Project description:Post-hybridization washing is an essential part of microarray experiments. Both, the quality of the experimental washing protocol and the adequate consideration of washing in intensity calibration ultimately affect the quality of the expression estimates extracted from the microarray intensities. We conducted experiments on GeneChip microarrays with altered protocols for washing, scanning and staining to study the probe-level intensity changes as a function of washing cycles. Particularly, three Affymetrix GeneChip HGU133plus2 arrays were hybridized and equilibrated for 16 hours in the hybridization oven. For one of the three arrays washing and staining was performed according to the manufacturer’s instructions. For another array the first scan was done immediately after low stringent wash and staining without intermitting stringent washing. Then, the array was stringently washed and scanned in alternating order three more times where each washing step consists of a definite number of washing cycles. The third array was low stringently washed followed by two stringent washing cycles and staining before the first scan. Subsequently it was analogously processed as array A. All three chips are repeatedly processed in a second series of alternating wash/scan-cycles which was performed using the same protocol for each chip as in the first series as described above. As in the first series the arrays were also stained a second time to compensate for any loss of bleached fluorescent dye. Analysis of the washing kinetics shows that the signal-to-noise ratio doubles roughly every ten stringent washing cycles. Washing can be characterized by time-dependent rate constants which reflect the heterogeneous character of target binding to microarray probes. We propose an empirical washing function which estimates the survival of probe bound targets. The washing function allows calibrating probe intensities for the effect of washing. On a relative scale, proper calibration for washing markedly increases expression measures especially in the limit of small and large values.
Project description:Cationic antimicrobial peptides (CAPs) are promising novel alternatives to conventional antibacterial agents, but the overlap in resistance mechanisms between small-molecule antibiotics and CAPs is unknown. Does evolution of antibiotic resistance decrease (cross-resistance) or increase (collateral sensitivity) susceptibility to CAPs? We systematically addressed this issue by studying the susceptibilities of a comprehensive set of antibiotic resistant Escherichia coli strains towards 24 antimicrobial peptides. Strikingly, antibiotic resistant bacteria frequently showed collateral sensitivity to CAPs, while cross-resistance was relatively rare. We identified clinically relevant multidrug resistance mutations that simultaneously elevate susceptibility to certain CAPs. Transcriptome and chemogenomic analysis revealed that such mutations frequently alter the lipopolysaccharide composition of the outer cell membrane and thereby increase the killing efficiency of membrane-interacting antimicrobial peptides. Furthermore, we identified CAP-antibiotic combinations that rescue the activity of existing antibiotics and slow down the evolution of resistance to antibiotics. Our work provides a proof of principle for the development of peptide based antibiotic adjuvants that enhance antibiotic action and block evolution of resistance.
Project description:The response of antibiotic adapted resistant mutants of B. cenocepacia J2315 to antibiotic stress was investigated using expression profiling of three biological replicates and comparing the profiles to the J2315 parent control grown without antibiotics.<br>A reference design was used with Cy3 labeled genomic DNA of B. cenocepacia J2315 as common reference. Three test conditions with three biological replicates each were compared to three replicates of the control condition.<br>Test conditions: J2315-A grown in the presence of 250 ug per ml amikacin, J2315-M grown in the presence of 8 ug per ml meropenem and J2315-T grown in the presence of 60 ug per ml trimethoprim and 300 ug per ml sulfamethoxazole.<br>Control condition: J2315 parent strain grown without antibiotics.
Project description:Analysis of Antibiotic Resistant Organisms recovered from Clinical and Environmental Sources in Manitoba, Canada Genome sequencing and assembly
Project description:The Antibiotic Resistant Sepsis Pathogens Framework Initiative aims to develop a framework dataset of 5 sepsis pathogens (5 strains each) using an integrated application of genomic, transcriptomic, metabolomic and proteomic technologies. The pathogens included in this initiative are: Escherichia coli, Klebsiella pneumoniae complex, Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae. This submission pertains to strain BPH2986.
Project description:The Antibiotic Resistant Sepsis Pathogens Framework Initiative aims to develop a framework dataset of 5 sepsis pathogens (5 strains each) using an integrated application of genomic, transcriptomic, metabolomic and proteomic technologies. The pathogens included in this initiative are: Escherichia coli, Klebsiella pneumoniae complex, Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae. This submission pertains to strain 4496.
Project description:The Antibiotic Resistant Sepsis Pathogens Framework Initiative aims to develop a framework dataset of 5 sepsis pathogens (5 strains each) using an integrated application of genomic, transcriptomic, metabolomic and proteomic technologies. The pathogens included in this initiative are: Escherichia coli, Klebsiella pneumoniae complex, Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae. This submission pertains to strain 947.