Establishment and comparison of pulsed-field gel electrophoresis, multiple-locus variable number tandem repeat analysis and automated ribotyping methods for subtyping of Citrobacter strains / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To establish and compare the pulsed-field gel electrophoresis (PFGE), multiple-locus variable number tandem repeat analysis (MLVA) and automated ribotyping for subtyping of Citrobacter strains.</p><p><b>METHODS</b>PFGE protocol was optimized in terms of plug preparation procedure, restriction enzymes and configuration of electrophoretic parameters. MLVA method was evaluated by finding variable number tandem repeats in two genomes of Citrobacter strains. The ribotyping was performed by using the automated RiboPrinter system.</p><p><b>RESULTS</b>We optimized the plug preparation procedure, focused on the cell suspension concentration (turbidity of 2.5 to 3.5), SDS addition (no SDS needed) and lysis time (1 h), and selected the appropriate restriction enzyme (XbaI) and the electrophoretic parameters (1.0 s-20.0 s for 19 h) of PFGE. There was nearly no discriminatory power of MLVA between Citrobacter strains. For 51 Citrobacter strains, automated ribotyping gave a D-value of 0.9945, while PFGE gave a D-value of 0.9969. Both PFGE and automated ribotyping clustered strains from the same sources (with the same species from the same place at the same time identified as the same source) and divided strains from different sources (from different years, places and hosts) into different subtypes.</p><p><b>CONCLUSION</b>PFGE protocol established in this paper and automated ribotyping are suitable for application in Citrobacter subtyping.</p>

Arsenic trioxide induces socs-1 gene demethylation in myeloma cell lines / 中国实验血液学杂志

The aim of this study was to explore the effect of arsenic trioxide (As(2)O(3)) on the methylation status of socs-1 gene in multiple myeloma cell lines U266, RPMI8226. The cell viability was assayed by MTT method. The methylation status of socs-1 gene was detected by methylation specific PCR. The expression of socs-1 gene mRNA was determined with real-time PCR. The cell apoptosis was analyzed by flow cytometry. The results indicated that hypermethylation of CpG island of socs-1 gene was observed without expression of socs-1 in myeloma cell lines U266, RPMI8226. The expression of socs-1 gene mRNA in each myeloma cell line increased significantly after exposure to As(2)O(3) for 72 hours as compared with the cell lines of wild type (p < 0.05). And cell proliferation was significantly inhibited, both early apoptosis and later apoptosis ratios increased in dose-dependent manner. It is concluded that As(2)O(3) may induce socs-1 demethylation and up-regulate the expression of the gene. This study provides a new thought and direction for exploring possible mechanism of cell apoptosis induced by As(2)O(3) and multiple myeloma treatment by As(2)O(3).

Cloning and characterization of a novel glutathione transferase gene from Penicillium chrysogenum / 生物工程学报

Glutathione transferases (GSTs) are a family of multifunctional proteins that mainly catalyze the conjugation of intracellular glutathione (GSH) to a wide variety of endogenous and exogenous electrophilic compounds. GSTs play important roles in stress tolerance and in the detoxification metabolism in organisms. A novel GST gene, Pc gstB, was cloned from penicillin producing fungus Penicillium chrysogenum using RT-PCR. The open reading frame (ORF) of Pc gstB was 651 bp and encoded a peptide of 216 residues. The deduced amino acids sequence had conserved GST domain and showed 65% identity to the characterized Aspergillus fumigutus gstB. The entire ORF of Pc gstB was inserted into vector pTrc99A and transformed into Escherichia coli DH5alpha. Recombinant PcGstB was overexpressed and its GST activity toward substrate 1-chloro-2,4-dinitrobenzene (CDNB) was validated.