• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.29-36
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• 2011

Pseudomonas aeruginosa is an opportunistic pathogen that causes various infections on urinary track, cornea, respiratory track, and burn wound site, and mainly relies on quorum sensing (QS) for its virulence. To control the infectivity of P. aeruginosa, we previously synthesized the structural analogues of a major QS signal, N-3-oxododecanoyl homoserine lactone (3OC12-HSL) to use as a QS inhibitor. Two of them (5b and 5f) had been confirmed to have an inhibitory effect on LasR, a major QS signal receptor of P. aeruginosa in the screening by the recombinant Escherichia coli reporter. To further evaluate these compounds, we tested their efficacy to control the QS and virulence of P. aeruginosa. Unlike the result from E. coli reporter, both 5b and 5f failed to affect the LasR activity in P. aeruginosa, but instead they selectively affected the activity of QscR, another 3OC12-HSL receptor of P. aeruginosa. Interestingly, their effect on QscR was complex and opposite to what we obtained with E. coli system. Both 5b and 5f enhanced the QscR activity at the low concentration range (< 10 ${\mu}m$), but high concentration of 5f (${\approx}$1 mM) strongly inhibited QscR. While 5b and 5f didn't affect the production of proteases, the key virulence factor, they significantly reduced the biofilm formation that is important in mediating chronic infections. Especially, 5f inhibited the initial attachment of P. aeruginosa, rather than the biofilm maturation. Based on our results, we suggest that 5f can be applied for an anti-biofilm agent without increasing virulence of P. aeruginosa.

• Journal of Korean Historical Folklife
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• no.27
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• pp.267-361
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• 2008

This article traces how the modern Chinese "nation" was constructed as an "imagined community" around Huang-ti (the Yellow Emperor) in late Qing. Huang-ti was a legendary figure in ancient China and the imperial courts monopolized the worship of him. Many late Qing intellectuals appropriated this symbolic figure and, through a set of discursive strategies of "framing, voice and narrative structure," transformed him into a privileged symbol for modern Chinese national identity. What Huang-ti could offer was, however, no more than a "public face" for the imagined new national community, or in other words, a formal structure without substantial contents. No consensus appeared on whom the Chinese nation should include and where the Chinese nation should draw its boundaries. The anti-Manchu revolutionaries emphasized the primordial attachment of blood and considered modern China an exclusive community of Huang-ti's descent. The constitutional reformers sought to stretch the boundaries to include the ethnic groups other than the Han. Some minority intellectuals, particularly the Manchu ones, re-constructed the historic memory of their ethnic origin around Huang-ti. The quarrels among intellectuals of different political persuasion testify how Huang-ti as the most powerful cultural symbol became a site for contests and negotiations in the late Qing process of national construction.