Transcription profiling by array of Bacillus cereus ATCC14579 and its isogenic SecDF deletion mutant
ABSTRACT: SecDF is a highly conserved accessory protein of the Sec-translocase located in the cytoplasmic membrane. The deletion mutant (delta Bc4405) of Bacillus cereus ATCC14579 shows multiple phenotypic changes, including aberrent cell division starting at transitionary phase. To understand the underlying processes genotypic profiling was carried out at 3h and 4h after inoculation. The morphology of the mutant seems to be more severe if glucose is added to the LB medium, thus all cultures contained 1% glucose.
The aim of this study was to explore the role of SecDF in protein secretion in Bacillus cereus ATCC 14579 by in-depth characterization of a markerless secDF knock out mutant. Deletion of secDF resulted in pleiotropic effects characterized by a moderately slower growth rate, aberrant cell morphology, enhanced susceptibility to xenobiotics, reduced virulence and motility. Most toxins, including food poisoning-associated enterotoxins Nhe, Hbl, and cytotoxin K, as well as phospholipase C were less a ...[more]
Project description:B. thuringiensis 407 nprA::lacZ strain was compared with an isogenic delta-nprR-nprX strain to explore the effects of nprR-nprX deletion. NprR is a transition state regulator which is activated towards the end of the exponential phase by a part of the signaling peptide NprX. We made direct comparisons of RNA from the two strains collected at T1 and T3, one and three hours after the transition to stationary phase, respectively. T1 was thought to be the early phase of NprR activation, while T3 was thought to be around the peak of NprR activation. All samples are biological replicates, and dye swap was performed between the different comparisons.
Project description:The transcriptional global profiles of the wild-type strain Bacillus thuringiensis 407 and a cdgF deletion mutant were compared after 1.5 hours of growth in an planktonic culture to analyze the effect of deletion of cdgF, which is involved in c-di-GMP signaling, on the global expression profile of B. thuringiensis 407
Project description:Comparison at t2 (two hours into post-exponential phase growth as analyzed by OD measurements) of global expression profiles from a Bacillus thuringiensis 407 delta-sinI delta-sinR double gene deletion strain versus a Bacillus thuringiensis 407 delta-sinI single gene deletion strain, to analyze global expression changes following deletion of the sinR transcriptional regulator gene in a sinI-negative background.
Project description:Salmonella transcription profiles were obtained from samples flown on space shuttle mission STS-115, and compared to profiles from Salmonella grown under identical conditions on the ground. Keywords: stress response, transcriptional profile Triplicate experimental samples were hybridized to slides that contain three identical Salmonella ORF arrays. Each hybridization was performed with Cy3 labeled total RNA and Cy5 labeled gDNA as control.
Project description:S. enterica sv Kentucky 3795 and S. enterica sv Enteritidis NalR were grown to mid-log phase in TSB, then subjected to three different acidic conditions generated by two different acids: HCl to pH4.5, HCl to pH5.5 and CH3COOH to pH5.5. After 10min, total RNA was harvested und compared to total RNA harvested from identical control cultures grown in TSB without the pH alteration. At least three biological replicates were performed for each strain and acidic condition. Total RNAs were harvested, and labeled by the conventional protocol of Brown et al, then hybridized onto a Salmonella-specific PCR product array that covered over 97% of the Enteritidis genome.
Project description:Salmonella has a natural ability to target a wide range of tumors in animal models. However, strains used for cancer therapy have generally been selected only for their avirulence rather than tumor-targeting ability. To select Salmonella strains that are avirulent and yet efficient in tumor-targeting, a necessary criteria for clinical applications, we measured the relative fitness of 41,000 Salmonella Typhimurium transposon insertion mutants growing in mouse models of human prostate cancer and melanoma. Two classes of potentially safe mutants were identified. Class 1 mutants showed reduced fitness in normal tissues and unchanged fitness in tumors (e.g., mutants in htrA, SPI-2, and STM3120). Class 2 mutants showed reduced fitness in tumors and normal tissues (e.g., mutants in aroA and aroD). Class 1 mutants are more suitable for delivery of therapeutics for cancer therapy. A library of 41,000 Salmonella mutants containing mini-Tn5 transposon insertions was constructed and pooled. The pool was injected into six human prostate (PC3) and six melanoma (MDA-MB-435) tumors growing subcutaneously in nude mice, and injected intravenously into three tumor-free mice. Bacteria were recovered after two days from tumors and spleens, livers, and lungs of tumor-free mice. During in vivo selection, defective mutants in genes contributing to fitness in the selective environment are lost from the pool. Differences in the mutant pool composition before (input pool) and after selection (output pool) can be detected using microarray hybridization: Transposons were used that carry the T7 promoter sequence, allowing the specific amplification of genomic sequences adjacent to each insertion, which are then mapped on the Salmonella genome using a gene microarray
Project description:Comparisons of overexpression of PreA (in wt or preAB mutant Salmonella) to Salmonella lacking preA or preAB in late log phase growth in LB preA was externally supplied to wt or preAB mutant Salmonella typhimurium on a pBAD18 plasmid, which was then induced by 10mM arabinose and grown to late log phase (OD0.74). Transcription profiles were compared with those obtained from preA or preAB mutant Salmonella harboring pBAD18 only as vector control.