Proteomic analysis of Salmonella enterica serovar Enteritidis following propionate adaptation

<p>Abstract</p> <p>Background</p> <p><it>Salmonella </it>Enteritidis is a highly prevalent and persistent foodborne pathogen and is therefore a leading cause of nontyphoidal gastrointestinal disease worldwide. A variety of stresses are endured throughout its infection cycle, including high concentrations of propionate (PA) within food processing systems and within the gut of infected hosts. Prolonged PA exposure experienced in such milieus may have a drastic effect on the proteome of <it>Salmonella </it>Enteritidis subjected to this stress.</p> <p>Results</p> <p>In this study, we used 2 D gel electrophoresis to examine the proteomes of PA adapted and unadapted <it>S</it>. Enteritidis and have identified five proteins that are upregulated in PA adapted cultures using standard peptide mass fingerprinting by MALDI-TOF-MS and sequencing by MALDI LIFT-TOF/TOF tandem mass spectrometry. Of these five, two significant stress-related proteins (Dps and CpxR) were shown (via qRT-PCR analysis) to be upregulated at the transcriptional level as well. Unlike the wild type when adapted to PA (which demonstrates significant acid resistance), PA adapted <it>S</it>. Enteritidis ∆<it>dps </it>and <it>S</it>. Enteritidis ∆<it>cpxR </it>were at a clear disadvantage when challenged to a highly acidic environment. However, we found the acid resistance to be fully restorable after genetic complementation.</p> <p>Conclusions</p> <p>This work reveals a significant difference in the proteomes of PA adapted and unadapted <it>S</it>. Enteritidis and affirms the contribution of Dps and CpxR in PA induced acid resistance.</p

Numerical stability assessment for slopes and boulders subjected to blasting

Conference Theme: Geotechnical Engineering for Infrastructure and Developmen

Seismic site effects in Hong Kong

This paper describes an investigation into the potential seismic site response effects for the ground conditions in Hong Kong. A site classification map for the Hong Kong region has been produced using current IBC site classes. Published geological maps and detailed ground investigation information have been used for the classification. One-dimensional site response analyses have been carried out to determine how various representative types of site profiles of Hong Kong will potentially respond to earthquake ground motion. The response of soil profiles was investigated using three input earthquake ground-motion levels corresponding to bedrock motion with 50%, 10% and 2% probability of being exceeded in 50 years. The results are presented in terms of spectral ratios for the different Site Classes. A simplified manual procedure for rapid assessment of site response effects has been developed by the University of Hong Kong to produce displacement-based design response spectra. There are extensive areas of reclamation in Hong Kong and the potential for liquefaction in these areas, and other areas underlain by non-cohesive, saturated soils, was considered sufficiently high to warrant investigation. The methodology and results of a liquefaction assessment are presented in the final part of this paper

Seismic hazard of Hong Kong

This paper reviews the probabilistic seismic hazard assessment studies undertaken in recent years to estimate the potential seismic ground motion levels on bedrock in Hong Kong. A detailed catalogue of historical and recent seismicity within the South China region has been compiled. A suite of published empirical and stochastic attenuation relationships have been used with alternative source models and source parameters in a logic tree hazard analysis. Uniform hazard bedrock ground-motion spectra having various probabilities of being exceeded in 50 years have been calculated. The results have been de-aggregated to investigate what earthquake magnitude and distance combinations have contributed most to the hazard levels for the different probabilities and structural periods. The obtained uniform hazard spectra have been compared to the study using an alternative assessment approach developed by the University of Hong Kong. Recent recorded earthquake ground motions in Hong Kong are also presented with the uniform hazard spectra