Genetic transformation as a tool in the studies of DNA replication and recombination
Abstract
Mechanism of chromosome replication by the use of transformation and genetic recombination are reviewed in Bacillus subtilis. The order of gene replication can be determined by marker frequency analysis during exponential growth when the cells are asynchronous. Alternatively, in synchronized cells density transfer combined with transformation reveals the order of replication of markers. The frequency of the replicated genes is influenced also by their position relative to the origin of replication when the nutritional environment varies. A position effect may be shown by the sequential appearance of certain metabolic functions as a consequence of gene order on the chromosome. The origin and terminus of replication are membrane bound as seen by radioactive labeling and marker frequency. The membrane-DNA complex can be isolated and used for the study of the basic mechanics of replication. In vitro studies are feasible to compare initiation, elongation, repair and localization data with those obtained in in vivo systems. In vitro analysis of recombination seems desirable but remains unsuccessful. An understanding of the basic biology of these functions promises important practical applications.