ABSTRACT: Microarray Tracking of transposon mutants for a H. pylori mouse colonization screen described in Baldwin DN et al. Screen in NSH57 H. pylori strain background. Original 50,000 clone transposon library was plated and patched to make 25 pools of 48 clones. Clones were infected into 4-8 C57Bl/6 mice and stomach bacteria from at least two mice were harvested at 1 week or one month. Semi-random PCR was used to amplify and label the DNA next to the transposon insertion from the input (Cy3) and output pool (Cy5) genomic DNA for each array. Two arrays were done per mouse. One array labeled from the left side of transposon (primers S, 2C) and one array labeled from the right side of the transposon (primers N3, 2C). Transposon insertions were defined by spots with signal four standard deviations above background in both arrays. We also counted insertions where two adjacent gene spots (after arranging the data in genome order) gave signal from the two different sides of the transposon (but not both). A pathogenicity experiment design type is where an infective agent such as a bacterium, virus, protozoan, fungus etc. infects a host organism(s) and the infective agent is assayed. Keywords: pathogenicity_design
Project description:Microarray Tracking of transposon mutants for a H. pylori mouse colonization screen described in Baldwin DN et al. 2007. Screen in NSH79 H. pylori strain background. Original 2000 clone transposon library was plated and patched to make 25 pools of 48 clones. Clones were infected into 4-8 C57Bl/6 mice and stomach bacteria from at least two mice were harvested at 1 week or one month. Semi-random PCR was used to amplify and label the DNA next to the transposon insertion from the input (Cy3) and output pool (Cy5) genomic DNA for each array. Two arrays were done per mouse. One array labeled from the left side of transposon (primers S, 2C) and one array labeled from the right side of the transposon (primers N3, 2C). Transposon insertions were defined by spots with signal four standard deviations above background in both arrays. We also counted insertions where two adjacent gene spots (after arranging the data in genome order) gave signal from the two different sides of the transposon (but not both). A pathogenicity experiment design type is where an infective agent such as a bacterium, virus, protozoan, fungus etc. infects a host organism(s) and the infective agent is assayed. Keywords: pathogenicity_design
Project description:Microarray Tracking of transposon mutants for a H. pylori mouse colonization screen described in Baldwin DN et al. 2007, I&I, 75(2):??, doi:10.1128/IAI.01176-06. Screen in NSH57 H. pylori strain background. Original 50,000 clone transposon library was plated and patched to make 25 pools of 48 clones. Clones were infected into 4-8 C57Bl/6 mice and stomach bacteria from at least two mice were harvested at 1 week or one month. Semi-random PCR was used to amplify and label the DNA next to the transposon insertion from the input (Cy3) and output pool (Cy5) genomic DNA for each array. Two arrays were done per mouse. One array labeled from the left side of transposon (primers S, 2C) and one array labeled from the right side of the transposon (primers N3, 2C). Transposon insertions were defined by spots with signal four standard deviations above background in both arrays. We also counted insertions where two adjacent gene spots (after arranging the data in genome order) gave signal from the two different sides of the transposon (but not both).
Project description:Microarray Tracking of transposon mutants for a H. pylori mouse colonization screen described in Baldwin DN et al. 2007, I&I, 75(2):??, doi:10.1128/IAI.01176-06. Screen in NSH79 H. pylori strain background. Original 2000 clone transposon library was plated and patched to make 25 pools of 48 clones. Clones were infected into 4-8 C57Bl/6 mice and stomach bacteria from at least two mice were harvested at 1 week or one month. Semi-random PCR was used to amplify and label the DNA next to the transposon insertion from the input (Cy3) and output pool (Cy5) genomic DNA for each array. Two arrays were done per mouse. One array labeled from the left side of transposon (primers S, 2C) and one array labeled from the right side of the transposon (primers N3, 2C). Transposon insertions were defined by spots with signal four standard deviations above background in both arrays. We also counted insertions where two adjacent gene spots (after arranging the data in genome order) gave signal from the two different sides of the transposon (but not both).
