An outbreak associated with Streptococcus suis infection in humans emerged in Sichuan province, China in 2005. The outbreak is atypical for the apparent large number of human cases, high fatality rate and geographical...An outbreak associated with Streptococcus suis infection in humans emerged in Sichuan province, China in 2005. The outbreak is atypical for the apparent large number of human cases, high fatality rate and geographical spread. To determine whether the bacterium has changed, we compared both human and animal isolates from the Sichuan outbreak with those collected previously within China and in other countries using whole genome PCR scanning (WGPScaning) comparative sequencing of several known virulence factor genes and multilocus sequence typing (MLST) analysis. WGPScanning analysis showed that all primer pairs yielded PCR products of the expected sizes in all four strains tested. The nucleotide sequences of all the detected virulence factor genes are identical in the four strains and MLST results showed that the four isolates studied and reference strain all belonged to the ST1 com-plex. No new genetic changes were found in the genome structure of the isolates from this Sichuan outbreak.展开更多
Genomic compositions of representatives of thirteen S. dysenteriae serotypes were investigated by performing comparative genomic hybridization (CGH) with microarray containing the whole genomic ORFs (open reading fram...Genomic compositions of representatives of thirteen S. dysenteriae serotypes were investigated by performing comparative genomic hybridization (CGH) with microarray containing the whole genomic ORFs (open reading frames, ORFs) of E. coli K12 strain MG1655 and spe-cific ORFs of S. dysenteriae A1 strain Sd51197. The CGH results indicated the genomes of the serotypes contain 2654 conserved ORFs originating from E. coli. However, 219 intrinsic genes of E. coli including those prophage genes, molecular chaperones, synthesis of specific O antigen and so on were absent. Moreover, some specific genes such as type II secretion system associ-ated components, iron transport related genes and some others as well were acquired through horizontal transfer. According to phylogenic trees based on genetic composition, it was demon-strated that A1, A2, A8, A10 were distinct from the other S. dysenteriae serotypes. Our results in this report may provide new insights into the physiological process, pathogenicity and evolution of S. dysenteriae.展开更多
We report on the preparation and superconductivity of metastable γ-Ga islands on Si(111) substrate. The Ga grows in a typical Volmer-Weber mode at a low temperature of 110 K, resulting in formation of Ga nanoislands ...We report on the preparation and superconductivity of metastable γ-Ga islands on Si(111) substrate. The Ga grows in a typical Volmer-Weber mode at a low temperature of 110 K, resulting in formation of Ga nanoislands at various sizes with the identical γ-phase. In-situ low temperature scanning tunneling spectra reveal quantized electronic states in ultrathin Ga islands. It is found that both the lateral size and thickness of the Ga islands strongly suppress the superconductivity. Due to substantial surface energy contribution, the transition temperature Tc scales inversely with the island thickness and the minimum thickness for the occurrence of superconductivity is calculated to be two monolayers.展开更多
Comparative Genomic Hybridization (CGH) microarray analysis was used tocompare the genomic compositions of all eighteen Shigella boydii serotype representative strains.The results indicated the genomic ''backb...Comparative Genomic Hybridization (CGH) microarray analysis was used tocompare the genomic compositions of all eighteen Shigella boydii serotype representative strains.The results indicated the genomic ''backbone'' of this subgroup contained 2552 ORFs homologous tononpatho-genic E. coli K12. Compared with the genome of K12199 ORFs were found to be absent in allS. boydii serotype representatives, including mainly outer membrane protein genes and O-antigenbiosynthesis genes. Yet the specific ORFs of S. boydii subgroup contained basically bacteriophagegenes and the function unknown (FUN) genes. Some iron metabolism, transport and type Ⅱ secretionsystem related genes were found in most representative strains. According to the CGH phylogeneticanalysis, the eighteen S. boydii serotype representatives were divided into four groups, in whichserotype C13 strain was remarkably distinguished from the other serotype strains. This groupingresult corresponded to the distribution of some metabolism related genes. Furthermore, the analysisof genome backbone genes, specific genes, and the phylogenetic trees allowed us to discover theevolution laws of S. boydii and to find out important clues to pathogenesis research, vaccinationand the therapeutic medicine development.展开更多
Trichophyton rubrum (T.rubrum) is one of the most common human fungal pathogens that cause chronic infections of the skin and nails. To identify antifungal responsive genes, cDNA microarray analysis was performed for ...Trichophyton rubrum (T.rubrum) is one of the most common human fungal pathogens that cause chronic infections of the skin and nails. To identify antifungal responsive genes, cDNA microarray analysis was performed for T. rubrum to reveal global transcriptional profiles of drug-specific responses to 5-Flucytosine (5-FC). cDNA microarray was constructed from the T. rubrum expressed sequence tag (ESTs) database, the minimum inhibitory concentration (MIC) of 5-FC was determined, and microarray hybridization and data analysis were applied. The expression pattern of 7 genes observed by microarray was confirmed by the quantitative real-time reverser transcription polymerase chain reaction (RT-PCR). Data analysis indicated that a total of 474 genes were found differentially expressed, 196 showed an increase in expression and 278 showed a decrease in expression. Marked down-regulation of genes involved in nucleotide metabolism (such as CDC21), transcription (such as E2F1), and RNA processing (such as SGN1, RIM4 and NOP1) was observed. Other genes involved in signal transduction, chaperones, inorganic ion transport, secondary metabolite biosynthesis, amino acid transport, lipid transport and potential drug resistance mechanism were also affected by 5-FC. Quantitative real-time RT-PCR of the selected genes confirmed the reliability of the microarray results. This is the first analysis of transcriptional profiles in response to 5-FC for T. rubrum. The findings may be valuable for the identification of genes involved in mechanisms of action and mechanisms of antifungal drug resistance of 5-FC.展开更多
基金Supported by the National Key Technologies Research and Development Program (Grant No. 2005BA711A09)from the Ministry of Science and Technology of China
文摘An outbreak associated with Streptococcus suis infection in humans emerged in Sichuan province, China in 2005. The outbreak is atypical for the apparent large number of human cases, high fatality rate and geographical spread. To determine whether the bacterium has changed, we compared both human and animal isolates from the Sichuan outbreak with those collected previously within China and in other countries using whole genome PCR scanning (WGPScaning) comparative sequencing of several known virulence factor genes and multilocus sequence typing (MLST) analysis. WGPScanning analysis showed that all primer pairs yielded PCR products of the expected sizes in all four strains tested. The nucleotide sequences of all the detected virulence factor genes are identical in the four strains and MLST results showed that the four isolates studied and reference strain all belonged to the ST1 com-plex. No new genetic changes were found in the genome structure of the isolates from this Sichuan outbreak.
