Induced cellular resistance to ultraviolet light in Saccharomyces cerevisiae is not accompanied by increased repair of plasmid DNA.

Many reports show that resistance of Saccharomyces cerevisiae to a large UV dose can be enhanced by pre-induction with a smaller one given some hours before. This work tests if such increased cell survival is associated with increased DNA repair on UV damaged plasmid transformed into yeast. There was no change in transformation efficiency of UV-damaged plasmid DNA under conditions where RAD cell survival increased 5-fold, and where rad1-1 and rad6-1 survival increased 2-fold. It is concluded that DNA repair activity involving the RAD6 and RAD3 pathways is either not inducible or is unable to work on plasmid DNA. It is suggested that the enhancement of cellular survival detected may be based on changes in cell-cycle behaviour which permit cells generally proficient in repair a greater chance to recover.