Project description:We characterized the bacterial diversity of chlorinated drinking water from three surface water treatment plants supplying the city of Paris, France. For this purpose, we used serial analysis of V6 ribosomal sequence tag (SARST-V6) to produce concatemers of PCR-amplified ribosomal sequence tags (RSTs) from the V6 hypervariable region of the 16S rRNA gene for sequence analysis. Using SARST-V6, we obtained bacterial profiles for each drinking water sample, demonstrating a strikingly high degree of biodiversity dominated by a large collection of low-abundance phylotypes. In all water samples, between 57.2-77.4% of the sequences obtained indicated bacteria belonging to the Proteobacteria phylum. Full-length 16S rDNA sequences were also generated for each sample, and comparison of the RSTs with these sequences confirmed the accurate assignment for several abundant bacterial phyla identified by SARST-V6 analysis, including members of unclassified bacteria, which account for 6.3-36.5% of all V6 sequences. These results suggest that these bacteria may correspond to a common group adapted to drinking water systems. The V6 primers used were subsequently evaluated with a computer algorithm to assess their hybridization efficiency. Potential errors associated with primer-template mismatches and their impacts on taxonomic group detection were investigated. The biodiversity present in all three drinking water samples suggests that the bacterial load of the drinking water leaving treatment plants may play an important role in determining the downstream community dynamics of water distribution networks.
Project description:Various mutations in the rpoB gene, which encodes the RNA polymerase beta subunit, are associated with increased vancomycin (VAN) resistance in vancomycin-intermediate S. aureus (VISA) and hetero-VISA (hVISA) strains. We reported that rpoB mutations are also linked to the expression of the recently found slow VISA (sVISA) phenotype (Saito et al 2014 AAC). Because RpoC and RpoB are components of RNA polymerase, we examined the effect of rpoC(P440L) mutation on the expression of the sVISA phenotype in the Mu3fdh2*V6-5 strain (V6-5), which was derived from a previously reported hVISA strain with the VISA phenotype. V6-5 had an extremely prolonged doubling time (72.2 min) and high vncomycin MIC (16 mg/L). However, the phenotype of V6-5 was unstable, and the strain frequently reverted to hVISA with concomitant loss of slow growth rate, cell wall thickness, and reduced autolysis. Whole genome sequencing of phenotypic revertant strain V6-5-L1 and comparison with V6-5 revealed a second mutation F562L in rpoC. Introduction of the wild-type rpoC gene using multi-copy plasmid resolved the sVISA phenotype of V6-5, indicating that rpoC(P440L) mutation expressed the sVISA phenotype in hVISA. To investigate the mechanisms of resistance in the sVISA strain, we independently isolated additional 10 revertants to hVISA and VISA. In subsequent whole genome analysis, we identified compensatory mutations in the genes of three distinct functional categories; rpoC gene itself as regulatory mutations, peptidoglycan biosynthesis genes, and relQ which is involved in stringent response. It appears that rpoC(P440L) mutation causes sVISA phenotype by augmenting cell-wall peptidoglycan synthesis, and through the control of stringent response.
Project description:Lamin A/C proteins, major components of the nuclear lamina, are encoded by the LMNA gene. These proteins have multiple cellular functions. LMNA has implications in cancer; however, its mechanisms of dysregulation in cancer cells are not yet fully understood. Among the LMNA transcript variants, we focused on a spliced variant 6 (termed LMNA-V6), which contains unique 3 exons upstream of exon 1 of LMNA. In this study, after LMNA-V6 levels were modulated by overexpression or silencing in colon cancer HCT116 cells, gene expression profiles were measured using microarray analysis.
Project description:Hepatic transcriptional profiling of fish exposed to sewage to evaluate temporal and concentration trends. Two experiments (Year 1 and 2), each with 6 concentrations (0%, 0.05%, 0.1%, 0.7%, 2% and 5/10%) of sewage diluted in seawater at 4 timepoints (1, 4, 8 and 16 days).
Project description:We characterized the bacterial diversity of chlorinated drinking water from three surface water treatment plants supplying the city of Paris, France. For this purpose, we used serial analysis of V6 ribosomal sequence tag (SARST-V6) to produce concatemers of PCR-amplified ribosomal sequence tags (RSTs) from the V6 hypervariable region of the 16S rRNA gene for sequence analysis. Using SARST-V6, we obtained bacterial profiles for each drinking water sample, demonstrating a strikingly high degree of biodiversity dominated by a large collection of low-abundance phylotypes. In all water samples, between 57.2-77.4% of the sequences obtained indicated bacteria belonging to the Proteobacteria phylum. Full-length 16S rDNA sequences were also generated for each sample, and comparison of the RSTs with these sequences confirmed the accurate assignment for several abundant bacterial phyla identified by SARST-V6 analysis, including members of unclassified bacteria, which account for 6.3-36.5% of all V6 sequences. These results suggest that these bacteria may correspond to a common group adapted to drinking water systems. The V6 primers used were subsequently evaluated with a computer algorithm to assess their hybridization efficiency. Potential errors associated with primer-template mismatches and their impacts on taxonomic group detection were investigated. The biodiversity present in all three drinking water samples suggests that the bacterial load of the drinking water leaving treatment plants may play an important role in determining the downstream community dynamics of water distribution networks. 3 different drinking water samples (Orly, Ivry, Joinville drinking water sample)