(e) Quantification (FACS analysis) of phosphatidylserine externalization and loss of membrane integrity using annexin V/PI co-staining (at day 5) and of DNA fragmentation using TUNEL staining (at day 3) of chronologically ageing wild-type (WT) and Δspe1 cells with or without supplementation of 0.1 mM spermidine as indicated. Data represent means ± s.e.m. (n = 3; *P 0.001). 