCR method was utilized to detect class Ⅰintegron, and subsequently gene cassettes were analyzed by sequencing. Results The resistant rates to 13 routinely used antibiotics were quite different from 18. 3 to 77.5% among 71 strains of P. aeruginosa. The prevalence of class Ⅰ integron was 38%. These integrons include 5 gene cassettes ( aadB, aac (6) - Ⅱ , PSE-Ⅰ , dfrA17 and aadAS), in which dfrA17 and aadA5 gene cassette were frequently found. Comparing with the negative strains of integron, the positive strains of integron has obviously higher resistance to ten the antibiotics including piporacillin, piperacillin-tazobactam, ceftriaxone, cefepime, ceftazidime, gentamicin,amikacin, tobmmycin, levofloxacin, and ciprofloxacin. Conclusions The resistant rates of P. aeruginosa to 13 drugs were different, and the resistant rates of integron positive strains were obviously higher than integron negative strains, which indicates that integron may play an important role in multidrug reisistance of P. aeruginoosa.

By-products released from pretreatment process of lignocellulose seriously hinder the development of cellulosic fuel ethanol. Therefore, the great way to increase the efficiency of cellulosic ethanol production is improvement of Saccharomyces cerevisiae tolerance to these inhibitors. In this work, the effects of LCB4 gene overexpression on cell growth and ethanol fermentation in S. cerevisiae S288C under acetic acid, furfural and vanillin stresses were studied. Compared to the control strain S288C-HO, the recombinant strain S288C-LCB4 grew better on YPD solid medium containing 10 g/L acetic acid, 1.5 g/L furfural and 1 g/L vanillin. Ethanol yields of recombinant strain S288C-LCB4 were 0.85 g/(L·h), 0.76 g/(L·h) and 1.12 g/(L·h) when 10 g/L acetic acid, 3 g/L furfural and 2 g/L vanillin were supplemented into the fermentation medium respectively, which increased by 34.9%, 85.4% and 330.8% than the control strain S288C-HO. Meanwhile, ethanol fermentation time was reduced by 30 h and 44 h under furfural and vanillin stresses respectively. Further metabolites analysis in fermentation broth showed that the recombinant strain produced more protective compounds, such as glycerol, trehalose and succinic acid, than the control strain, which could be the reason for enhancing strain tolerance to these inhibitors from pretreatment process of lignocellulose. The results indicated that overexpression of LCB4 gene could significantly improve ethanol fermentation in S. cerevisiae S288C under acetic acid, furfural and vanillin stresses.