کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2823552 1161393 2008 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Rate heterogeneity in the evolution of Helicobacter pylori and the behavior of homoplastic sites
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم کشاورزی و بیولوژیک بوم شناسی، تکامل، رفتار و سامانه شناسی
پیش نمایش صفحه اول مقاله
Rate heterogeneity in the evolution of Helicobacter pylori and the behavior of homoplastic sites
چکیده انگلیسی

Helicobacter pylori are bacteria with substantial inter-strain variability and phylogenetic reconstructions of sequence data from the organism have common homoplastic sites. Although frequent recombination events have been proposed to contribute to the variation, the effects of nucleotide substitution rate heterogeneities on the reconstruction of H. pylori genealogies have not been studied. We analyzed the substitution pattern of a housekeeping gene, a homologue of the ribonuclease reductase gene (rnr), to characterize rate heterogeneities between 11 H. pylori isolates. Evidence of limited recombination was demonstrated by the Sawyer's runs test, but the homoplasy test and site-by-site compatibility tests indicated frequent recombination events. Within the 1935 nucleotide gene, 292 sites were polymorphic with an average pair-wise difference of 5.01%. Xia's distances for amino acids at non-synonymous codon substitution sites were smaller at homoplastic sites than at sites that were not homoplastic. Transitions were significantly more common among homoplastic than among non-homoplastic nucleotide substitutions. Simulations of evolution with or without recombination indicated the transition/transversion ratio is expected to be higher in homoplastic sites with no recombination. Despite evidence of recombination, analyses of the rnr genealogy does not show a random tree but rather base substitution behaviors characteristic of both recombination and substitution saturation at some sites. Analyses of sequences in the H. pylori multilocus sequence-typing database provided similar evidence for substitution saturation in multiple housekeeping genes.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Infection, Genetics and Evolution - Volume 8, Issue 5, September 2008, Pages 593–602
نویسندگان
, , ,