Advanced Materials Research Vols. 343-344

Abstract: To investigate the combined effect of kappa-selenocarrageenan (KSC) and paclitaxol (Taxol) on MCF-7 cells in vitro. The cytotoxic effect of both drugs on MCF-7 cells was measured by MTT assay, and the King’s principle was used to evaluate the interaction of drugs combination. KSC and Taxol alone have significant growth inhibitory effects on HepG-2 cells in dose- and time-dependent manners, and the combination groups show more remarkable anti-proliferative activities than the two drugs alone. The IC₅₀ values of KSC and Taxol alone on HepG-2 cells for 72h are 48.445 mg/L and 2.592 nmol/L, respectively. While combining with 30 mg/L KSC, IC₅₀ value of Taxol decreases sharply to 0.353 nmol/L. Q values of their combination are 0.908~1.051, which demonstrates additive effect. In short, selenium polysaccharide has striking inhibition effect on MCF-7 cells and can enhance efficacy of chemotherapeutic agents and reduce their side effects.

Abstract: A field Marek’s disease virus (MDV), named as BY strain, was firstly isolated from Tibetan chickens in Sichuan province, China, by method of co-cultivation of the lymphocytes with duck embryo fibroblasts (DEF). Analysis of the oncogenic genes showed that there were 2 copies of 132-bp repeated sequence in long terminal repeat of the BY strain, The nucleotide and amino acid sequence identities of Meq gene of BY strain with other prevalent MDV strains in China were 97.6-100.0% and 98.8-100.0%, respectively, and some point mutations assumed to be relevant to the oncogenecity of MDV also existed in the Meq gene of BY strain. The result of animal challenge test on specific-pathogen-free (SPF) chickens showed lymphomas may occur in a variety of organs as early as 18 days post challenge, and the rate of tumor occurrences and mortalities reached to 73.33% and 66.67% in HVT immunized chickens, respectively. In conclusion, an MDV strain charac-terized of acute oncogenicity was isolated from Tibetan chickens in China, though there were no obvious difference between the oncogenic genes of this strain and other virulent MDV strains isolated in China in recent years.

Abstract: The subtype of avian leukosis virus (ALV) was mainly determined by the gp85 glycoprotein. A subtype J ALV strain SCDY1 associated with hemangioma was isolated from grandparent breeding chicken and the highly antigenic region of its gp85 gene was amplified and expressed in Rosetta Escherichia coli using the pET-32a(+)vector. The fusion protein, which was expressed at a high level, was similar antigenically to the native gp85 protein as determined by Western blot assay using polyclonal antibodies against ALV-J strain. The fusion protein was also purified. This research lays a foundation for using this recombinant protein for development of indirect enzyme-linked immunosorbent assay (ELISA) for serum antibody detection or for production of monoclonal antibodies against prevalent ALV-J.

Abstract: A strain improvement program was developed to increase lipase production by Acinetobacter calcoaceticus D29, in which mutants were generated by Ultraviolet (UV) radiation and selected by resistance to 1.5% (w/v) sodium citrate. One of the mutant strains UN9 exhibited 48.69% more lipase activity than the original strain did. Although the UV random mutagenesis alone is an effective method for general strain improvement, our results showed that UV mutagenesis combined with selection for sodium citrate resistance is a more efficient strategy for screening mutant strains with enhanced lipase production.

Abstract: This article summarizes the development of current condition of bio-energy development simply, including the most bio-ethanol and biodiesel are potential, but the material is the biggest obstacle. Inulin is present as a reserve carbohydrate in the roots and tubers of plants,which will maybe use to ethanol fermentation, single cell oil production and inulooligosaccharide(IOS) production.

Abstract: Ypsizigus marmoreus is a newly cultivated medicinal and edible mushroom with higher antitumor activity. In this paper, a uniform design was used to optimize the medium formula with four factors each at six levels, and a regression model was constructed to predict the antitumor exopolysaccharide production. The optimal concentrations for the enhanced exopolysaccharide production were determined as 30% (w/v) glucose, 8.4% (w/v) soybean peptone, 3% (w/v) KH₂PO₄ and 30% (w/v) sweat potato flour. Subsequent experiment confirmed the validity of the model. Under the optimal condition, exopolysaccharide yield reached 3.39g/L in shake-flask culture, which was 3.53 fold higher than that obtained in the basic medium. The results highlight the future application of optimized medium for high yield production of antitumor exopolysaccharide by fermentation of Hypsizigus marmoreus.

Abstract: Bacillus subtilis is potential to play an important role on biological control of aflatoxin-producing fungi. The liquid fermentation medium of Bacillus subtilis LN for production of bioactive metabolites inhibitory to mycelial growth and aflatoxin biosynthesis was optimized by single factor experiments. The results showed that optimum carbon source was glucose, the optimum nitrogen source was soy peptone, and the optimum inorganic salt was MgSO_4. These screened optimal carbon, nitrogen and inorganic salt sources could be used for high yield fermentation of bioactive metabolites for developing biopesticide against aflatoxin contamination in foods.

Abstract: Single-strand conformation polymorphism (SSCP) method for detecting of HVR1 quasi-species of HCV is necessary for hepatitis C diagnosis. In this study, we described a rapid and sensitive SSCP method to analyze HCV quasi-species using common equipment. After RT-PCR reaction, denaturing was conducted with heating and Chilling. By varying the electrophoresis temperature, voltage and total acrylamide concentration，the extent of cross-linking in the gels (1-2.5%) and the concentration in glycerol ( 0-10％), SSCP method was established. With the optimized procedure, variants representing 2-3% of the whole quasi-species could be detected. By isolating visible bands from electrophoresis gel followed by sequencing, the genetic variability of HCV can be concluded. This method has high accuracy and reproducibility, simplicity and low cost, which could be a useful tool in laboratory practice.

Abstract: Styela clava were exposed to sublethal concentrations of methamidophos (5.0, 10.0 and 15.0 μg/L) for 96 h, its biochemical stress response was studied taking into account carboxylesterase (CbE), catalase (CAT), SOD and glutathione S-transferase (GST) activities, as well as reduced glutathione (GSH) levels in tissues. In all exposed groups CbE was significantly inhibited. GSH level was reduced after exposure, and CAT activity decreased continuously. 24 h exposure to methamidophos did not affect GST activity. The results show that the early inhibitory effect in CAT activity and GSH content produced by methamidophos may be associated with a high degree of oxidative stress. CbE inhibition is a good biomaker for methamidophos exposure. This study revealed that S. clava developed adaptive response to neutralize the oxidative stress following pesticide exposure and that SOD and GPx can be used as biomarker in determining methamidophos toxicity due to its early response at even low concentration levels.

Abstract: Based on the semi-static two compartment model, the bioconcentration and elimination of copper with tissues of Styela clava were investigated. The kinetic parameters (accumulation rate constant k₁, elimination rate constant k₂, bioconcentration factor BCF, biological half life t_1/2 and maximum equilibrium concentration C_Amax) were obtained by non-linear regression. The results showed S. clava could accumulate copper from the aquatic environment and that BCF decreased with increasing metal concentration in water. When the accumulation achieved balance, C_Amax showed positive correlation to metal concentrations in water. Concentrations of copper in different tissues of S. clava were in the order of gonad > digestive gland ≈ other part >tunic, and t_1/2 of copper was 12.57 to 38.18 days in elimination phase. The high rate to accumulate and eliminate copper from its body exhibited a useful potential biomonitor of short-term copper fluctuations status in marine system.