Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Critical Care giúp cho các bạn có thêm kiến thức về ngành y học đề tài:Reduced selection leads to accelerated gene loss in Shigella. | Open Access Research Reduced selection leads to accelerated gene loss in Shigella Ruth Hershberg Hua Tang and Dmitri A Petrov Addresses Department of Biological Sciences Stanford University Serra Mall Stanford CA 94305 USA. Department of Genetics Stanford University Serra Mall Stanford CA 94305 USA. Correspondence Ruth Hershberg. Email ruthersh@ Published 8 August 2007 Genome Biology 2007 8 RI64 doi gb-2007-8-8-rl 64 The electronic version of this article is the complete one and can be found online at http content 8 8 R164 Received 1 June 2007 Revised 22 July 2007 Accepted 8 August 2007 2007 Hershberg et al. licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License http licenses by which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Abstract Background Obligate pathogenic bacteria lose more genes relative to facultative pathogens which in turn lose more genes than free-living bacteria. It was suggested that the increased gene loss in obligate pathogens may be due to a reduction in the effectiveness of purifying selection. Less attention has been given to the causes of increased gene loss in facultative pathogens. Results We examined in detail the rate of gene loss in two groups of facultative pathogenic bacteria pathogenic Escherichia colt and Shigella. We show that Shigella strains are losing genes at an accelerated rate relative to pathogenic E. coli. We demonstrate that a genome-wide reduction in the effectiveness of selection contributes to the observed increase in the rate of gene loss in Shigella. Conclusion When compared with their closely related pathogenic E. coli relatives the more niche-limited Shigella strains appear to be losing genes at a significantly accelerated rate. A genomewide reduction in the effectiveness of purifying selection plays a role .
