Project description:Investigation of whole genome gene expression to identify overlooked sRNAs and sORFs. Background The completion of numerous genome sequences has introduced an era of whole-genome study. However, many real genes, including small RNAs (sRNAs) and small ORFs (sORFs), are missed in genome annotation. In order to improve genome annotation, we sought to identify novel sRNAs and sORFs in Shigella, the principal etiologic agents of bacillary dysentery or shigellosis. Results Firstly, we identified 64 sRNAs in Shigella which is experimentally validated in other bacteria based on sequence conservation. Secondly, among possible approaches to search for sRNAs, we employed computer-based and tiling array based methods, followed by RT-PCR and northern blots. This allowed us to identify 12 sRNAs in Shigella flexneri strain 301. We also find 29 candidate sORFs. Conclusions This investigation provides an updated and comprehensive annotation of the Shigella genome, increases the expected numbers of sORFs and sRNAs with the corresponding impact on future functional genomics and proteomics studies. Our method can be used for the large scale reannotation of sRNAs and sORFs in any microbe whose genome sequence is available.
Project description:Investigation of whole genome gene expression to identify overlooked sRNAs and sORFs. Background The completion of numerous genome sequences has introduced an era of whole-genome study. However, many real genes, including small RNAs (sRNAs) and small ORFs (sORFs), are missed in genome annotation. In order to improve genome annotation, we sought to identify novel sRNAs and sORFs in Shigella, the principal etiologic agents of bacillary dysentery or shigellosis. Results Firstly, we identified 64 sRNAs in Shigella which is experimentally validated in other bacteria based on sequence conservation. Secondly, among possible approaches to search for sRNAs, we employed computer-based and tiling array based methods, followed by RT-PCR and northern blots. This allowed us to identify 12 sRNAs in Shigella flexneri strain 301. We also find 29 candidate sORFs. Conclusions This investigation provides an updated and comprehensive annotation of the Shigella genome, increases the expected numbers of sORFs and sRNAs with the corresponding impact on future functional genomics and proteomics studies. Our method can be used for the large scale reannotation of sRNAs and sORFs in any microbe whose genome sequence is available. Study using total RNA recovered from five conditions.
Project description:Background Compelling evidence indicates that Shigella species, the etiologic agents of bacillary dysentery, as well as enteroinvasive Escherichia coli, are derived from multiple origins of Escherichia coli and form a single pathovar. To further understand the genome diversity and virulence evolution of Shigella, comparative genomic hybridization microarray analysis was employed to compare the gene content of E. coli K-12 with those of 43 Shigella strains from all serotypes. Results For the 43 strains subjected to CGH microarray analyses, the common backbone of the Shigella genome was estimated to contain more than 1,900 open reading frames, with a mean number of 729 undetectable ORFs. The mosaic distribution of absent regions indicated that insertions and/or deletions have led to the highly diversified genomes of pathogenic strains. Conclusion These results support the hypothesis that by gain and loss of functions, Shigella species became successful human pathogens through convergent evolution from diverse genomic backgrounds. Moreover, we also found many specific differences between different lineages, providing a window into understanding bacterial speciation and taxonomic relationships. Keywords: comparative genomic hybridization
Project description:to analyse the transcriptomic response of human intestinal tissue engrafted in SCID mice to Shigella infection Keywords: infection, Shigella, gene expression, intestinal cell
Project description:The Shigella bacterium is one of the most significant causes of waterborne and foodborne bacterial dysentery. A lytic bacteriophage infecting Shigella flexneri was isolated from wastewater in Japan. We report here the complete genome sequence of this bacteriophage, revealing that it belongs to the Myoviridae family and possesses linear genomic DNA.