Molecular design, structural analysis and bactericidal activity of derivatives of antimicrobial peptide buforin II / 药学学报

A novel peptide, named BF2-X, was designed based on the structure-activity analysis of an analogue of Buforin II, named BF2-A. The BF2-X was a hybrid peptide containing the N-terminal residues 5 to 13 of BF2-A and three repeats of the C-terminal regular alpha-helical motif RLLR, and the residues 8 valine were replaced by leucine. The results of bioinformatics analysis had showed that compared with BF2-A, the helicity, positive charge, hydrophobicity rate and C-terminal amphipathy of BF2-X had remarkably enhanced. Both peptides showed a random coil structure in an aqueous solution, while displaying a typical alpha-helical structure in 50% trifluoroethanol solution (a membrane mimic condition). BF2-X exhibited higher alpha-helical contents than BF2-A in hydrophobic environment. BF2-X displayed potent antimicrobial activities against a broad spectrum of microorganisms. And BF2-X showed stronger antimicrobial activities against bacteria tested than parent peptide BF2-A. These results suggest that the alpha-helical content was directly correlated with the enhanced antibacterial activity. Both peptides had no hemolytic action on mouse erythrocyte.

The Influence of Peptidoglycan of Lactobacillus on Immune Function of Mouse / 中国生物工程杂志

Mice was stimulated by peptidoglycan from Lactobacillus sp and detect cytokines production。It was found that PG induced the production of inflammatory cytokines (IL-1,TNF-? in peritoneal macrophages,IFN-? in spleen cell)and did not induce the IL-2 production in spleen cell. Affymetrix MOE430A genechip was used to analyze changed gene expression of immune cells. It was found that expression of cytokines and related genes were changed under peptidoglycan administration. This might induced by activation of TLR-NF-?B signal pathway.

Effect of Foreign Plasmid DNA on Material and Energy Metabolism of Spleen in Mice / 中国生物工程杂志

To study the influence of foreign plasmid DNA on spleen metabolism in immune-stimulated mice via the gastrointestinal tract. Mice were oral administered by pipette with 200?g of plasmid pcDNA3 and spleen were isolated at 4h and 18h after oral administration. Total RNA were extracted from spleen and spleen gene expression profile of Balb/c mice was analyzed by using Affymetrix oligonucleotide genechip after oral plasmid pcDNA3 administration. Functional cluster analysis was conducted by Genmapp and MAPPFinder software. By functional cluster analyzing the genes which were up-regulated more than twofolds, Genmapp results showed that plenty of metabolic pathway were induced in spleen after oral administration of plasmid pcDNA3. These metabolic process included purine metabolism, pyrimidine metabolism, protein synthesis, cholesterol synthesis, fatty acid synthesis, Glycolysis, TCA cycle and mitochondria oxidative phosphorylation pathway. The similar results also took place at 18h after oral administration. The result indicated that foreign plasmid DNA can modulate metabolism process in spleen of mice via the gastrointestinal tract, and may help understand the mechanism of action of foreign plasmid DNA uptaked via the gastrointestinal tract.

Effect of different zinc sources and levels on inhibition of the apoptosis induced by glucocorticoid of thymocytes in vitro.

This experiment was conducted to investigate the effects of zinc sulfate and zinc methionine (Zn-Met) and their levels on apoptosis induced by glucocorticoid of thymocytes and the possible mechanism. Dexamethasone was used to make the apoptosis model of thymocytes; zinc sulfate and zinc methionine were supplemented to the medium at levels of 0, 50, 100, 500, and 1000 microM. The activity of cells, Cu,Zn superoxide dismutase (Cu,Zn-SOD), DNA ladder pattern, intracellular calcium concentration, and the percentage of apoptosis nuclei were determined. Both ZnSO4 and Zn-Met could modulate apoptosis; they inhibited apoptosis and decreased DNA fragmentation. The regulation was concentration dependent. At levels of 50 and 100 microM, the effect of Zn-Met on inhibiting apoptosis was less efficient than that of ZnSO4 (p<0.05), but the activity of the cells cultured with Zn-Met was higher than those cultured with ZnSO4; they showed no difference in modulating apoptosis when added at levels of 500 and 1000 microM to the medium (p>0.05). Intracellular calcium concentrations of cells cultured with Zn-Met were higher than those cultured with ZnSO4 at the same levels. Zinc supplementation decreased the concentration of intracellular calcium significantly (p<0.05) and increased the activity of Cu,Zn-SOD in the extract of the cells (p<0.05). Both zinc sulfate and Zn-Met could modulate apoptosis of thymocytes induced by glucocorticoid; the mechanism might involve the exchange of intracellular calcium, the redox of cells, and the two forms of zinc might go different ways in the regulations.

Effects of nucleotides on apoptosis of thymocytes / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the effects of nucleotides on apoptosis of thymocytes in mice.</p><p><b>METHODS</b>Apoptosis model in vivo was first established and 25 KM mice, 4 weeks old, were randomly divided into 5 groups. One group was control, and the others were test groups. Mice in test groups were injected with DEX (25 mg/kg) and the controls were treated with normal saline. 4, 8, 16, and 24 hours later the thymus and spleen were weighed and lymphocytes in thymus were separated. The apoptosis of lymphocytes was analyzed by using DNA electrophoresis and flow cytometry. 16 hours later lymphocytes apoptosis reached a peak and lasted 24 hours. Methods used to establish apoptosis model in vivo were: mice (4 weeks old) were injected with DEX (25 mg/kg), and thymus lymphocytes were separated 16 hours later and analyzed. The effects of nucleotides on apoptosis of mice thymocytes were investigated in experiment 2. Sixty KM mice, 20 g +/- 2g, 4 weeks old, were divided into four treatments: negative control group (NC), positive control group (PC), nucleotides-additive group 1 (NTS1) and nucleotides-additive group 2 (NTS2).</p><p><b>RESULTS</b>Body weight gained in NST1 and NST2 were 3.71 g, 4.01 g respectively, significantly higher than NC (2.74 g) (P < 0.01) and in NST2 was significantly higher than in PC (2.96 g) (P < 0.01). Thymus index and spleen index were decreased significantly (P < 0.01), and no difference was found with the supplementation of nucleotides (P > 0.05). [Ca2+]i increased to 167.37 nmol/L, 191.16 nmol/L, 180.78 nmol/L in PC, NST1 and NST2 with DEX, being significantly higher than in NC (103.76 nmol/L) (P < 0.01). The percent of apoptosised thymocytes in groups were 0.31%, 11.93%, 9.82%, 11.15%, respectively. Thymus index and spleen index, cell apoptosis and [Ca2+]i were not differed significantly among PC, NTS1 and NTS2 groups.</p><p><b>CONCLUSION</b>Nucleotides should have no significant effects on apoptosis of thymocytes in mice in vivo.</p>

The development of peptide nucleic acid in gene regulation / 生物工程学报

Peptide nucleic acid(PNA) is a kind of artificial DNA mimic. PNA hybridizes with DNA or RNA by means of Watson-Crick's base-pairs complementary with high stability, affinity and selectivity. PNA not only regulates. DNA replication, but also adjusts DNA transcription (or reverse transcription) and translation. Many applications have been explored as a new kind of molecular biological tool and a gene-targeting strategy.