Fig 5. Occurrence of bleaching under heat and light stress despite inhibition of caspases (and hence presumably of apoptosis).

(A,B) Four independent experiments were like those of Fig 2C and 2D except that some tubs were treated with the caspase inhibitor Ac-DEVD-CHO at 2 μM (added from a stock solution in DMSO) or with the same concentration of DMSO alone (see Materials and Methods). Experiment 4 was of only short duration and was intended only to provide additional evidence of the effectiveness of the caspase inhibitor during the time when caspase activities would otherwise be elevated; no algal counts were performed. (A) Caspase activities. As in Figs 2–4, the section labeled "Ctrl" shows measurements on anemones that were held under control conditions (27°C, no additives) for the full 12 (Experiments 1 and 3) or 4 (Experiment 2) days of the experiments. (B) Numbers of algae per unit protein. In each panel, horizontal lines indicate the mean values for all animals at that time-point. In B, the results of grouped ANOVA and unpaired t tests are indicated as in Fig 2. (C,D) In a single experiment, anemones under otherwise standard culture conditions (27°C, 25 μmol photons m^-2 s^-1) were treated with Ac-DEVD-CHO (2 μM final concentration) and monitored for caspase activities (C) and numbers of remaining algae (D).