HEAVY-ION-INDUCED DNA DOUBLE-STRAND BREAKS WITH YEAST AS A MODEL SYSTEM

Cells of diploid yeast, Saccharomyces cerevisiae, were exposed to a va riety of energetic heavy ions (provided by the UNILAC facility at the Gesellschaft fur Schwerionenforschung, GSI), Am-241 alpha-particles an d 80-keV x-rays after which they were assessed for DNA double-strand b reaks (DSB) using either the neutral sedimentation or the pulsed-field gel electrophoresis (PFGE) technique. Both yielded comparable results . The DSB production cross-sections are compared with inactivation stu dies performed for the same cells under identical conditions. The meas urements show that with lighter ions DSB induction cross-sections incr ease with linear energy transfer (LET), but the situation is less clea r with the heavier ions. A close parallelism was found between DSB ind uction and cell inactivation in these yeast cells.