UV-induction of thymine-containing dimers in Saccharomyces cerevisiae.

In haploid and diploid S. cerevisiae the dimer yield ratio TT/CT is found to be 1.2/1 and 1.3/1, resp., at the UV (254 nm) unit dose 1 erg/mm2, the share of TT and CT in a UV (254 nm) lethal hit being 0.7 TT and 0.6 CT. A general formulation of the UV lethal hit is given and discussed. The TT+CT yields obtained for S. cerevisiae are compared to those reported for other organisms. It is found that there obviously exists a directly proportional linear correlation between genome size and TT+CT yield for the UV dose range well below the stationary levels of the TT and CT formation kinetics.