文摘Genomic compositions of representatives of thirteen S. dysenteriae serotypes were investigated by performing comparative genomic hybridization (CGH) with microarray containing the whole genomic ORFs (open reading frames, ORFs) of E. coli K12 strain MG1655 and spe-cific ORFs of S. dysenteriae A1 strain Sd51197. The CGH results indicated the genomes of the serotypes contain 2654 conserved ORFs originating from E. coli. However, 219 intrinsic genes of E. coli including those prophage genes, molecular chaperones, synthesis of specific O antigen and so on were absent. Moreover, some specific genes such as type II secretion system associ-ated components, iron transport related genes and some others as well were acquired through horizontal transfer. According to phylogenic trees based on genetic composition, it was demon-strated that A1, A2, A8, A10 were distinct from the other S. dysenteriae serotypes. Our results in this report may provide new insights into the physiological process, pathogenicity and evolution of S. dysenteriae.
基金supported by the National Natural Science Foundation of China(Grant No.11374336)
文摘We report on the preparation and superconductivity of metastable γ-Ga islands on Si(111) substrate. The Ga grows in a typical Volmer-Weber mode at a low temperature of 110 K, resulting in formation of Ga nanoislands at various sizes with the identical γ-phase. In-situ low temperature scanning tunneling spectra reveal quantized electronic states in ultrathin Ga islands. It is found that both the lateral size and thickness of the Ga islands strongly suppress the superconductivity. Due to substantial surface energy contribution, the transition temperature Tc scales inversely with the island thickness and the minimum thickness for the occurrence of superconductivity is calculated to be two monolayers.
文摘Comparative Genomic Hybridization (CGH) microarray analysis was used tocompare the genomic compositions of all eighteen Shigella boydii serotype representative strains.The results indicated the genomic ''backbone'' of this subgroup contained 2552 ORFs homologous tononpatho-genic E. coli K12. Compared with the genome of K12199 ORFs were found to be absent in allS. boydii serotype representatives, including mainly outer membrane protein genes and O-antigenbiosynthesis genes. Yet the specific ORFs of S. boydii subgroup contained basically bacteriophagegenes and the function unknown (FUN) genes. Some iron metabolism, transport and type Ⅱ secretionsystem related genes were found in most representative strains. According to the CGH phylogeneticanalysis, the eighteen S. boydii serotype representatives were divided into four groups, in whichserotype C13 strain was remarkably distinguished from the other serotype strains. This groupingresult corresponded to the distribution of some metabolism related genes. Furthermore, the analysisof genome backbone genes, specific genes, and the phylogenetic trees allowed us to discover theevolution laws of S. boydii and to find out important clues to pathogenesis research, vaccinationand the therapeutic medicine development.
基金Supported by the National High Technology Research and Development Program of China (Grant No. 2006AA020504)
文摘Trichophyton rubrum (T.rubrum) is one of the most common human fungal pathogens that cause chronic infections of the skin and nails. To identify antifungal responsive genes, cDNA microarray analysis was performed for T. rubrum to reveal global transcriptional profiles of drug-specific responses to 5-Flucytosine (5-FC). cDNA microarray was constructed from the T. rubrum expressed sequence tag (ESTs) database, the minimum inhibitory concentration (MIC) of 5-FC was determined, and microarray hybridization and data analysis were applied. The expression pattern of 7 genes observed by microarray was confirmed by the quantitative real-time reverser transcription polymerase chain reaction (RT-PCR). Data analysis indicated that a total of 474 genes were found differentially expressed, 196 showed an increase in expression and 278 showed a decrease in expression. Marked down-regulation of genes involved in nucleotide metabolism (such as CDC21), transcription (such as E2F1), and RNA processing (such as SGN1, RIM4 and NOP1) was observed. Other genes involved in signal transduction, chaperones, inorganic ion transport, secondary metabolite biosynthesis, amino acid transport, lipid transport and potential drug resistance mechanism were also affected by 5-FC. Quantitative real-time RT-PCR of the selected genes confirmed the reliability of the microarray results. This is the first analysis of transcriptional profiles in response to 5-FC for T. rubrum. The findings may be valuable for the identification of genes involved in mechanisms of action and mechanisms of antifungal drug resistance of 5-FC.
