MOLECULAR EVOLUTION OF COLICIN PLASMIDS IN BACTERIA

细菌中抗生素耐药编码质粒的研究已取得进展 认为染色体外分子提供了一种快速 细菌间遗传信息的进化和频繁转移 血统。然而，人们对人口动态和 大多数自然产生的质粒的进化。它们是否代表一种 细菌基因组的延伸，作为运输载体 细菌基因，或者它们是具有生物完整性的寄生虫 与它们的宿主不同，从而构成不同的物种？ 在这项建议中，使用大肠杆菌的粘连素质粒作为 研究影响人口动态的力量的模型 和质粒的分子进化，并因此将“质粒称为 物种“的概念。限制图谱和DNA的结合 测序将被用来评估分子的水平和模式 一个具有代表性的粘菌素质粒样品的多态性及其意义 粘菌素基因。这些数据将提供关于……稳定性的信息 质粒谱系、水平转移的程度。 并确定了其进化的速率和模式。 基因。关于染色体基因的类似数据的可用性 这里使用的相同的大肠杆菌集合允许比较 并确定了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.