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Category: Bacterial Pathogenesis
The Impact of Horizontal Genetic Exchange on Bacterial Population Structure: Insights from the Genera Neisseria and Campylobacter, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555817114/9781555819354_Chap03-1.gif /docserver/preview/fulltext/10.1128/9781555817114/9781555819354_Chap03-2.gifAbstract:
The concept of clone is fundamental to the study of prokaryotic evolution and is the essential starting point for any discussion on horizontal genetic exchange. Neisseria and Campylobacter share the property of being accidental pathogens—in that they cause human disease as a consequence of dysfunctional or accidental associations with humans—but the disease syndromes that they cause are very different. Neisseria and Campylobacter populations are, however, similarly structured, both exhibiting extensive evidence of frequent horizontal genetic exchange. In the case of Neisseria, the phenotype of interest is the proclivity of certain genotypes to cause invasive disease, which is apparently paradoxical in organisms that have evolved to colonize humans asymptomatically. In the case of Campylobacter, the question relates to the genetic bases of the association of particular genotypes with different animal species. This chapter talks about the impact that studies of the population biology of these genera have had on our understanding of the bacterial species concept. Horizontal genetic exchange has recently become central to discussion of bacterial species and speciation, although there remains much argument concerning the nature of bacterial species and the means whereby they arise and are maintained. In many species, including N. meningitidis and C. coli, bacterial populations show structuring, with evidence for some clonal signal notwithstanding high rates of recombination. Multilocus sequence typing (MLST) studies have substantially advanced our understanding of the population biology and evolution of many pathogenic bacteria and an increasing number of bacteria that are not pathogens of humans.
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