Duplication processes in Saccharomyces cerevisiae haploid strains.

Duplication is thought to be one of the main processes providing a substrate on which the effects of evolution are visible. The mechanisms underlying this chromosomal rearrangement were investigated here in the yeast Saccharomyces cerevisiae. Spontaneous revertants containing a duplication event were selected and analyzed. In addition to the single gene duplication described in a previous study, we demonstrated here that direct tandem duplicated regions ranging from 5 to 90 kb in size can also occur spontaneously. To further investigate the mechanisms in the duplication events, we examined whether homologous recombination contributes to these processes. The results obtained show that the mechanisms involved in segmental duplication are RAD52-independent, contrary to those involved in single gene duplication. Moreover, this study shows that the duplication of a given gene can occur in S.cerevisiae haploid strains via at least two ways: single gene or segmental duplication.