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@#The changes in intestinal flora are usually associated with different gastrointestinal diseases, and intestinal flora homeostasis can enhance immune tolerance and regulate intestinal immune balance.Previous studies have found that the increase of the relative abundance of Bacteroides fragilis (B.fragilis) in Bacteroides intestinalis can significantly enhance the expression of intestinal regulatory T cells (Treg) and anti-inflammatory cytokines, thus alleviating intestinal inflammation.However, the mechanism of B.fragilis regulating intestinal immunity is still unclear.In this study, an acute colitis model was constructed by giving 3% DSS in drinking water solution to SPF-grade C57BL/6 mice for 7 days, and exogenous supplementation B.fragilis was given to mice by gastric gavage to study its regulatory effect on intestinal immunity and its mechanism of action.The results showed that B.fragilis could improve the intestinal flora disorder in mice with colitis and increase the content of short-chain fatty acids (SCFAs), the main metabolite of the intestinal flora.By extracting mouse tissue lymphocytes, naive CD4+ T cells, and liposome-modified siRNA knockdown mouse Smad3, it was further discovered by flow cytometry that B.fragilis induced the expression of intestinal Treg cells and related cytokines through the TGF-β/Smad3 signaling pathway, which enhanced intestinal regulatory immunity and alleviated colitis.It was also found that B.fragilis activated TGF-β by increasing the expression of reactive oxygen species (ROS), thus inducing Treg cell differentiation and playing an immunomodulatory role.
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Marine actinomyces LYG-1 was isolated from marine mud flats in Lianyungang,China.Strain LYG-1 was identified using the methods of morphology,physiological and ehemotaxonomic characterization and 16S rRNA gene sequence analysis.The results showed that strain LYG-1 was a marine variable species of Streptomyces roseosporus.The fermentation broth of strain LYG-1 exhibited conspicuous antitumor activity against HepG2,MCF-7,HCT116 and MDA-MB-231 cell lines,and the IC50 values were defined by MTT method respectively.
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Aim: To construct a prokaryotic expression vector carrying NuBCP-9-tumstatin(74-98) (abbreviated as NT) gene and to obtain the fusion peptide with antitumor activity. Methods: Nucleotide sequences of antitumor peptides, NuBCP-9 and Tumstatin( 74-98), were connected via a linker(G_4S)_3 based on biased codons of E. coli the fused NT gene was reconstructed using SOE PCR, and inserted into pET32a(+) vector, and transformed in E. coli BL21(DE3). After expression, the novel fusion peptide was purified through nickel-affinity chromatogra-phy, Factor Xa digestion and ultrafiltration. Biological activity of the fusion peptide on ECV304 and A549 cells was evaluated by MTT assay. Results: A prokaryotic expression system with NT gene was successfully constructed. The soluble fusion peptide was accounted for approximately 25% when induced by 0. 5 mmol/L IPTG at 30 ℃ for 4 h. The purified fusion peptide could inhibit cell growth of ECV304 and A549 with inhibition rates of 60. 8% and 65. 2% at 20 μmol/L, respectively. Conclusion: A novel fusion peptide with antitumor activity was cloned, expressed and purified.
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Objective To extract and purify a polysaccharide SEP from eggs of sea urchin Strongylocentrotus nudus. and to determine its purity, molecular weight and immunological activity in vitro. Methods The orthogonal design was employed to obtain the best possible combination of the critical parameters for polysaccharide extraction. By ultrafiltration, DE-AE Sepharose Fast Flow anion-exchange chromatography and Sephacryl S-400 gel filtration chromatography, the deproteinated crude polysaccharide was purified. The homogeneity of SEP was proved by HPLC, polyacrylamide gel electrophoresis and paper chromatography. Its molecular weight was determined by HPGPC in reference to standVd T-series Dextran. Lymphocyte proliferation assay was made to investigate the immuno-modulating activity of SEP. Results and Conclusion The results indicated SEP was a homogeneous polysaccharide. Its molecular weight was about 1950KD. SEP increased remarkably spleen lymphocyte proliferation. The homogeneous polysaccharide SEP showed significantly immunological activity in vitro.
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Objective To study bioactive metabolite produced by marine actinomyces M326.Methods Based on the index of antimicrobial activity,the relation between activity of metabolite and conditions of culture in different media and time were researched,and the stability of bioactive metabolite treated with different temperatures and pH were obseved,and the bioactive ingredients were extracted and separated by organic solvent and by macroporous resin.Results The GBP medium made by artificial seawater or distilled water were suitable for production of strong bioactive metabolites.The antimicrobial substances were stable under pH 2～11 and were heat-resistant under strong acidic condition.It could not be extracted by usual organic solvent,but could be absorbed by AB-8 macroporous resin under alkaline situation.Conclusion The metabolites have strong activity against gram-positive bacteria and have different antimicrobial activities against gram-negative bacteria and drug-resistant strains moreover,the polarity of antimicrobial substances is strong.