The nature of mutation in microorganisms has been debated for a long time. Two theories have been at odds: random spontaneous mutagenesis vs. adaptive mutagenesis. “random mutagenesis” means that mutations occur in proliferating cells before they encountered the selective agent. “adaptive mutagenesis” means that advantageous mutations form in the environment where they have been selected, in non-replicating or poorly replicating cells even though other, non-selected, mutations occur at the same time. In the last 20 years it has been definitely shown that random as well as adaptive mutagenesis occur in bacteria and yeast. microorganisms in nature do not divide or divide poorly because of adverse environmental conditions; therefore adaptive mutations could provide cells with a selective advantage and allow evolution of populations. Here we will focus on some fundamental aspects of adaptive mutagenesis in the yeast Saccharomyces cerevisiae. We begin with a historical overview on the nature of mutation. We then focus on experimental systems aimed at proving or disproving adaptive mutagenesis. We have briefly summarized the results obtained in this field, with particular attention to genetic and molecular mechanisms.
Adaptive mutagenesis in the yeast Saccharomyces cerevisiae
ACHILLI, Alessandro
2006
Abstract
The nature of mutation in microorganisms has been debated for a long time. Two theories have been at odds: random spontaneous mutagenesis vs. adaptive mutagenesis. “random mutagenesis” means that mutations occur in proliferating cells before they encountered the selective agent. “adaptive mutagenesis” means that advantageous mutations form in the environment where they have been selected, in non-replicating or poorly replicating cells even though other, non-selected, mutations occur at the same time. In the last 20 years it has been definitely shown that random as well as adaptive mutagenesis occur in bacteria and yeast. microorganisms in nature do not divide or divide poorly because of adverse environmental conditions; therefore adaptive mutations could provide cells with a selective advantage and allow evolution of populations. Here we will focus on some fundamental aspects of adaptive mutagenesis in the yeast Saccharomyces cerevisiae. We begin with a historical overview on the nature of mutation. We then focus on experimental systems aimed at proving or disproving adaptive mutagenesis. We have briefly summarized the results obtained in this field, with particular attention to genetic and molecular mechanisms.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
