MOLECULAR EVOLUTION OF COLICIN PLASMIDS IN BACTERIA

对细菌中抗生素耐药性编码质粒的研究导致了 认为染色体外的元素提供了一种快速的方法， 细菌之间的进化和遗传信息的频繁转移 血统 然而，人们对种群动态知之甚少， 大多数自然发生的质粒的进化。 他们是否代表一个 细菌基因组的延伸，作为运输工具， 细菌的基因，或者它们是具有生物完整性的寄生虫， 与其宿主不同，从而构成不同的物种？ 在该建议中，大肠杆菌的大肠杆菌素质粒被用作 研究影响种群动态的力量的模型 和质粒的分子进化，从而解决“质粒作为 物种”概念。 限制性酶切图谱和DNA 测序将用于评估分子水平和模式， 大肠杆菌素质粒的代表性样品的多态性及其 colicin基因。 这些数据将提供有关稳定性的信息， 质粒谱系、质粒在E. 大肠杆菌和质粒的进化速率和模式确定 基因. 来自染色体基因的类似数据的可用性 相同的E.这里使用的大肠杆菌可以比较 染色体和质粒之间的进化模式 基因.

Research on antibiotic resistance encoding plasmids in bacteria has led to the view that extrachromosomal elements provide a means for rapid evolution and frequent transfer of genetic information between bacterial lineages. However, little is known about the population dynamics and evolution of most naturally occurring plasmids. Do they represent an extension of the bacterial genome, serving as transport vehicles for bacterial genes, or are they parasites with a biological integrity distinct from that of their hosts, and thus constitute separate species? In this proposal colicin plasmids of Escherichia coli are employed as a model to investigate the forces that influence the population dynamics and molecular evolution of plasmids and thus address the "plasmids as species" concept. A combination of restriction mapping and DNA sequencing will be used to assess the levels and patterns of molecular polymorphism for a representative sample of colicin plasmids and their colicin genes. These data will provide information on the stability of plasmid lineages, the extent of horizontal transfer of plasmids in E. coli and the rates and patterns of evolution for plasmid determined genes. The availability of similar data for chromosomal genes from the same collections of E. coli employed here allow a comparison of rates and patterns of evolution between chromosomal and plasmid determined genes.