Total RNA from wild-type W303 or BY4741 cells grown to early exponential phase (OD 600 = 0.25) in YPD media and treated with chemical compounds for 200 min was separated on 1.2% denaturing agarose/formaldehyde gels and analysed by northern hybridization using a probe complementary to the 5 0 -end of mature 25S rRNA (starting at position +40). This RNA species was chosen in the first place, since effects on 28S rRNA have been observed in apoptotic mammalian cells (8, 38, 39) . On treatment with two oxidants, H 2 O 2 and menadione, extensive decay of the mature 25S and accumulation of specific degradation products was observed, whereas little or no degradation occurred for other chemicals tested ( Figure 1A , data shown only for W303 strain and treatment with H 2 O 2 , menadione, CHP and t-BHP). This indicates that RNA cleavage accompanies some oxidative stress pathways, as it is known that different oxidants elicit specific cellular responses that, though partly overlapping, induce different groups of genes and require individual sets of specialized defence functions to maintain resistance (1, 2, 24) .