Functional synergism of pyoverdine and the S-type pyocins of Pseudomonas aeruginosa / 生物工程学报

Pyocin S2 and S4 in Pseudomonas aeruginosa use the same uptake channels as the pyoverdine does in bacteria, indicating a possible connection between them. In this study, we characterized the single bacterial gene expression distribution of three S-type pyocins (Pys2, PA3866, and PyoS5) and examined the impact of pyocin S2 on bacterial uptake of pyoverdine. The findings demonstrated that the expression of the S-type pyocin genes was highly differentiated in bacterial population under DNAdamage stress. Moreover, exogenous addition of pyocin S2 reduces the bacterial uptake of pyoverdine so that the presence of pyocin S2 prevents the uptake of environmental pyoverdine by non-pyoverdine synthesizing 'cheaters', thereby reducing their resistance to oxidative stress. Furthermore, we discovered that overexpression of the SOS response regulator PrtN in bacteria significantly decreased the expression of genes involved in the synthesis of pyoverdine, significantly decreasing the overall synthesis and exocytosis of pyoverdine. These findings imply a connection between the function of the iron absorption system and the SOS stress response mechanism in bacteria.

Discovery of topAp4 as a new sensing element for TNT detection / 军事医学

Objective To screen the sensing elements for TNT detection in Escherichia coli genome.Methods A genome promoter library with cutting E.coli K-12 MG1655 genome was constructed.Bacterial luciferase luxCDABE was used as a reporter gene during promoter screening.We discovered TNT sensing elements through several rounds of screen-ing.Through analysis of sensitivity, specificity and timeliness, the promoter activity of the elements was evaluated,and the functional sequence of the elements was further confirmed.Results and Conclusion We successfully constructed an E.co-li K-12 MG1655 genome library , from which a TNT sensing element was discovered,which had a good performance in the analysis of sensitivity, specificity and timeliness.In this study, we reported that the topAp4 is a TNT sensing element for the first time.We also verified its excellent promoter activity.

Antimutagenic Effects of 17 Compounds / 第二军医大学学报

The inhibitory and antimutagenic effects of 17 compounds, cysteine (1), cinnamic acid (2), rutin (3), tannic acid (4), germanium dioxide (5), fluro uracil (6), sodium copper chlorophylline (7), B-sitosterol (8), vitamin C (9), coumarin (10), vitamin E (11), L-glutathione (oxidized form) (12), L-glutathione (reduced form) (13), sodium selenile (14), organic germanium (15), L-methioine (16) and proline (17) on the SOS response induced by N-methyl-N'-nitro-N-nitrosoguanidine, niethly muthanesulfonate, benzo (a)pyrine and UV were studied by using SOS chromotest. The results showed that compounds 1~15 revealed inhibitory effects, and compounds 2~8 and 10-11 revealed antimutagenic effects. It was demonstrated that cinnamic acid is the best antimutagen among 17 compounds. Cinnamic acid has not only inhibitory effect but also antimutagenic activity towards a wide variety of mutagens/carcinogens. The modes, specificity and end point of action of antimutagens are discussed.