Specialized Genetic Recombination Systems in Bacteria: Their Involvement in Gene Expression and Evolution,
Abstract
Intermolecular exchange of a DNA segment, that is, genetic exchange or crossing over between homologous parental chromosomes resulting in the formation of a hybrid molecule, has long been recognized. This marvelous process is important in providing the breadth of phenotypic diversity seen within a single plant or animal species. Classical genetics and recent studies in molecular genetics have revealed a variety of genetic exchange systems in bacteria. These recombination systems can be divided into two broad categories: (a) generalized, and (b) specialized. In short, general recombination systems mediate genetic interchange at random points between largely homologous deoxyribonucleotide segments, whereas specialized recombination processes act in the absence of general recombination or apparent sequence homology between the interacting DNA regions. Specialized recombination systems are responsible for promoting the integration, deletion, transposition, or inversion of discrete DNA segments and can also influence the expression of nearby genes. Bacterial evolution was thought until recently to occur by a slow process involving small chromosomal alterations (i.e., mutations), environmental selection for the desirable mutations, and the accumulation of beneficial mutations through intercellular genetic exchange and generalized recombination. Mutational events which involve the addition, deletion, or substitution of only one or a few nucleotides can be called micro-evolutionary. Since the 1960's, however, a catalog of macro-evolutionary events has been amassed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1980
- Accession Number
- ADA094873
Entities
People
- D. J. Kopecko
Organizations
- Walter Reed Army Institute of Research