Specialized Genetic Recombination Systems in Bacteria: Their Involvement in Gene Expression and Evolution

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摘要：

A variety of phenomenal DNA units, aided by specialized recombination processes, are responsible for a major proportion of the "spontaneous" chromosomal alterations observed in bacteria. These structurally and genetically distinct DNA segments (i.e., bacterial viruses, insertion sequence elements, and transposons) can be inserted within many chromosomal loci. In addition to causing insertion mutations and encoding new genetic potential, these discrete units act as supernumerary genetic regulatory switches capable of enhancing or eliminating the expression of nearby genes. Furthermore, recombination promoted by these DNA elements can result in various chromosomal rearrangements affecting large or small chromosomal DNA regions and involving the joining of unrelated DNA regions that lack apparent nucleotide sequence homology. Though this review is aimed at describing the intensive study of recombination mediated by viruses and transposable elements in bacteria, there is considerable evidence to suggest that transposable elements are also significantly involved in genetic reorganization and regulation in higher organisms (McClintock 1957; Bukhari et al. 1977; Kleckner 1977; Starlinger 1977; See Sect. F).

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关键词：

BACTERIA GENETICS INTERACTIONS DEOXYRIBONUCLEIC ACIDS CHROMOSOMES HYBRID SYSTEMS MOLECULAR BIOLOGY GENES RECOMBINATION REACTIONS SELECTION