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Browsing by Author "Zhu, Jun"

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    Regulatory targets of quorum sensing in Vibrio cholerae: evidence for two distinct HapR-binding motifs
    Tsou, Amy M.; Cai, Tao; Liu, Zhi; Zhu, Jun; Kulkarni, Rahul V. (2009-05)
    The quorum-sensing pathway in Vibrio cholerae controls the expression of the master regulator HapR, which in turn regulates several important processes such as virulence factor production and biofilm formation. While HapR is known to control several important phenotypes, there are only a few target genes known to be transcriptionally regulated by HapR. In this work, we combine bioinformatic analysis with experimental validation to discover a set of novel direct targets of HapR. Our results provide evidence for two distinct binding motifs for HapR-regulated genes in V. cholerae. The first binding motif is similar to the motifs recently discovered for orthologs of HapR in V. harveyi and V. vulnificus. However, our results demonstrate that this binding motif can be of variable length in V. cholerae. The second binding motif shares common elements with the first motif, but is of fixed length and lacks dyad symmetry at the ends. The contributions of different bases to HapR binding for this second motif were demonstrated using systematic mutagenesis experiments. The current analysis presents an approach for systematically expanding our knowledge of the quorum-sensing regulon in V. cholerae and other related bacteria.
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    A study for preserving and renovating the main building of Solitude at Virginia Tech
    Zhu, Jun (Virginia Tech, 1995)
    The main building of the Solitude complex is one of the oldest buildings on the campus of Virginia Polytechnic Institute and State University. The purpose of this study is to provide preliminary research for the master preservation plan of the historic landmark. In order to preserve and renovate the building, a field survey was conducted to collect data. Under the guidelines of the Historic American Building Survey, the building has been fully documented on measured drawings, and visible defects have been inspected. Computer programs were used as a means to execute drawings; a written report of the survey was organized according to the major building components. By using the knowledge of architectural history, building construction, preservation philosophy, and wood preservation technology, the collected data was analyzed, the causes of the defects were diagnosed, and the preservation treatments were suggested. Furthermore, recommendations for adaptive reuse are proposed. Meanwhile, this study also leaves openings for further study in some special fields.