Inhibition of Aspergillus parasiticus and Cancer Cells by Marine Actinomycete Strains

Ten actinomycete strains isolated from the Yellow Sea off China＇s coasts were identified as belonging to two genera by 16S rDNA phylogenetic analysis： Streptomyces and Nocardiopsis. Six Streptomyces strains （MA10, 2SHXF01-3, MA35, MA05-2, MA05-2-1 and MA08-1） and one Nocardiopsis strain （MA03） were predicted to have the potential to produce aromatic polyketides based on the analysis of the KSa （ketoacyl-synthase） gene in the type II PKS （polyketides synthase） gene cluster. Four strains （MA03, MA01, MA10 and MA05-2） exhibited significant inhibitory effects on mycelia growth （inhibition rate 〉50%） and subsequent aria- toxin production （inhibition rate 〉75%） of the mutant aflatoxigenic Aspergillus parasiticus NFRI-95. The ethyl acetate extracts of the broth of these four strains displayed significant inhibitory effects on mycelia growth, and the IC50 values were calculated （MA03： 0.275 mg mL-1, MA01：0.106 mg mL-1, MA10：1.345 mg mL-1 and MA05-2：1.362 mg mL-1）. Five strains （2SHXF01-3, MA03, MA05-2, MA01 and MA08-1） were selected based on their high cytotoxic activities. The ethyl acetate extract of the Nocardiopsis strain MA03 was particularly noted for its high antitumor activity against human carcinomas of the cervix （HeLa）, lung （A549）, kidney （Caki-1） and liver （HepG2） （IC50： 2.890, 1.981, 3.032 and 2.603 μgmL-1, respectively）. The extract also remarkably inhibited colony formation of HeLa cells at an extremely low concentration （0.5μgmL 1）. This study highlights that marine-derived actinomycetes are a huge resource of compounds for the biological control of aflatoxin contamination and the development of novel drugs for human carcinomas.

Inhibition of Proliferation of Human Hela Cells by Small Interference RNA against Pokemon Gene

Objective： The transcriptional repressor Pokemon （encoded by the Zbtb7 gene） is a critical factor in oncogenesis. Pokemon overexpression leads to overt oncogenic transformation both in vitro and in vivo in transgenic mice, The objective of this study was to investigate the effect of retrovirus expressing the siRNA targeting Pokemon in human cervical cancer cells. Methods： We constructed and identified the recombinant retrovirus particle expressing siRNA of Pokemon gene, and then testified the suppression of recombinant plasmid and evaluated the gene-silencing effect. Results： We got the positive evaluation from colony forming experiment we found that the retrovirus expressing siRNA targeting Pokemon had repressing effect. Conclusion： Our work provides basis for the study of suppression effect of retrovirus in vivo and the design of the target-complex.

Reconstruction of hematopoietic function in irradiated mice promoted by polysaccharide peptide

Objective: To study the effect of polysaccharide peptide (PSP) on the reconstruction of the hematopoietic function in mice irradiated by lethal dose. Methods: The characteristics of proliferation of colony forming unit granulocyte macrophage (CFU GM) and colony forming unit spleen (CFU S) were measured after continuous injection of PSP in mice for seven days with different doses. Results: Injection of 25 mg/kg PSP in mice could promote and increase CFU GM proliferation and cell mitosis, markedly enhance survival ratio, survival time and CFU S. Conclusions: PSP has significant regulative effects on the reconstruction of the hematopoietic and the immunologic functions in mice irradiated by lethal dose.