tailieunhanh - Báo cáo y học: "Structure and dynamics of the pan-genome of Streptococcus pneumoniae and closely related species"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: Structure and dynamics of the pan-genome of Streptococcus pneumoniae and closely related species. | Donati et al. Genome Biology 2010 11 R107 http 2010 11 10 R107 Genome Biology RESEARCH Open Access Structure and dynamics of the pan-genome of Streptococcus pneumoniae and closely related species idic i rhe IO of i 1i l I I I i co I lillcr2 Tdttdlin3 Ạ Ì I I77Í1 I r re ll i- t Cr4 lol Aioe iii ir ili3 Claudio Donati IN Luisa Hillel Herve letlelill Alessandro IViuzzi Nicholas J Croucher jciliue V Angiuoli Marco Oggioni5 Julie C Dunning Holopp3 Fen Z Hu2 David R Riley3 Anlonello Covacci1 Tim J Mitchell6 Stephen D Bentley4 Morgens Kilian7 Garth D Ehrlich2 Rino Rappuoli1 E Richard Moxon8 Vega Masignani1 Abstract Background Streptococcus pneumoniae is one of the most important causes of microbial diseases in humans. The genomes of 44 diverse strains of S. pneumoniae were analyzed and compared with strains of non-pathogenic streptococci of the Mitis group. Results Despite evidence of extensive recombination the S. pneumoniae phylogenetic tree revealed six major lineages. With the exception of serotype 1 the tree correlated poorly with capsular serotype geographical site of isolation and disease outcome. The distribution of dispensable genes - genes present in more than one strain but not in all strains - was consistent with phylogeny although horizontal gene transfer events attenuated this correlation in the case of ancient lineages. Homologous recombination involving short stretches of DNA was the dominant evolutionary process of the core genome of S. pneumoniae. Genetic exchange occurred both within and across the borders of the species and S. mitis was the main reservoir of genetic diversity of S. pneumoniae. The pan-genome size of S. pneumoniae increased logarithmically with the number of strains and linearly with the number of polymorphic sites of the sampled genomes suggesting that acquired genes accumulate proportionately to the age of clones. Most genes associated with pathogenicity were shared by all S. pneumoniae strains but were .