Chapter 12 : Stationary-Phase-Induced Mutagenesis: Is Directed Mutagenesis Alive and Well within Neo-Darwinian Theory?

Abstract:

This chapter attempts to raise questions about mutagenesis and how these processes enhance evolution. The focus of the chapter is on the controversial process that has been termed "adaptive" mutagenesis. Although the work described in the chapter concentrates on prokaryotic model systems, it is clear that all organisms under stress appear to have genetic mechanisms that permit increase in allelic diversity. The chapter adds to the renewed interest in directed mutagenesis, retromutagenesis, transpositional mutagenesis, stationary-phase-induced mutagenesis, and the influences that these processes have had on the evolution of species. In 1988, an article by John Cairns and his collaborators forced a rethinking about how spontaneous mutants might arise, and challenged the very tenets of neo-Darwinian theory. It explores some of the possibilities that might exist for departures from the classic mode of thinking associated with the generation of mutations. Adaptive or stationary-phase-induced mutagenesis may be under genetic control and part of eubacterial development. Mismatch repair (MMR) was first suggested to be involved in "adaptive" or stationary-phase-induced mutagenesis in the study of the lac system in E. coli. There is an ancient superfamily of DNA polymerases that are error prone (they make mistakes during the replication process). These polymerases must play an important role in the survival of species otherwise they would not have been conserved during the evolutionary process. The phenomenon called adaptive or stationary-phase-induced mutagenesis presents a model for investigating the mechanisms associated with the evolutionary process.