CHANGES IN THE EXPRESSION OF SOLUBLE-PROTEINS EXTRACTED FROM THE SYMBIOTIC ANEMONE ANEMONIA-VIRIDIS ACCOMPANY BLEACHING INDUCED BY HYPERTHERMIA AND METAL STRESSORS

1. The phenomenon of bleaching is associated with the loss of endosymbiotic zooxanthellae (and/or their pigments) from within the endoderm of many colonial and solitary coelenterates. 2. To understand this phenomenon at the molecular level, A. viridis maintained at 15-degrees-C or acclimated to and maintained at 20-degrees-C were subjected to heat-shock and exposure to heavy metal ions. 3. Following heat-shock at 28 or 32-degrees-C, the numbers and mitotic index of released algae rose significantly compared with controls. 4. Concomitant with these changes were the gradual appearance of proteins at 39 and 69 kDa, and the significant enhancement of proteins at 30, 31 and 35 kDa in animals originally maintained at 15-degrees-C. Most of these stress proteins were already expressed in anemones acclimated at 20-degrees-C and were not enhanced in these animals when heat-shocked to 28-degrees-C. 5. Unlike other treatments, acclimated animals did not show continued increasing release of zooxanthellae 1-4 h after heat-shock suggesting that the steady-state presence of stress proteins were predictive of an acclimated state. Identical proteins were strongly expressed in animals exposed to copper ions.