Abstract:
Superoxide dismutases (SOD) serve as an important antioxidant defense mechanism in aerobic organisms,
and deletion of these genes shortens the replicative life span in the budding yeast Saccharomyces
cerevisiae. Even though involvement of superoxide dismutase enzymes in ROS scavenging and the aging
process has been studied extensively in different organisms, analyses of DNA damages has not been performed
for replicatively old superoxide dismutase deficient cells. In this study, we investigated the roles
of SOD1, SOD2 and CCS1 genes in preserving genomic integrity in replicatively old yeast cells using the
single cell comet assay. We observed that extend of DNA damage was not significantly different among
the young cells of wild type, sod1D and sod2D strains. However, ccs1D mutants showed a 60% higher
amount of DNA damage in the young stage compared to that of the wild type cells. The aging process
increased the DNA damage rates 3-fold in the wild type and more than 5-fold in sod1D, sod2D, and ccs1D
mutant cells. Furthermore, ROS levels of these strains showed a similar pattern to their DNA damage contents.
Thus, our results confirm that cells accumulate DNA damages during the aging process and reveal
that superoxide dismutase enzymes play a substantial role in preserving the genomic integrity in this
process.
