The oxidants utilized, except for H 2 O 2 , had not been tested for apoptotic effects in yeast. One of the most recognized apoptotic markers is fragmentation of chromosomal DNA. Internucleosomal DNA laddering, typical for mammalian apoptosis, has not been detected during PCD in yeast; nevertheless, a higher order chromatin fragmentation to segments of several hundred kilobases also occurs in yeast (30, 40) . This DNA breakdown can be monitored either by the terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) assay or by using PFGE of genomic DNA. The latter approach was applied to verify which oxidative agents lead to apoptotic phenotypes. Chromosomal DNA from cells treated with H 2 O 2 (1 mM), menadione (0.5 mM), CHP (0.2 mM), paraquat (5 mM), diamid (2 mM) and t-BHP (1 mM) for 200 min was analysed using PFGE ( Figure 1D ). Clear DNA degradation was observed only for cells exposed to H 2 O 2 and menadione, other treatments did not result in a visible apoptotic fragmentation. This is in a striking agreement with rRNA degradation that occurred only in H 2 O 2 -and menadione-treated cells. This strongly indicates that rRNA decay phenotype can be related to apoptosis.