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Jerry Wells

Publications and source records attributed to Jerry Wells.

4 recordsLinked to original sources
PubMed2006

Comparison of different approaches for comparative genetic analysis using microarray hybridization.

A robust analysis of comparative genomic microarray data is critical for meaningful genomic comparison studies. In this paper, we compare our method (implemented in a new software tool, GENCOM, freely available at http://www.ifr.ac.uk/safety/gencom ) with three commonly used analysis methods: GACK (freely available at http://falkow.stanford.edu ), an empirical cut-off value of twofold difference between the fluorescence intensities after LOWESS normalization or after AVERAGE normalization in which the fluorescence intensity is divided by the average fluorescence intensity of the entire data set. Each method was tested using data sets from real experiments with prior knowledge of conserved and divergent genes. GENCOM and GACK were superior when a high proportion of genes were divergent. GENCOM was the most suitable method for the data set in which the relationship between the fluorescence intensities was not linear. GENCOM has proved robust in an analysis of all the data sets tested.

Algorithms↗
PubMed2004

Interconnection of competence, stress and CiaR regulons in Streptococcus pneumoniae: competence triggers stationary phase autolysis of ciaR mutant cells.

Of the 13 two-component signal transduction systems (TCS) identified in Streptococcus pneumoniae, two, ComDE and CiaRH, are known to affect competence for natural genetic transformation. ComD and ComE act together with the comC-encoded competence-stimulating peptide (CSP) and with ComAB, the CSP-dedicated exporter, to co-ordinate activation of genes required for differentiation to competence. Several lines of evidence suggest that the CiaRH TCS and competence regulation are interconnected, including the observation that inactivation of the CiaR response regulator derepresses competence. However, the nature of the interconnection remains poorly understood. Interpretation of previous transcriptome analyses of ciaR mutants was complicated by competence derepression in the mutants. To circumvent this problem, we have used microarray analysis to investigate the transition from non-competence to competence in a comC-null wild-type strain and its ciaR derivative after the addition of CSP. This study increased the number of known CSP-induced genes from approximately 47 to 105 and revealed approximately 42 genes with reduced expression in competent cells. Induction of the CiaR regulon, as well as the entire HrcA and part of the CtsR stress response regulons, was observed in wild-type competent cells. Enhanced induction of stress response genes was detected in ciaR competent cells. In line with these observations, CSP was demonstrated to trigger growth arrest and stationary phase autolysis in ciaR cells. Taken together, these data strongly suggest that differentiation to competence imposes a temporary stress on cells, and that the CiaRH TCS is required for the cells to exit normally from the competent state.

Bacterial Proteins↗
PubMed2001

The Fbe (SdrG) protein of Staphylococcus epidermidis HB promotes bacterial adherence to fibrinogen.

Staphylococcus epidermidis strains HB and K28 express surface proteins called Fbe or SdrG, respectively, that have sequence similarity to the clumping factors ClfA and ClfB of Staphylococcus aureus. A mutation in the fbe gene of strain HB was isolated by directed plasmid integration using the broad-host-range temperature-sensitive plasmid pG(+)Host9 (pVE6155). An internal fragment of fbe was cloned into pG(+)Host9 and the chimaeric plasmid was mobilized from S. aureus RN4220 to S. epidermidis 9142 by conjugation promoted by plasmid pGO1. The plasmid was then transferred to S. epidermidis strain HB by phage-48-mediated transduction. The plasmid integrated into the chromosomal fbe gene at a frequency of 2.8 x 10(-4). All the survivors tested had a copy of pG(+)Host9'fbe' integrated into the chromosomal fbe gene either as a single copy or as a tandem array. Western immunoblotting showed that the wall-associated Fbe protein was absent in the mutant. Wild-type S. epidermidis HB adhered to immobilized fibrinogen in a dose-dependent and saturable fashion whereas the mutant did not bind. The Fbe proteins of HB and K28 were expressed at a high level in Lactococcus lactis MG1363 using the expression vector pKS80. These strains adhered strongly to immobilized fibrinogen. These results confirm that Fbe is a fibrinogen-binding adhesin.

Adhesins, Bacterial↗