Project description:Genomic DNA from pools of H. pylori strain G27 Clones as indicated (pools of 300 (300p) or insertions in specific mapped genes) were amplifed using the MATT method to label DNA adjacent to the site of transposon insertion with the primer pairs indicated. The left side of the transposon was labeled in the Cy3 channel (Primer S) and the right side of the transposon was labeled in the Cy5 channel (Primer N). Computed
Project description:Genomic DNA from pools of H. pylori strain G27 Clones as indicated (pools of 300 (300p) or insertions in specific mapped genes) were amplifed using the MATT method to label DNA adjacent to the site of transposon insertion with the primer pairs indicated. The left side of the transposon was labeled in the Cy3 channel (Primer S) and the right side of the transposon was labeled in the Cy5 channel (Primer N). Keywords: reference_design
Project description:Genomic DNA from pools of H. pylori strain G27 Clones as indicated (pools of 300 (300p) or insertions in specific mapped genes) were amplifed using the MATT method to label DNA adjacent to the site of transposon insertion with the primer pairs indicated. The left side of the transposon was labeled in the Cy3 channel (Primer S) and the right side of the transposon was labeled in the Cy5 channel (Primer N). The results of these experiments are published in Salama et al. 2004. J Bact. 186(23):7926-7935.
Project description:Chronic infection of the human stomach with Helicobacter pylori leads to a variety of pathologic sequelae including peptic ulcer and gastric cancer, resulting in significant human morbidity and mortality. Several genes have been implicated in disease related to H. pylori infection including the vacuolating cytotoxin and the cag pathogenicity island. Other factors important for establishment and maintenance of infection include urease enzyme production, motility, iron uptake and stress response. We utilized a C57BL/6 mouse infection model to query a collection of 2400 transposon mutants in two different bacterial strain backgrounds for H. pylori genetic loci contributing to colonization of the stomach. Microarray based tracking of transposon mutants allowed us to monitor the behavior of transposon insertions in 758 different gene loci. Of the loci measured 223 (29%) had a predicted colonization defect. These include previously described H. pylori virulence genes, genes implicated in virulence in other pathogenic bacteria and 81 hypothetical proteins. We have retested 10 previously uncharacterized candidate colonization gene loci by making independent null alleles and confirmed their colonization phenotype using competition experiments and determination of the dose required for 50% infection. Of the genetic loci retested, 60% have strain specific colonization defects while 40% had phenotypes in both strain backgrounds for infection, highlighting the profound effect of H. pylori strain variation on the pathogenic potential of this organism. This SuperSeries is composed of the SubSeries listed below.
Project description:Performed en masse sequencing of transposon insertions among A. tumefaciens mutants deficient in unipolar polysaccharide (UPP) production in two different genetic backgrounds, each one specific for one of the two chemical species of UPP (UPPGlcN and UPPGalN)
Project description:As transposon sequencing (TnSeq) assays have become prolific in the microbiology field, it is of interest to scrutinize their potential drawbacks. TnSeq results are determined by counting transposon insertions following the PCR-based enrichment and subsequent deep sequencing of transposon insertions. Here we explore the possibility that PCR amplification of transposon insertions in a TnSeq library skews the results by introducing bias into the detection and/or enumeration of insertions. We compared the detection and frequency of mapped insertions when altering the number of PCR cycles in the enrichment step. In addition, we devised and validated a novel, PCR-free TnSeq method where the insertions are enriched via CRISPR/Cas9-targeted transposon cleavage and subsequent Oxford Nanopore sequencing. These PCR-based and PCR-free experiments demonstrate that, overall, PCR amplification does not significantly bias the results of the TnSeq assay insofar as insertions in the majority of genes represented in our library were similarly detected regardless of PCR cycle number and whether or not PCR amplification was employed. However, the detection of a small subset of genes which had been previously described as essential is indeed sensitive to the number of PCR cycles. We conclude that PCR-based enrichment of transposon insertions in a TnSeq assay is reliable but researchers interested in profiling essential genes should carefully weigh the number of amplification cycles employed in their library preparation protocols. In addition, we present a PCR-free TnSeq alternative that is comparable to traditional PCR-based methods although the latter remain superior owing to their accessibility and high sequencing depth.